you say motor was just rebuilt when all else fails try retorqing head bolts had the same problem when it went into closed loop.

 

I have to pull all of the rockers off when I get the correct length pushrods and I was going to retorque them then. I guess its worth a shot, but wouldn't loose headbolts cause way more problems than stumbling at lower RPMs? More like burning antifreeze or something along those lines?

What was your car doing? Samething as mine

Thanks for the reply

 

Have you figured anything out?
You can't read misses on an OBDI Camaro with a scanner because they don't have a crank sensor. There are a couple ways to detect which cylinder is missing though if there is a miss. One is an engine analyzer, which no one really uses now that there are scanners, another is a lab scope, which is really the thing to buy instead of an engine analyzer. You hook a lead up to the plug wire and it detects spark.
I would rule out the pushrods as the cause or even a contributing factor; I have a highly modified z28 and the pushrods used by the previous owner were extremely underlengthed; I replaced them but they didn't seem to affect the way the car ran. I think the only problem with incorrectly lengthed pushrods is stress on the valve stems, not affecting how the car runs.
I don't know how a car will run if the knock sensor is active but there might be a possibility that's your problem. You can just unplug it I think and see if it helps. A big cam seems smoother, not causing as much vibration over 2500, where you say your problem isn't as bad. Maybe.

 

I'm not getting hardely any knock, even at WOT so I'm ruling out knock retard right now. Injineer helped me read my scan and my motor is running about 10% more rich on the drivers side than the passengers side, but I have an exhaust leak on the drivers side that I have been trying to fix, but I'm not having much luck getting it sealed up. My pushrods were .250 to long and I truely believe thats at least part of my problem and the exhaust leak being another. I recieved my MAP pigtail and am going to install that tomorrow and I also got a Opti wiring harness since when I have searched some people replace that and the problem goes away. I checked the vaccum lines and a couple were cracked so I replaced those but no change. I think the combination of the exhaust leak and my motor running rich is fouling my plugs and causing a miss, or there is something wrong with my tune or ??????

I really don't know whats wrong, my motor basically has no power under 3000 RPMs, like to the point that if I go up a small hill I will loose about 7-10 mph in OD where before I could go up a steeper hill and not loose any speed in the same gear.

But I honestly don't know what the problem is, I don't want to keep throwing new parts on it, but it seems to be the only thing I can do. And my stall converter isn't right, it feels like a stock converter but I am going to buy a 3200 Vig if I can find out whats wrong with the motor and it isn't really expensive.

But I'll keep this thread updated as I figure more out, but right now I'm just waiting for parts

 

Finally got to install my new pushrods last night and it idles alot better compared to before. I set them close cold, or so I thought but once it fired up there was alot of clattering coming from the passengers side so I have to tear it apart again to tighten them up. Also installed my new Opti wiring harness so that might have made a difference too. But its nice out today so hopefully I can get my valves set right and take it out and see how it feels now, but it seems to idle alot better.

 

any new info ?

 

Well, I installed my new Opti wiring harness and I put the new pushrods in and set them to 1/8 turn past zero lash and started it and it ran alot better but the rockers were really noisey so I took my valve covers off again and when I tried to tighten them some more the rocker bottomed on the stud, so now my pushrods are too short. And right now I'm just getting discouraged since everything I do to this car I have to do twice and its getting pretty old. And I obviously don't know how to measure the pushrods and I really can't afford to pay someone to do it right now so I'm kind of at a stand still. I have to talk to a few local guys and see if they would be willing to help me out, otherwise I'm going to take it to the guy that did my machining on my motor and just have him do everything (check for the correct length pushrod and set my valves)

Sorry for not updating, but as soon as I figure something out I'll let you guys know

 

Alright, I ordered another set of pushrods and they will be here probably Thursday and I'm going to solder my MAP pigtail today or tomorrow before work, right now I just have my fingers crossed that I ordered the right length.

Not a real good update, but I should have something by this weekend

 

Alright new update....finally. Replaced opti wiring harness, pushrods, and MAP pigtail with absolutely no change at all. The car idles alot better than it did before, but I have horrible shutter between 2000-3000 RPMs when the car is warm and driving and it cleans up a little at 3000 until I go WOT then it breaks up some. My brother was following my in his Cobra ('94 with bolt-ons) and he probably could have passed me when I went WOT, he had to let out of 3rd gear or he would have run into me. And when my car was stock I would have beat him by 2 or 3 links in a race and now we would probably be even or he would beat me by a fender.

Should I replace my 02 sensors? I guess it really wouldn't hurt so I'll probably order those today. Anything else that should be looked into? The car runs good when its cold, but when it warms up it starts to get all messed up.

Heres a list of what I have replaced so far, besides internal motor parts that only have 60 miles on them as of right now......

MAP sensor
MAP Pigtail
Opti Wiring Harness
Plugs Gapped at .050 which may be part of the problem???
Wires, none are burnt or loose
Temp Sensor on Water Pump
TPS
and I'm sure I missed something, but that should give you some of an idea. Now on the other hand this is what I'm planning.....

02 Sensors
Clean MAF, but according to my scan its working fine
Possibly have a better tune done by a friend
???????Suggestions?????

 

Except for what you said about it running fine until it warms up, it sounds like it could be a miss. I know you said you checked your plug wires but I would check them again. Actually take each one off and feel for hard spots and look for white spots if you haven't already. I have cost myself a whole lot of time and trouble before with my 94 doing lots of uneccessary work because I didn't check the wires thoroughly enough in the beginning and ruled them out. If that's not the problem, I would consider replacing the opti whether it runs fine for the first few minutes or not.
Good luck.

 

Well I agree with you, but I don't want to keep throwing money at it if I don't have to. With my old motor the Opti was fine, no problems at all. I'm really leaning towards the O2 sensors and will have them installed tuesday morning. I went over the plug wires today and all of them are tight so I'm ruling that out as of right now. None of the wires are burnt or anything like that.

A friend of mine with tuning software was going to come over today and try to work with my tune and see if thats an issue, but he never showed so I may have to wait on him.

But anyway I'm going to replace the O2s and see if that helps at all and in the process I'm going to fix my small exhaust leak and a few other small things that have nothing to do with the motor.

And if the O2s aren't any help the opti is next on the list.

Thanks for the reply and I'll be sure to post anything up whether I make any progress or not.

 

I finally got time to change my O2s and it still misses. The only time the car doesn't miss is when its cold. I'm getting ready to order a new opti, but I really don't think I need it. I really can't figure this thing out and I'm really in a bind as far as vehicles and need to have this thing driveable for a little while. I'm going to take it out with the MAF unhooked and see if that helps at all, but I doubt it will......nothing helps this car

 

That is just a b----. Your problem should be a challenge to everyone on this forum; I know a lot of us take pride in being able to fix these things. I'm curious to know what it turns out to be. Anecdotes can be the best way to learn.
If you're getting a new opti I recommend a Borg Warner cap and rotor (sold by O'Reilleys, and nowhere else that I know of), and a refurbished back piece, whatever it's called from Advance(?). The reason being, the O'Reilleys cap and rotor is lifetime warranteed, and the Advance (or it might have been Autozone) optical piece, used to be lifetime warranteed, and still is as far as I know. So you'll have a lifetime guaranteed piece of crap if you go that way.

 

Thanks for the post man. I took it to my buddy thats working with some tuning software and he redid my tune so the computer stayed in open loop, but the results were unchanged. The car still misses and surges. I even swapped coils and ICMs from his car to mine with no change so its neither of those. He said that the only thing that he would say is that its either something to do with the fuel system (pump or regulator) or its the opti. I ordered an opti last week (New Delco unit), so hopefully it will show and I'll put that on and see. I'm also going to check the fuel pressure, but my buddy said he'd sell me his complete racetronix 255 fuel pump (ready to drop in without any mods) and hotwire kit for $125 so I'm going to take it off his hands for him as soon as I get some cash

Other than that everything has been replaced so I don't know what else it could be. Oh and I'm picking up some random false knock so I need to get the LT4 KM too

So now my weekend project is....
Check fuel pressure
Install new opti
LT4 knock module
and then running if all goes well

 

did you try the ICM mode by spacing the ICM off the head to keep it from getting too hot?heard this cuases missing when the car gets hot.with the icm being right on the head.