I had a mechanic reinstall the my stock cam in my 93 z28 (m6). It is doing the exact same thing as it was before. He has checked everything he can think of and can find nothing that would cause the car to run this way. Basically it will only start with your foot right to the floor on the pedal, when it does start it runs super rich and will not idle or run below 2000rpm. It immeadiatly stalls when your foot is lifted. What could cause this? I am now on month 10 or trying to figure this out!

 

My new motor acted the exact same way initially. Check your TPS. Mine was not getting any voltage at all.

 

He actually mentioned the tps, however we both didn't think it would cause such a big problem. I am sure he knows, but how exactly do you check the tps?

 

I did a search and found a guide to check the tps... any other suggestions? I am heading over tonight and want to have a list of things.

 

I hate to say it but you might want to try to find a different mechanic who is a little more versed in tracing problems in fuel injected vehicles. A decent mechanic should have one of several brands of scan tools which plug into the computer and can read most of the sensors as the car is running or in the on position. If nothing else most of the sensors can be checked with an ohm meter or oscilliscope and checked against the specs. At the absolute minimum your mechanic needs to check the engine codes to see what they offer up. Too many options to just guess at.

As a precaution have him run a compression check on all the cylinders to make sure he didn't run the rockers down too tight and hold the valves open.

 

There are no codes present, I am actually not 100% sure what he has checked. He has suggested there may be a problem with the ECM. I am getting desperate and will probably have the car towed back here and start going over everything myself. I have had several people look at the car and no one seems to be able to figure it out.

 

I don't have my service manual here in front of me or I'd tell ya what to do. Is most definitely can cause a problem like that, as I personally found out.

However, if your TPS was indeed bad, you should, and I say SHOULD, be throwing code 22 for the TPS voltage range. I can't remember right off hand if the EMC gets traced as a potential fix in the DTC chart, but I'll be sure to take a look for you later this evening when I can get to my manual.

 

The tps is going to be checked within the next day or so. I will post with the results.

 

sounds like a possible TPS problem but Id also take off the TB and clean... maybe try replacing the IAC(idle air contoller) as well.

 

The tps was checked it is in working order. I have the car back at my place now. Any other suggestions. It seems to want to start now, while turning it over you get a few coughs however just not enough for it to run. I am starting to suspect my injectors as pretty much everything else is new.

 

Hey I have a 93 and on my hot cam install it did the exact same thing. I was freaking. I shut the motor down and looked around and noticed the wire on the passenger side of the throttle body was not hooked up. I plugged it in and it ran perfectly. Im overseas and cant remember what its called. Maybe your wires are not sending juice there or the senser is bad. I did exacly what you said though. So some how its got to be that part.

 

The two wires going to the TB components on the passenger side of the TB are:

Upper = TPS

Lower = IAC

 

Was he aware of the proper opti orientation?

 

Its pretty straight forward on a 93 Lt1, however I had it off myself 3 times before I gave it to him and I made sure that it slid on 100% before bolting it on. I also put number 1 at tdc on its compression stroke and checked the rotor, it was pointed straight down which as I understand it is #1.

The tps and IAC are most definitly both hooked up, along with everything else. I am replacing the wires and plugs on saturday, just to be 100% that the plugs aren't just to fouled to fire. Also I am having a friend bring down his snap on diagnostic computer to see if he can find anything.

I forgot to mention berfore that the oil smells strongly of fuel and the oil level even seems to be rising slightly

 

Any ideas? like I said I am starting to think injectors, as the car runs like it is only on a few cylinders. Since I know there is spark, compression and fuel pressure I can't see what else could be causing the problem. I have allready checked for injector pulse, and if I can get ahold of a multimeter I am going to check the resistance of the injectors on saturday when I change the plugs/wires.