Perplexed

[SKYGZR]

It can't be this complicated. As mentioned before, the machine was running just fine till the no spark issue. Ran fine after that, even for awhile after filling the tank. It's gotta be something simple. I'm leaning towards sliding back the tank and checking underneath. Double checking the HES Connector, and the Coil connections for security and proper fitment. Changing the fuel filter also, even though it appeared to have a good strong stream when cycling the key/fuel pump on/off. Will even double check the HES install to rule out any problems there.

[Stan Walker]

**Yes the Oil temp sensor wire (the one behind the Oil Level Window) is connected***

 

I do believe that the sensor by the Oil Level Window is the Oil Pressure Sensor. The Oil Temperature sensor is on the top RH side near where the oil line exits to the oil cooler.

 

Stan

[Joe Frickin' Friday]

This is an oilhead we're talking about, right?

 

Have you tried reading the fault codes from the Motronic?

 

Click Here, and go to page 71 to see how to read any fault codes that may have been stored.

 

Note that you will get fault codes 1122 and 1123 (indicating no HES signal) unless you actually start the engine.

[Unhofliche_Gesundheit]

[John844]

Where are you located? There might be someone on the board willing to swing by and help lend their expertise.

 

PS, not volunteering my expertise, as this seems out of my league

[Richard_D]

When the problem is solved , I think you should give a prize to the person with the right diagnosis. Make it interesting !

[kiwiaudio]

I'm with a few guys that have already said this - bad in the box HES. Wherever you got it, give them your story, and ask to try a replacement.

 

Unless - whatever made you think the HES was bad in the first place, is still causing a problem ! Hmmmmmm !

[ElevenFifty]

I have been following this (though not THAT closely so apply the proverbial grain of salt) ... and the only constant seems to be temperature ... bike goes so far and then craps out ... sits awhile and runs ... craps out again.

 

Intermittent fault, temperature related = electronic component.

 

Primary suspects: HES - and ???? (more experienced voices needed here but I'd suspect inputs to the Motronic, e.g. O2 sensor)

[Mike T]

I was betting on water in the gas as the culprit. The next time t bike does not want to start try the following:

 

-Make sure you have spark at the plugs. Remove a plug and ground it while the starter is cranking and check for spark from the plug using something insulated to hold the plug.

 

-If spark is present I would pull one fuel injector and hold it in a glass jar. While cranking the engine make sure you have a nice mist spray vs squirting gas. Do for both sides. This will ensure you do not have a clogged injector. You can also re-check the glass jar for any signs of water or contamination.

 

-Hook up a fuel pressure gauge using a 'T' fitting on the fuel line coming from your fuel filter to the intake fuel line on your fuel pressure tubing. If you can start the bike, tape the pressure gauge to the tank and ride with it hooked up to see if the pressure stays steady around 3 bars when the bike starts running rough. It's possible that you have a fuel pump starting to crap out. If the bike craps out and the pressure remains stead we can eliminate fuel issues as a candidate.

 

-Also as mentioned before, when you slide the tank back to check your HES connector also check the oil temp sensor connector which (as Stan said) is located on the top right side of your engine and is a different sensor from the oil pressure sensor located on the left side of your engine.

 

[Joe Frickin' Friday]

This is an oilhead we're talking about, right?

 

Have you tried reading the fault codes from the Motronic?

 

Click Here, and go to page 71 to see how to read any fault codes that may have been stored.

 

Note that you will get fault codes 1122 and 1123 (indicating no HES signal) unless you actually start the engine.

 

[T__]

SKYGZR, we haven’t heard from you in a couple of days .. (you get a handle on it yet?)

 

If not maybe you can get a direction from this-- what does the tachometer act like when you get it sort of running? If it is erratic or acting strange then suspect the new HES or it’s related wiring..

How about the RID oil temp gauge? If that temp is not matching what you think the engine temperature should be then suspect the oil temp sensor,, sensor connection,, or related wiring/connecter..

 

If those are rock steady & acting normal then look at the other sensors or back to the fuel system..

 

 

Twisty

 

[SKYGZR]

SKYGZR, we haven’t heard from you in a couple of days .. (you get a handle on it yet?)

 

**I haven't had the time to begin to tear into it. I'm planning on this weekend.**

 

If not maybe you can get a direction from this-- what does the tachometer act like when you get it sort of running?

 

**Acts normal. Nothing erratic, not jumping around, or giving false readings. When it does idle, the tach reports as expected**

 

If it is erratic or acting strange then suspect the new HES or it’s related wiring..

How about the RID oil temp gauge? If that temp is not matching what you think the engine temperature should be then suspect the oil temp sensor,, sensor connection,, or related wiring/connecter..

 

**RID seems to be functioning just fine. Clock is OK, Fuel bars showed up just fine after pouring in the 3 gallons of "fresh" petrol. Temperature bar(s) reported OK last time it ran fine (when I ran it "dry" and the headers started glowing Red)**

 

If those are rock steady & acting normal then look at the other sensors or back to the fuel system..

 

**First thing I plan to do is replace the fuel filter, try to start it. Then if it doesn't cooperate, pull the plugs to check them, pull back the tank and check under there, the coils/plug wires, etc.. Take off the belt cover and recheck the HES install. I'll Be Back***

 

 

Twisty

[StuGotz]

Mike T had some good stuff for ya to try..Did ya do it?

 

A ways back in the thread you mentioned idling for a time and your headers got RED hot. This would be normal if for an extended time, but would signify LEAN fuel condition if otherwise.

 

And you mentioned the "magic" 2 1/2 mile mark your bikes cuts out. I would venture a guess that you are exceeding fuel supply at this distance? Pump/filter would be suspect here.

 

You are probably tired of all this, but stay with it. Retrace all that you did before the problem developed. We have all overlooked something simple that sets us back.

 

Good luck,

 

MB>

[SKYGZR]

Mike T had some good stuff for ya to try..Did ya do it?

 

A ways back in the thread you mentioned idling for a time and your headers got RED hot. This would be normal if for an extended time, but would signify LEAN fuel condition if otherwise.

 

**Yes, this was when I was running the tank "dry" after siphoning out, and "fuel pumping" till "air" was spitting from the external fuel filter. After all that, the machine did start, and ran just fine..long enough to "glow" the headers. Ran just fine till it finally ran "dry". So this would be a normal condition.**

 

And you mentioned the "magic" 2 1/2 mile mark your bikes cuts out. I would venture a guess that you are exceeding fuel supply at this distance? Pump/filter would be suspect here.

 

**Just Today, replaced the fuel filter with a new unit, same problem**

 

You are probably tired of all this, but stay with it. Retrace all that you did before the problem developed. We have all overlooked something simple that sets us back.

 

** I am in the process of doing just that. So, this is what I have so far:

 

Replace/Install New Fuel Filter: Same Problem

Pull #5 fuse for a minute or so, and the CCR. Try to start/run with CCR removed, same problem. Reinstall, same problem.

Pull Plugs: Black, heavy smell of fuel. Indicates Way Rich mixture.

This is probably due to having it try to get it to run on the fast idle position.

Check coil Resistance: aprx temp 37^F Mains: 6.86 Secondary .7-.9

Check Plug Wire Resistance: Left: 5.98 Right: 6.43

All connections to the Coil were "tight" and correct.

Checked and verified that the TPS, ground on the left Throttle Body, HES plug in, HES Mounting plate (unit), Both Oil sensors are connected and secure.

 

When I did the Canesterectomy, I didn't plug the exposed end tube at the solinoid, and left the electrical connection connected. I have since done that, yet have tried to start it since. (Don't know if this would affect anything or not).

 

More to follow..I don't want to, but might have to remove the tank internals just to make sure something isn't F'd Up inside there.

 

Seems a bit weird that after siphoning, pumping, and running "dry", (and running fine at that last moment), that after pouring in a fresh fill of 3 gallons has caused this running issue.

 

So following that bit of "logic"..it would seem that since the tank was "about" empty after siphoning and pumping out what could be siphoned/pumped..the fuel level would have fallen below "normal" pick-up level of a "riding" machine scenario.

 

After dumping in 3 gal. of fuel, this would have raised the "empty" tank to above the pump, screen, float level assembly, and thusley may be presenting a reason to remove the assembly.

 

When I Re-located the filter to the outside of the tank, I used a similar length of copper tubing to replace the "gap" between hoses where the filter is normally inside the tank. I was meticulous in making sure all clamps and hoses were pristine, and secured.

(Even replaced the "screen" on the end of the fuel pump, since the "original" was split on both ends.)

 

So, since it ran "fine" with almost no fuel in the tank, then after about 3-gallons dumped in, and running like Sheit, ie; nine ruun, F'ckd, it might appear that flooding the tank with that much fuel, may have raised the level above the pick-up level of the pump, and there may be some kind of a connection/insuction problem within the internals.

 

Ran just fine with/when "out of"/almost no fuel, yet..when..

3 gallons added, will not run worth a shieit....something's funny going on here....

 

 

More to follow

 

All connections (external) to fuel tank are secure, not pinched, and not leaking. Throttle Body Vacuum tubes are plugged.

The pulley/alternator belt drive has yet to be removed, and the position of the trigger assembly has yet to be checked, yet since it ran fine while "running it dry", I doubt that there is any problem there.

 

 

 

 

MB>

[T__]

SKYGZR, I posted some of this earlier but it seems like parts of it still might apply..

 

 

Maybe next try disconnecting the 02 sensor just to eliminate a simple test like that.. I haven’t seen where you tried this yet.. Simple process & that can make it run very erratic or rich.. Can even effect you on a cold engine if the 02 signal stays within the range the Motronic is looking for just not a correct output.. Not very likely on cold engine but can happen.. (simple plug disconnect)

 

Maybe try pulling the fuel return hose where it connects to the tank hose then run an extension on that then into a glass bottle.. That will allow you to look at a few things.. First it will show you what (quality) of fuel you are seeing at the fuel injectors (will also show any water delivered) ,, next it will show you if you have enough fuel pump pressure/flow to even open the pressure regulator valve,, it will also show you how much fuel is flowing “to” the injectors.. – I guess if all OK here & no water shows up in the bottle after sitting you can pretty well pass the fuel system as not being the cause.. (This should pretty well clear your fuel system)..

You really should rig a fuel pressure gauge but the above will tell you quite a lot about your fuel system..

 

Maybe try new spark plugs (or known good used) just to eliminate that as any possible area of concern..

 

If still a problem then move on to testing the TPS output (both high & low output sides) & check the curb idle TPS voltage to be under .4volts.. Make sure the TPS supply voltage is around 5 volts +/- not much.. (The TPS voltage being out of spec will flat drive your engine runability crazy.. (Between the RPM input & the TPS input those are the main things that control the amount of fuel injected by the fueling computer)..

 

Pull the oil temp sensor & track that from freezer cold to heated oil hot using an ohmmeter (should see a nice even controlled sweep of the resistance with no jumps or holes in the tracking).. (This is the third most important fueling computer input for fuel control)

 

Ohm out all the wires including grounds from the oil temp sensor & TPS back to the Motronic.. (An open or excess resistance in any of the senor wires is like having a bad sensor or a sensor disconnected)

 

 

Verify you are getting full voltage to the ign coil & fuel injectors as low voltage to either of those will drive your system crazy.. (low voltage to either can really effect the engine operation)..

 

This is new__ If you are convinced that the engine ran better when you were running it out of fuel & that was due to the pump picking up less fuel then duplicate that again (very simple to go back through the tank draining process).. If it does in fact operate more normal as it is running out of fuel then suspect a blockage in the fuel return side of the system (maybe the quick disconnect on the return side not plugged together fully or a plug or blockage in the return side hose or fitting).. If that is OK then look back at the oil temp sensor as can make the fueling control go real rich if it is out of normal operating range) or (the TPS voltage being out of spec can make it go real rich),, or the 02 sensor acting strange due to heater voltage leaching to the sensor output side or erratic grounding)..

 

I know it is a pain but you really need to systematically go through your Motornic input systems & clear those of errors in feedback.. You also need to clear your fuel system of any contribution to the poor running..

 

 

“When I did the Canesterectomy, I didn't plug the exposed end tube at the solinoid, and left the electrical connection connected. I have since done that, yet have tried to start it since. (Don't know if this would affect anything or not).”

 

If you have/had the vacuum ports on the bottom of the TBI units plugged off then it would make no difference.. If you still had the vacuum lines running from the TBI’s to that solonide then you would have a small vacuum leak on warm engine & at above idle (only)…

 

Twisty

 

[SKYGZR]

SKYGZR, I posted some of this earlier but it seems like parts of it still might apply..

 

 

Maybe next try disconnecting the 02 sensor just to eliminate a simple test like that.. I haven’t seen where you tried this yet..

 

***Tried this (disconnected from the connector zip tied to the frame down tube under the tank), as getting to it at the header pipe is almost impossible. No improvement, yet the tank is pretty empty, yet enough fuel remains to allow it to try to run with the fast idle engaged***

 

Maybe try pulling the fuel return hose where it connects to the tank hose then run an extension on that then into a glass bottle.. That will allow you to look at a few things.. (This should pretty well clear your fuel system)..

 

**did this at the newly installed external filter. Fuel looks fine in a glass jar. Cycled the key to "On" with the filter in the jar, and it spit out a strong stream, no "piddle" or "dribble".***

 

This is new__ If you are convinced that the engine ran better when you were running it out of fuel & that was due to the pump picking up less fuel then duplicate that again (very simple to go back through the tank draining process).. If it does in fact operate more normal as it is running out of fuel then suspect a blockage in the fuel return side of the system (maybe the quick disconnect on the return side not plugged together fully or a plug or blockage in the return side hose or fitting)..

 

**No quick disconnects on this machine**

 

**Tried this again, and this time, it's still not running, nor won't run except with the fast idle engaged. Runs, but not correctly, dies upon giving it throttle. Trying to start it, with fast idle off, and throttle opened a bit, no go..stumbles and "burps", and won't start. (This could be due to almost no fuel in the tank at this time.)***

 

. You also need to clear your fuel system of any contribution to the poor running..

 

**That's where I'm at right now. I'm gonna pull the internals, and check to make sure the Pump filter mesh screen is intact, that the piece of copper tubing used when relocating the filter externally is still in place. (Don't know for sure if Gasoline affects copper in a way that might have caused the tube to somehow disintegrate.)**

 

Twisty

[SKYGZR]

**That's where I'm at right now. I'm gonna pull the internals, and check to make sure the Pump filter mesh screen is intact, that the piece of copper tubing used when relocating the filter externally is still in place. (Don't know for sure if Gasoline affects copper in a way that might have caused the tube to somehow disintegrate.)**

 

 

Ok, this is done. Did not totally remove the internals, yet lifted up the assembly enough to verify that the pump filter screen is in fact attached, and the copper tube is in fact still in place. I did suction out about an additional 3/4 gallon of residual fuel, along with some black gunky remains from the original pump filter that had degraded and turned black vs. the green color of the new one.

 

The fuel sucked out is "murky", yet no sign of water sinking, or standing on the bottom of the sample collected in the jar I used.

 

So next step will be to re-install the tank, put in some fuel, and check the spray pattern of the injectors. (That is if it still continues to exhibit the same symptoms.)

[4wheeldog]

"Murky" fuel is likely the problem. Gasoline will absorb a fairly large amount of water, and petro companies do use solvents to clear lines. Gasoline that is not visually clear is likely not all gasoline. Fuel injected motors don't like that. Here is hoping your problem is behind you. Good Luck!

[StuGotz]

Maybe bad fuel, maybe not...I'm leaning Motronic now...Just wonder if the fuel mapping has changed.

 

Make sure fuel system is clear of debris before you proceed...

 

MB>

[SKYGZR]

Maybe bad fuel, maybe not...I'm leaning Motronic now...Just wonder if the fuel mapping has changed.

 

**Well after the fuel sat for a day, the "Murkyness" has dissapaited, and the sample is now relatively clear. The jar was sealed, and no evaporation was present.** There was quite a bit of the black remnant remains, but not nearly enough to cause serious "blockage" at the pump filter/pickup.** I may be forced to get an analog meter (or make a test light) to check the fault codes if it turns out to be a "Motronic" issue.**

 

Make sure fuel system is clear of debris before you proceed...

 

**The tank is absolutely "bone dry" at this time. What other "debris" would be present??**

 

MB>

[T__]

SKYGZR, might as well clear the top of the injectors while there.. Remove the fuel line to the top of the injectors so you can look at that area.. There are some very fine inlet screens on the inlets to the injectors that can plug up .. Doesn’t sound like your problem but might as well clear that area as a problem so you can move on to other areas..

 

Twisty

 

[SKYGZR]

Pulled the left hose, couldn't see any screen. So, got the tank back on, put a couple gallons of petrol in. Same problem. Removed the Alt. belt pulley on the Crank shaft end to check the fitment of the trigger. Looked like it was rubbing a bit on the HES, repositioned it. Same Problem. Checked the TPS voltage, was a bit low, adjusted to 400mv, same problem. Getting ready to pull the injectors to check spray pattern.

[SKYGZR]

Getting ready to pull the injectors to check spray pattern.

 

P.S. What should I be seeing when testing these. Have the machine on a charger right now to make sure the battery is fully up prior to testing.

[T__]

SKYGZR, I’m surprised you didn’t see the little screens deep down in the injector inlets..

 

Attached is an injector testing of Bosch fuel injectors.. Keep in mind your smaller engine requires less fuel so won’t squirt this amount of fuel but it gives you an idea of an injector spray pattern..

 

If you are getting a wimpy spray pattern keep in mind that slow cranking speed as well as TPS voltage & Motronic sensor temperatures can really effect amount of fuel required so a low squirt quantity can be from the fuel management system,, or low voltage at the injector pintle coils,, or short pulse width command.. Low battery voltage to the injectors can also cause low injector output or a spastic injector pulse (make sure you have 12+ volts feeding the injectors pintle coil)

 

You can power the injectors directly from the battery,, then ground the other injector terminal to get a prolonged spray pattern for testing purposes..

 

 

 

Bosch injector pattern

 

 

Twisty

[AndyS]

Getting ready to pull the injectors to check spray pattern.

 

P.S. What should I be seeing when testing these. Have the machine on a charger right now to make sure the battery is fully up prior to testing.

 

As a rough and ready test, you could remove one injector at a time, and locate it over a small test tube(ideally it should be graduated) - maybe a syringe. Crank the bike on the starter button and count how many squirts you are getting.

Measure the amount of fuel in the tube.

Repeat the proceedure with the other injector, and see if you are getting somewhere near the same amount.

 

This won't tell you if the actual amount is right, but it will point you towards an injector failure on one side.

 

Andy

[SKYGZR]

Last night before my last post, I had pulled the left injector and while cranking over the motor, had it pointed into a glass jar. There was virtually no visable, if any spray. The engine did start and run for a bit, obviously firing on the right side. Then the battery decided to give out, that's when I put in on the charger.

 

Perhaps later tonight, i'll check it again.

[SKYGZR]

Confirmed that both injectors are working. Each has a fine misting spray of what seems to be the same. Used a piece of cardboard held in front of each one to check the pattern and coverage. Confirmed that there is indeed good spark on each plug.

[Mark K]

I've been following this thread since it started and I'm equally perplexed...I wish I had more to offer.

 

You have now confirmed fuel, air and spark. What's left other than the spark is coming at the wrong time?

[StuGotz]

I've had three problems follow me from each BMW motorcycle I've owned..

 

In this order of frequency:

 

1. Tires

2. Batteries

3. Kick stands

 

Maybe you should check the kickstand!

 

Sorry, bad joke, yer prob pissed right about now...

 

MB>

[SKYGZR]

I've been following this thread since it started and I'm equally perplexed...I wish I had more to offer.

 

You have now confirmed fuel, air and spark. What's left other than the spark is coming at the wrong time?

 

Don't know how the spark could be coming at the wrong time, since the HES trigger is located correctly, the gap in the trigger would pass the magnetic pick-ups on the HES at the correct interval, providing the fuel pulse, then the spark pulse to ignite the fuel.

 

You really can't put that trigger on wrong, since the little tab on it nestles in the notch on the end of the crank.

 

I still think this is somehow fuel related, and it's running way too rich. (Yet that might be related to having to have the fast idle actuated just to get it to even try to run.)The air cleaner has been checked, and is not clogged or overly contaminated. (new about 6,000 miles ago).

 

The one thing that is totally baffelling is that it won't take any throttle, period! Normally, an engine should start ok when giving it some throttle. This just wants to cough, burp, and slightly back fire when trying a bit of throttle to start it (without the fast idle engaged.) With the fast idle engaged, it really runs rough before stalling out, and produces some really heavy exhaust, not black, but contaminates the garage really fast.

 

I doubt the CatConverter could be clogged up in only 37,000 miles.

[SKYGZR]

yer prob pissed right about now...

MB>

 

If I didn't have the K-Bike to ride I do believed pissed might be in order...even touching suicidal...

[kiwiaudio]

Have you connected a timing light to see if the spark is erratic. I wonder if the original HES was actually not faulty at all, but perhaps the wiring to/from it is !

[T__]

SKYGZR, sounds like you haven’t verified that your spark is occurring at the correct time.. (you really need to do that)—Use an inductive timing light on a plug wire then point the light through the timing hole.. Or bring a piston to TDC then paint mark the front pulley to case.. I suggested this in an earlier post but it doesn’t sound like you have done it yet.. There is just no guarantee that new HES is operating correctly,, or giving the Motronic correct TDC data..

 

 

“Don't know how the spark could be coming at the wrong time, since the HES trigger is located correctly, the gap in the trigger would pass the magnetic pick-ups on the HES at the correct interval, providing the fuel pulse, then the spark pulse to ignite the fuel.”.. ____

--There is a TDC & a BDC output from the HES.. If those are mis wired or somehow not right it could cause spark at the incorrect time..

 

 

 

You really need to verify the TPS is set correctly & is tracking correct voltage on BOTH the low & high wiper.. Not sure if you have done this yet.. You also need to be sure the TPS info is getting all the way to the Motronic..

 

You also need to verify (correct) oil sensor temp input at the Motronic connector.. If the Motronic is not getting the correct engine temperature it can effect the amount of fuel injected..

 

I presume you have good compression? Have you checked it yet?

 

Have you tried new spark plugs? Center electrode fouled plugs can look good,, can spark good under no compression load,, but still be a problem under compression & cylinder load..

 

IF, you have good compression,, have good fuel delivery TO the cylinders,, have good air supply INTO the cylinders,, have good spark AT THE CORRECT TIME on GOOD spark plugs,, & the exhaust can get out.. IT HAS TO RUN.. What are you missing?

 

 

 

Twisty

 

[Richard_D]

I'd try a new HES.

[Ken H.]

A few more thoughts I don’t think have been covered…

 

Have you checked the fuel pressure yet?

 

When the bike will run (at any RPM) what does the sync show?

 

If you closely observe the TBs as you just barely rotate them off their idle stop screws, do they physically seem to come off at the same time?

 

For that matter are they both on their idle stop screws at throttle idle?

 

Is there a difference in behavior cold start vs. warm start?

 

Is there a difference in how it behaves when you slowly try to add throttle, vs. whacking it up rather suddenly?

 

As Twisty mentioned, you need to check the TPS voltage tracking.

 

How does it behave with the TPS disconnected?

 

The tank has been off recently, yes? No chance that a wire to one of the injectors is pinched somewhere? (Its actually the same circuit to both.)

 

[SKYGZR]

SKYGZR, sounds like you haven’t verified that your spark is occurring at the correct time.. (you really need to do that)—Use an inductive timing light on a plug wire then point the light through the timing hole.. Or bring a piston to TDC then paint mark the front pulley to case.. I suggested this in an earlier post but it doesn’t sound like you have done it yet.. There is just no guarantee that new HES is operating correctly,, or giving the Motronic correct TDC data..

 

**Nope haven't done this yet..But Why would it run just fine for awhile, then do this little trick??** When it first stranded me, I confirmed that there was no spark, which led to the removal and testing of the original HES, and the cutting open of the wiring harness to verify that everything was good. It tested OK, and the wires are just fine on the original. After the install of the new HES, fired right up, ran just sweet till this started happening.**

 

 

“Don't know how the spark could be coming at the wrong time, since the HES trigger is located correctly, the gap in the trigger would pass the magnetic pick-ups on the HES at the correct interval, providing the fuel pulse, then the spark pulse to ignite the fuel.”.. ____

--There is a TDC & a BDC output from the HES.. If those are mis wired or somehow not right it could cause spark at the incorrect time..

 

**How could they be mis-wired when the machine ran just fine after the install of the new HES? This doesn't make sense**

 

You really need to verify the TPS is set correctly & is tracking correct voltage on BOTH the low & high wiper.. Not sure if you have done this yet.. You also need to be sure the TPS info is getting all the way to the Motronic..

 

**I checked and set the TPS to 400mv, since the machine won't run/idle/take throttle, how can one check the "high wiper"?**

Just how does one verify TPS info is getting to the Motronic?

The plug in to the Motronic has not been disturbed. Some of the

original wiring loom had degraded over time, and I used some electrical tape to re-wrap the areas, but did not disconnect anything when re-insulating with the tape. None of the wires

exposed were worn through or damaged.***

 

You also need to verify (correct) oil sensor temp input at the Motronic connector.. If the Motronic is not getting the correct engine temperature it can effect the amount of fuel injected..

 

**How would one do this little test?**

 

I presume you have good compression? Have you checked it yet?

 

**Don't have a compression tester, but remember, it was running just fine. i doubt this to be a problem unless the AP3923's holed a piston like in the other thread here.**

 

Have you tried new spark plugs? Center electrode fouled plugs can look good,, can spark good under no compression load,, but still be a problem under compression & cylinder load..

 

**I picked up a couple new APP3923's on the way into the Shity this morning.**

 

IF, you have good compression,, have good fuel delivery TO the cylinders,, have good air supply INTO the cylinders,, have good spark AT THE CORRECT TIME on GOOD spark plugs,, & the exhaust can get out.. IT HAS TO RUN.. What are you missing?

 

**That's the perplexing problem. Since it ran just fine for awhile after installing the new HES, some of these issues seem not to apply**

 

Twisty

[SKYGZR]

I'd try a new HES.

 

I thought about re-installing the original since it tested OK, and the wiring isn't damaged, yet the unit was replaced due to no spark.

 

I replaced that one with a new in the box Bosch from beemerboneyard. I suppose I could shell out another couple hundred bucks, but....

[SKYGZR]

A few more thoughts I don’t think have been covered…

 

Have you checked the fuel pressure yet?

 

**Not "formally", yet with the external filter spraying into a jar/gas can, it was throwing a strong steady stream**

 

When the bike will run (at any RPM) what does the sync show?

 

**It will barely idle, let alone run**

 

If you closely observe the TBs as you just barely rotate them off their idle stop screws, do they physically seem to come off at the same time?

 

**Yes, they each move off at the same time, and all cable junctions are seated correctly in their respective collars**

 

For that matter are they both on their idle stop screws at throttle idle?

 

**Yes, when the throttle is fully closed, I used my fingers to check and make sure the butterfly's were each against their stops**

 

Is there a difference in behavior cold start vs. warm start?

 

**Can't tell, since it won't run long enough to even put one bar on the RID display**

 

Is there a difference in how it behaves when you slowly try to add throttle, vs. whacking it up rather suddenly?

 

**Instantly dies no matter how the throttle is applied. Won't take ANY THROTTLE PERIOD**

 

As Twisty mentioned, you need to check the TPS voltage tracking.

 

**Once again, how does one preform this little test?**

 

How does it behave with the TPS disconnected?

 

**Haven't checked, yet since it barely starts and runs with it hooked up, probably won't do anything with it disconnected**

 

The tank has been off recently, yes? No chance that a wire to one of the injectors is pinched somewhere? (Its actually the same circuit to both.)

 

**Nope, have traced them all, and as far a I can see/tell they're just as they were when the machine was running OK. Did not disturb them anywhere except at the injectors themselves. They are fully engaged and the lock spring clip is actuated in it's correct position**

[StuGotz]

When you've gotten the bike to start and run, have you checked (read) the plugs

right after it has quit?

 

One side gas washed?

Both sides?

One side oil fowled?

Both sides?

One side cold?

Both sides?

 

Cheap compression test with your finger. Plugs out,plugs grounded to case, finger over spark plug hole, crank engine. Should feel good pressure on finger. Both sides equal.

 

Wish you had access to a Motronic unit to swap out...

 

MB>

[Unhofliche_Gesundheit]

sympathically,

call me crazy but at this point couldnt you take the bike to your friendly neighborhood bmw motorad dealer or indy and have them take a look?

 

=> tech has big supply of parts to swap in and out at no cost for the part if it is not the problem

 

=> if you are performing troubleshooting steps for the first time based on written instructions only you might not recognize when something is not right - no substitute for experience (which i readily agree i do NOT have).

 

 

[SKYGZR]

When you've gotten the bike to start and run, have you checked (read) the plugs

right after it has quit?

 

One side gas washed?

Both sides?

One side oil fowled?

Both sides?

One side cold?

Both sides?

 

**Both sides Black, no oil, indicative of overly rich mixture possibly due to the fast idle engaged. No help wire wheeling and re-installing, same problem**

 

**when checking for spark last night, engine did fire when i had the right plug removed, and there was considerable air (compression) pumping out, enough to blow my pants leg that I could feel it, it kinda startled me when it lit off.**

 

Cheap compression test with your finger. Plugs out,plugs grounded to case, finger over spark plug hole, crank engine. Should feel good pressure on finger. Both sides equal.

 

**This would be kind of difficult considering the depth to the plug socket inside the head and valve cover**

 

Wish you had access to a Motronic unit to swap out...

 

**Yea, that would be sweet**

 

MB>

[StuGotz]

Not askin' you to put your finger IN the hole, but you get the idea..

 

MB>

 

[Ken H.]

OK, I see, most of my questions revolved around the fact that the bike would (was at some point) run at least a bit. E.g. – idle, however poor.

 

One point though – An oilhead will normally idle with the TPS disconnected. So I would at least try that to see, if nothing else, if the idle improves.

 

ISFA testing the TPS, what you are looking for is a smooth voltage swing (an analog needle voltmeter is better than a digital one for this) from one end of its rotation to the other. On both sets of wipers. I can’t recall the max. voltage at the moment (and am not where I can access my notes) but I believe it is around 1.5v. Twisty may be able to confirm/correct that.

 

I don’t think a spray pattern test is a valid verification of fuel pressure. You need to rig a fuel pressure gauge on the high side to know for sure.

 

And despite what was, what is, now, would drive me to doing a compression check anyway.

 

[SKYGZR]

One point though – An oilhead will normally idle with the TPS disconnected. So I would at least try that to see, if nothing else, if the idle improves.

 

**Tried, relatively no difference**

 

I don’t think a spray pattern test is a valid verification of fuel pressure. You need to rig a fuel pressure gauge on the high side to know for sure.

 

And despite what was, what is, now, would drive me to doing a compression check anyway.

 

**If I decide to purchase a compression and fuel pressure tester(s) perhaps I will.**

 

**New plugs installed, same problem** Hooked up a timing light, and it's firing exactly as it should. (Checked it with the marks painted on the Pulley mentioned in this thread): Marking TDC

 

So this seems to eliminate the "spark not coming at the correct time" scenario.

 

Both cylinders seem to be "pushing" (compressing) just fine. I left the new left plug out, resting on the fins, firing spark..fast idle engaged, started, and ran for a bit on the right side only. While running, was put'n out quite a nice little push of air..same thing that happened earlier on the right side. Although not a "formal" compression test, it's push'n allot of air on each side.

 

[Yeeha! Stephen]

Remember the old "shade tree" (dangerous) trick of pouring gas down the carb to see if the engine would run...

 

How about hooking up hoses to the TB vacuum nipples and dropping them into a cup with a little fresh gas in it. Crank the motor and see if it will run on that little bit of gas. If it does, I'd say there's a fuel problem somewhere. If it still does the "run crappy" thing... I'd say HES.

 

When the murky gas was settled in a jar, there were Black bits in the bottom... how about a deteriorated fuel line. Cheap ones, or ones not designed for fuel emersion might start to come apart internally, or collapse.

[tallman]

Yeehaw, could be.

See this month's MOA magazine for column about the effects of ethanol on older BMW's (like this one) fuel systems.

[SKYGZR]

How about hooking up hoses to the TB vacuum nipples and dropping them into a cup with a little fresh gas in it. Crank the motor and see if it will run on that little bit of gas. If it does, I'd say there's a fuel problem somewhere. If it still does the "run crappy" thing... I'd say HES.

 

**So would I pinch off the main fuel supply hose to restrict fuel from the tank while trying this trick?**

 

**I may try (just for ), reinstalling the supposed non working HES and see what happens**

 

When the murky gas was settled in a jar, there were Black bits in the bottom... how about a deteriorated fuel line. Cheap ones, or ones not designed for fuel emersion might start to come apart internally, or collapse.

 

**The internals were recently checked, and verified all intact. All the hoses are the originals. I do believe the black residue was from the original pump filter screen that had degraded and turned black**

 

[SKYGZR]

Yeehaw, could be.

See this month's MOA magazine for column about the effects of ethanol on older BMW's (like this one) fuel systems.

 

**Care to "copy/paste" that article here?. Went to the site, looked around, couldn't find it. I'm also not a member there, so access is limited. BTW, the K is 11 years "older" that the R, and all the tank internals (except the filter of course), are the originals. Ethanol hasn't affected anything there.**

[SKYGZR]

... I'd say HES.

**I may try (just for ), reinstalling the supposed non working HES and see what happens**

 

Well now this has turned from perplexing to bordering on the ridiculously unexplainable.

 

Took some shrink tube, (had to slit it) to re-wrap the wires on the original HES. I have the good kind, that has glue on the inside. So double wrapped the wires with the tube and shrunk it down. Remember, this unit tested fine, and the wiring was/is in pristine condition...So..

 

Removed the "new" one, installed the original/old one (ie; the one that stranded me..the one that "failed"...the one that provided no spark),...thought i should check the spark...na...it's not gonna work, just turn the key on and try it anyway...

 

BOOM....the thing just blew UP.... ....ie; started right up, no fast idle engaged...runs just like it should. WTF?

Push it out into the driveway, fire it up again..

runs just fine..long enough to get it to 5 bars. Fast idle runs it up to about 4000 RPM (is this a bit too high?). Seems to be idleing a bit high, perhaps this is due to resetting the TPS to 400mv? Will have to do a TB synch just to check that.

 

Needless to say this is TOTALLY WEIRD

[AndyS]

... **I may try (just for ), reinstalling the supposed non working HES and see what happens**

BOOM....the thing just blew UP.... ....ie; started right up, no fast idle engaged...runs just like it should. WTF?

Push it out into the driveway, fire it up again..

runs just fine..long enough to get it to 5 bars. Fast idle runs it up to about 4000 RPM (is this a bit too high?)....Needless to say this is TOTALLY WEIRD

 

Why is this weird?

 

If your replacement HES was defective then the bike won't run.

 

If your original old HES loom was what was making the unit not run, but you have repaired it (even if temporarily) then when the bike runs this should't shock you. But it does seem to re affirm what some have posted a long way back about replacing the HES with another unit. Or am I missing something.

Whether I am or not. I do hope that this has resolved the issue, because I feel sypathy for the amount of hassle you have been going through.

Hopefully this is THE fix.

Best wishes.

Andy