Hey guys. I have been having some issues with my 94 z28 that I have not been able to quite put my finger on. I have tried several things that have not solved the issue and wonder if anyone has any ideas.

Here is a list of engine related mods to give an idea of what I have.
1994 z28 6-spd
-Moroso CAI
-Granatelli mass airflow sensor
-Edelbrock LT1/LT4 manifold
-CompCams #305 220 int./230 exh. duration, 0.510 int./0.510 exh. lift
-Isky springs and retainers
-Some light port matching has been done to the heads
-BBK shorty headers (junk)
-Cat deleted with 3'' from the collector back to a flowmaster
-New summit optispark
-MSD 6-AL ignition box
-MSD blaster coil
-Taylor 8mm wires

Basically I bought this car from a guy who had had some work done to it and had done some work and mods himself. I have spent most of the time I have owned it trying to iron out little issues and fix things they screwed up.

The issue I am currently dealing with is that it has developed a tendency to stall while driving. It starts, runs, and drives fine for approximately 10 minutes and then the car will just shut off. This now happens everytime that I drive it. When the car dies, it will not start again imediately. It will sit and crank slowly and then eventually the cranking rate will increase and it will fire. This is generally after 3 or 4 minutes of sitting. The stalling does not happen if the car is sitting and idling, only when the vehicle is driven.

My first feeling was that I am loosing fuel pressure so I changed the filter and the fuel pressure relay. The issue continued so I tested the fuel pump and it seems to work fine and engage and pressurize every time the key is turned (even when the car is sitting and cranking and not starting) . I don't feel it is the fuel pressure regulator but I could be wrong.

The next idea I was turned on to by a friend was that there could be a problem with the ignition box. I did not feel this would be the cause but never the less I swapped the Holley box I was running, for a 6-AL box that I had. This also did not help with the issue.

Next I was told to look into the computer being the problem. I felt like there could be a possibility that I screwed up the computer somehow by continueously "reprogramming it" with the POS hypertech programmer that I had. I really don't know if that could have caused a problem or not. About this same time I came across an old Car Craft that featured an article where a reader had written in with almost the same issue. He had swapped his computer and it did not solve the problem. Car Craft writers suggested that the EGR was the issue.

As of now my EGR tube is detached and just hanging. I had Hooker long tubes on which had no prevission for the EGR therefore it was hanging then and there was no issue with stalling. With the BBK's which are on it now, I originally had the EGR hooked up but have since cut off the EGR tube prevission on the headers. Therefore the EGR tube is hanging again.

Sorry for writing an essay with thread guys, but it would be awsome if anyone has any input for me or has experienced something similar.

 

An engine needs 4 things to run
-Fuel
-Air
-Spark
-Compression


I suggest hooking up a fuel pressure gauge,so you can see at all times what the fuel pressure is.I assume you are getting air to the engine.Have you replaced or pulled any of the spark plugs to see what they look like ? Could you be having a charging system problem ?

 

Much of the mystery you're experiencing may be alleviated by hooking up a scanner to your car and seeing what codes your car is throwing - While doing this reply I forgot if you stated you've got a '96? If so, you've got an OBD2 system which can be read by borrowing a scanner from kragen or another parts store - you can even buy one for about $100-$150. If you have an earlier car than a '96, you've got OBD1 which can still be read by an OBD2 scanner by making an adapter - there are "how to's" on this site that can tell you exactly how to adapt the OBD2 scanner to your car. Or, you could simply buy an OBD1 scanner- i think they run about the same price I mentioned earlier.

 

OK - my bad! You're probably gonna have to buy an OBD1 scanner unless you have access to one already - Auto Xray is a good brand and you can find them easily on ebay.

 

i have a feeling it could be the fuel pressure regulator.has this car been tuned for these mods ?

 

you might want to check into the distributor cap and rotor from moisture damage.. the distributor is prone to getting moisture in through the venting system. i reciently rebuilt mine after having a similar encounter but never running for ten min than just dying.. that is really odd.

 

Im in the process of fixing the same problem. My fuel system checked out, and i changed all the igniton components from the opti to the module. Still no luck....

 

I am also having that issue. Mine will idle for five to fifteen and then die. It will also drive for ten to fifteen and then die. My cluster flickers like it might be electrical when I turn key to on position.