Audi A4 B5 Cold start problem.
09-17-2021, 08:07 AM
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Audi A4 B5 Cold start problem.
Hello guys,
I'm new account holder, however I follow this forum from a long time, anyway I finally decided to share my problem here because I can't find the source of it. I'll provide some specs on the car first and will list the problem bellow, I replaced many part since I bought it and I'm always trying to keep it under OEM specs. Enough talking here's the car details:
Audi A4 B5, 1997, 1.8L, FWD, engine code ADR, 5-speed manual, 92KW/125hp this is a non-turbo model.
Car has installed LPG system, however always starts on GAS and after engine warm up (70°C) then switch to LPG.
Motul 8100 X-CESS 5W-40, all filters are Mahle Knecht.
Car runs flawlessly on both fuel systems, but from a month ago begin to have cold start problems and specifically RPM drops. I know there a ton of discussions on that matter, but hear me out. First start up try is usually fail or engine revs to 1200RPMs than drop dead. Second try car revs again to 1100-1300 RPMs hold it for for few seconds and then drop to 300-500 RPMs which if I leave it like that, will recover after 20-30 seconds to 1100RPMs. Third try revs to 1300 and usually hold it around 1100, but engine is shaking like is under load or probably bad fuel mixture. Now the plot twist when car run in that condition if I power up the A/C engine revs to 1400 and drop and hold 900 if I don't do that it's usually after a few seconds ride or warm up 80-90°C by itself drop to 900. After that point car runs smooth, start flawlessly. I noticed that the ambient temperature determines the number of tries, outside temperatures are not that bad usually in the morning is around 10-14°C.
Two years ago I replaced sparks and cables with NGK. Fuel filter is replaced also two years ago but hasn't been driven more than 2K kilometers. I hook it up to diagnostic but no errors were recorded also checked the sensors - all operate nominal. I'm pretty sure it's an air sensor or coolant temperature sensor, thermostat is also being replaced with Wahler. If you guys have any clues where to look will be much appreciated!
Thanks in advance!
I'm new account holder, however I follow this forum from a long time, anyway I finally decided to share my problem here because I can't find the source of it. I'll provide some specs on the car first and will list the problem bellow, I replaced many part since I bought it and I'm always trying to keep it under OEM specs. Enough talking here's the car details:
Audi A4 B5, 1997, 1.8L, FWD, engine code ADR, 5-speed manual, 92KW/125hp this is a non-turbo model.
Car has installed LPG system, however always starts on GAS and after engine warm up (70°C) then switch to LPG.
Motul 8100 X-CESS 5W-40, all filters are Mahle Knecht.
Car runs flawlessly on both fuel systems, but from a month ago begin to have cold start problems and specifically RPM drops. I know there a ton of discussions on that matter, but hear me out. First start up try is usually fail or engine revs to 1200RPMs than drop dead. Second try car revs again to 1100-1300 RPMs hold it for for few seconds and then drop to 300-500 RPMs which if I leave it like that, will recover after 20-30 seconds to 1100RPMs. Third try revs to 1300 and usually hold it around 1100, but engine is shaking like is under load or probably bad fuel mixture. Now the plot twist when car run in that condition if I power up the A/C engine revs to 1400 and drop and hold 900 if I don't do that it's usually after a few seconds ride or warm up 80-90°C by itself drop to 900. After that point car runs smooth, start flawlessly. I noticed that the ambient temperature determines the number of tries, outside temperatures are not that bad usually in the morning is around 10-14°C.
Two years ago I replaced sparks and cables with NGK. Fuel filter is replaced also two years ago but hasn't been driven more than 2K kilometers. I hook it up to diagnostic but no errors were recorded also checked the sensors - all operate nominal. I'm pretty sure it's an air sensor or coolant temperature sensor, thermostat is also being replaced with Wahler. If you guys have any clues where to look will be much appreciated!
Thanks in advance!
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