I am at my wits end. I just spent $400.00 at a so called performance shop, and my car runs worst they when I brought it in. No more mechanic's. This problem started two months ago. The car would keep stalling upon warm up. So using my FSM it suggested changing coolant temp sensor. That seemed to help a little, but it still stalled 6 or 7 times until it reached 200 degrees. Then the car would idled perfect. However when you went to step on the gas the car hesitated. I tried adjusting the timing. That seemed to do no good. So I wrestled with getting the car warmed up. Once it warmed up it seemed to idle perfect but when you stepped on the gas the car would hesitate. It threw a O2 sensor code so I changed the O2 sensor. It still kept stalling so I changed both IAC motors. Still no change. So I made the mistake of taking to the professionals. They kept the car for over two weeks weeks. Had all kinds of excuses as to why they were taking so long to fix it. After a week I went to the shop and they said the changed the TPS sensor and they said that helped. So I insisted on picking the car up today. The bill says changed TPS sensor, checked Fuel pressure good, unable to determine problem, and I was handed a bill for $381.00. When I arrived at the shop the car was running. As I drove out the car it stalled in the street. Tried to start it but the car kept stalling. Finally I after about 10 stalls and starts the car would run as long as I kept the RPMs below 1000. I drove 6 MPH trying to get the car home. After about 4 miles I was able to get the car up to 28 mph without stalling. As I kept driving and I was able to get the car up to 50. After about 7 miles the car ran almost normal. I was even able to get it into passing gear without stalling but it seemed very lame. Now at home THANK GOD, The car wont even idle as I try to start it. Just starts and stalls immediately. I am open to any and all suggestions except throwing a lit match into the interior.

 

Wow. What a bummer. Just take a day or two to cool off before tossing matches. I have found most professional mechanics, for both cars and boats, are generally too rushed to truly analyze a problem and solve it. So much pressure from tying to get cars in and out of the shop.

If this car starts and drives, like you said it will, you do not need to take it to a shop to fix it.

I am no expert auto mechanic. I certainly don’t know nearly enough to call myself a weak auto mechanic!

There are some brilliant mechanical analysts on this forum. I followed along one thread as these guys helped a lady with her ‘85 for months until they solved her problem.

They will be reading this soon and start giving you direction. Tom400CFI, Buccaneer, ctmckloskey, and others are a great help. They certainly helped get my 82 Crossfire running right.

If I were you, I would start by posting a little mechanical history of the car. Any modifications or maintenance you have done recently. Sometimes grounds can become loose or new parts are not the right ones. This information will help.

Do you understand “Closed Loop” verses “Open Loop” operation? Read up on it.

Some pictures of the engine bay might also be useful.

Take a day off and don’t mess with the car. Then start fresh.

 

Ignition module ? But I would think it would run when it's cold and get worse as the engine gets warmer....but you never know....

 

Plugged cats, or exhaust?
Start with your basics, fuel pressure, check spark plugs for condition, and then do a compression test. These 3 should point you in the right direction to start.
Remember, "Only YOU can prevent Corvette fires."

 

Let it sit for 5 hours. Still wont idle?

 

No cat on vehicle. Plugs good. Compression 150 in all cylinders. Xram intake 85 fuel pump 8746 ECM. Old school mods car ran fine for the 12 years I owned it.

 

I am assuming no codes?
How about your vacuum lines around your MAP?

 

Fuel pressure at rail?

 

One of the issues the shop said they checked was fuel pressure for my $400.00

 

Christ, you got boned for them guessing and throwing parts at it. Not many diagnostic guys out there today just guys that own tools
Hope you get to the bottom of things

 

With the 84, fuel pressure seems very critical. I just went through some fuel pressure issues on my 84. I would verify fuel pressure based on everything that you've said has been checked, replaced or verified good. If the shop was unable to tell you what the fuel pressure they checked was and how they measured the fuel pressure, I would go over it again myself just to be safe. Does the injector pattern appear strong once the car is idling? Once it starts to break up and stall, can you see the injectors losing pressure?

Also, with the air filter housing off, can you confirm that have have no vacuum leaks? Having an intake manifold leak can cause terrible running issues and oil leakage if the front small gasket has hardened.

Some issues that can arise that lower fuel pressure are the rubber feed line that runs from the fuel pump to the pickup assembly can sometimes fail. I have seen them develop a split and they bleed off fuel pressure. The 84 is also sensitive to clogged fuel filters and pickup filters. Recently I went through this and ended up replacing my entire fuel feed system, to include the tank. Runs perfect now. How old is your fuel pump? Do you suspect that it is having issues either in feeding fuel or that the wiring is not great? Here's hoping some of this helps. Keep us updated on what you find out.

 

I had a similar problem on a TBI blazer... it would have a hard start sometimes... crank for longer than normal but also not abnormal for TBI... but then start and idle okay. When you nail it, does it just fall flat on its face then pick up or does it bog down first then just go? Any smoke out the exhaust when it's happening?

 

I just have to ask, did your problem start after you put gas in the car ? (or within a day or so ?).

 

I will be looking forward to the call and chatting with you about your issue and feel certain we can get you running again with a little patience and T/S.

 

Great talking with you today. It doesn't seem that bad unless the ECM is a player which we talked about. I sure as hell hope for your sake it is not the ECM, would be a mess from what you described. Let me know how it goes on the tests.

 

Do the injectors need replacing? I know that with the cross-fire injection that there would be only 2, but this sounds eerily like what the early ZR-1 owners experience with the non-ethanol compliant injectors before they upgrade them to what the 93-95 ZR-1s use.

 

Although I found the cap and rotor in poor shape and am replacing them today, I do not think this will solve the problem. I am about to test the TPS sensor when my test harness arrives from X-Fire Performance. Tested coil in cap and ignition module according to FSM directions. Both good.