98 3.8 Vibration in park and drive with foot on brake

[Ratchet]

Re: 98 3.8 Vibration in park and drive with foot on brake

Again, did you do a case relearn on it?

Yes. That was done with the new balancer.
Also took it to the muffler shop just to be sure and had them test the converter. They said it checked out fine.

[Ibanezz]

Idle air control? Or a similar vacuum leak

[Ratchet]

Re: 98 3.8 Vibration in park and drive with foot on brake

Idle air control? Or a similar vacuum leak

Wouldnt I be throwing a code if it was either one of those? Ive looked to see if the engine or trans was hitting the body anywhere and unless the transmission or back of the engine is hitting back there where I cant reach, Im stumped.

Since this post Ive had the fuel injectors cleaned and fuel filter replaced. Im averaging 26mpg on the highway and 20 around town. If I was misfiring you would think my mpg would be suffering.

[HeadyFirebird'00]

Re: 98 3.8 Vibration in park and drive with foot on brake

Dude, my 2000 firebird does the same exact thing. Or incredibly similar to what you describe. I've tried almost everything to fix it as well.

My ride shakes and vibrates a different amount every day kinda. Somedays she’s smoother running than others. Generally tho it still get the loose change rattle or inside plastic molding rattle. I’d think the SoCal weather wouldn’t have an affect but Idk. Idc She still runs damnit. And she is always needing some TLC somewhere. I can’t believe I’ve had this car for 10 years now.

At 126600 miles, My car burns thru and leaks around 1/2 a quart or so of oil every 3000 miles. I top it off every 1500 miles. I know the pistons and valve seals will never be like new again. She puffs a slight plume out the tailpipes on startup.

After years now I just live with it. Spent hours of reading/researching. I’ve concluded the idle quality is not going to go away easily. For me, it’s a compression thing. That plus maybe mix in with one or two older stock emission parts (EGR, IAC). Do a compression test or have a shop do one. You can YouTube how to do it if you are feeling up to it. Just my suggestive advice.

[3.4grapeofwrath]

Re: 98 3.8 Vibration in park and drive with foot on brake

I had the same problem years ago with my camaro. I kept a list of all the things I did and replaced and finally discovered it was the exhaust system causing all the vibration. I replaced all the rubber hangers. Some were very brittle due to the heat and age.

[htmabe]

Re: 98 3.8 Vibration in park and drive with foot on brake

Everything I've read sounds like a p102 Maf sensor. They are high dollar like 160 new 95 rebuilt. So if you had a known "good" one perhaps swap it out even though you have no code see what that does. I'm not suggesting with no code to spend 160 dollars on a theory but if you can swap for a known good one free go for it. 3.8's are known for Maf sensor probs which like the iac controls your idle and most vital info to the computer. If it fails it will drive you nuts chasing down plugs wires icm pcm o2 sensors vacume leaks etc etc. Imho.