OK I'm getting really frustrated. I've been hunting down this miss that the car has for days now and can't seem to figure it out. I just put a cam in and changed out the opti. The old one had 78K on it. I put bigger 30# injectors in also. I have no vaccume leaks and my fuel pressure is good. I did the resistance check on my coil and it was good. The plugs are new Delco's and I'm 100% sure that the wires are hooked up in the right spot on the opti. Also the car seems to be eating more than the normal amount of gas. ( haven't been driving just at idle while working on this problem ) I also checked for arcing under the hood. When it misses it almost burps out of the exhaust and the whole motor shakes. My IAC counts are reading like 60 which I know is a little high but don't think thats what is causing the miss. The miss is random. I've been working on this for 5 days or so now and am about fed up! Can anybody shed some light on the subject for me? Thanks

 

Oh yea, it misses up to 3000 rpm's. Don't know if it happens above that because I didn't take it that high.

 

Did you have the PCM reprogrammed for the larger injectors?

 

sounds familiar, have you changed you Knock Module?

Im about to do that in mine... could make the difference.

 

Bad O2's possibly.

 

As for programing for the injectors yes I changed the constants to 31.7. The Knock module is stock and the O2 mv and readings seem to be fine on freescan.

Just found a small bit of oil around the bottom of the brand new opti though I did a search on the oil leak and found where someone said that an oil leak here could cause a miss. Looks like I'll be changing out an opti seal. Does this mean that my brand new opti with 0 miles on it is now crap? Thanks for the replies

 

The waterpump drive gear seal is more likely the culprit...the oil drools down to the opti.

 

Test each cylinder with an infrared laser thermometer. They can be had as cheap as ~$30 and it will certainly help you narrow down the problem. The bad cylinder will be cold (test each header primary), while the rest will heat up to normal temp

 

Sometimes the car is hard to start. By pushing the gas peddle to the floor and going into clear flood mode it wil start but then the miss is still there. If I was running rich would that cause a "miss" and slight "pop" noise out of the exhaust.

 

A pop is caused by a bad cylinder not firing. IE: gas being ignited inside your headers.

 

I've checked the plug wires several times and they are on the plugs tight. The plugs are new ac delco's. The coil was proven good. Could the ignition control module cause the popping? Sometimes when I start it up it will idle just fine for a minute or two but eventually the "pop" will come back. I'm just out of ideas here.

 

Once the car starts missing and making the popping sound sometimes it will actually miss so bad that it dies! when the car isn't missing (like when I first start it up sometimes) it sounds really good.

 

I didn't change my Injector offset vs. battery voltage table with tunercat for the 30#ers. That woulkn't cause it to do this would it?

 

I seriously think you just need a good program for those 30#ers...

 

you got to get a waveform on the hi and lo resolution signal from the opti-one while cranking and one while idling and blipping the throttle. without a (proper)hi res signal expect long crank times and similar symptoms to yours. "but i just put in a BRAND NEW opti" yeah i know. im at my shop right now, on my desk in front of me are 2 BRAND NEW optis (optii?) one i just pulled off of my own car, it was installed by me when i did the lt4 conversion 2 or 3 weeks ago, and the second one is the warranty replacement from my delco warehouse to replace the first. had all kinds of intermittent driveability symptoms, never a code to work off of. so i pulls out my dso a little injector current\voltage\pulsewidth checks, AND some ic signals to the module-which at that time it was behaving all were acceptable-still bought some new injectors cause them multecs were lookin pitiful. then on to the opti signals and there it was choppy glitchy signal that was causing the problems-could watch the wave and hear the engine fumble and pop and fart in synch with the signal. once again out of the probably extremly low count of new out of the box opties i get the special one. maybe you might have one too.