Ok everything that i have read so far had mentioned plugs wires egr al as the problem. I have replaced the header gaskets, wires, plugs,egr valve, fuel filter and pcv valve.Its still there??any ideas guys please help me

 

there's a bunch of threads on this topic, some good suggestions in all of them, just search for 'hesitation' or something of the like.

shoebox has some good suggestions on this matter and check out his info he linked to in another thread: http://csce.uark.edu/~jgbertr/rb/4th...html#opti_test

check your opti. Check the 4wire pigtail that goes into the opti for corrossion. check for any arc'ing around the coil, helps if it's dark out. Check to make sure you have a heat shield around the coil to opti spark-plug-like wire. Look into getting a new $15 coil. ground your coil mount to the chassis. look into your ignition module. Look into your TPS (take it off and hit it up with a ohmeter and twist it to see if it's returning consistent resistence). look into your IAC. try a throttlebody coolant bypass. hook up a fuel pressure gauge and test all scenarios. "reset' the ECM by unplugging the power from the battery and then back on (i know this works on the TPI, but unsure on `94+ ECMs). check for vacuum leak. There are other things to look at, but that's all that comes to mind right now.

good luck.

 

Might want to try your coil wire its been known to cause a similar problem, and also your opti, but obviously this would be the worse case scenario. Does your car act like it hits a rev limiter at around 4k or a little higher?

 

opti?

 

I had a 1800-2k rpm stumble. A new opti fixed the problem.

 

when they say opti, they are referring to the optispark, which is basically a fancy distuributor.

 

mine is dong the samething. I am putting in a new opti on saturday. Hopefully I will tell you sunday that it fixed the problem.

 

Replace the coil it took care of my low rpm stumble.

 

Mine feels like it hits the limiter around 5200rpm, anyone know what is causing it???

 

Well I did have that high rpm stumble before but the opti was replaced twice, the first time the dealer did something wrong and it went bad again. At that same time I had replaced all of those things,opti, coil, coil wire and ignition module. Now all of this has started since I had headers installed and when I saw the posts about burnt wires and bad plugs I went that route. I dont have the tools, the time or the place to do it myself and I cant seem to find a place that has the time and I can trust to get it done. That and I have had a bad string of luck with this thing, since the header install I have spent about 3500-4000 dollars trying to get this thing straight so I can get it through emissions and Ive had no luck. I mean hell I dont mind spending money on the car to fix it but damn I just want it fixed??

I will keep you posted on how this works out.

Rich T

 

Ok here is the latest with this 2000 rpm stumble thing. Now they tell me its throwing a code 154 which they say is from my o2 sensor???? My o2s were replaced back when the headers wert installed so I really hope this is not true. There is also another misfire code and egr code but i dont think that the cpu was reset after the egr was installed. Again I will post any updates so While I wait feel free to chime in, thanks.

Rich T

 

i have the same problem. i have changed many things like yourself. however, the o2's could be the problem. i have talked to several people that said new o2's fixed their problem. but, opti is a possibility also. i hope it is not that. i have my o2's ordered from jason cromer but they are not in yet. its been a week so i hope they are coming. what kind of o2's are you running? i have heard problems from people running non-delco oxygen sensors. i will be changing the tps and coil when i find time. other people said a new map sensor and a lt4 knock module fixed their problem. i have replaced both without any success. i will keep you posted if i find anything else out. let us know if you find your problem.

 

These kinds of things don't need to be such a mystery. I hate to see you guys doing the dealer thing and throwing parts at the car until it runs ok. That's a huge waste of time and money - money that could've gone towards bolt-on's or a cam swap.

Get some basic diagnostic tools/test equipment. Shoebox has mentioned this stuff specifically both here and on his site (if I remember correctly, anyway).

A Haynes manual ($12) will provide the testing procedures for just about anything, a multimeter ($20 for a heavy duty one at Lowes), spark plug tester ($10 at any auto parts store), fuel pressure guage ($35 or so, same stores), and a vacuum guage ($35 or so, same stores). With these tools you can isolate just about any problem. Get some means of scanning with an AutoXray type device or a pc/laptop with a cable and scanning software and you're really cooking with gas!

No, it's not fun to go buy all of this stuff. Headers, gears, etc, are much more exciting. But these things will save you time, money, and (probably most important) peace of mind.

Just my suggestion..

 

this prob is a major pain, i replaced the opti, bt the way thanx for the great price jason! but that didnt fix it, we did a few cheap things but now i am looking into plugs/plug wires......engine scope said it was a misfire....thats all......from what cylinder and whats causing it, who knows!