custom computer chip/idle speed

[dlg423]

I recently installed a GM high performance crate engine in my '81 and am presently using the original computer. I have the stock quadrajet 4-barrel carb, stock distributor and coil. The problem is my idle speed. It goes as low as 4800 and as high as 15000. I spoke with the tech a the mail-order company where I bought the engine and he told me that the stock computer does not recognize the cam in the hp crate engine. He recommended getting a custom computer chip. Has anyone out there had a similar problem and corrected it with a custom chip?

 

[macx]

Check this out

I'm about to experience the same problem - shortly to start upgrading to "more motor" - was wondering the same thing about the 81 computer. Found a
"street power chip" in this site - go to the proper year, select engine & engine compartment in the categories, scroll down a few pages.

http://www.corvettecentral.com/

Can't find anyone that's tried one, though. Guess I'll try to email the mfg and see what they say about it.

 

[dlg423]

carb bush/idle speed

After a considerable amount of research I have decided that the computer chip in my 81 does not control the idle speed. It only controls the carb and timing. With that said, I will have to lookl elsewhere for the variable idle. A good place to start will be the bushings on the carb. I had a carb kit done but I don't know if they rebushed it.

 

[sscam69]

Vacuum leak?

 

[KC-21]

I am having the same problem, and I talked to an 80 owner today with the same deal, we both replaced the cams in our cars (mine has a 300+ hp cam and the other guy said his was hotter than stock too but I don't know what he used) and that is when the problem started. On start-up they don't want to idle for the first few minutes then they even out and run and idle just fine, but if you shut it off for a few minutes then start them up again it's the same thing all over again. I was told that the stock chip isn't recognizing the cam and throwing everything into a default rich condition until it finds a happy medium.
Is this true and will a performance chip solve this? I was told by an old Chevy Hot-Rodder that it would but he didn't tell me what chip to get....

HELP?????

KC

 

[dlg423]

performance chip

I talked to the motorvation folks, the maker of performance chips and he told me that they do not make a chip for the stock computer. It might come down to dumping the computer and going with after market carb and distributor. You probably will boost you hp and torque with this set-up. Good luck, keep me posted! the other option is going with a later model used computer and performance chip and installing fuel injection. That What I'm considering.

 

[KC-21]

I know Hypertech makes a chip for the 81 computer, I'm just trying to find out now if it will cure the problem.
I'll try to keep you posted!

KC

 

[dlg423]

go with earlier year quadrajet

After talking with my mechanic today I think I know how to correct the idle speed problem besides the other problems that have recently croped up. I now have a gas leak from the carb onto the maniford and mis-fire when accelerating. It seems that the computer is giving the carb a "rich mix" and causing the gas leak and mis-fire in addition to the variable idle speed. The solution...purchase a used 1976-1980 quadrajet carb which does not have the mixture control selenoid (feed back), rebuild it, and and HEI distributor with vacuum advance. this should shut up that pesky computer and fix all of the above. Second option would be to go with a high performance carb and dist from one of the mail-order places. I have't decided which way to go yet? anybody tried either of these solutions?

Just wondering...could the gas leak onto the manifold ignite due to the heat of the manifold?