Rough Idle/Hesitation/Backfire

Originally Posted by Gary Yarbrough

Thanks for all the advise. I got plug #8 changed and I would say that the problem is about 98% cured. I can easily take off with no hesitation with either the DRM or JVD chip. I just get a little touch of hesitation if I'm rolling below 1200-1500 RPM (hard to tell exactly...at about 8 mph) and floor it. Maybe that's not a good idea anyway or maybe I needed new plugs too... Also, there is no more backfiring! Thanks again for all the help!

Take it up to 6th at at about 40 mph and mash the gas, it should pull smooth if everything is good.

[Gary Yarbrough]

I suppose I still have a problem. The car revolts if I floor it in 6th at 40mph. It will accelerate smoothly with gentle throttle. Any suggestions about what to try next?

Gary these are steps you should take, skip the ones you have done already. Steps go from easiest to more difficult.

1) Inspect spark plugs. Looks for cracks in the porcelain.
2) Ohm out plug wires
3) Ohm out injectors
4) Ohm out coils


The only other thing outside of these issues is a failing ECM or DIS module. Eliminate as much as possible and let me know on the ECM, I have a test box I keep around for things like this.

[FU]

5) Do a compression test.

[Gary Yarbrough]

I'll probably be Saturday before I can Ohm out the plug wires (I'm on jury duty...).
However, I wonder if it might be something else. My belt tensioner is rattling a bit more than what I think is normal. I got my wife to floor the car for me while I had my head under the hood. I noticed that I get a sort of clapping sound when it gets floored from idle and the noise is in sync with a very large movement of the tensioner. Could a failing tensioner be my problem?

Originally Posted by Gary Yarbrough

Could a failing tensioner be my problem?

No.

[Kb7tif]

Originally Posted by Gary Yarbrough

Thanks for all the advise. I got plug #8 changed and I would say that the problem is about 98% cured. I can easily take off with no hesitation with either the DRM or JVD chip. I just get a little touch of hesitation if I'm rolling below 1200-1500 RPM (hard to tell exactly...at about 8 mph) and floor it. Maybe that's not a good idea anyway or maybe I needed new plugs too... Also, there is no more backfiring! Thanks again for all the help!

Your running good now. Leave well enough be.
You have new accel coils, injectors, wires. Plugs?
You chip is pry tuned for top end not flooring it in 6th at 1K rpm.

[Gary Yarbrough]

Yeah, I've got new coils, injectors (~6 months old), and plugs. The wires are, however, a year old. Tomorrow, I'm putting the other chip back in to see if it will pull better in 6th at 1K rpm. I've got mixed feelings...I like for things to be perfect. But maybe I need to follow the DIMWIT rule in this case?

On another topic, how seriously should I take the belt tensioner issue? It really moves around a lot and does make some noise.

[flyin ryan]

Originally Posted by Gary Yarbrough

On another topic, how seriously should I take the belt tensioner issue? It really moves around a lot and does make some noise.

Jeff already gave you an opinion but if you are that worried about it just change it out & call it done. My 90 jump's around a bit too, I put a long TQ. arm/bar on it while it was running to take off say 70-80% of the load...didn't change the world all that much .

[Gary Yarbrough]

Don't get me wrong, I fully trust Jeff's opinion that the belt isn't causing the hesitation and I am very grateful for his and everyone else's advise! I was just asking if it is a problem in a more general sense. The loud clapping sound that seems to be coming from it when I floor it from idle doesn't seem like a good thing. But, I've got a lot to learn...