97 rtp with surge issues

[Copless-rtp]

Hi everyone, this is my first , and long awaited, BMW. I traded straight across for my v star 650.....did I mention I was very happy? Anyway being a newbie, I have done as much research as I can. So now I need help. It has 56k miles on it and it hesitates or surges in the lower gears at lower rpm's. Not as noticeable at freeway speeds. I have read " fuel filter, fuel filter, fuel filter" but have also read sync the TB's. I plan on taking it apart over the winter to address some other issues. Did I mention it has an ABS fault on key up? I mentioned before. I am very happy.....at least for now.

Thanks for all the help

[SKYGZR]

Plugs to APP or AP3923 (AP=Platinum Electrode, APP=Platinum Anode & Electrode) Valves on the "loose side", plus the TBS, and TPS check/adjust. ABS could be a sensor. Fuel filter/strainer may be suspect, renew/air filter/renew. Keeping the "rev's" up will help mask the surging, yet it's an inherent issue with this/these model year machines.**NOTE** Replace the HES NOW!! and carry a spare (plus the tools/know how) to replace it.

 

Another **NOTE**--should the machine tip/fall over to the throttle (right) side while running (and perhaps not), DO NOT TRY TO START IT..till you pull the plugs and turn it over to evacuate the oil that will fill the cylinder/and air box. If you Don't do this, it will HydroLock, grenading the starter and strand you while you wonder WTF just happened.

 

"Happy" is a relative term, you are now a mechanic/troubleshooter.

 

P.S. welcome to the world of BMW "happiness".............

[Copless-rtp]

Thanks for the tip over note, good to know. Pardon my ignorance, but what is the HES? And do you mean change plugs out to AP or APP?

[AndyS]

With regard to your bike surging. You have covered what you need to do first.

Do you have any form of after market fuel control unit fitted (techlusion / power commander)? if so it may be worth initially disconnecting it and checking all the base settings of the bike are top notch.

Give the bike a service. Spend a lot of time getting the valve clearances spot on. Also I reccomend you check the ignition timing is spot on (I wouldn't normally bother with this, but seeing as you have surging issues it is worth the check. normally a little bit out doesn't effect things too much, but why not check to see it spot on and then you know all is good).

Then clean theTB's up, check that the Big Brass Screws (for adjusting idle) are checked and cleaned - replacing their O rings for good measure.

Check obviously plugs and air filter are all good.

Check the inlet rubbers are sound and their O rings are correctly sealing.

Do a throttle body synch really carefully.

Then get back to us.

 

Andy

[dirtrider]

Morning

 

On your surge?

 

You first need to determine if your problem is a hesitation or a surge and if just the common (steady throttle) surge at what engine RPM/Load it is happening at.

 

You REALLY need to identify at what RPM range, road load, and throttle opening your problem is appearing at before laying it up for winter work. (you won’t fix it if you can’t define it)

 

The 1100’s have a basic light load mid RPM surge as pretty well standard. If you do indeed have a hesitation not a surge then that is a horse of a different color.

 

So does your problem happen at steady throttle (surge) or as you open the throttle (hesitation).

 

At what engine RPM does it happen at?

 

Is it there cold engine, or both cold/hot engine, or only hot engine?

 

If your problem is there on hot engine, steady throttle, light road load then it is probably the common BMW boxer lean surge.

If so, start with a new set of spark plugs to eliminate that straight off.

 

Then re-set the TPS voltage to .385 volts on hot engine closed throttle (no choke)

 

Then ride the bike.

 

If your surge is still there remove the CCP from the fuse box and ride it again. If that helps reinstall the CCP then unplug the 02 sensor and ride it again.

 

The common 1100 boxer light engine load 3K-4K area surge is a lean surge due to large combustion chambers and central spark plug location/poor fringe or outer chamber combustion. If you can get it rich enough you can cover up that lean surge (if your problem is in fact the common light throttle surge). As long as the 02 sensor is active it just won’t let you richen the hot engine light throttle light load running RPM range as the 02 sensor is the ultimate fuel mixture controller in that operating range.

 

Again, BEFORE laying it up for the winter fully identify whether it is surge or a hesitation and at what operating parameters your problem is appearing at. You can’t fix it if you can’t define it.

 

[Danny caddyshack Noonan]

Copless,

Go here self service pdfs and browse through the BMW 259 engine docs. There are a handful of items on the page for your bike that will help get you up to speed on the surging as well as other mechanical work.

 

If you have a BMW dealer nearby, he should have the feeler gauges with handles to do the valves. These make the job a bit easier.

[NonComp]

And have a look here for a good modification to eliminate the ABS fault at cold startup issue.

 

ABS relay delay modification

[Copless-rtp]

Wow, you guys and this site are awesome. Thanks so much for the advice! I'll get to those road checks. There isnt any aftermarket controlers at all. It appears mostly stock. The bike came with a Hanes book. Not bad but it seems vague. Is there a must have list of tools on the site? The plugs were new AP3923. I guess I should check the gap. It actually starts a little hard ( with choke on) and stalls after a few seconds. It seems fine on second start. Coughs a couple of times but then smooths out. The surge is mostly prevalent below 3500rpms. It did hesitate a couple of times on quick take offs, once warm it seems to improve, but has popping exhaust note on throttle let off, mainly at slow speeds and gears. Thanks again for the advice....I wasn't sure where to start, but I think I have my marching orders in place.

[NonComp]

I agree with what Dirtrider said. I'd clean out the Big Brass Screw ports and check the TPS voltage. I use the XP3923 irridium spark plugs with good results.

[SKYGZR]

HES is the Hall Effect Sensor which is on the end of the crankshaft, and tells the engine when to fire the plugs. When this goes (and it will, sooner or later), no spark, no go, stranded. Now where's that spare I should have been carrying

[dan cata]

Morning

 

Then re-set the TPS voltage to .385 volts on hot engine closed throttle (no choke)

 

 

Why does the engine need to be hot while setting the TPS?

[dirtrider]

Morning

 

Then re-set the TPS voltage to .385 volts on hot engine closed throttle (no choke)

 

 

Why does the engine need to be hot while setting the TPS?

 

Evening Dan

 

Because that is where you want the TPS voltage output to be the most accurate. The TPS is basically a resistor (variable but still a resistor) and resistance of the TPS can change slightly with temperature. Not big deal but you never want the hot curb idle TPS voltage to exceed .399 volts.

Some even go so far as to have the engine running during the TPS setting but I haven’t ever found that be needed as the sensor voltage supply regulator in the Motronic is pretty well throttled to 5 volts regardless of the input voltage.

 

[Copless-rtp]

Ok, how do you reset the TPS?

[dan cata]

Ok, how do you reset the TPS?

 

 

http://advwisdom.hogranch.com/Wisdom/tps3.1.pdf

[dirtrider]

Ok, how do you reset the TPS?

 

Morning Copless-rtp

 

Dan’s link is written for the 1150 but the basic idea will work just fine on your 1100. You can skip the “remove the fuse or disconnect the battery key on twist the throttle twice” part as your 1100 Motronic 2.2 system doesn’t have a learnable TPS like the 1150 Motronic 2.4 system does.

 

I have also found over the years that on your 1100 you probably want the TPS voltage closer to .385 rather than the .360 suggested.

 

If you are using a good modern high impedance digital voltmeter then definitely set to .385 volts. If you are using an older lower impedance meter than maybe (just) slightly lower to account for the meter load on the circuit during measuring.

 

In any case make darn sure the choke (fast idle) lever is ALL the way off and that the L/H throttle plate is fully closed with the shaft lever resting solidly on the idle stop screw.

 

After your adjustment, stroke the throttle a couple of times (key on engine off) while watching the TPS voltage to verify the voltage returns to your initial setting and DEFINITELY under .399 volts.

 

[Copless-rtp]

Thanks much, I saved it on my iPad. I will be starting that project first. Once the TPS is dialed in and the TBs are synced, what else should I be doing since the plastic is off? Should I swap out the HES, belt, and fuel filter? I might have answered my own question. Is there anything else....maintenance wise under the plastic? The fairings do seem pretty easy to remove. I just know that I tend to brake stuff and loose pieces in processes like that. Maybe I should have got an R.

[DavidEBSmith]

Set the valve clearances and sync the throttle bodies and check for air leaks and clean the BBS and ensure proper freeplay in the throttle cables and see how it runs before you touch the TPS. I've seen several bikes where the owner jumped in and started changing the TPS first thing and had a h*ll of a time getting it running right again. The TPS should be your last resort, after everything else is set properly.

[Copless-rtp]

Thanks David, I might wait till after the new year. I need to acquire a few tools first. I'm adding them to my letter to Santa as we speak.

[NonComp]

TPS should be your last resort, after everything else is set properly.

TPS was the last thing that I changed - and I wish that it wasn't, because it was simple to check and fix, and it was ultimately a major cause of my problems. The previous owner had already fiddled with it and/or the screws were loose, and it was way off spec.