1. From a stop, up to 8 mph and 1200 rpm, I have a horrible deep toned vibration w/ a wobble sound.

2. Rolling at 8 mph from 1000-1200 rpm in ANY FORWARD GEAR I get the same thing.

3. Rolling at 8 mph, holding 1000-1200 rpm in NEUTRAL I get the same thing.

4. Parked in ANY GEAR and/or NEUTRAL, holding 1000-1200 rpm I get the same thing.

5. In PARK and/or NEUTRAL, with a quick Rev it does it as it passes up through the 1000-1200 rpm range and when it falls back through the 1000-1200 rpm range.

* Number 1 sounds the worse.

I've checked the following:

1. Exhaust system from the down-pipe back. I recently had the down-pipe disconnected when removed turbo for rebuild and high-flow outlet install so thought maybe I had a clearance issue somewhere.

2. All turbo bolts are good including pedestal bolts (and no oil leak).

3. Removed serpentine belt to check all pulley and tensioners. Found the powersteering fluid to be low and it didn't feel very good when I rotated the pulley in either direction. So, replaced powersteering pump.

Questons:

1. Do you guys think Torque Convertor?
2. When I had the turbo off, can the up-pipes move in such a way that they can vibrate on the back of the engine and the collector still line up with the turbo?
3. Possible internal engine issue?

**Sound seems to be at the near the rear of engine, low to mid way up, very near the firewall.

 

The up pipe could be in contact with downpipe.

Could it possibly be you were the only unlucky one and when overhauling your turbo its out of balance? I doubt it but just a thought.

Let me know if we need to tear it down over a weekend.

 

I'm going to pull trans fluid and engine oil samples this evening and mail 1st thing in the morning to Blackstone.

I just spoke with a tranny guy at Wabash Trucking. He said it may be the TQ going south. The rpm range is about right too. It's like a 1300 stall. He said if it's going it will go quickly and a UOA could show a high aluminum content.

I don't know what to think. I may definately take you up on your help if it comes to dropping the trans or pulling the turbo again.

 

I guess I'd have to buy in on the TC theory. A missing injector can really make a bad vibration too but it's be hard to explain it going away at higher rpm's.

Just pulling stuff out of my hat here, but you don't have the new CPS, do you?

 

When my torque convertor started going out you could here a rattle comming out of the TC with the inspection cover off idling in gear. Then when you were accelerating onto the highway it would hold overdrive then jump into lockup really hard. I drove it for 10,000 miles that way then the metal coming from the TC started causing shifting problems really bad, like it would stick in first, jump to drive. Really bad ordeal, if you even suspect it is the TC I would not drive it again untill you make sure it isn't the TC. I spent $4,000 on my tranny. But I was opting for a lot more power in the future.

 

I go wiyh alpine was just under there and the downpipe and manifold flange where up-pipes hookup are very close
and you stated you had the down pipe unhooked

 

I had a very similar issue with mine, rattling on midrange. It was more pronounced when towing and i came up around 1800rpm. I too thought it was my up pipes or even and engine mount.... but could not find the problem.

It turned out to be my IC pipe. When i installed it, i left it real close to the A/C - Heater core unit by the firewall and rubbed when throttling up.

Its a long shot, but you might have installed it rubbing on the heater core unit.

 

Thanks for the ideas guys. Keep em coming. I've adjusted my 4" exhaust 2 times now. It definitely seems closer to the exhaust manifold and trans cross member since the TN high flow out-let install.

I will go check the intercooler pipe tonight, It seems to be getting worse. I will probably end up pulling the turbo again to see if the intake shroud back plate has come lose. The compressor wheel feels great. As you'd expect a rebuild to fell I suppose.

 

Got it figured out. My down-pipe was vibrating on the outlet.