Rebuilt my S2 3b few years ago, now I have AAN ignition and ECU, running MTM chip with 1.4 bar. Suddenly my narrowband lambda stopped moving and jammed on 0,8 only comes down when shifting. Vag com shows no faults, have replaced three lambdas. Also replaced injectors and pressure regulation valve (3b-AAN) and PRV(3b- 7A). As we measured CO, the result was: with AAN injectors CO was 1,800 and with 3b injectors it was 1,200. During 15 minute warmup in the morning the car consumes 0,4 liters gasoline. The mistery is that when the temperature scale hits 90+, lambda starts moving again. After next start its stuck with 0,8 again
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Call me, I can most likely help you...
5151622
P.S.
There is no "MTM chip" with 1.4 bar.
You have wrong software in car most likely or your MAF is bad... anyway, easier to talk on the phone.
Your car is running rich all the time, and your ECU can barely compensate for it. When engine is not fully warm, it runs a bit richer, and that puts it over the limit. Your error codes regarding lambda limits not reached, are not because of bad lambda, whoever told you to replace it has no business diagnosing these engines...Last edited by prj; 21 December 2010, 12:26. -
if you will find the problem , please write it here... because I have simullar opinion about 3b and aan injectors on AAN software..Comment
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So far it seems the ECU does not see lambda value.
With lambda stuck at 0.8V there are no codes and short term fuel trim is 126.
This is not how the AAN ecu should operate. So my theory is that something in the wiring harness is connected wrong... this will be tested and an update will be written.Comment
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Is it possible that the G62 ECU Coolant temp sensor is causing this problem, i.e. it has failed and the ECU thinks it is cold out all the time?
Some G62 info:
RS2'd 93 UrS4 5 spd sedan
94 UrS4 V8 6 spd manual avantComment
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Yeah, that is possible as well...
But the guy just disconnected the lambda sensor and there are no codes in the ECU.
IIRC I instantly got a code if I disconnected the sensor.
Which pin should the lambda be on? He has it on PIN 28.Comment
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AAN ECU T55 Pin-out with hyperlinks to devices
Yes, the O2 (lambda) sensor should be on pin 28, as shown in this AAN ECU pin-out (with hyperlinks to the various devices)
RS2'd 93 UrS4 5 spd sedan
94 UrS4 V8 6 spd manual avantComment
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Coolant temp sensor - Group 1, Value 2 shows 85 degrees, as it should.
Disconnecting lambda does not throw a code, but the adaptation value *slightly* changes when it is reconnected. It increases, which should mean adding fuel.
Voltmeter measures close to stoich when lambda is disconnected, but when it is connected mixture just goes rich.
The only thing I can come up with is an electrical fault in the wiring. A different ECU has been tried as well and the results were the same.Comment
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well if the "qba" do the pin swap from 3b to aan , they don't need to touch pin 28 (lambda probe) . check the wiring between lambda and ECU, the wire must be in contact.
when do you do pin swap to AAN..? now or before? if you do it before , do you drive normal in middle time on AAN ECU? I do the same swap , and you need to have aan injectors, and 4 bar FPR. thats all.
I think that lambda probe is dead.Comment
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Checked. Resistance 0.3 ohm.
No, you don't need. 3B injectors are fine at 3 Bar FPR, because they flow exactly the same as AAN injectors with 4 bar FPR.when do you do pin swap to AAN..? now or before? if you do it before , do you drive normal in middle time on AAN ECU? I do the same swap , and you need to have aan injectors, and 4 bar FPR. thats all.
No, it toggles perfectly fine and he has tried three different ones. The issue is not lambda being dead, but the ECU not reacting to it.I think that lambda probe is dead.Comment
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sorry I didn't see that you already try to change the lambda probe.
well than is not he problem in lambda. how did engine work? are they shaking or some other strange things are happened ? do you thy to change MAF ?
in some cases I have a same problem, my conection on MAF have cold joint , but I can't find where. every 3 weeks at cold start at morning it start to have very rich mixture , I have some shitt AFR gauge and I see it amediatly on it (for this is good) , open the hood and do a little shake on MAF conector, and it is good for another 3 weeks, than again ... I will drive a little while with this "problem" ,because at spring my MAF will go in past...
thy to do this...Comment
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they flow the same like 3b injectors with 3b FPR ?????Comment
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Can't test WOT much with all the snow here. MAF has been changed.
In this case, motronic will throw a code due to adaptation limit being exceeded, or at least the adaptation will be high up.in some cases I have a same problem, my conection on MAF have cold joint , but I can't find where. every 3 weeks at cold start at morning it start to have very rich mixture , I have some shitt AFR gauge and I see it amediatly on it (for this is good) , open the hood and do a little shake on MAF conector, and it is good for another 3 weeks, than again ... I will drive a little while with this "problem" ,because at spring my MAF will go in past...
thy to do this...
Right now the value is at RICH all the time and motronic does not remove fuel.
If I take my car and constantly apply 0.8V on the lambda input, it leans the mixture, until I am running 25 AFR and the engine is barely working, then throws a code.
His ECU is not doing anything. Also his ECU does not throw a code if the lambda probe is completely disconnected.Comment
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are you 100% shore that aan injectors with 4bar FPR flow the same like 3B injectors with 3.2 bar FPR (stock fpr)...?Comment
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