bodydroppeddually

just got done with my engine. it has a big cam, headers, forged pistons, all new engine parts except ignition parts. the car had the same gas in it for a little over a year. got all the gas out and put in 110. started it up and the engine don't idle very well. when you rev the engine it pings. when you try to stay a speed the car acts like it is out of time. when it idles sometimes it backfires. (not alot) i have a stock computer. any help will be great.

GreenDemon

ECM Tuning?
Stock Ignition w/ high compression?

rskrause

Sounds like the timing is way off.

Rich

bodydroppeddually

yes the car run rich.

Hotwire

computer tuning... opti????

bodydroppeddually

i am thinking that it is the opti got a new one on the way. then i am doing some tuning next week.

shoebox

The opti could be installed wrong.

Hotwire

how long did it sit during the rebuild? One thing you can do is pull the cover off the opti and clean the rotor and pins inside, just like old school 350s. Also check to make sure you're getting fuel to all the cylinders, pull the plugs and see if you can tell anything.

rskrause

Incorrect Opti install is one of the common ways the timing can be all futzed up. Besides timing, the valves might be completey out of adjustment.

Rich

bodydroppeddually

the valves are set good. i am getting fuel to all of the cylinders. is there any kind of opti that is better than the other.

Hotwire

a vented opti from 1995+ motors are better than the sealed optis, it allows engine vacuum to pull fresh air through the assembly to remove charged air and contaminants to increase the life of the optical pickup inside. MSD just came out w/ a new style opti that has upgraded components, but is expensive. Summit racing and jegs are selling them now.

I would like to venture and say try tuning the motor first before you start plug and play. When I first tried to get my engine running I had 6 out of 8 injectors plugged w/ rust from the old fuel line, then the tune was so bad it wouldn't even idle, had ported and gasket matched heads and intake, stock valvetrain, and cc502 cam. Once I got the tune halfway decent it will idle, had to reduce the ve tables across the board, it was putting way too much money to the engine.

If you have an off the shelf cam, you can most likely find the tune for that cam from another car, then import it to get you a little closer to an ok tune that the motor will run on.

Injuneer

What year is your car? Basic info like that helps people answer your questions. Not all years are exactly the same.

And you need to tell us more than "big cam"..... what's the displacement, what is the static compression ratio, what are the cam specs, was any tuning done to the "stock PCM"?????? Any other specs and mods will help people help you.

I'd hesitate to jump to the conclusion that it is the Opti. However, as noted in a few of the posts above, it is possible to index the Opti incorrectly to the cam. With the 93-94 cars, the error can be one or two teeth on the splined driveshaft..... runs, but not well. With the 95-97 cars, its harder to make an error with the location of the dowl pin, but it is possible.... the error is so big it might not even start. Knowing the year of the car helps sort out these possibilities.

bodydroppeddually

the car is a 94 camaro. i will get the cam specs asap. there was no tuning done with the stock pcm.

bodydroppeddually

the car will idle but when it sets the car will load and die.

Hotwire

drop the VE down about 5% from 0-1000k rpm and see if that helps. You've just change the efficiency of the engine and the stock tune isn't going to get it.

Do you have all the sensors hooked up? Throwing any codes?