I finished my LT4 hotcam install last weekend. Car started fine and ran fine for about 5 days until yesterday morning. I cranked the car up to head for work and when it reached closed loop it started misfiring really bad. I have a hypertech scanner which isnt the best of scanners but allows me to get a good idea of what is going on. The misfire is constant and all throughout the RPM range. Here is everything I have observed.

1. Runs great in Open Loop leading me to believe a sensor malfunction
2. high IAC count 45-70 in idle...100+ at cruise
3. high MAP 50-60 kPA at idle compared to the BAR of 104 kPA
4. Bank 1 runs really rich. Pegged at 108 in nearly every fuel cell

I know that the cam will throw off some of the sensors but I dont believe it should cause a major misfire especially after it ran great for 5 days. Here is what I have done thus far with no positive results.

1. changed plugs and wires on driver's side since that is the only side that is scanning abnormaly
2. swapped injectors
3. cleaned TB and replaced TB gasket
4. replaced IAC
5. cleaned MAP
6. swapped driver's side O2 sensor
7. readjusted valves...set screws at 1/2 turn past zero lash

Someone please give me an idea of what could be going on here. I am at a loss.

 

ttt

 

Is you waterpump leaking at all? If you have a leak you might be having opti problems. Of course you might have some bad plug wires but that would happen all the time (I think anyway).

What other mods do you have done?

 

Both the waterpump and Opti are less than 6 months old. I replaced all the seals on the front cover and I can find no signs of a leak except for a small oil leak from the crank position sensor. I have headers but those have been on for almost 2 years with no problem.

 

Just wondering if you figured out what was wrong with your car...

Sounds similar to some of my problems.

102 bar and 68 map
iac counts 63 at idle 90 and up cruising
misfires randomly under load