Motronic - long, & not for the uninitiated.

[Robin-535im]

For those interested in the pedantic details of the Motronic, I think I have it all figured out. For those who know where I'm wrong... please enlighten me! For those of you who don't care, this will be really boring. :)

Here goes: The main purpose of the Motronic (aka DME, ECU) is to make the car run at the 14.7:1 air:fuel ratio that is the accepted best point for a balance of power, emissions and fuel economy. It does this by setting the spark advance timing and the fuel injector pulse duration.

There are several operating modes including startup, warm running, WOT; the last two being those of most interest to us.

Warm running: Engine RPM and air flow are used to look up the correct timing advance and fuel pulse duration for that run point. The computer looks first at the ECU maps (the thing chip tuners modify) and adds to that an offset value for the pulse duration that is learned over time by the history of O2 corrections made in the past. This is the "learning" that our cars do: as we drive down the road, the O2 circuit is constantly trying to make the car run at 14.7:1 air:fuel ratio. It reads the exhaust gas, and modifies the injector pulse duration to reach that ratio. It gradually builds a map of adjustment values for each RPM/Air Flow operating point and adds that to the map that chip tuners program as the starting point, and twiddles it continuously to make the right output ratio.

So reprogramming the fuel map and adding a larger FPR should have no persistant effect to performance in the warm-running condition. All you can do is increase the timing advance as much as you can before it pre-detonates, and let the Motronic stabilize the fuel pulse duration to make the exhaust hit 14.7:1. Note: if in fact your engine needs more gas than can be delivered in the max pulse duration, a larger FPR will overcome that and let you have more fuel, but only up to the point where it again reaches equilibrium. This is most likely to happen at high speeds, where both load and RPM are maxed out and the time available in the cycle for injecting fuel is less than the pulse duration required. Just adding a larger FPR will make the car run rich for the first 10 minutes or so, until the car adapts, and then you're back at 14.7:1, in the warm-running mode.

This is why chips take a while to fully set up. When you first put it in you have to unplug the DME from the car, which erases the learned fuel-pulse-duration-offset map. Your timing is now advanced, but the fuel map is not stabilized at the best setting for 14.7:1 operation - it's just whatever was programmed by the chip tuner. As you drive around town (heavy footed now because it's so much more fun that way) the computer watches all the corrections it has to make at all the RPM/Air Flow operating points and stores that away, averaging them over time. Gradually, this learned fuel duration offset map stabilizes, and it acts as a feed-forward command (any controls engineers out there?) to the engine, so that instead of having to read the O2 signal and correct after the fact, it anticipates the correct pulse duration and uses that as a starting point. The O2 signal is still used to fine tune the pulse duration, and if anything changes in the system, the car will adapt to it over time to within reasonable limits.

Wide Open Throttle (WOT): In this case, the O2 signal is ignored. The engine RPM is used to determine the pulse duration and timing advance. There is no learning... the chip map is it. Here's where the fuel map programming matters too, because what you program is what you get. In this case, a perfect chip would have both timing advance and fuel map programmed for your particular car and you can choose to run at a different air/fuel ratio, such as 13.5:1 which is close to the "maximum power" point. But to get it to run there, you have to read the exhaust gas for all the operating points, and manually tune the pulse duration as well as the timing to make the WOT map just right.

Conclusions? Well...
1) To really tune your car right you need to read the exhaust gas and optimize the WOT map fuel pulse duration.
2) Those of us who drive at 6000 RPM a few times a day will probably benefit from a larger FPR, but you need to look at the exhaust to know for sure.
3) I have too much time on my hands.
4) The learning feature of our cars means all we can really change is the timing advance in the warm-running mode, the rest will adapt.

[632 Regal]

Very good write up, I followed it and even understand it!!

[gale]

Thanks for sharing your insights Robin. Along those lines, I'm still not clear whether the DME & TCU (automatic) are very tightly integrated on engines that have the EML throttles. Know anything about them? My interest is I'd love to do an m70 conversion with a manual trans but don't know what intricacies are involved, I know it's been done but largely with 850 parts. Wouldn't want to get 90% into one only to have it go into permanant limp mode.

Mine is a plain bread & butter m30 with the conventional mechanical direct cable throttle so had no issues with it.

[BennyM]

.

[George M]

yup...nice summary Robin. You hit 6K RPM a few times a day? Wow!
:-)

[DanDombrowski]

It probably is pretty integrated, but I'm not sure about the BMWs, I'm basing my assumption on working with our Jeep which, when the tranny output sensor went bad, made the engine have some wacky throttle patterns, and that has an EML if I'm not mistaken.


Thanks for sharing your insights Robin. Along those lines, I'm still not clear whether the DME & TCU (automatic) are very tightly integrated on engines that have the EML throttles. Know anything about them? My interest is I'd love to do an m70 conversion with a manual trans but don't know what intricacies are involved, I know it's been done but largely with 850 parts. Wouldn't want to get 90% into one only to have it go into permanant limp mode.

Mine is a plain bread & butter m30 with the conventional mechanical direct cable throttle so had no issues with it.

[DanDombrowski]

This adaptation is what allows most people to run a low boost turbo setup without extensive computer modifications, as the car adapts to the extra air. Been meaning to try it on my Volvo as many people have done for under $300, but I'll be damned if every time I try I keep getting calls asking why I'm not at work. They want me to go EVERY Monday through Friday? Geez!

Where did you find information that the computer ignores the O2 readout at WOT? As I understand it from riding in cars w/ A/F meters, thats the only time that you can actually read the gauge accurately, as at partial throttle it jumps all over the place. Not saying that the ECM doesn't ignore it, just wondering where you read that.

Now, let me know when you find some way to plug into these cars ECMs and get diagnostic data on a PC. I've been doing that alot at work lately, and you can get some pretty in depth info from newer cars.

Good luck



For those interested in the pedantic details of the Motronic, I think I have it all figured out. For those who know where I'm wrong... please enlighten me! For those of you who don't care, this will be really boring. :)

Here goes: The main purpose of the Motronic (aka DME, ECU) is to make the car run at the 14.7:1 air:fuel ratio that is the accepted best point for a balance of power, emissions and fuel economy. It does this by setting the spark advance timing and the fuel injector pulse duration.

There are several operating modes including startup, warm running, WOT; the last two being those of most interest to us.

Warm running: Engine RPM and air flow are used to look up the correct timing advance and fuel pulse duration for that run point. The computer looks first at the ECU maps (the thing chip tuners modify) and adds to that an offset value for the pulse duration that is learned over time by the history of O2 corrections made in the past. This is the "learning" that our cars do: as we drive down the road, the O2 circuit is constantly trying to make the car run at 14.7:1 air:fuel ratio. It reads the exhaust gas, and modifies the injector pulse duration to reach that ratio. It gradually builds a map of adjustment values for each RPM/Air Flow operating point and adds that to the map that chip tuners program as the starting point, and twiddles it continuously to make the right output ratio.

So reprogramming the fuel map and adding a larger FPR should have no persistant effect to performance in the warm-running condition. All you can do is increase the timing advance as much as you can before it pre-detonates, and let the Motronic stabilize the fuel pulse duration to make the exhaust hit 14.7:1. Note: if in fact your engine needs more gas than can be delivered in the max pulse duration, a larger FPR will overcome that and let you have more fuel, but only up to the point where it again reaches equilibrium. This is most likely to happen at high speeds, where both load and RPM are maxed out and the time available in the cycle for injecting fuel is less than the pulse duration required. Just adding a larger FPR will make the car run rich for the first 10 minutes or so, until the car adapts, and then you're back at 14.7:1, in the warm-running mode.

This is why chips take a while to fully set up. When you first put it in you have to unplug the DME from the car, which erases the learned fuel-pulse-duration-offset map. Your timing is now advanced, but the fuel map is not stabilized at the best setting for 14.7:1 operation - it's just whatever was programmed by the chip tuner. As you drive around town (heavy footed now because it's so much more fun that way) the computer watches all the corrections it has to make at all the RPM/Air Flow operating points and stores that away, averaging them over time. Gradually, this learned fuel duration offset map stabilizes, and it acts as a feed-forward command (any controls engineers out there?) to the engine, so that instead of having to read the O2 signal and correct after the fact, it anticipates the correct pulse duration and uses that as a starting point. The O2 signal is still used to fine tune the pulse duration, and if anything changes in the system, the car will adapt to it over time to within reasonable limits.

Wide Open Throttle (WOT): In this case, the O2 signal is ignored. The engine RPM is used to determine the pulse duration and timing advance. There is no learning... the chip map is it. Here's where the fuel map programming matters too, because what you program is what you get. In this case, a perfect chip would have both timing advance and fuel map programmed for your particular car and you can choose to run at a different air/fuel ratio, such as 13.5:1 which is close to the "maximum power" point. But to get it to run there, you have to read the exhaust gas for all the operating points, and manually tune the pulse duration as well as the timing to make the WOT map just right.

Conclusions? Well...
1) To really tune your car right you need to read the exhaust gas and optimize the WOT map fuel pulse duration.
2) Those of us who drive at 6000 RPM a few times a day will probably benefit from a larger FPR, but you need to look at the exhaust to know for sure.
3) I have too much time on my hands.
4) The learning feature of our cars means all we can really change is the timing advance in the warm-running mode, the rest will adapt.

[Hector]

the EAT chip, optimum performance will not be achieved right away until a "learning curve" has been established. ...and I thought all this was just a crap shoot :o)

[MarkD]

Hi Robin,
what you posted is basically correct but there is still more that could be added. (such as timing CORRECTION MAPS that retard timing based on IAT and coolant temperature)

Also, the WOT maps are trimmed based on the value that the software sees it has to trim the Part Throttle (PT maps) by. Part Throttle mode is what you call "warm running". The DME switches between PT and WOT mode by looking at for the WOT switch on the TPS to close. This usually happens at around 75% of the gas pedal depression.

Since the software trims the WOT fuel maps, increasing fuel pressure or using bigger injectors does not work as well as could be expected, unless you adjust the WOT fuel maps in the chip to supply more fuel also.


Mark



For those interested in the pedantic details of the Motronic, I think I have it all figured out. For those who know where I'm wrong... please enlighten me! For those of you who don't care, this will be really boring. :)

Here goes: The main purpose of the Motronic (aka DME, ECU) is to make the car run at the 14.7:1 air:fuel ratio that is the accepted best point for a balance of power, emissions and fuel economy. It does this by setting the spark advance timing and the fuel injector pulse duration.

There are several operating modes including startup, warm running, WOT; the last two being those of most interest to us.

Warm running: Engine RPM and air flow are used to look up the correct timing advance and fuel pulse duration for that run point. The computer looks first at the ECU maps (the thing chip tuners modify) and adds to that an offset value for the pulse duration that is learned over time by the history of O2 corrections made in the past. This is the "learning" that our cars do: as we drive down the road, the O2 circuit is constantly trying to make the car run at 14.7:1 air:fuel ratio. It reads the exhaust gas, and modifies the injector pulse duration to reach that ratio. It gradually builds a map of adjustment values for each RPM/Air Flow operating point and adds that to the map that chip tuners program as the starting point, and twiddles it continuously to make the right output ratio.

So reprogramming the fuel map and adding a larger FPR should have no persistant effect to performance in the warm-running condition. All you can do is increase the timing advance as much as you can before it pre-detonates, and let the Motronic stabilize the fuel pulse duration to make the exhaust hit 14.7:1. Note: if in fact your engine needs more gas than can be delivered in the max pulse duration, a larger FPR will overcome that and let you have more fuel, but only up to the point where it again reaches equilibrium. This is most likely to happen at high speeds, where both load and RPM are maxed out and the time available in the cycle for injecting fuel is less than the pulse duration required. Just adding a larger FPR will make the car run rich for the first 10 minutes or so, until the car adapts, and then you're back at 14.7:1, in the warm-running mode.

This is why chips take a while to fully set up. When you first put it in you have to unplug the DME from the car, which erases the learned fuel-pulse-duration-offset map. Your timing is now advanced, but the fuel map is not stabilized at the best setting for 14.7:1 operation - it's just whatever was programmed by the chip tuner. As you drive around town (heavy footed now because it's so much more fun that way) the computer watches all the corrections it has to make at all the RPM/Air Flow operating points and stores that away, averaging them over time. Gradually, this learned fuel duration offset map stabilizes, and it acts as a feed-forward command (any controls engineers out there?) to the engine, so that instead of having to read the O2 signal and correct after the fact, it anticipates the correct pulse duration and uses that as a starting point. The O2 signal is still used to fine tune the pulse duration, and if anything changes in the system, the car will adapt to it over time to within reasonable limits.

Wide Open Throttle (WOT): In this case, the O2 signal is ignored. The engine RPM is used to determine the pulse duration and timing advance. There is no learning... the chip map is it. Here's where the fuel map programming matters too, because what you program is what you get. In this case, a perfect chip would have both timing advance and fuel map programmed for your particular car and you can choose to run at a different air/fuel ratio, such as 13.5:1 which is close to the "maximum power" point. But to get it to run there, you have to read the exhaust gas for all the operating points, and manually tune the pulse duration as well as the timing to make the WOT map just right.

Conclusions? Well...
1) To really tune your car right you need to read the exhaust gas and optimize the WOT map fuel pulse duration.
2) Those of us who drive at 6000 RPM a few times a day will probably benefit from a larger FPR, but you need to look at the exhaust to know for sure.
3) I have too much time on my hands.
4) The learning feature of our cars means all we can really change is the timing advance in the warm-running mode, the rest will adapt.

[winfred]

they wouldn't put numbers that high on the tach if they didn't want you to go there :) i make it a point to air em out a few times a day if for no other reason if i need to stomp on some unsuspecting fartcan honda it doesn't belch out that nasty cloud of soot that accumulats, now on diesels i love that cloud, it's fun to fart all over some ******* that riding your bumper if i didn't have too many car projects allready id take on the 524td that's at the shop 5 speed it, intercool it, add a egt gauge, and start turning up the injection pump and wastegate


You hit 6K RPM a few times a day?

[George M]

hehehe...I love your style Winfred!

[MarkD]

Where did you find information that the computer ignores the O2 readout at WOT? As I understand it from riding in cars w/ A/F meters, thats the only time that you can actually read the gauge accurately, as at partial throttle it jumps all over the place. Not saying that the ECM doesn't ignore it, just wondering where you read that.

Good luck


The DME can't use the O2 sensor at WOT because the sensor output is very non-linear. (it's not a wideband O2 sensor) Since the WOT a/f ratio is not close to stoichiometric (and the narrowband sensor wants to see an excursion through this point) the DME runs open-loop in WOT. Some new cars have wideband sensors that allow sampling the O2 sensor at WOT also. The New Beetle, some Porsches, and Cadillacs have wideband O2 sensors.

(edited after posting) : I forgot to mention that the reason you see the narrowband afr meter display juming all over the place is because the O2 sensor is switching between roughly .2V and .8V about 20 times a second. These two voltages indicate lean and rich, and .5V indicates lambda = 1.0

When running WOT, the a/f ratio will stay around 12.5 to 13.6 : 1


Mark

[DanDombrowski]

Interesting. BTW mark, I still have 2 of those chips at home from the group buy if you want me to send them somewhere or back to you.


The DME can't use the O2 sensor at WOT because the sensor output is very non-linear. (it's not a wideband O2 sensor) Since the WOT a/f ratio is not close to stoichiometric (and the narrowband sensor wants to see an excursion through this point) the DME runs open-loop in WOT. Some new cars have wideband sensors that allow sampling the O2 sensor at WOT also. The New Beetle, some Porsches, and Cadillacs have wideband O2 sensors.

Mark

[MarkD]

Interesting. BTW mark, I still have 2 of those chips at home from the group buy if you want me to send them somewhere or back to you.

Dan,

don't send them back here, please keep them in case someone wants them in the USA. If you were going to the Chicago meet I'd say take them there in case anyone is looking for one, but I don't think you'll be driving that far.

Mark

[DanDombrowski]

I'd love to go to the Chicago meet but no, thats too long to drive. Perhaps a South Florida meet if I'm in town when one goes on. I'll hang on to them in my office until whenever, its no big deal.



Dan,

don't send them back here, please keep them in case someone wants them in the USA. If you were going to the Chicago meet I'd say take them there in case anyone is looking for one, but I don't think you'll be driving that far.

Mark

[Bellicose Right Winger]

This is a fabulous discussion on the operation of the DME, thanks for taking the time Robin.

On the WOT issue, it's important to recognize that an engine produces maximum torque at 85-90% of lambda, where lambda is the ideal A/F Ratio. This is 10-15% richer then stoichiometric. The DME tries to achieve this and emissions are secondary, as they should be, when you're making a pass on a two lane road.

I was unaware of wide band O2 sensors, being a stuck in the '80s kinda of a guy. Although I can't imagine why anyone would want to monitor much less control emissions at WOT. Must be a regulation. Thanks for the insight.

....O2 sensor switching...? Mark, I suspect you mean the O2 sensor output varies .2-.8v as a result of exhaust gas composition change caused by the PID loop the DME uses to continuously vary injector durations. All this in a effort to keep O2 sensor output in the desired range.

Anyone know where to get the latest version (1999, I think) of the Bosch Technical Instruction - Motronic"? It seems to be out of print and should be required reading for all board members. I've got a early '80's version I think I can email.

Paul Shovestul



The DME can't use the O2 sensor at WOT because the sensor output is very non-linear. (it's not a wideband O2 sensor) Since the WOT a/f ratio is not close to stoichiometric (and the narrowband sensor wants to see an excursion through this point) the DME runs open-loop in WOT. Some new cars have wideband sensors that allow sampling the O2 sensor at WOT also. The New Beetle, some Porsches, and Cadillacs have wideband O2 sensors.

(edited after posting) : I forgot to mention that the reason you see the narrowband afr meter display juming all over the place is because the O2 sensor is switching between roughly .2V and .8V about 20 times a second. These two voltages indicate lean and rich, and .5V indicates lambda = 1.0

When running WOT, the a/f ratio will stay around 12.5 to 13.6 : 1


Mark

[Robin-535im]

Hi Robin,
what you posted is basically correct but there is still more that could be added. (such as timing CORRECTION MAPS that retard timing based on IAT and coolant temperature)

Also, the WOT maps are trimmed based on the value that the software sees it has to trim the Part Throttle (PT maps) by. Part Throttle mode is what you call "warm running". The DME switches between PT and WOT mode by looking at for the WOT switch on the TPS to close. This usually happens at around 75% of the gas pedal depression.

Since the software trims the WOT fuel maps, increasing fuel pressure or using bigger injectors does not work as well as could be expected, unless you adjust the WOT fuel maps in the chip to supply more fuel also.


Mark

So there is a timing correction map that retards the timing set by the PT map by looking up the inlet air and head temperatures... Is that adaptive or programmed in ROM?

Also - the WOT map trimmed by the accumulated pulse duration offset map from the lambda control just like the PT map. So all you have to do is program the WOT map higher by the ratio you want the WOT a/f ratio higher than the PT ratio? I.e., if your WOT fuel map is 10% richer than the PT map, the car will still run 10% richer at WOT even after the trim map is applied, right?

Good info!

[Robin-535im]

This is a fabulous discussion on the operation of the DME, thanks for taking the time Robin.

On the WOT issue, it's important to recognize that an engine produces maximum torque at 85-90% of lambda, where lambda is the ideal A/F Ratio. This is 10-15% richer then stoichiometric. The DME tries to achieve this and emissions are secondary, as they should be, when you're making a pass on a two lane road.

I was unaware of wide band O2 sensors, being a stuck in the '80s kinda of a guy. Although I can't imagine why anyone would want to monitor much less control emissions at WOT. Must be a regulation. Thanks for the insight.

....O2 sensor switching...? Mark, I suspect you mean the O2 sensor output varies .2-.8v as a result of exhaust gas composition change caused by the PID loop the DME uses to continuously vary injector durations. All this in a effort to keep O2 sensor output in the desired range.

Anyone know where to get the latest version (1999, I think) of the Bosch Technical Instruction - Motronic"? It seems to be out of print and should be required reading for all board members. I've got a early '80's version I think I can email.

Paul Shovestul


I'm at robin(nospam).ritter@ngc.com w/o the (nospam)

[Bill R.]

any confusion. Lambda is Stoichiometric, this is the ideal point where combustion is the closest to complete, the 10 to 15% richer that Paul is talking about is the air to fuel ratio that maximum power is produced at.





This is a fabulous discussion on the operation of the DME, thanks for taking the time Robin.

On the WOT issue, it's important to recognize that an engine produces maximum torque at 85-90% of lambda, where lambda is the ideal A/F Ratio. This is 10-15% richer then stoichiometric. The DME tries to achieve this and emissions are secondary, as they should be, when you're making a pass on a two lane road.

I was unaware of wide band O2 sensors, being a stuck in the '80s kinda of a guy. Although I can't imagine why anyone would want to monitor much less control emissions at WOT. Must be a regulation. Thanks for the insight.

....O2 sensor switching...? Mark, I suspect you mean the O2 sensor output varies .2-.8v as a result of exhaust gas composition change caused by the PID loop the DME uses to continuously vary injector durations. All this in a effort to keep O2 sensor output in the desired range.

Anyone know where to get the latest version (1999, I think) of the Bosch Technical Instruction - Motronic"? It seems to be out of print and should be required reading for all board members. I've got a early '80's version I think I can email.

Paul Shovestul

[winfred]

i use to be a parts runner for a euro shop a long time ago and the shop car was a 240 diesel volvo wagon with a 4 speed od stick, oh that was fun painting a tailgaters hood and grill black, it's that bosch ve injection pump (same as 524 td) lotsa power lotsa smoke at high rpm 4-5k, turbos with this pump are even better


hehehe...I love your style Winfred!

[DanDombrowski]

damn, that thing must have been SLOW. My 240 is a gas sedan, and I didn't think it got any worse than that. A diesel wagon? I guess it don't matter when you're on the clock, right?



i use to be a parts runner for a euro shop a long time ago and the shop car was a 240 diesel volvo wagon with a 4 speed od stick, oh that was fun painting a tailgaters hood and grill black, it's that bosch ve injection pump (same as 524 td) lotsa power lotsa smoke at high rpm 4-5k, turbos with this pump are even better

[Bill R.]

emissions since the monitor a wider range more accurately from 11 to 1 all the way up to straight air.. they are able to control wide open throttle and keep it exactly at the required ratio for maximum power instead of having to go strictly off the map which may or may not take into consideration small faults or changes that affect the overall fuel ratio such as vacum leaks etc... the wide band will allow for these corrections.. Also on the newer direct injection gas engines that are coming out, they will run stratified charge and wide band is the only way they can accurately measure the ratios when they get that lean... It looks like its a win win deal to me except for the cost of the wide band sensors compared to the old 1,2,3 or 4 wire sensors...






QUOTE=Robin-535im]I'm at robin(nospam).ritter@ngc.com w/o the (nospam)[/QUOTE]

[MarkD]

So there is a timing correction map that retards the timing set by the PT map by looking up the inlet air and head temperatures... Is that adaptive or programmed in ROM?


It's programmed in ROM



Also - the WOT map trimmed by the accumulated pulse duration offset map from the lambda control just like the PT map. So all you have to do is program the WOT map higher by the ratio you want the WOT a/f ratio higher than the PT ratio? I.e., if your WOT fuel map is 10% richer than the PT map, the car will still run 10% richer at WOT even after the trim map is applied, right?

Good info!

Yes that is correct. Now I guess everyone here is going to start making their own chips. :(

[George M]

Mark....I think you are safe....LOL.

[MarkD]

emissions since the monitor a wider range more accurately from 11 to 1 all the way up to straight air.. they are able to control wide open throttle and keep it exactly at the required ratio for maximum power instead of having to go strictly off the map which may or may not take into consideration small faults or changes that affect the overall fuel ratio such as vacum leaks etc... the wide band will allow for these corrections.. Also on the newer direct injection gas engines that are coming out, they will run stratified charge and wide band is the only way they can accurately measure the ratios when they get that lean... It looks like its a win win deal to me except for the cost of the wide band sensors compared to the old 1,2,3 or 4 wire sensors...



Wideband sensors are actually getting quite cheap now. I think you can get a New Beetle sensor for around $50 USD and I have bought a few wideband sensors in Canada (from NAPA) for around $120 Canadian. Sorry I can't tell you what I'm doing with them yet. :D

Mark

[Jeff N.]

:)

[Jeff N.]

Dead slow. Fun to drive though. People'd get on yer ass and you'd just put the throttle to the floor. Thing would dump a soot cloud equal to a Navy destroyer. Best was when the abusing assrider was pinched behind you and had nowhere to go. They just had to sit there and suck fumes till traffic opened up.

Was much more entertaining at times then zooming around in the Turbo Saabs on the lot. :D

I seem to recalll those diesel 240s could drop quite a cloud as well. We had some of those but I think the Isuzu was even better. Now, I did really like the Volvo 760 Turbo Diesels...great highway car!

Jeff

[George M]

:p ...yes WBO2's are becoming quite common not only on production cars but in the tuner market. No mystery as they bring much more to the table which ties into a discussion previously about using stock NA engine management even with tweaked air/fuel and timing maps on boosted engines....where a WBO2 and either stand alone or piggy back engine management shines. Using a stock 02 sensor and say Autometer A/F gauge for insight is playing with fire unless you REALLY know what you are doing. Unless you have a way to tune the A/F ratio like with a S AFC or another controller of some sort it's just a lights parade. When you do have a signal conditioner for the MAP you can tune it for any open loop conditions. It doesn't do anything in closed loop because it's going to work to be as close to the 02 sensor cross over point of 14.7:1 as possible. This makes sense because in closed loop you are not loading the engine so even boosted it would be just fine to be tuned to 14.7:1
The contradiction is...understanding that a standard 02 sensor even heated 4 wire ones are only accurate in a VERY fine range around 14.7:1 and either side of that is less accurate in a semi-parabolic trend toward inaccurate the further they get from the cross over of 14.7:1

All the stock primary 02 sensor does is tell the DME 0 or 1, that's it. It's a discrete sensor that tells the DME iteratively if it's rich or lean.

So with the A/F gauge and stock 02 sensor all you can do is tune it to the green and hope it's close. Not to rich and not too lean. Even then an older sensor will be less accurate and even that changes with temp of the sensor.

Heated ones are just as inaccurate, but respond quicker.

Solution is to get an inexpensive wide band 02 sensor controller and install that. Then you'll have a real WB02 sensor and controller for under $400.

[Robin-535im]

Yes that is correct. Now I guess everyone here is going to start making their own chips. :(


... to ask him if they can buy a specially tuned chip just for their car. :)

[George M]

you may have made that statement rhetorically Robin...hehe. Just not cost effective for Mark or the buyer. Mark will tell you first hand, like most business big or small...its a numbers game. Because of the huge development cost...time mostly...laborious trial and error in large measure...in particular for a custom giddy up...no ROI. Would be cheaper to purchase a stand alone and do your own programming.

[Robin-535im]

you may have made that statement rhetorically Robin...hehe. Just not cost effective for Mark or the buyer. Mark will tell you first hand, like most business big or small...its a numbers game. Because of the huge development cost...time mostly...laborious trial and error in large measure...in particular for a custom giddy up...no ROI. Would be cheaper to purchase a stand alone and do your own programming.

Or rather, someone with too much time on his hands goes out and instruments his car to measure WB O2, timing, pulse duration, RPM, inlet air temp, etc., then orders up a chip with timing and WOT fuel maps specifically tuned to his car...

Someone... perhaps someone who hits 6000 a few times a day? Seriously though, I'm really trying to understand why my car runs really great some days and just mostly great other days, and if there is something cost effective (key word there) to make it run really great all the time.

[George M]

the aftermarket is sprinkled (littered?) with guys just as you describe...over the top tuners who want to control everything. I have such a friend with a modded Buick Grand National (turbo V6) that run's 11's. He is forever tweaking his stand alone in pursuit of just a bit more performance. As to why your car runs good some days and not so others...depends on how precipitous the divide but humidity and air temp are HUGE.
Ask the nitrous guys who run bottle warmers :-) or the guys who dry ice their intakes before runs :-)

[winfred]

i don't know if the injection pumps were outta time or they were just that crude that they ran that rich, you could restripe the road with a diesel pup or luv. mom likes her old 740 turbo diesel but it's for sale because she really likes the 90 325isa i got her


but I think the Isuzu was even better

[Bellicose Right Winger]

Hmm....this doesn't sound right George. O2 sensors produce a continuous analog signal that's inversely proportional to exhaust O2. The DME needs a continuous error signal in order for PID control to work. The error signal is the difference between O2 sensor output and the setpoint established by the DME. Just knowing the O2 sensor output is too low or too high isn't good enough to make PID control work.

Paul Shovestul


[QUOTE=George M
.....All the stock primary 02 sensor does is tell the DME 0 or 1, that's it. It's a discrete sensor that tells the DME iteratively if it's rich or lean.
[/QUOTE]

[Jeff N.]

i don't know if the injection pumps were outta time or they were just that crude that they ran that rich, you could restripe the road with a diesel pup or luv. mom likes her old 740 turbo diesel but it's for sale because she really likes the 90 325isa i got her

[Paul in NZ]

runs purely on the preprogrammed maps, or there still some "learning" to do.I would guess not as there is no feedback .Why would my car take a week or more to settle down after say abttery disconnect or the changing of a icv or similar.......

[George M]

Paul S....A friend of mine designs engine management for supercharged cars. We have had many discussions about how the DME interrupts a narrow band O2 input. Believe the analog signal is converted for expediency...binary comparison against DME baseline iterated/sampled many times per second (doesn't the D in DME stand for digital? :-))as the DME needs to adapt in milliseconds to O2 input. The DME doesn't have time to interpret an array of analog input from the O2 and adjust injector pulse duration accordingly.