2003 AWD Montana During Startup Idle will not engage

[1spoonman]

I have 195,000 miles on the van. Sometimes when I go to start it whether cold or hot the starter cranks just fine but the only way I can get the engine to run is by stepping on the gas pedal as soon as I take my foot off the pedal the engine just dies. No codes have been tripped at all. Injecters are clean, fuel pump is fine and the fuel filter is fine. When the idle engages the car runs great. It is only during the startup that i'm having a problem. My mechanic can't figure it out. Help!!!!!!!!!!!!! Has anyone else ever had his??????????????????

[Glen_T]

Some random thoughts:

I'd check the fuel pressure at the rail and fuel pump volume delivery. Perhaps you have a leaky fuel pressure regulator that is allowing the rail pressure to bleed off, and it takes awhile to build up pressure when you're cranking. By the time the pump has built up pressure, you've given up and have held the throttle open.

Or, you might have a bad throttle position sensor. Usually it sets a code when it goes bad, but perhaps you have a dead spot on the potentiometer (that's a lot of miles!) and the ECM doesn't know what to do as far as firing the injectors. Once you hit the throttle, you might be in a working section on the TPS, and the injectors then fire.

Another thought is that your idle bypass circuit is plugged or somehow is closing off when you try to start the van. With a closed throttle, you don't have enough air to support combustion. Once you crack the throttle, you will give it enough air to start and run. Maybe once the engine is running the idle air bypass valve or solenoid (not sure what is used) starts functioning.

Just some guesses.....there are some really good posters on this board and they may have some other ideas. If I think of other things, I'll post them.....good luck, Glen

[1spoonman]

Glen - Thanks for your thoughts. I'm going to forward this over to my mechanic. I'll let you know.

Jim