88 LN3 Vin C Still runs rough under load

[Drive-In]

Thanks SuperH - I got a noid set today and also just ordered an ALDL OBD1 cable... see if i can get more information that way too.

[Zeik75]

I believe injectors are more of a working or not deal, they can get buildup on the screens though which would affect atomization of the fuel. Is there any delay in the transmission when up or downshifting, letting the car do it though? Also you should probably replace the fuel filter if its 2 years old, its cheap and easy to get to. I usually pull the fuel pump fuse and run the car a bit to drain some fuel so it doesn't spill everywhere. Running it with an injector unplugged won't hurt, unless you forget to plug it back in.

[Drive-In]

Hey Zeik, thanks for that. I checked the injectors with a stethoscope and they're all working.

I have a question. I ran into info that suggested a loose torque converter bolt can cause an imbalance. My torque converter seal was replaced just under two years ago. The vibration started a few months later. Very faint at first, then more intense over time. My question is this, are the torque converter bolts are accessible through an access panel?

This particular problem feels like it's got my name on it. Vibration that seems to be neither RPM nor wheel speed dependent, I feel it through the floor not the steering wheel and it doesn't seem to come from either the right side or left side of the front end.

I've had a car drop on me and I hate getting under them and don't if I can avoid it...

Mike

p.s. - me having an ALDL cable is like having a pig read a watch so far...

[SuperHbody]

It very well could be, I've never had that happen ever nor has it been a problem with GM's.

Are you using an interpreting program for the ALDL readout? If so, what you'll be looking for is the car in the closed loop cycle which means it's warmed up and using sensor readouts for adjustments rather than a set parameter like in open loop. The readouts I would look at are TPS and the injectors. TPS or Throttle position sensor should read a zero at idle and climb instantly when you blip the throttle. For the injectors, you want to see a readout in the range of + or - 10. High positive indicates a lean condition so the computer has to add fuel which could be caused by an air leak. High negative means a rich condition which would indicate a leaky injector or faulty fuel system.

[Drive-In]

SuperH, thanks for that. I'm using Freescan as it's the only OBD1 package that I could establish the datastream with. I need to clock more time plugged in but your post is a HUGE help and a step forward and thanks again.

edit: I only ran into one reference to a loose TC bolt causing vibration. Also, it seems like less a GM issue than one with the mechanic who replaced the seal. Wrong bolt, no loc-tite or improper torque are 3 that occur to me. Or something from the "Secret Life of Bolts".

[Zeik75]

The bolts can be reached through a slot made for tightening them, it does require you to get under the car though no way around it. It would be worth a shot IMO. Underneath where the engine and trans bolt together there is a little plastic cover with 3 bolts in it. If you remove that you will have access to the 3 TC bolts. You will need to spin the engine to move the flywheeltill the bolts are within reach. If you block the rear wheels and set parking brake, then lift the car and support on jacks it should be safe to be under. After that you should be able to put it in neutral and spin the engine from the harmonic balancer bolt. It wouldn't be too bad, but a shop could also quickly check it on a lift tto i would think.