Ok im stumped. I finished up with an lt-4 hot cam and new headgaskets recently and for abotu 3 days it ran excellent but just in the last week it will start hard then miss really bad for awhile until it warms up a bit. When im driving it i can have my foot steady on the gas and fell it buck forward like it wants to go but then it will go back and keep doing this in all gears at all speeds and rpms. It is runnign extremely rich also. Another this is when im trying to come to a stop and barely creepign the car will violently buck forward until it is stopped. Im definaly thinking ignition. It was tuned after the cam install and ran extremely good for 3 days after. So far ive changed the coil, plugs/wires,and the icm to no avail. Im thinking opti but just want to be sure before i shell out the money for a new one. any help would be great. Not sure if its needed but this is what the car has as it sits now: Lt-4 hot cam kit (complete kit pn nal-12480002 out of summit),comp r lifters,hooker lts,sw y pipe,magnaflow cat-back,bbk58mm tb,mezire ewp,ported maf ends. Ignition is all stock. Thanks for any help.

 

did you have your computer tuned for your mods? maybe why it is running fat and sounds like plugs are getting fouled.

 

I would re-check your lifter preload. Set them at zero and then 1/4 turn with the engine not running. Then I would get a can of starting fluid and spray around the intake, tb, egr areas, vacuum lines etc... Listen for the engine to change rpms indicating a vacuum leak somewhere. When I did my cam install, the water pump driveshaft seal in the timing cover was leaking oil on my opti. It did have some oil in it when I opened it up but it turned out to be ok. I think it could have eventually ruined it. Are you sure you have no water pump leaks or seal leaks getting on the opti? Spray your intake elbow and make sure the seal is good on your tb. It could be coincidence but you may have an O2 going out. I had similar symptoms and ended up changing the MAF, opti, plugs, wires, injectors, map, and even computer. Nothing changed until I put in new O2 sensors. It turns out that the right one was bad and it made the computer just dump fuel like crazy. It was missing, surging badly, smoking, and just plain running like crap. Eventually it threw a code indicating the O2.

 

He said he is running comp r lifters so DON"T set the lash 1/4 past turn. Set them to zero lash and give them a 1/16 max past zero. I believe there preload is like .002-.003. It is extremely small but I have heard it can eat tons of power if you preload them too far.

 

Check too see if it is throwing any codes. If there are problems it doesn't necessarily light up every time. I would agree with the 02's. Maybe the tune is off also but running rich will kill the o2's. I had one go after 20 miles of doing my headers and my car ran like sh@t.! I could see the entire engine visibly shake at times with it idling. It looked like it was gonna just shake itself loose

 

well im thinking o2's, I know a/f gauges dotn do you much good but when crusing mine isnt bouncing back and fourth it is just all the lights flashing very very fast ll over the place not liek it used to. So tomarrow i will buy new o2's and let you guys know. thanks for all the replys.

 

Any codes? That would be the first place I would check

 

If you replaced head gaskets because they were blown, your O2s could be contaminated from the coolant.

 

double check all the plugs and wires... make sure the wires are all the way on the spark plugs and opti