dogrod

Looking for some clarification on my setup.

I have a 77,000 mile ls1 from a 2000 camaro SS in my 66 chevelle. Everything is in, plumbed up, wired up. All the normal tune up items (spark plugs, wires, front O2's, oil) have been preformed. There are no cats.

I removed the EGR, AIR, Upshift, Rear O2 sensors physically from the car (and properly plugged all holes, etc.). I have not yet tuned them out of the PCM (might make other mods, don't want to pay twice). I made a VATS bypass box so I can start up the car. She starts up fine, but its seems like there is misfire or something similar. The engine shakes, which causes the car to shake. I already checked and there isn't any issues with exhaust vibrating on something, and the engine and tranny mounts are OK (rubber). This happens at all rpms.

I'm in the middle of trying to case down the cause (no codes other than the ones from the items I removed, which is confusing because it seems like there is a code for a misfire situation). My question is, if I don't tune out/delete the EGR/AIR/rear o2 from the PCM, will that throw off the engine. From the searching I have done on this website, it seems like that would be a no. I just want to make sure I cover my bases before I get to far into the expensive diagnosis (i.e. eliminate the simple stuff first).

Thanks for any and all input.

ls1nova71

iTrader: (4)

What kind of scanner are you using? There are misfire codes, for each individual cylinder. Did you put the plugs in before installing the engine? I did that and cracked a plug, must have bumped it on something, but I got a misfire code with a TechII. The items you removed shouldn't have an effect on the way it runs, except the rear o2s but not until it goes into closed loop, on start up it wouldn't matter. EGR and AIR wont affect anything. BTW, some computer reprogrammers will do upgrades for free after the initial tune, just the inconvenience of shipping the computer again, I would ask before having it done. Good luck with your project.

dogrod

Thanks for the input ls1nova71. I didn't realize the rear o2's did anything other than mointer the cats.

All the plugs, etc. were done after the engine was fitted, so that rules that out.

I have a mutual friend with a shop that was kind enough to plug my computer into his scanner. There was nothing obviously wrong, but sent me back home with a couple of things to check. Basically to find out if there is a problem with an injector(s) and/or coil(s). When I go over there again, I'll see which scanner he has and see if it can indicate a misfire.

Frustrating problem, its so close to done.

MalibuRacing

iTrader: (1)

There was another similar thread on here recently. It ended up being clogged fuel injectors from sitting for a while. I can't remember what he used, but he soaked the injectors in something to clean them and it fixed his problem.

oange ss

iTrader: (50)

rear O2's are only used to monitor Cat effeicency, other than setting off a light they will have no affects on engine performance...

ls1nova71

iTrader: (4)

The rear o2's do just monitor the cats, but from the way I understand it, they would affect the way it would run in closed loop, as it would try to add or remove fuel to compensate for cat efficiency. I'm in no way an expert on this, just the way I understand it. This dosen't help the rough idle problem though.

oange ss

iTrader: (50)

they have nothing to do with fueling only monitoring

ACONLP

i would take it to a tuner with a dyno. tuner should fix all your problems. he can also turn the vats off inside the computer instead of having a vats bypass... and he can tune your car to get the most out of your motor

dogrod

I think I will get computer re-tuned sooner than later, but I think I have to figure out the root cause of the shaking engine. I've checked alot of things already, but there still a bunch of other things left to check. Just wishing I had checked the valve spring condition when I check the pushrods. I didn't realize that they could be another common source of problems on a ls1.