Limp Mode HELP!!!

[Mayor-G]

Ok I just bought my sisters 91 C4. Only 16k miles on it. It had an oil leak, needed intake mani gaskets. I picked it up and instantly noticed a power loss. I was told it went into limp mode. No check engine lights. The only thing I asked them to do was put in a 180 thermostat. They have had it for a day now and cant find the problem?? Im new to all of this and reading like crazy! It starts and idols fine. But when you punch the pedal... it down shifts one gear and acts like a 350 with a 2 bbl carb? I put 3 tube air induction, stage 2 hypertech chip and a Borla exhaust. I noticed a big difference. After the mani gasket job.... no power. ????ad Tx in advance... Greg

 

[Rob]

Ok I just bought my sisters 91 C4. Only 16k miles on it. It had an oil leak, needed intake mani gaskets. I picked it up and instantly noticed a power loss. I was told it went into limp mode. No check engine lights. The only thing I asked them to do was put in a 180 thermostat. They have had it for a day now and cant find the problem?? Im new to all of this and reading like crazy! It starts and idols fine. But when you punch the pedal... it down shifts one gear and acts like a 350 with a 2 bbl carb? I put 3 tube air induction, stage 2 hypertech chip and a Borla exhaust. I noticed a big difference. After the mani gasket job.... no power. ????ad Tx in advance... Greg

Greg,

Welcome to the Corvette Action Center.

I'm going to move your post into the C4 Tech forum for better exposure...

 

[Mayor-G]

Thank You!... Sorry for the brain fart! LOL

 

[Rob]

Thank You!... Sorry for the brain fart! LOL

No worries!

 

[catbert]

Your experience is why super low mileage older Vettes can be problematical. Look for vacuum leaks and check the health of the ignition system.. Also double check on that new intake gasket. There are several good Vette shops in Chi if all else fails.

 

[Mayor-G]

Your experience is why super low mileage older Vettes can be problematical. Look for vacuum leaks and check the health of the ignition system.. Also double check on that new intake gasket. There are several good Vette shops in Chi if all else fails.

A buddy of mine seems to think its the distributor being a tooth or couple a teeth off? Time will tell.... as soon as I know so will you guys!!

 

[ecss]

needed intake mani gaskets. I picked it up and instantly noticed a power loss. I was told it went into limp mode. No check engine lights.

After the manifold gasket job.... no power. ????ad Tx in advance... Greg

So they told you it's in limp mode but no codes are set? . :ugh

Could be a couple plug wires on the cap installed out of order.

When you set base timing you disconnect the EST wire. Start the engine and set the
base timing. Shut the engine off and reconnect the EST wire. This should set a code 42 which should stay in the ECM memory until it's cleared. Could be they set the timing by ear.

Timing mark on balancer has moved due to rubber deteriorating causing
timing to be set wrong.

Picture of EST wire by the side of the power brake booster.

 

[hoosierdaddy]

Welcome Aboard. . . . . . Glad you found us.

Welcome Mayor-G to CORVETTE ACTION CENTER

-Bill