# QG running rich



## p10driver (Apr 30, 2002)

I have a problem with my GF's Almera N16. It's powered by the QG15DE. I know you dont know this engine but it simmilar to the GA16 and the QG18. It has E-TB, VCT and two O2 sensors. The problem is that the car runs rich for some reason I can't find out. The plugs and the tail pipe are full of soot and fuel consumption is high. Car hesitates at low rpm. So far I checked:
Engine temp sensor, MAF changed by a used one (no change), O2 voltage looks ok (swinging), long and short term fuel trim goes to -10% (read out over OBD). I've also changed the air filter, plugs cleaned the TB but no effect. Any ideas?


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## rogoman (Dec 16, 2004)

The best thing to do at this point is to do an ECU code readout. If any fault codes are set, it'll help you to diagnose the problem. Replacing parts blindly is just wasting your money.

Some things to check:
- Check for good vacuum in the intake system. Use a vacuum gauge; reading at idle should be around 20 InHg.
- Fuel injectors may be leaking or dirty. Run some good injection cleaner, like Techron or Redline SL-1, through the system; give the cleaner about a week or two to do it's job. 
- Rather then cleaning spark plugs, replace them with new ones. Make sure to use OEM NGK plugs.
- Make sure the coolant temperature is where it should be. Too low a temperature will cause the ECU to richen the mixture.


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## p10driver (Apr 30, 2002)

ECU throws no code. Plugs are new. Yesterday I also checked the E-TB. It looks fine and TPS readings are OK. The engin temperature sensor is also OK but I never checked what temperature is reached during operation. The gauge shows litle less then half of it's range. Other problems with the engine so far were streched timing chain, crank and cam position sensors. I also dont believe that the injectors are leaking becouse the board computer shows the high fuel consumption also and I already used injector cleaner. In my opinion the ECU injects to much fuel for some reason and the parts playing a role are MAF, TPS, O2 sesnors and engine temperature sensor. I believe i have checked all of them and they work OK. Any other idea? I need input even your most stupid ideas .
Is there a way to check if the VCT works OK? Have no idea why wuld this make the car run rich but I would like to be shure that it works.


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