All please forgive the ignorance as I am new here, and if this is the inappropriate location to post this just let me know. With that out of the way here is my issue... a major one. I recently purchased a 1991 Z28 for a steal; however, with all vehicles purchased at a steal it didn't come absent issues. Upon purchase of the vehicle I drove it home, approximately 20 miles and in the garage it sits. I knew the vehicle was running rich due to smelling like i bathed in gas from my drive home. Other than that it drove great. I know the engine is a modified 305 that clearly has a mildly aggressive cam. The throttle body for the TPI has been upgraded to a Holley Hi Flow EFI Throttle body, It has Edelbrock headers. Now.... this is the only known modifications. I questioned the gentleman I purchased the car from further specifics about the modifications; however, he was unable to provide any information as he took the car in a trade and he didn't ask questions about the mods....


So upon arriving in my garage I went to basics and noted the ECM was throwing codes so, I used the old jumper trick and received the following codes:

12

13

34

43

53


So with these codes, began my repairs. Thus far I have changed all the spark plugs, the old ones were full of black soot and smelled of gas. I have inspected the rotor and distributor cap which appear to be in good shape. I inspected the ignition coil, which was upgraded to a MSD, and appeared to be in working order. I checked and repaired all vacuum lines which were broken or in bad shape. I replaced the old Idle Air Control Valve which was covered in black soot and also smelled of gas and reset the new one per specifications found here in the forum. I have installed a new MAP Sensor. I inspected the fuel lines and found a kink in the return line from the fuel rail, which I replaced. Finally I reset timing to factory 0 per the good old Hayes Manual.


Following these repairs I fired her up, to my surprise it started right up; however, it was idling high and was still running rich, but not a bad as before. I was able to adjust the idle and advanced the timing slightly and got her to idle at approximately 750-850 RPM, cant state exact as RPM gauge is currently not working, and greatly reduced the fuel smell. Once I had the RPM and throttle response where I thought it should be I took her for a spin around the block. This was a terrible drive.... LOL the car is lurching forward at low RPM and if i don't rev it to approximately 2500 to 3000 RPM it wants to stall at low speeds.


All this leads me to today, I am at a loss. I have suspicions that the rich nature of the fuel smell originally was due to the performance cam which is installed; however, i don't think its so aggressive that the fuel odor should stick to you... I could be wrong. If this is the case I feel the cam may cause the ECM to freak out in which case i'm considering converting from the TPI to a carburetor and taking the ECM out of the picture. But I want to keep the TPI if possible as I want to restore the vehicle to as original as possible with good performance. I'm at a loss any help or suggestions would be greatly accepted....