I thought it was my turbo but I just put in a brand new one and still have the problem.

When I just start my car and its cold I get a vibration when I hit my throttle and let off as the rpms come back down. I feel it most if I put my hand on my turbo's compressor housing or that general area. It pretty much goes away once the car is warmed up. Car still runs fine though. Any ideas?

thanks

 

how high is your cold idle speed?

 

does it run like ****?

 

ha!
no, it runs really well. Thats what's baffling me. Turbo spools up smooth with no vibration. Only vibrates coming down off throttle. And its not like an exhaust rumble vibration. Its very mechanical feeling and sounding like a grumble or churning sound. If it were the turbo I would expect it at all the rpm ranges not just when winding down?

Miraiz, my cold idle is about 2K and warms up quickly to a warm idle of 750 dead on. but even after warming up i rev it and let go and it does that vibration!

 

ttt

I was looking at my timing belt and although I put a new one in last spring (along with a new water pump) it looks aweful loose. there are no specs on how much play there is supposed to be, only about adjusting it in the helms manual. Can that be causing a vibration at like 2200RPM?

 

hmmm...don't know...i suppose you can try tightening the belts...all my belts have very little play especially the timing...timing belt doesn't flex at all. I used to own an Audi that had a bad engine vibration problem...it was due to bad oil rings ( yeah go figure...I don't know why either)..but if your car isn't smoking then I think its safe to rule out.

You might want to see if there are any moving parts rubbing against something. (belts etc...) or possible failing engine mounts? More HP = more wear.. Have you tried popping the hood and tugging on the throttle cable as well? Try to see what might be causing it.

Oh, one last thing I can think of is to check to see if the wastegate bolts are loose. My loosened up at one one point and made a horrible vibratating noise when revving...


[Modified by MiraiZ, 10:21 PM 5/22/2002]

 

I can reproduce it most with the hood popped and revving the engine slightly and letting go. I sense the vibration most at the area around the turbo. Happened with the old turbo and the new one. Its like a low fequency chatter or shuddering as the engine comes down and passes by around 2000RPM then idles fine with no vibration. No vibration over that rpm range either! I can't figure it out!!! Engine is not smoking and drives well.

 

Wastegate bolts dude!!....look at them carefully!!...Mine looked right too until I really got a good look...I noticed that the WG was riding up a bit...had to coat them thoroughly with lock tite and really clamp them down....don't use the crappy studs and nuts supplied with the kit....they're complete crap. Mine are laying my driveway now completely rusted and cracked...replace them with bolts drenched with lock tite

I'd also double check the manifold bolts which where also crap. Make sure that they are NOT loosening up as well


[Modified by MiraiZ, 10:40 PM 5/22/2002]

 

I got a firering gasket for the wastegate and I have it tightened down quite well. no leak (have to use a crowfoot wrench to get in there).

I also double checked the manifold and there is no leak there either. I don't think that is it?

what are you using for manifold bolts now? What about those locknuts on the exhaust manifold. They are a bitch. had to cut one off when I took it off last week.

I also use a high temp ceramic type thread locker on all my bolts.

[Modified by GruvyTune, 8:42 AM 5/22/2002]


[Modified by GruvyTune, 8:48 AM 5/22/2002]

 

It doesn't have to be leaking (much)...I was quite happily boosting like I normally did, but got strange rattling noises at low rpms....I used a small adjustable cresent wrench to tighten it....it was still a bitch to tighten it while it was bolted on the block..but do-able with patience....

at any rate...I doubt its anything serious....check engine mounts too...I head mounts should be replaced if going FI...(I haven't yet tho)

 

have you looked under the hood to see where it is comming from?

 

Miraiz!!!
You were correct. Much to my surprise, the exhaust manifold was not all bolted tight. Some got very loose. I can't believe those frigging stock lock nuts came loose. I know I tightened them all down. I had to cut one off (you know the really crammed in one in the bottom center) when I took the turbo off last week. Well, vibration seems to be totally gone, turbo spools clean and nice.

Thank god for other's with similar experiences. I was pulling my hair out.

Well, I'm off to retune the Hondata with the wideband. Doug and I put our heads together and I am going to try something sneaky and tricky to try and get that low rpm hesitation out.

torin

 

Hah.. I had a similar problem...

One of the bolts from the exhaust manifold to the turbo came loose...

 

yup...the problem sounded much too familar!