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Discussion Starter #1
Anyone has an idea why my car might be running rich at idle only?
STFT drops to -25%. I have problems with a start and can feel a fuel smell.
When it gets warm, I can easily start the engine, no fuel smell, but still at idle -25%. And only at idle.
Under normal driving conditions, no matter if it's in the city, or highway, Amul is around -300 +300

Injectors? Temperature sensor? Is it possible that failing DIC could be causing this?
No CE.

thanks
 

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Temp sensor is my first guess. I don't know why it would be only at idle, but if the computer thinks the engine is cold, it will enrich the mixture, and it's relatively common for our temperature sensors to fail. I don't think it will affect mixture at wide-open throttle, but it should make a difference at part throttle, and at idle.
 

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Air mass sensor?
They usually starts to give lower readings and engine is running rich.
AMM: 55557008
 

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Discussion Starter #5
Verified. There's a new, silicone pipe attached to it.
Is it possible that temperature sensor may cause such issue?
 

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Discussion Starter #7
Absolutely normal. It gets warm quite easily, and stays just above the middle of the gauge.
 

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Discussion Starter #8
I have to mention that I had problems with a start for few times, especially during winter. I usually saw a black smoke then, and engine was jerking and rpms were dropping (!) while using throttle. That would also confirm, that's running too rich. Normally it would go back to normal when engine got warmer and I could normally drive away. But still, STFT -25% at idle.
 

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Absolutely normal. It gets warm quite easily, and stays just above the middle of the gauge.
The temp gauge does not read temp in the 9-5. It reads what the computer tells it to. If it does not like the warm up cycle it will go to "0" so don't trust the temp gauge.
 

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Discussion Starter #10
redaero, that's interesting.
But is it generaly possible that temp sensor would cause rich fuelling only at idle?
 

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Is it only at idle present?
What hgappens if you raise the engine speed in idle with open clutch?
Are there errors in the ecu?
Up to now there is no indication that temperature reading is wrong.
What does the temperature read when the engine cooled down for 10...20h?
Does the obd scanner provide information like airmass?
 

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Discussion Starter #12 (Edited)
I have opensid installed, so I can read most of needed parameters.
Yes, it's only at idle. It's jerking and rpms drops after a cold start when car has been standing for a longer period of time and when it's cold outside. If I try to rise the engine speed during above conditions after a cold start, rpms will drop not rise, and the engine will choke, black smoke appears. If I try to drive away, the car jerks. it goes away when the engine gets a bit warmer and the temp needle passes the blue zone on the gauge.

I think I'll try to replace the temp sensor at first, it's not a big investment. Worth a try.
 

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I will always check plausibilty of coolant temp. Air temp and ambient temp after longer cooldown phase.
But change temperature sensor might help.
 

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Leaking fuel pressure regulator? I seem to recall you can apply vacuum to a port to test it, but I haven't messed with an FPR in years.
 

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I would test fuel pressure. There is a schrader valve on the fuel rail. That is the definitive test and easy to do and you can borrow a fuel pressure tester at Autozone
 

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Discussion Starter #16 (Edited)
Today's morning another strange issue. Suddenly CE came up, after reading the codes - p1312, p1334. First thought - DI cassette but..why would it cause rich fuelling? I'd rather say that rich fuelling caused missfires, hence these errors. Any ideas?
CE came up after starting the engine.
I'll try to replace temp sensor anyway and check fuel pressure, but these errors and general situation is a bit tricky and mysterious..
 

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It could be the DIC. Do you have one you could borrow? And this would be very rare for this engine, but you might want to do a compression check. Easy to do and you are eliminating the possibility of an internal engine issue
 
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