I have a 1994 Z28 m6. When i am driving on the interstate in 5th or 6th gear my car is hesitating and bogging down. Even at 85 90 mph the car has horrible acceleration. Also some times off the line the motor will drop in rpms and will give a big jerk. And another thing when i go up to about 4500RPMs if fells like i am hitting my rev limiter. Please can someone help me .



P.S. I have had the car for 3 weeks now. I do not know about the history about it. I bought it for really cheap. I assume it has been happening for a while


66000 miles on motor

 

MOst likely on an LT1 it just needs a good tune up since you just got it. I would change plugs and wires also fuel filter. Hope that helps ya out a little.
Kenneth

 

I just solved my stubling problem by changing the wires. I took off the #7 wire and it was melted to the metal holder/guide thing. It might be your wires. Im might also be your opti. I would gues opti because of your description of the problem at 4500 RPM's. I would try the wires because they are the cheapest, oh and the plugs too.
Zack S.

 

could be the cat trying to stop up on you.

 

I just replaced the wires with 9mm wires and ACDelco platinum plugs. I have not replaced the fuel filter yet. The cat on my exhaust is about a year old with the borla exhaust.


Some people are telling me it could be my distributer and that is alot of $$$. I heard the LT1 in 1993 1994 were famous for this problem.

Thanks Mark

 

Yes, it could be your optispark, if it is and you have a 94, might as well upgrade to the 95+ vented opti. 93-94 sealed optisparks once wet, will hold water causing corosion, with vented, opti gets wet, opti drys off inside and out.

I had the bogging problem too on my a4, while in 4th doing 60, coming off an exit, it seems like I have to push the pedal in more and get her into 3rd to accel.

I have already had a dealer look at it, basicaly they said there was nothing wrong with it, they hooked up a portable scanner, showed nothing all a/f looked good. So I replaced the plugs, (ac delco plats.) and that cured for a while. So I've just learned to deal with it.

I dont have a cat, so its def. not that.
as well as a new optispark
Good luck.

 

I usually say plugs & wires then Opti but you symptoms are like what mine were when my cat crapped out on me. Don't count it out. If it feels like it just wont go like it should without missing on the highway or if it feels as if it isn't breathing well then it very well could be the cat like 97Z-M6 mentioned.

 

it could be the opti... i dont think so however.

it sounds like you are trying to say the car shakes and studders when you are in 4th or 5th or 6th gear and bogging the motor under 1500 RPM. if that is accruate..then does this quit happening when you get up into the 4000 RPM range?

 

dude, do the cheap easy stuff first. Fuel FILTER. 15 bucks, 5 minutes to change. Lack of fuel caused by a clogged filter means no fuel for higher RPM's.

 

What I am trying to say is in any gear reaching red line around 4500 and up the motor fells like it is running out of fuel or like it is hiting the rev limiter and I can not go any higher. Sometimes off the line it will stumbled very bad and shake the car violently. But everytime on the interstate in 5th and 6th it will fell like the car is missing and will take forever to accel. I have to be at 2500RPMs to even keep the car moving in 6th. Also for some reason the cruise control will not work and then it will work sometimes.

These are when the symptons are most noticeable.

But it can happen anytime i press the pedal.

 

was it stumbling before you changed the plugs and wires or did it start after. I had the same problem, and it was just a burnt wire that was my cause.

 

Change fuel filter first, then try opti, then maybe the fuel pump could be the culprit. Either way, the filter/opti are good tuneup things to do and will save you headaches int he future.

 

The problem has been occuring before i replaced the plug and wires.

Thanks for the information guys, I am going to replace the fuel filter first and then seen if it is the opti. My friend and I are replacing the intake manifold gasket, there is a pretty bad leak. So we will find out the problem.

Thanks again Mark Tisdale

PS the problem is so bad i lost to a 325is BMW. Pretty Bad.

 

read em again. fuel filter, then wires, i say SeaFoam/DeepCreep also, O2 sensors....and then...maybe - Opti or fuel pump.