Im glad i started reading this thread before i made another one... Yesterday i noticed mine started bogging down when i would cruise at any speed... for say, id be doing 50 in 5th gear cruise about 1/2 a mile try to give it some throtte and... putputputput nothin then all the sudden surge and take off... also now when i come to a stop it seems like it wants to stall.. rpm drops to like 300 and it catches and comes back to about 900 and levels off... i have noticed that these problems happen more often and more severe after i really jump on it... im would like to try fixing it tomorrow... any ideas on where to start? as in easy and quick fixes to try first? thanks guys

 

My 95 just started doing this today after driving in an extreme thunderstorm. Anyone ever have any problems with water getting in the Ram Air set up? I thought it could be the opti/msd but it is pretty coincidental that it happened right after the storm. any suggestions?

 

Man I cant believe how many people have this same problem and dont seem to find the fix! I too am one of those people, mine has been going on since my headers were installed. I have heard that lower backpressure from the headers can cause it but have heard no fix for it. Also if that were the problem wouldnt everyone on here with headers have the problem? I have replaced just about everything like you guys and it still does it? BUT now that I saw the post saying that an 02 might not throw a code unless it is really bad, I might be in luck....MIGHT. I had new 02s installed along with the headers so just maybe it was put in wrong or just a defect???? Because after about 2 months I got an 02 code

So same question as above, is there any truth to the 02 not throwing a code if it is semi working??????

Man I hope we all get our cars back again!

Rich T

 

stands up in his chair...."hi I'm Brett and my car also stumbles at 3k rpm and backfires and I've replaced everything opti, msd wires, plugs, tested coils, checked 02's.....tested EGR, and am replacing the ICM today".......

this really sucks...so many things it could be but reading this post sounds like most all of us have done the basics. I'm a pretty good mechanic and tech, but this is baffling and frustrating.

Anyone get their stuff running PM me please.

 

well ruled out the ICM for whoever suggested it...not sure what else to check.

 

Well Brett, I am about to get some tuning done to the computer so I will let you know what happens? Just wondering though....Does your stumble happen more when it is hot outside? I have noticed that when my car sits out in the heat on really hot days, the stumble seems to happen alot more and worse than when its cold out. And if it has anything to do with heat, I think it happens more to me when I have the AC on. Tonight I drove home with the heat on and she didnt stumble once. P.S. my fans dont work unless I use a jumper wire so the car runs a little hot. I really hope to find the cause because I would like to be a graduate from the " I have a 2000 RPM stumble" club!

Rich T

 

OK

New Opti, O2's (actually Wideband), Plugs, Wires, ICM, coil, 2 Different MAF's, new 30# Injectors, EGR Gone, OBD1 PCM and STILL THERE!!!! just a little stumble cruising at a steady RPM could it be trans?

ADDED:

My AIR is gone as well
I forgot to mention, Had since about 30,000 miles NEVER could fix

 

Im not sure if this helps but I have had similar problems with both my 95a4 and a 94a4.
My 95 went down hill after going to the track. Started by backfires when racing it up in the driveway, then intake backfiring around 4500 in all gears. I changed wires, plugs, coil, etc, and nothing happened. Ended up being the opticrap. Car ran strong for a few months after repairs. When I did all the work, I added a homeade CAI. After a few months, I had a rough idle. Ended up being a dirty mass air. I cleaned it twice and nothing. The third time, I didnt use the Windex as suggested, I used electrical contact cleaner and a qtip. That did the trick, good idle, back to normal.
Now, the 94 was a car I worked on for someone. Came in on a flatbed in pieces from someone who didnt know what they were doing, trying to "fix" it. I rebuilt the opti, wires, coil, etc, and did my CAI. A month later , comes back ideling rough and missing at low speed. Though I knew exactly what to do, clean the MAF right? lol, Ended up cleaning the TB out and more importantly the pintle on the the IAC was filthy as hell. Cleaned all, and it runs fine now. I decided to clean the 95's IAC also, glad I did, it was nasty too. I suspect when I cleaned his TB originally with intake cleaner, it must have loosened up junk in the IAC.

 

Maybe you should try a new MSD Blaster Coil.. I know of a few people that have been saved by one...

 

thanks for all the input. My coil tested out at 7100 ohms which is good in fact as good as an aftermarket. tried a new ICM it's fine, I'll look at the IAC which I think is right behind the TB. Some TB cleaner and a long nozzle and flashlight I guess, unless I just unbolt it...might be better that way. I hope that's it. Now I'm wondering if my NEW OPTI crapped out ...but I kept my old one and rebuilt it this weekend. Only thing wrong with it was the rotor had one screw that backed out. Locktite and cleaned the contacts good and also cleaned the mitsubishi eye...it's like a brand new one. So I may tear down the NEW opti and at least inspect the rotor make sure all is well. I'm going to pull all 8 plugs tonight and inspect...only 3 weeks old....anymore suggestions post em...thanks.

oh yeah mine is stumbling at about 4k rpm on a hard take off all gears cold or hot and while cruising around 3k it does the same.

 

I don't believe it's in the Ignition! I've replaced my ENTIRE ELECTRICAL system, have custom programming and that stumble is still there, It's not on all LT1's but it is on quite a few when I rebuilt the car last winter I took ALL wiring harness apafrt and checked them, no problems there, I MEAN I casn't seem to figure it out it's been there forever I just learned to ignore it mine never is there when giving it the gas just a little when cruising BTW I have a lingenfelter TB and a NEW IAC so I know that's not it! It's become one of those pet projects I work on when I have some Cash to burn!!

 

I am curious to find out how many people have had this problem occur after installing headers? The problem started right after my header install and I think it will be with me an d my car forever? I am so worried about going further due to the fact that I am spending money on guesses : (

I just dont have enough money to say here take it and find fix everything until you fix it. But I have spent a great deal so far.

Im sure everyone with the problem knows how excited I will be if I ever get her back to normal. I drive 30 miles to work everyday and all it does is misfire going to and from work. Such a PITA!

I hope we ALL get our cars back soon. And thanks to everyone trying to help out.

Rich

 

my car ran fine after header install....and after opti, plugs, wires, etc. I sure wish someone from Advanced would jump in here and read everything most of us have done with the same problem. It's getting old this problem, my gas mileage sucks, sick of the backfiring and hate the stumble at 4000 rpm

 

I'm on my second round of misfire problems. The first happened around 5k and was solved by changing the plugs and wires. Recently I've been noticing a stumble at lower rpms and then last week at the track it was missing on the 2-3 shift as if it was bouncing off of the rev limiter. On the way home it was running warm and I had worse hesitation and stumble. I've took it out the other day and noted that it is harder to start, and that the stumble and hesitation, while not as bad, is present through 2-3k rpms. I did burn a wire and used an older stocker to get me by so I am going to change that and the coil. However, I think its time for a new opti....102k on the original

 

Your's probably is the Opti.

What I've noticed is that my hesitation only occurs after the car is warm, and ONLY when I accelerate hard between 1000-2000rpm's, and also the idle is juuuuust a bit rough. I've been told that a sticky EGR can be the culprit.

The header thing makes some sense, I have JBA's, I've replaced everything except the EGR, so that's what I'm changing next.

Hey Brettinator, and everyone else for that matter, have y'all taken off & cleaned out your Throttle Body's & IAC valve that is attached to the bottom of the TB? That would help tremendously, my car responded very well with the cleanup.
So far, here's what's been changed in my car.

New Opti
New plugs & MSD blaster coil/MSD wires.
New O2 sensors.
New chip(93).
IAC valve cleaned out & fully functional.
No codes being thrown.

I'm taking my car to Superior Automotive in Anaheim so they can replace the EGR & I'll let you know what they find.

BTW, I wouldn't remove the EGR, at least not for me, in California the smog laws are VERY STRICT, someone could get fined up to $5000.00 bucks AND have to convert back to meet smog. It's not worth it to me.