96 Pontiac Sunfire starting problem

[bauekel]

I have a 96 pontiac sunfire, 2.2 L engine with 110,000 miles. It will start up perfectly fine from a cold state, but doesn't like to start when the engine is warm. This has been going on for about a year and is continually getting worse.

When I try to start the engine while warm, it will turn over normally but it won't fire. When the car does eventually fire, the engine will catch, shudder and chug as if it is not getting enough gas. Then the car will jerk and stall out.

If I press the gas pedal when the engine fires, I can push through the chugging, stuttering stage and the engine will stay running but the idle will be very rough.

If I let the car sit for couple hours after it was warmed up, (so the engine is cool again) it will start up normally.

I have had new plugs and wires installed.
Fuel pump tested o.k.
Fuel Filter replaced.
Crank shaft sensor replaced.
I had the entire fuel system and spark plugs thouroughly cleaned.
No sensor lights are on.

I have invested over $1000 in the car and it still has this problem. Does anyone know what is going on? I would really appreciate any input as I am really not in a situation where I can afford to buy a new car.

Thanks so much!

-Kelly

[idol]

Kelly, hello and welcome. I just read your dilemma, but before I give you my thoughts. Give me a couple hours to check something on the particuar engine. Then I'll be back.....IDOL

[idol]

Kelly, back now. As I read your problem, I noticed you said that you could push through the chugging and it will run. Hard starts only when warm and stalls. In the past your mechanic would tell you it's a "stuck choke". On vehicles today, that device has been replaced by other devices. One of those devices is called the "Throttle Position Sensor" or TPS. From what you are describing and from what I have seen on similar engines (2.2l) I am willing to say that your TPS has failed. I would recommend that you take the car to an Advance Auto or an Auto Zone and ask them to pull the codes (I noticed you wrote you tried this already) see if you get an indication. The summary may not say specifically TPS but the fault will contain a code that points to it. If not, well if you brought the car to me, based upon the symptom it was demonstrating ; the TPS is where I would begin. I believe that you local Advance or Auto Zone Parts place can call up the testing procedures on their computer. If so, test it, the check is quick. If not I would recommend you begin by assuming the TPS is bad. Let us know if this helped.........IDOL