I thought I had the low RPM Stumble, But I failed to realize it only occured in OD. When light peddle pressure is applied when the car is in 4th it stumbles to the point it will not pull. If I pull it down to 3rd or D it goes fine. It also does it a speeds over about 115 or so when it shifts to 4th. the car is a 93 z28 107000mls Auto.
Any suggestions or does anyone know the exact problem.
Thanks
Tyler

 

well, i can't tell you the exact problem but i could give you some suggestions. i think many lt1 owners have this problem. i would say it is either bad plugs, wires, opti, or o2's. now, there are many other possible things that it could be. are you feeling a miss or stumble at high rpm? if so, most of the time it is plugs, wires or coil. how long has it been since you have replaced opti, plugs/wires, and o2's. if your plugs/wires and o2's are old, i would replace them. if your still on your stock opti, you've done good. i replaced my o2's and this helped this stumble out a lot. i don't think it fixed the problem 100% but i got rid of 75% of it. let us know how old some of these items are and we can go from there. also, if the fuel filter is old, i would replace that also. not only will this improve fuel economy but it will help acceleration if it is dirty.

 

Many people experiencing this with both autos and sticks.

I have a 93 A4 with 90K miles and have been experiencing the same thing for at least 50K miles

I have went through the following some to try and fix the stumble/surge and some just because of failures nothing really helped

- head gaskets
- lifters
- two set of spark plugs/one set wires
- O2 sensors
- tested coil
- fuel filter
- others
- 1 full set of four tires/1 set of only two (all balanced)

I have been watching this problem and what I see is it isn't just one problem it seems to be different for everyone or even a combinations of more than one thing.

Lately I have added automatic transmission fluid friction modifier and that has improved my tourque converter locking and unlocking (it used to shudder) and my GM buddy says my stumble/surge is coming from my transmission or converter. I seem to agree with him as my engine runs like a top and gets decent mileage. I will keep looking but I also am waiting for something to fail as it costs money to keep looking and needlessly relacing parts.

I know I haven't really answered your question but I am too looking for the same answers and thought I could share what I have seen so far in my search.

Good luck

 

If you have a 93 then I think you dont have the 4l60E you just have the 4l60. Maybe the shiflt linkage on the the throttle is out of adjustment?? But that might through all your shift points off too.

just a thought

jason

 

I have the same problem. My car is away getting repaired but I suggest one thing you guys need to try your fuel pump and or fuel pressure regulator. I'm hoping when I get my car back it will be repaired! I will let u guys know if that worked besides all the other stuff I'm replacing Opti,wires,plugs,etc

 

Do NOT rule out the EGR valve