R1100RT "Zero-Zero" Tune-up; Checking for 0.370 V

[SWB]

I've just completed some major work on my Beemer which requires me to re-tune it. I replaced the throttle cables, fast idle cable, soaked the Throttle Bodies (which required removal of the TPS), replaced all "O" rings, and replaced the large brass screws. All the tuning adjustments need to be reset. I've adjusted the valves, and am now tuning using (the late) Rob Lentini's zero-zero TPS tuning method.

 

The instructions direct loosening the throttle cables (altering throttle, fast idle, and throttle adjustment screws), then backing out the throttle set screw until the throttle stop flange no longer contacts the screw, i.e. true "zero throttle", before increasing it to back to "zero volts" (0.010 to 0.006 DCV). Then the left throttle body throttle stop is advanced until the DVM reads between 0.370v and 0.400v, and the throttle bodies are balanced.

 

Question: Shouldn't we be able to check the TPS with a DVM without altering the throttle stop set screws, getting a baseline voltage something close to 0.370 to 0.400 DCV? If the value is higher or lower, then adjust the throttle stop set screws (starting with the TBS adjusted to reflect 0.010V).

 

Thanks.

[ShovelStrokeEd]

Wellll, kinda but not exactly although I have just tweaked my TPS position to attain 0.370 volts using the factory stop screw settings and let it go at that.

 

The intent of the zero=zero method is to have the true, closed throttle position right at the bottom of the effective range of the potentiometer (zero) when the throttle plates are fully closed (=zero). One then adjusts the left throttle stop screw to bring the throttle on that side to an opening angle the corresponds to 0.370 volts. A sync from there, engine running and using only the right side throttle stop screw, brings the right throttle body into agreement, flow (as required by the engine) wise. The BBS are then adjusted on both sides to acquire both sync and the desired idle speed. One could probably perform the last steps with both screws either fully closed (low idle speed) or the standard 1.5 turns open. I prefer the fully closed method.

 

This is in opposition to BMW's method of setting throttle plate angle, via the throttle stop screws, so that a precise amount of air (done on a flow bench) will flow through each throttle body and then they adjust the TPS to some nominal value. They then allow the BBS to compensate for any small difference in actual engine flow requirements.

 

Either method will work quite well so long as both the engine and the air metering assemblies are in perfect mechanical condition. I think the Lentini method is far superior for use on an older engine where throttle shafts may be worn, other subtle leak sources may have crept into the parlor and both cylinders may no longer have exactly the same pumping efficiency.

 

Did that clear anything up??

[SWB]

Wellll, kinda but not exactly although I have just tweaked my TPS position to attain 0.370 volts using the factory stop screw settings and let it go at that.

 

The intent of the zero=zero method is to have the true, closed throttle position right at the bottom of the effective range of the potentiometer (zero) when the throttle plates are fully closed (=zero). One then adjusts the left throttle stop screw to bring the throttle on that side to an opening angle the corresponds to 0.370 volts. A sync from there, engine running and using only the right side throttle stop screw, brings the right throttle body into agreement, flow (as required by the engine) wise. The BBS are then adjusted on both sides to acquire both sync and the desired idle speed. One could probably perform the last steps with both screws either fully closed (low idle speed) or the standard 1.5 turns open. I prefer the fully closed method.

 

This is in opposition to BMW's method of setting throttle plate angle, via the throttle stop screws, so that a precise amount of air (done on a flow bench) will flow through each throttle body and then they adjust the TPS to some nominal value. They then allow the BBS to compensate for any small difference in actual engine flow requirements.

 

Either method will work quite well so long as both the engine and the air metering assemblies are in perfect mechanical condition. I think the Lentini method is far superior for use on an older engine where throttle shafts may be worn, other subtle leak sources may have crept into the parlor and both cylinders may no longer have exactly the same pumping efficiency.

 

Did that clear anything up??

 

I understand your points; Thanks, Ed, as always.

 

You added some more interesting information. Basically, if I check the voltage on 100 factory set BMW's, they ought to be identical since BMW is setting every single throttle body throttle stop set screw to the same value. Lentini's method is to readjust this value to match the (possibly deteriorated) condition of the actual bike. So, checking the TPS voltage without setting the stop screws may be interesting, but irrelevant in light of the condition of the machine, with possibly warn butterfly shaft bushings, etc..

 

When I first checked the voltage after ensuring the cables were all loose, I got some unworldly value like 1.3V. That's what made me think about what the value should be. I was so freaked out that I got a 1.5V battery to test the calibration of the DVM. (FYI, when I had the TPS off the throttlebody during cleaning, I scribed the original position so that I'm pretty certain it's in the original position.)

 

I'm going to run though this tomorrow (as I think I will have enough time to do it). That's the way I do this kind of work. Read about it. Research. Talk about it. Get ready to do it. Read about it again. Think it through. Memorize the steps. Question all the steps. Question what the heck I'm doing this all for. Get delayed cause of my job. Start over....

 

I'm thinking about just using the throttle cable adjusters, i.e. set the left to 5mm, and then balance the TBS using the right side, and then fine tune using the brass screws. That's the "book" method. I'll need to do this again after my new cables stretch a bit in any case. The bike had a slight, occasional "flutter" at idle, and seemed to lose sync rapidly. So, cleaning the TBS's, new cables, new rubber "O" rings and re-tuning will hopefully clear it up. Haven't done the "WD-40" or propane test around the butterfly shafts; will do that when it's running. Haven't started it since NOV 06, so that's the first step - get her running half way decently, test the tranny, and then go back and fine tune or do the Zero-Zero thing.

 

I've done so many things to this bike that I'm running a bit scared. I powered up the bike (ignition, no start) for the first time last weekend. Checked lights and etc - yup, all working. Powered it up two or three more times to make sure I heard the fuel pump. Yup.. good there. Then there was a "tssssssss" sound like an electrical short. "Oh oh...". Went to the other side of the bike; gas puddle on the ground. "Yup.. fuel pump works fine...". After I did some dismantleing, found out one of the two supply hoses were leaking ("Whew... least it wasn't the big gasket I replaced during the fuel filter change..".

 

I think it's going to be like this for a while.

[ShovelStrokeEd]

Actually, if you check the voltage on a random sampling of BMW's you may find a wild variation in base TPS voltage some of which depends on which species of Motronic is fitted to the bike. Earlier bikes tend to be in the 320 to 370 mV range, later ones, where the Motoronic doesn't just learn WFO but also learns the base line voltage you may see voltage as low as 1.5 or even less. It is less important on the later ones and, in fact, the zero=zero doesn't apply to these bikes.

 

It may be helpful to understand the two functions of the TPS on the earlier Motronic systems. Perhaps a short explanation of how the Motronic works would better precede those. The Motronic is a simple n-alpha fuel injection/spark control system. Stored inside the box is a map/maps of various numbers which more or less represent fuel injector on times. These numbers are selected for the next pulse by engine RPM (the "n") and throttle angle (the alpha). Change either and the next pulse will come from a different part of the table. There is also all sorts of interpolation going on plus modification of the pulse width by other sensors but, that is the basic.

 

Now the engine RPM is obvious. Throttle angle information is provided by our old friend the TPS. The primary function of the TPS therefore, becomes obvious, it provides throttle angle information so the Motronic knows which of the 700 or so numbers to pick. The second function, is fuel cutoff. BMW's efforts to meet emission standards are well known and one of those efforts was to design the system such that if the throttles were closed and engine RPM was above 2000 or so, the Motronic would provide a zero pulse width signal to the injectors. Makes sense, the bike will burn less gas and produce less emissions. This fuel cutoff point is partially determined by that TPS voltage. It has to be below 400 mV to indicate to the brain that the throttle is closed. BTW, fuel delivery kicks back in at around 1500 or so to keep the motor from stalling.

 

Now, why 370 mV? Well, the closer you can make it to the fuel cutoff point the less broadly the effect of that fuel cutoff will be felt. Incidentally, the higher your entire TPS voltage range can be shifted, the higher in the map you will operate. This can provide a tiny bit richer mixture when operating at very light throttle openings and somewhat improve engine performance at those openings. Remember surge? But I ain't revealing all my secrets. It has a minuscule effect on larger throttle openings and can be ignored.

 

That oughta give you some more to chew on.

[SWB]

Thanks, Ed. Good stuff.

[T__]

SWB, ShovelStrokeEd did a great job of explaining the basic Motronic operation..

 

I will just add a little about one of those sensors he talked of..

 

Seeing as your complaint seems to come at idle, as long as the TPS is basically under .4 volts at closed throttle idle & the engine is warm your idle fuel mixture should basically be controlled by the 02 sensor.. That 02 sensor basically holds idle, light throttle, & steady throttle up to about mid throttle to basically 14.7 to 1.. It reverts to the basic speed density maps (no 02 control) on any changing throttle,, heavy throttle,, decel,, WOT..

 

If you still have an intact & operating 02 sensor then that is controlling your hot idle mixture (unless your set up is so far out of whack that it is outside the operating parameters that the 02 can control to).. If you have pulled the CCP that will also disable 02 control on the 1100.. In either case if you don’t have 02 control (no 02 or no CCP) then you will have a fairly rich base idle mixture.. BMW used an idle CO potentiometer (you should have wires under the seat for that) to control (adjust) idle mixture on non 02 controlled 1100 bikes.. In most cases they will idle just fine at a rich idle mixture but if a little on the rich side it can carbon up a spark plug at idle & give you an occasional idle misfire.. Sometimes opening the spark plug electrode gap a little will show an idle improvement (probably shouldn’t go .040” though..

 

Twisty

[SWB]

Seeing as your complaint seems to come at idle, as long as the TPS is basically under .4 volts at closed throttle idle & the engine is warm your idle fuel mixture should basically be controlled by the 02 sensor.. That 02 sensor basically holds idle, light throttle, & steady throttle up to about mid throttle to basically 14.7 to 1.. It reverts to the basic speed density maps (no 02 control) on any changing throttle,, heavy throttle,, decel,, WOT..

 

If you still have an intact & operating 02 sensor then that is controlling your hot idle mixture (unless your set up is so far out of whack that it is outside the operating parameters that the 02 can control to).. If you have pulled the CCP that will also disable 02 control on the 1100.. In either case if you don’t have 02 control (no 02 or no CCP) then you will have a fairly rich base idle mixture.. BMW used an idle CO potentiometer (you should have wires under the seat for that) to control (adjust) idle mixture on non 02 controlled 1100 bikes.. In most cases they will idle just fine at a rich idle mixture but if a little on the rich side it can carbon up a spark plug at idle & give you an occasional idle misfire.. Sometimes opening the spark plug electrode gap a little will show an idle improvement (probably shouldn’t go .040” though..

Twisty

 

FYI:

Uses an O2 sensor (also new/just replaced).

CCP still installed

 

At 57K miles, the problem could have been anything. So, when I tore it down for the tranny, I rebuilt it with new parts. New fuel regulator (tubes on the old were crushed), new cables, new brass screws, new "o" rings, GS intake tubes, new O2 sensor, new air filter. Most "wear" items were replaced. New (3K miles) ignition coil and plug wires & plugs.

 

Thanks!

[SWB]

I need help reading my DVM. I've figured out enough to tell the difference between resistance, current, and voltage (DC or AC).

 

The voltage part of the dial reads "200m, 2, 20, 200, and 600".

 

At the "20" setting with the ignition on, the DVM shows a .083 at "zero throttle" (i.e. the left throttle stop screw backed out until the flange doesn't contact the screw). Is this the correct DVM setting to read Volts? It's a long ways between .006/.010 to .083. I haven't touched the TPS yet. Is it possible that the TPS is that far off? Lentini indicated that at this point "You should see an indication on the DVM near zero." .083 is a long way from zero (.000), as well.

 

FYI, I'm using a Commercial Electric HDM350, identical to the one this guy is using. .

[ShovelStrokeEd]

OK, meter range readings. Depends on the number of degrees of precision.

They typically come in either 3 1/2 or 4 1/2 digits of precision. If you paid less than $175 or so, you probably have a 3 1/2 digit meter.

 

Your 83 mV reading will show up like this on the various scales.

 

200M, which is 200 mV. 83.x could be anywhere from 82.5 to 83.4.

2 will show 0.083 or maybe .083

20 will show .08

200 will show .1

 

You are using the right scale at 2 volts.

 

What you need to do is to adjust the TPS position now to obtain a reading of 0.006 or so volts. Loosen two screws, just slightly, and very lightly tap the TPS around till you get that reading. This can be a PITA to do. Basically you want to be at the end of the stroke of the TPS. Be careful here to be sure you don't create a dead band where tiny movement of the throttle plate does not result in any change in the meter reading. I like to back the pot off till I get no change in the reading and then go back upward till I get the first change and lock things down there.

 

Another point. Below 400 mV, the O2 sensor is not taken into account for mixture control. The Motronic does use a map for idle mixture control or open loop running as it is normally called.

[SWB]

OK, meter range readings. Depends on the number of degrees of precision.

They typically come in either 3 1/2 or 4 1/2 digits of precision. If you paid less than $175 or so, you probably have a 3 1/2 digit meter.

 

Your 83 mV reading will show up like this on the various scales.

 

200M, which is 200 mV. 83.x could be anywhere from 82.5 to 83.4.

2 will show 0.083 or maybe .083

20 will show .08

200 will show .1

 

You are using the right scale at 2 volts.

 

What you need to do is to adjust the TPS position now to obtain a reading of 0.006 or so volts. Loosen two screws, just slightly, and very lightly tap the TPS around till you get that reading. This can be a PITA to do. Basically you want to be at the end of the stroke of the TPS. Be careful here to be sure you don't create a dead band where tiny movement of the throttle plate does not result in any change in the meter reading. I like to back the pot off till I get no change in the reading and then go back upward till I get the first change and lock things down there.

 

Another point. Below 400 mV, the O2 sensor is not taken into account for mixture control. The Motronic does use a map for idle mixture control or open loop running as it is normally called.

 

Thanks again. When I rechecked it, it read right on zero (0.006). I moved it to 0.010, and started adjusting the throttle stop from there. I found that every time I tightened the lock nut, the value went down, as if the screw was backing out of the flange when I tightened the lock nut. It maybe stripped. Seems to be holding how. It was a bear to get set. I finally got it to where it varied between 0.375 and about 0.385, between cycles of turning off the ignition, "blipping" the throttle, and then turning the ignition back on and rechecking the DVM. The variation may simply be the inaccuracy of the cheap DVM I have. I'm going to recheck everything after about 500 miles.

 

For now, though, it won't start. I'm not that surprised. It's been six months. I've replaced a ton of stuff, and I could have messed up in lots of different places. Fuel pump is providing pressure; doesn't seem to be getting gas.

 

Will run the routine checks tomorrow.. fuel injectors, fuel regulator.. and if there is fuel getting to the cylinders, then check for spark. Has to be something basic.

 

Or maybe I should go ahead and rebuild that HES now anyway, instead of waiting until I have it running.

 

That's for another thread.

[T__]

ShovelStrokeEd, I usually don’t use just a part of a quote but this one is kind of a stand alone & I only want o address this part.. If it’s a problem for you let me know & I won’t do it again..

 

Another point. Below 400 mV, the O2 sensor is not taken into account for mixture control. The Motronic does use a map for idle mixture control or open loop running as it is normally called.

 

That is not true if the bike comes equipped with an 02 sensor & the pink CCP.. Co at idle is a very large part of emission control so you basically have two choices, (1)- allow the 02 to control the base (under .4v) idle Co output,, or (2)- use a stand alone Co potentiometer to control the base idle Co output.. The foreign non 02 equipped 1100’s came with an 02 adjustment pot (the wires are there for that) ,, the USA 1100 came with a heated 02 sensor..

 

If you don’t believe what I just said just monitor the 02 cross counts at idle on a hot engine.. BTW I have..

 

Twisty

[ShovelStrokeEd]

Not doubting that the O2 sensor continues to output at any and all RPM. The point is whether or not the Motronic pays any attention to it. The fact is, it does not at idle RPM nor does it above about 5000 RPM and 35% throttle or so. The O2 sensor is there to optimize fuel mixture to keep a catalytic converter lit, not for control of CO. At idle, there is neither sufficient fuel running through the motor to keep the converter lit (hence no need for O2 sensor) nor is the 14.7:1 mixture dictated by the O2 sensor strong enough to maintain good idle.

 

The CO pots are fitted to bikes without the catalytic converter and are used to, as you stated, keep emissions down, but they are a different breed of cat, pardon the pun.

 

I remember this discussion on the Pelican Parts R1100S board from a couple of years ago and one of the guys there, who had attended a number of schools on the Motronic system, at Bosch, stated that closed loop operation is actually canceled, by the Motronic below 1500 RPM.

 

Keep in mind, the O2 sensor is actually a thermal conductivity device, and from my work with scientific equipment I can state that it will do nothing to measure CO if it is optimized to measure O2. I'm gonna go check on that but, I'm pretty sure I'm correct. Just don't want to confuse memory with facts.

[ShovelStrokeEd]

OK, I did some checking but the literature is both dense and diverse and doesn't give me what I am looking for. A definitive answer will have to wait till Tuesday night when I am back in our lab at work.

 

I have, available to me, a highly sensitive thermal conductivity device that will allow me to make quantative measurements of the amount of a particular gas entrained in a flowing stream of some other gas. I'll set it up to do some runs flowing a neutral background gas such as N2 or HE. I'll then inject equal quantities of O2 and CO and provide a graph of the difference.

[smiller]

An R1100 with a Power Commander installed definitely does use the O2 sensor to control A/F ratio at idle, i.e. the idle mixture will be whatever I set the closed loop A/F value to be. It could be that the Power Commander totally changes the original BMW design but I doubt it. O2 sensors are commonly used to control idle mixture in cars and I would expect that the Motronic operates in the same manner.

 

And the O2 sensor doesn't have to monitor CO values directly... it is intended to help the ECU set a specific mixture resulting in an assumed CO value, and the cat does the rest.

[ShovelStrokeEd]

Doesn't look at CO at all, only excess O2 in the exhaust stream. That's why it is called an O2 sensor not a CO sensor.

 

I would be very surprised if it is in the mixture control at idle. No load on the motor and hence, EGT is very low and that has a huge effect on the conductivity of gases. Gas velocity is also way down and that would make the thing even dumber than it already is.

[smiller]

Doesn't look at CO at all, only excess O2 in the exhaust stream. That's why it is called an O2 sensor not a CO sensor.

We're agreeing here. Guess I misunderstood your earlier comment.

 

I would be very surprised if it is in the mixture control at idle. No load on the motor and hence, EGT is very low and that has a huge effect on the conductivity of gases.

That's what heated O2 sensors are for (among other things.) And clearly it can be made to work because most modern automotive ECU systems operate in closed-loop at idle.

 

I can say with little doubt that the O2 sensor is being used to control the idle mixture in my example (R1100RT equipped with a Power Commander), it's very obvious when looking at it all on the Power Commander data port with my laptop. As I said, it's possible that the Power Commander does this while the stock Motronic does not, but I doubt it. BMW bikes equipped with cat converters have heated O2 sensors just like a car, and I don't see why they would operate differently. Lastly, why doesn't the CO pot exist on the cat-equipped bikes? If the O2 sensor isn't used at idle, wouldn't they need the same trim adjustment as the non-cat bikes?

[T__]

Not doubting that the O2 sensor continues to output at any and all RPM. The point is whether or not the Motronic pays any attention to it. The fact is, it does not at idle RPM nor does it above about 5000 RPM and 35% throttle or so. The O2 sensor is there to optimize fuel mixture to keep a catalytic converter lit, not for control of CO. At idle, there is neither sufficient fuel running through the motor to keep the converter lit (hence no need for O2 sensor) nor is the 14.7:1 mixture dictated by the O2 sensor strong enough to maintain good idle.

 

The CO pots are fitted to bikes without the catalytic converter and are used to, as you stated, keep emissions down, but they are a different breed of cat, pardon the pun.

 

I remember this discussion on the Pelican Parts R1100S board from a couple of years ago and one of the guys there, who had attended a number of schools on the Motronic system, at Bosch, stated that closed loop operation is actually canceled, by the Motronic below 1500 RPM.

 

Keep in mind, the O2 sensor is actually a thermal conductivity device, and from my work with scientific equipment I can state that it will do nothing to measure CO if it is optimized to measure O2. I'm gonna go check on that but, I'm pretty sure I'm correct. Just don't want to confuse memory with facts.

 

 

ShovelStrokeEd, seeing as idle emission control is a very large part of modern emission compliance just find me ANY heated 02 controlled vehicle that doesn’t use that 02 for idle fuel/air mixture moderation.. It makes no sense what so ever for BMW to ignore the 02 at idle & hope the cat. converter can remove all the Co at idle.. Unless combustion mixture is held at close to the mid 14:1 range the converter is not active enough to do much.. I guess the question would be why in the world would you even want to ignore the 02 at idle.. Sure WOT, high mid range power, or changing throttle but what would you gain at idle except higher emissions & carbon buildup..

 

As I mentioned just look at the 02 cross counts at HOT engine idle,. You CAN’T have cross counts without 02 feedback to the fueling computer & the computer responding to the 02.. If the computer was relying on only fixed mapping you would have either a set 02 output or a biased 02 output (either above or below .45mv) but you would NOT have 02 cross counts.. Those cross counts come form the computer seeing either rich or lean from the 02 then adding or subtracting fuel until the 02 flops over to the other side of .45mv.. About all a narrow band 02 can do is tell the computer rich or lean but really can’t tell it how much so it uses cross counts to keep the mixture in the stokiometric range..

 

Your saying that “Not doubting that the O2 sensor continues to output at any and all RPM” sort of says you didn’t think it trough.. The standard (narrow band) lambda 02 sensor is only accurate in a very narrow range so the fueling computer doesn’t really look at it’s voltage output as a finite control (just can’t be used in that fashion) instead it looks at the 02 cross counts to know when proper stokiometric mixture is maintained.. In fact if the computer sees a steady 02 voltage for long it assumes the 02 has failed..

 

 

Back in the early days before heated 02’s there was always the chance 02 would drop under about 600°f at idle so would become inactive.. Since the heated 02’s appearance that just doesn’t happen anymore..

 

Twisty

[ShovelStrokeEd]

Granted to both with a couple of comments. First off, all cars are multicylinder devices with all 4 more or less minimum cylinders dumping into one cat and one O2 sensor. That is more exhaust flow and more importantly an exhaust flow with 1/2 the variation over time that a twin will see. The O2 sensor has to see a variation in the excess oxygen in the exhaust stream but to measure it, it needs a sufficiently homogeneous mixture to sample. At idle rpm, I submit that is not the case. Yes, there will be a smoothing effect caused by the length of the system but I doubt it is sufficient to make the sensor act properly. There is already a significant lag at even 3K RPM with this primative device. What you may be seeing at idle might well represent this pulsing effect, not any pulse width modulation on the part of the Motronic.

 

I'll stick to the guy who went to school for it and he tells me, the early Motronics (R1100) did not use closed loop operation below 1500 RPM.

 

It is no trick at all to tune an idling engine down to 2% CO or below using only map information. I have done it on more than one custom EFI system. Does make it a little tough to start at zero throttle and, if you are not careful with the next step up the map, throttle response off idle can be problematic.

[T__]

Granted to both with a couple of comments. First off, all cars are multicylinder devices with all 4 more or less minimum cylinders dumping into one cat and one O2 sensor. That is more exhaust flow and more importantly an exhaust flow with 1/2 the variation over time that a twin will see. The O2 sensor has to see a variation in the excess oxygen in the exhaust stream but to measure it, it needs a sufficiently homogeneous mixture to sample. At idle rpm, I submit that is not the case. Yes, there will be a smoothing effect caused by the length of the system but I doubt it is sufficient to make the sensor act properly. There is already a significant lag at even 3K RPM with this primative device. What you may be seeing at idle might well represent this pulsing effect, not any pulse width modulation on the part of the Motronic.

 

I'll stick to the guy who went to school for it and he tells me, the early Motronics (R1100) did not use closed loop operation below 1500 RPM.

 

It is no trick at all to tune an idling engine down to 2% CO or below using only map information. I have done it on more than one custom EFI system. Does make it a little tough to start at zero throttle and, if you are not careful with the next step up the map, throttle response off idle can be problematic.

 

 

ShovelStrokeEd, actually I believe the very early 1100 (1994) didn’t even use closed loop at all.. As far as small engines using the 02 at idle.. All that I know of do.. There are some 1.1- 3 cylinder engines using the 02 for idle mixture modulation & some of those idle at way less than 1000 RPM’s.. How about an American 3.4 engine idling at 500 RPM’s using a separate 02 in each exhaust manifold..

 

Harley is using 02’s for idle fuel control on some of their twin cylinder engines..

 

The 02 operates in a sealed to the outside environment so it really doesn’t care how many pulses per minute it gets.. It simply measures the completeness of any combustion it is exposed to.. Complete combustion consumes most of the oxygen.. About the only problem at low exhaust gas flow is the 02 cooling off below 600°f but with the heated 02 units that isn’t a problem..

 

If that 02 is toggling over center voltage (cross counts) it IS DOING THAT IN RESPONSE TO THE FULING COMPUTERS injector pulse width control.. The 02 can’t respond fast enough to cross over it’s center voltage due to firing pulses & even if it could there is no outside influence of non combustion gas to influence it.. What would (even could) make that 02 toggle high to low or low to high due to just firing pulses?? It simply looks for non consumed oxygen in the exhaust so where would it find that?

 

That 02 sensor (the narrow band type) simply measures the amount of oxygen consumed in the combustion process & compares that to the oxygen in the air outside the exhaust system.. All it needs is combustion gas from firing cylinders in it’s sensor proximity & of course be above 600°f..

 

I guess, AGAIN, the question is: if you were designing an emission system that had to meet multi country exhaust emission regulations & had a heated 02 sensor already in place why in the world would you use a fixed map for idle control as that would make idle emission compliance very difficult to maintain.. I can see an aggressive lean default idle map in case the 02 gets lazy at cold slow idle but that sure wouldn’t be my primary idle fueling mixture control if I had an operational 02 sensor in the system..

 

If that base mapping is so good that it doesn’t need the 02 then way even bother with the Co. pot on some non US entries?

 

Twisty

[ShovelStrokeEd]

Well, I have a very early R1100 bought it in Aug of '93, and there is an O2 sensor on there. By your logic it shouldn't be using it in closed loop mode, but, by your other logic, it uses closed loop idle fuel control.

 

The fact that other gases are not introduced is not pertinent, there can and will be gas mixtures of varying strength in and around the O2 sensor, even with a constant output pulse width to the injectors. The distance, in time, between these will depend on idle RPM, distance of the sensor from the exhaust port and pipe diameter along with the temperature of the exhaust gases. In fact, the position of the sensor on the RS/RT exhaust is kinda poor at best, being in the collector and well downstream of the exhaust valves. Does have the advantage of getting an average from both cylinders though.

 

I guess the efficacy of such a system would depend, ultimately, on how often and when, if low cyclic rate, the sensor was polled and how much correction was applied based on the count. Yeah, I even suppose it could be done, after all, it's only software.

 

Care to guess when/where on the map the CO pot gets rendered ineffective? I know, from playing with one, that it can have a bad effect on throttle response off idle if adjusted too zealously on the green side of things.

[T__]

ShovelStrokeEd, obviously your 93 1100 uses closed loop if it has an 02.. Does it have a CCP? I read a 2.2 Motronic usage chart that showed the first 1100 usage wasn’t closed loop.. Either what I read was wrong, or not all were the same, or it was country specific..

 

As far as polling the sensor ? The Motronic doesn’t actually do that.. It simply monitors the voltage from the 02 sensor high side output.. It looks for a change in 02 voltage as it crosses the .45mv range.. I believe the 2.2 only uses 3 (internal) assigned values for the 02 input & that is determined by the voltage range that the 02 voltage comes in at.. That 02 is a simple chemical voltage generator & doesn’t care about exhaust pressure, flow rate, pulse rate.. It simply compares the oxygen it sees inside the exhaust to the oxygen level it sees outside the exhaust system.. It has a fairly slow response so the voltage it puts out would be a slow average at best.. Actually if you pulled the 02 out of the engine & just heated it’s sensor to over 600° with a torch it should put out somewhere’s around .5-.6 volts give or take..

 

On your Co. pot question.. That is a good question.. Logic would say probably around 1500 RPM’s but it could be just throttle position controlled (maybe the fine output side of the TPS).. Obviously if you had it effect throttle response at part throttle it had some effect in that range.. The information I read said the early 1100 -2.2 only had one map in the computer (probably wouldn’t have had a CCP if that were fact though).. I do know (well read anyhow) that IF some of the 2.2 systems had a OPERATIONAL 02 it wouldn’t respond to a Co. pot,, not sure what the usage or country was there though.. My information came from Opel engineering as one of the fuel system engineers I worked with originally came from Bosch.. He didn’t go back as far as the 2.2 development but had some basic 2.2 system charting & tuning manuals available.. Sure wish I had copied them but at that time it was just interesting reading never though I would need it.. I have access to most all of the Delco (Delphi) PCM usage & operational tuning info & limited access to the later Bosch info but Bosch is very tight lipped about the early 2.2 & 2.4 info (even the auto end of the 2.2 & 2.4).. In fact I worked on the early Delco closed loop systems well before the public even knew they existed way back in the early 70’s..

 

Twisty

[ShovelStrokeEd]

Mine does have (or did, I have a custom chip in it) a CCP. Probably a country specific thing.

 

The throttle response thing I was talking about was off-idle throttle response, or better described as response in transition from idle, which would fall into that 1500 RPM nicely. In fact, that may be where I have been lead astray in that the Motronic will cancel the effect of a CO pot but not that of the O2 sensor.

 

I suspect we have long since caused the OP's eyeballs to spin but I enjoy stuff like this.