OK, I feel like I have tried everything.

I have a 1977 corvette with a th350. The car sat for a few years while I customized the body. When I bought the car it had a Q-jet but never really ran well but would move the car in the driveway. I have replaced the Q-jet with a retrotek powerjection I system.
The car starts easily but will die quickly if I do not press on the accelerator. Once I give it some gas, the car tries to idle for a while but revs between 750-1100rpm until it eventually dies. This happens in park and in drive. The car accelerates fine and the transmission shifts well, but when my foot is not on the accelerator the rpms wonder again and the car will eventually die.
I have replaced the spark plugs twice. The first time I bought r44t and they were fouling out so I adjusted the air fuel ratio from 13.5-1 to 14.7 which helped but they were still fouling after cleaning. So today I installed a hotter plug (r45ts) but this did not help the idle quality. I have also cleaned the o2 sensor with sensor safe tbi cleaner to get the carbon deposits off. I have plugged all vacuum lines to see if maybe there was a leak in the booster/pcv/trans modulator but this did not help and also checked the small hose at the vacuum modulator on the trans. I replaced the cap and rotor on the computer controlled small cap HEI distributor and the plug wires. I also tried spraying the TBI cleaner around the intake to check for vacuum leaks and heard no change it the rpm other than the normal cycling between low and high revs. Timing is set at 35 degees all in.
I really have no idea where to look now. Any ideas? I tried to take it to my favorite mechanic but he will not look at it because he does not want to mess with an aftermarket fuel injection. I am really frustrated so any help or recommendations?
Thanks,
Scott

 

I should also add that the previous owner states it has a fireball cam which I do not have the specs on. I have about 17Kpa manifold vacuum at idle.

 

Well I just went to Retroteks web site and had a quick look around. It seems that you could get lots of help over there.
In the troublshooting section it says "Hunting,surging,running rough at idle can be caused by a high TPS reading".....whatever that is???(old school here).
Here is a link to the install guide to help
http://www.retrotekspeed.com/product...on_pdf-138.pdf

Hope this helps some

I looked it up.....TPS= throttle postion sensor

 

Scott,

Does it run smooth if hold it at high idle while in nuetral, say 1200rpm?

Did it run okay with the Qjet? Was it driveable?

Roger

 

Yes, it runs smoother with the idle elevated. Car did not run right with the Q-jet but it has been so long since I have run it with the carb, I do not remember the symptoms.

 

You need to look down the carb and see if its dripping at idle. If it is your float or needle float valve is stuck. If no drips look for vaccuum leak.
Good Luck

 

Have you checked with Retrotek?? Seems they'd be the best first stop for advice on their injection system. It'll be interesting to learn the fix to this, I'm considering one of their (or the EZ FAST) systems later this year.

 

Had the same thing, mine had sat a long time and had got rust inside the carb. Check to made sure your secondrys are not dripping, mine were and was flooding it out at idel. Maybe you need to rebuld the carb to clean out all the rust and crud in it from sitting I opened mine up and just bought a new one

 

He doesn't have a carb - he is injected. Read his post.

 

Nice avatar Lars...If I was younger,it looks like me....

 

I know less than dick about your specific setup, but I've had the exact same thing happen on other fuel injected cars when the IAC motors either die or aren't getting/sending a clean signal. That'd be where I'd start.

 

I am checking with retrotek but am waiting on the call back. I tried e-mailing them but got no response. Hopefully they can help me figure it out. I just did not want to bother them if there was some non-fuel issue that I was missing.

 

There's his problem right there, he lost his carb...LOL
OOPs on me for not reading

 

apparently the problem has to do with my IAC and setting it with the idle adustment screws. The retrotek tech guy pointed me in the right direction. I am still dialing it in but it is running much better.
Thanks