AFR Problem

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I have a mixture problem for a few months, and I tried a lot of stuff but I couldn't make any difference.

the problem exists only on cold start. When I start the engine, it first goes 16-17 AFR; I touch the gas pedal, and I set the rpm at 1100 and wait like that. And when the engine gets warm, I begin to move the car. It happens at that time, when I move the car and take it to 2nd gear, afr suddenly falls to 10!!!. Car starts to choke? And sometimes it stops. I found the answer by hitting gas pedal. If I hit the gas pedal 4 or 5 times, and rev up to 4000rpm, it goes normal, and it never happens again till I stop the engine.

I changed my injectors, fuel pump, fuel pressure regulator, but it didnt make any effect. Also I cleaned up my MAF sensor. What else should I do ? Should I change my MAF ?

[Ca_Silvia]

check for vacuum leaks

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could it be TPS or O2 Sensor ?

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the problem continues, also it does the same thing every time, I can't move the car to anywhere, when I leave the gas pedal the afr goes to 10-10.5 and after a few seconds engine stops because of over rich. But if I hit the gas and take the rpm to 4000, the afr goes to 13-13.5 but I can't go all the time like that, why this is happening, is it because of maf failure or something else ? I really need an answer ca guys. you're my last hope.

[ca18detgabby]

You sound like you are having a vac leak. often a pain in the arse to find.....

could be a stuck secondary valve.

could also just be a dirty tb that is stuck shut too much.

check your 02 sensors, check for codes on the ECU, and check out the fuel pressure and report back.

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The fuel pressure is set at 3 bar with a regulator. I also use a walbro fuel pump.Euro spec ca's dont have O2 sensors here. So I eliminated the O2 sensor too.TB is also ok. Just cleaned few weeks ago.

The only place I didnt look up is Vac. Leak. Yes it could be anywehere... So you say, it's not with the Maf ?