I drove my car yesterday for the first time in about a week. It ran fine for me the whole 20 or so miles I was going. After I was ready to come home, I jumped in the car and took off. A friend pulled next to me in his Formula and I kinda goosed it a little. As soon as I dropped back to cruising speed, the car started missing and stumbling. At first I thought it was just in low RPMs, but then I noticed it was doing it no matter what, but was much worse at low speeds. I stopped at a friends house to check it out, and we drove it around his cul de sac for a little bit. I noticed it did it more when the motor was warm than cold. From idle to about 2K it is really bad, almost doesn't even go. After 2K, it kinda stalls and misses, making the car lurch kinda. I have a Predator tuner on it, and we removed the performance tune and put back stock, but it did it worse then. Re-installed performance tune, and then made sure it was not throwing any codes. No SES light thru the whole thing, and no codes in system, nor any knock detected. I drove it on home, but even at cruising speed it was stumbling here and there, and if I were going uphill it did it really bad. To the point a couple of times that at 60 MPH, I would have to shift back to fifth just to make it up the hill that sixth would pull normally with no problem.
I had a similar problem on the old WS6 I had, but it turned out to be a hole in the small section of hose connecting the PCV valve to the manifold. I cannot find a hole in this one. What could this be?! I have no idea where to start.
BTW, on the Predator, it looks as though the car is not pulling any timing and the O2s are reading okay. Two of them are reading high #s, and two low #s, but when you get on it they all 4 read about the same high #s. Thats normal right?
I'll bet it is a plug wire/plug issue. I had this same thign happen a long time ago.. driving down the highway, got on it a little, when I got off it and went back to cruising speed, car was stumbling, etc.etc. Got home, started nosing around, adn I noticed I could see white on one of the plugs... plugged the wire back in, never had another problem.
Other thigns you could look for are battery or alt. problem.. is teh voltage reading o.k.? If that's not abnormal, get someone with an autotap.. that will tell you what is going on for sure.
First are you throwing any CODES? That would be the first place I would look. The condition that you have described sure indicates you should have some codes. Also the condition you have would indicate more than a plug or a plug wire is the problem. I would check the connectors on the Coils package. If one of them came loose that would create major problems. I don't believe one cylinder is your problem.
__________________ 2002 SS - #1953, M6 with SLP LT Headers & Cats, SLP 36 lbs injectors, LS6 Ported heads, and LS6 cam. FAST Intake/90MM TB and 85MM MAF (ZO6).
SW: HP TUNERS, EFILive, & Autotap
my charged lt1 car did that same thing. i had bad plug wires.
normal driving it as fine, but under a load/WOT it would misfire.
changing plug wires on that car was such a PITA. that powerdyne unit was right in the f'n way. on a side note - the 'charger was UNDETECTABLE at idle..and for the most part, my exhaust covered it up during accel. trapping 114 without n2o in a "quiet" lt1 made everyone say WTF?
__________________ no more lsex in my garage. caught vette fever, though.
Bill, no I am throwing no codes whatsoever. Thats what confused me. I am still thinking vaccum leak, but I don't know. I still haven't had time to look at it, but I will try tonight. I am going to check the plug wires and coils. Man I hate this ****.
Okay guys, I checked for vaccum leaks, but found none. Checked most of the plugs/wires/connections, and they all looked good. I was just about to call it a night when I decided to pull the EGR tube out of the intake and check it. The gasket was really out of shape, and had a few pinch marks on it too. Do you all suppose this could be my problem? Please don't look at how shitty the pic is (camera problems). Look at the shape of this thing though. It waves.
Also, something else I caught tonight was that when I shut the car off, and the engine completely stops, I hear this quite loud sucking air sound. I know all the air intake tract is nice and tight. It only does it for a sec, but it is loud enough that if it was doing it before, I would have heard it. Possibly directly related to the EGR tube gasket? Maybe. I am gonna go ahead and get a new one tomorrow and see what that does...
I had this happen to me before. My problem was the plug wires. I checked the connections - all were good, I then checked the resistance on all the wires - my numbers matched for about 5 of them. I ordered new wires and my problem was solved. Simply checking the connections on the wires themselves may not be enough in your case - it wasn't for me. Also, this problem happened all of a sudden. I left my house, drove for about 20 minutes (about 14 miles) had breakfast, came out, car was stumbling. Something to look at.
I Had a problem kind of similar to this today. i got up, drove to work, raced an sti on the way there , and everything was running perfect. when i went to leave work got in and it started right up, but as soon as it started, the engine dropped to about 400 rpms or so and sputtered a couple times. eventually it worked its way back up to idle, so i decided to leave. it would take off fine but every time i would push in the clutch, the rpms would drop unusually fast all the way down to about 400 or so, i got out and checked the filter and wires, but everything ok. i drive home not wanting to shut the car off for fear it might not start, and the whole time it feels like a loss of power in the engine. finally i get it home shut it off and then restart it----and everything is fine???!!! im not sure what to think, computer, wires, plugs, or what? its fine now but im unsure when it might happen again but something is definately up with it, maybe my problem is similar to yours, so it will be good to know if the egr fixes it.
Tonight, OneMeanZ and I decided we were going to find out what was wrong. It wasn't the EGR seal, so it had to be something else. We in the meantime, decided to remove the AIR and EGR shat. Well, after we removed the EGR itself, Shane said he saw one of the plug wires touching the manifold. Well he reached down to move it, and it just flopped over. Apparently this thing had been off there for a pretty good while, cause the wire end was filled with corrosion and the plug end was cover as well. Still got no trouble codes.So we replaced the plug and wire, and everything is good now. I must not have been able to really check good with all the EGR stuff in the way.