My car will not idle. When I first try to start the car it will fire right up and run for about 2 seconds and then stall. I try it a second time and it will crank several times and then once again start up and stall. The third time I try it won't do anything but crank. There is a smell of gasoline by the third try, it's as if the motor is flooded. If I continue to try to start it, it will sometimes start up but will begin to backfire and then stall out.

I have a friend who told me to replace the ignition module which I did, I also replaced the TPS, IAC, and the coolant temperature sensor, the throttle body looks clean, I checked for vacuum leaks.

The ecm has been replaced, and there is an existing Hypertech chip installed by the previous owner.

Just before it wouldn't start at all the car would run fine and had plenty of power for about 15 minutes and then it would stall out when I slowed down, but it would start right back up again with no problem until just recently.

This car is bone stock except for the chip and all the replacement parts that I put on. The car has less than 52,000 miles.

I'm hoping that somebody has an idea as to what I should try next.

 

When you replace the TPS and IAC did you follow the proper procedures for setting them? Did you also set the base timing?

 

I set the TPS to .48v at closed throttle, I checked the IAC pintal distance at 1-1/8" and screwed it in. I didn't do anything else. I didn't move the distributor so I didn't check the timing. As you can tell I don't know much about these fuel injection systems.

 

You may have leaky injectors or a bad fuel pressure regulator. Invest in a test gauge ($41.99 ad Advance) and check your system pressure.

 

Do I need to check the timing? What should I have done when I installed the IAC besides checking the pintal distance? What should the fuel pressure be and where do I connect the gauge?

 

There is an actual procedure for setting the IAC while it is on the car. I don't have the book in front of me right now. In fact you really should do all three (IAC, TPS, Base Timing) in a specific order to get your idle properly set. If you do some some searching someone has probably posted the order and the individual steps on the board.

 

It won't hurt to check the timing, but incorrect timing does not result in intermittent failure, unless the ECM is bad. You set your base timing (there is a pigtail that you have to disconnect) and then the computer adjusts your timing according to present conditions.

To check fuel pressure, there is a schrader valve on your passenger side fuel rail. It has a cap on it. You remove the cap, and attach your fuel pressure gauge.

When you turn the key on, your fuel pump should prime the system for about 2 seconds. You should have about 43psi static (without starting the engine). Leave the engine off and watch the gauge -- if the pressure drops within a few seconds, you have a leak somewhere.

If you start the engine, your pressure should stay above 35 psi.

If your pressure is too low, or it bleeds down quickly when you shut it off, you need to look for leaks.

 

Would the EGR valve cause the kind of problems I having?

 

EGR valve can certainly affect your idle, but the clue for me here is that you smell fuel.

 

I have a similar problem with my 1987 Z28 TPI. Only mine starts up every time but immediatly stalls unless I keep the throttle at least slightly open. Afterwords I get Trouble Code 22 "TPS - Low Voltage". I believe this is a result of the stalling rather than the cause, since I checked/adjusted the TPS. Also, I tried replacing IAC (had a spare on hand) and it made no difference. I also don't see any way of adjusting the IAC or the need for adjusting it.

Also, my engine is all origional. I've only added headers, 3" exhaust & NOS.

 

I followed your suggestion and put a fuel pressure gauge on the motor and discovered that I only had 20 psi fuel pressure. I changed the original fuel filter which was all clogged up and now have around 40 psi. The car started right up and actually stayed running. Changing the filter made a big differen in performance also.

I still have to get the idle figured out though. I'm thinking that I still need to adjust the TPS a little more. I have the idle set at 1100 RPM just to keep it running. It will run fine for a while and then sometimes when I'm waiting at a traffic light it will hesitate, stumble and stall out. It starts right back up though.

At least it's on the road again. Thanks everyone for your suggestions

 

It looks like you just need to do some fine tuning now to get it idling right. Congrats!