Fuel/Air Ratio Off?

OK, here it goes.

 

My '04 LGT 2.5L with 114k has been acting up since it's gotten cold in Buffalo. It hesistates to start and if it does, it idles for maybe 2-3 seconds before dying. I can keep the engine running by lightly tapping the gas pedal until the car warms up, then it runs normally. No CEL or codes at all.

 

 

Here is what I have done so far:

 

Took it to a shop to check in the fuel system and injector pressure test which was fine. They also told me my timing belt was in rough shape and timing could be off.

 

Timing belt - old belt was really worn and one of the cams jumped a tooth. Got the new one, timings good, still have the same problem.

 

Valve cover gaskets - kind of irrelevant but whatever. Spark plug tubes had a little oil in them so I did all the gaskets. White spark plugs showed that the engine has been running hot, which lead me to the next attempt. Also did oil change after getting it back together.

 

Coolant temp sensor - started right up in my garage after I was done and thought that was the fix. Drove it 15 miles that evening with no signs of trouble. A night outside proved otherwise. Wouldn't start in the morning but it gave me 4 codes.

 

P0102: MAF or VAF A Circuit Low Input

P0113: IAT Sensor 1 Circuit High Input

P0171 pending: System Too Lean (Bank 1)

P0174 pending: System Too Lean (Bank 2)

Cleaned MAF with the electronics air stuff. Not sure what the next step is in fixing this problem. I'm pretty sure it's a sensor malfunction at low temperatures because the engine runs and sounds fine when warm.Does anyone have ideas?

 

 

Merry Christmas,

 

Chris

 

Edited to add: Engine bay smells like gas when attempting to start up the car.

Anyone???? I just replaced the MAF....and that didn't fix a damn thing.

I think every car smells like gas when it starts.

 

My guesses:

 

1. replace spark plugs/wires

2. replace the MAF

3. check for vacuum leaks

cold start yes it smells like gas.

Sounds like your Lambda probe (O2 sensor) is going.

 

In practice this means it can no longer heat itself up to it's workingtemperature.

 

Now the outside temperatures gone low in Buffalo, it gets really in trouble and cannot give a proper cold-idle anymore.

 

Once hot, it will only give a very rich fuel mixture on low engineload, end therefor rising fuelconsumption.

 

(On full engineload, the ECU use the MAF sensor to give the right fuelmixture)

Well?

 

You asked for help, and got some.

 

Would be nice to hear from you again.

^

Turns out it was the fuel pump this whole time! I don't know what kind of bs the shop gave me about testing the fuel pressure, but 1 pump and a half hour later everythings back to normal.