this is getting irritating. my car has been off the road for the last 2 months. Here's what happened.

The car misses, stumbles, and shakes BAD. It seems to start getting bad when the car warms up. When i start off in 1st, the car just starts buckin, the car starts shaking, and then as I give it more throttle is clears up and starts driving OK when i'm at above 80% throttle. My scanmaster shows up to 18 degrees knock retard because of all the shaking. It seems to do this only at part throttle but not full throttle as much, even though it still misses a little bit at 100% throttle it is much more drivable. Also, at idle, at times the car will get slight backfires and you can just hear it runnin rough at times at idle.

The car throws no codes, I replaced all the spark plugs and wires, still the same thing. I also double checked the wires to make sure the firing order is correct. I bypassed my aftermarket ignition, same thing still runs terrible. I am pretty sure it's not a clogged cat, the exhaust manifolds aren't glowing red or anything. Any suggestions as far as how to isolate the problem or maybe how to eliminate the OPTI as a problem before I replace that?? What are things I should check before I order a new opti, which I want to make SURE IS BAD before i order it. Could this be a fuel problem???

Brian

 

My car used to have a really bad stumble down low too. The problem was that the oil from the K&N filter had coated the resistors on the MAF. I cleaned it and then it was fine!! Check your MAF! Hope this helps.

 

Also make sure that the plug wires are all the way on the opti terminals. I had that problem and the terminals ended up getting corroded and I had to replace it.

 

thanks for the inputs guys. As far as the opti, I made sure all my wires were 100% and they clicked on the terminals, I just made the wires yesterday and put them on 4 hours ago, everything is brand spanking new.

And the MAF, i haven't oiled my k&n since I got it, probably 2 years ago. I pulled the MAF and looked inside, its clean and I still have the screen there nothing damaged it.

I'm going to run the car cold tomorrow to see is it only stumbles when the car warms up, maybe I can isolate it that way. I'll reply later and let u know what happened.

I'm not really an expert when it comes to vacuum checks and the fuel system, anything I should look at there??

Also, can bad 02's cause this, should I buy new o2's??

Thanks again

Brian

 

update: runs bad wether it's warmed up or not.

Also, the exhaust smells like rotten eggs real bad, running really rich I'm assuming......

I ordered a set of 02's anyway, they are original might as well replace them. Any other suggestions before I have to order a opti??

Brian

 

...sorry no more idea's, but here's a ttt for ya! Good luck!

 

UPDATE:

I replaced the following:

new plugs
new wires
new PCV valve
new o2's

I also did the following:
-added fuel injector cleaner
-used a stethoscope and made sure each injector is clicking when running
-measured the resistance of each injector, they are all good


Now, is there anything else I can check that could be a problem?? Or is the last thing to do now is the opti, I want to get the cheap stuff out of the way. I'm not a mechanic and don't try to be, but I can do things if I read the book and as far as troubleshooting I'm not an expert. Anyone else have any other ideas or checks I can do?? I bought one of those spark testers to make sure each plug is getting spark, I'm going to do that next.

After I do that, where to go next??

I would normally just eat it and buy the opti, but the labor to do it is a PITA, i already did the waterpump a few months back. ALso, I just bought a 2005 R6 I can't keep blowing money on this car, i want it to run right again

Thanks
Brian

 

Also check your coil.. Had simular problem before, did full tune up and had no other problems, didn't single out a problem though

 

update2:

I bought a new optispark, a new coil, and a new ignition control module. I'll put these in when I get them.

Any other ideas?? If this doesn't work then what?

Brian

 

Do you still have a catyletic converter on it? A "rotten egg" exhaust smell usually means a bad cat.

Frank

 

Optical sensor, I just had the same problem, the new dist. without the cap and rotor fixed the problem. Purchase the dist. without the cap and rotor and save yourself some money. The cap and rotor are easy to replace, the small torx screws are tricky, most hardware stores have the very small nutdrivers,
just be sure to use plenty of rtv to seal it.

 

My problem sounds kind of similar....

http://web.camaross.com/forums/showthread.php?t=321212

 

I agree change your cat or remove it.

 

Is it just doing that when it's running, or when it idles too?

 

have you checked fuel pressure??? im having the same problem found out that when my car was acting stupid i had 20 psi and when it runs fine it runs at a constant 25psi when spec is 41-47psi so im in need of a new pump i would of checked pressure/ fuel filter before you started throwing parts at it how the problem gets solved...