WHEN INITIALLY FIRST STARTED ENGINE WILL START ...
2001 Chevrolet Monte Carlo
February, 10, 2013 AT 11:59 PM
When initially first started, engine will start and run for a moment and then stall. When restarted, the engine idles perfectly fine, and will restart consectively for as many times you try. But let the car set for 10 to 30 mins, and it will start/stall on first turn of key again. Work that has been done so far. MAF sensor replaced, catalytic converter (was plugged and was cause for initial problem), plenum and gasket replaced (had coolant leak). Also have a code po171, but that was there before these other problems arose. Code sets at idle and after 1 to 8 mins after cold start up.
I would do a fuel pressure leak down test sounds like the fuel pressure is bleeding down causing extended cranking. As far as your code P0171 I would do a smoke test to check for vacuum leaks.
February, 11, 2013 AT 12:39 AM
I have already checked the fuel pressure, and checked for leak down, it holds at 50psi for about 20mins and slightly increases a few pounds. There was no noticable difference from when problem happens and when it starts and idles properly. I am a ASE cert Master tech. The O2 sensors at idle, and in closed loop, sit at the bottom of scale until engine is reved up, but after left to idle they fall back to low limits. If I hold throttle down slightly when starting I don't have a stall problem. I have also replaced the IAC motor also, to no change. I have cleared the memory by disconecting battery for 30mins. I have sprayed carb spray around intake, vacum lines and anywhere I thought may have a small leak, but no change in idle or readings on my scan tool. It seems that after sitting for awhile, it doesn't have the proper air/fuel mix on a cold startup, or is delayed for some reason.
February, 11, 2013 AT 12:42 AM
I forgot to say that it doesn't have extended cranking when it happens, it just starts right up and after a short moment just stalls. It imeadiatly restats and idles fine.
February, 11, 2013 AT 5:12 AM
You know the best way to look for vacuum leaks is with smoke its way better then using carb spray. You can find the smallest leaks and hinden hard to get to leaks. Have you checked the coolant temp sensor yet?Also the best way to use carb spray to find vacuum leaks is watch the fuel trims on the scan tool while spraying that is best way.