Idle vibration

[garner49]

Bought the car back in January and and have dealt with the idle vibration since. I swapped the stock plugs to the Iridium IX (gapped at .045) and new wires yesterday, but the vibration is still there. Yes, I was hoping that would cure it; but the stocks still looked pretty good for 51k miles. It does run smoother and has quicker pick-up. The vibration is most noticeable when stopped at a light, foot brake held - if I release the brake a tad, it's not as bad. It's enough to see the back side of the hood bounce.

I hope this may help mpg too...well see on that.

Any idea's?

[drskully]

sounds like injector or vac leak.

[Hooligan]

Originally Posted by garner49

Bought the car back in January and and have dealt with the idle vibration since. I swapped the stock plugs to the Iridium IX (gapped at .045) and new wires yesterday, but the vibration is still there. Yes, I was hoping that would cure it; but the stocks still looked pretty good for 51k miles. It does run smoother and has quicker pick-up. The vibration is most noticeable when stopped at a light, foot brake held - if I release the brake a tad, it's not as bad. It's enough to see the back side of the hood bounce.

I hope this may help mpg too...well see on that.

Any idea's?

I see that you have a Turbo, the following info was taken from the "Sticky" in the performance section;


Quote:

Is there a procedure that details the spark plug replacement for an '06, PT
turbo?
I may be wrong but aren't the spark plugs on all the turbo's easily reached without touching the upper manifold so there's really no instructions needed except 3 things; don't use platinum plugs, use anti-seize on the lug threads and use the correct gap for the turbo (which I believe is anywhere from .032 - .038

As you see the recommended gap is .032 - .038. I don't know if that would help with the vibration or not

[garner49]

Recommended gap is .050 - the stocks that came out were more like .065! I don't see how a tighter gap would get rid of it. I read all the posts about gaping, decided to go with the upper limits of .045.

Oh, and no, you cannot get to the plugs without moving the intake (especially the two inside) - at least I couldn't.

I've looked for a vacuum leak, haven't found anything, all hoses look good and tight.

[Cal Cruzer]

Since you addressed the most obvious I would start looking for a small vacuum leak first. Zip tie all of the vac lines.

Do you notice any difference at idle with your foot on the brake? If so you could have a problem with the booster, not likely but a thought.

[Mean Green]

Actually with the right swivel socket combo you can get to the plugs.

Irridium plugs should be gapped between .028 - .032.

You can't look at hoses and tell if they are leaking. With a turbo'd car boost leaks will kill performance. Like Cal Cruzer said all vacuum lines should be zip tied and intercooler hoses should have t bolt clamps.

[garner49]

So, tell me what the difference is in a tighter gap... More power, less/more mpg's??? Is it worth re-gaping them? I set them at .045 and it runs better than the stock's; haven't had enough time to judge mpg's.

[reklaweelmada]

Check your motor mounts also.

[Mean Green]

Originally Posted by garner49

So, tell me what the difference is in a tighter gap... More power, less/more mpg's??? Is it worth re-gaping them? I set them at .045 and it runs better than the stock's; haven't had enough time to judge mpg's.

Tighter gap equals less chance of spark blowout causing a missfire. Yes, regapping is worth it. What does running better than stock mean? I used stock Copper Plus plugs in my 280 hp GT and use them in my 350 hp SRT-4 and the cars run like a runaway express train. IMHO irridium plugs are overpriced and all they do is last a bit longer than stock plugs. Stock plugs are supposed to be changed every 30k so I'm not surprised your car was running a bit rough with stock plugs 21k miles overdue for a change. Also, there is no way new wires and/or plugs will give you more power and better mpg unless your plugs were old and crap to begin with. Then new plugs and/or new wires will allow for the power and mpg the car was designed for and not more than that.

[garner49]

Thanks for the info - it wasn't running rough, just a bit a idle - was hoping the new stuff would smooth that out. I have a 1.8L Miata and it idles so smooth, you can't feel it. I'll regap the plugs sometime soon. I couldn't find the stock plugs locally and found a deal on wires and Iridium's on-line while I was looking, and I bought them.