No boost after installing turbo....


calm as Hindu cows
Jun 8, 2001

I installed a used turbo and now I've got absolutely no boost, the needle on the boost gauge never leaves the vacuum side of the dial. The used TE62 came with a stock style wastegate that I decided to use because it seemed to have a different bracket that fit the larger compressor housing. I'm certain all my vacuum lines are correct from the solenoid to the compressor housing and wastegate. My only concern is that the puck in the THDP is too small in diameter. I took a digital caliper to it and it looked like it would be close, but should completely cover the hole on the exhaust side of the turbo. I've got the wastegate rod tightened down to the point where I would think it would be running too much boost.

I was running a TA-49 before the swap, but I roasted the 49 so it's in pieces right now. I'm not sure what else to check, am I missing something obvious? It's a stock block car with basic bolt-ons running a Turbotweak chip.

I'll post pics later once I get home of how I've got the vaccum hoses routed. Thanks in advance for any suggestion you guys may have.
Car runs fine otherwise? What about a loose intercooler pipe? IMHO even if the flapper is stuck open all the way, you should still see a little boost. Boost leak tester is my friend when I have an issue like this. Boost leak tester is a 3" (or whatever size inlet your turbo has) PVC coupler with a 3" PVC end cap RTV'd in one end (and pipe clamped) with a schrader (sp?) valve tapped in the end cap and then just a pipe clamp on the other end to be clamped on the turbo inlet. Once tightened down, hook an air conpressor up to the valve and fill the system with air while keeping an eye on the boost gauge...sometimes that means you need an extra person to say stop...I run 20psi, so ill do a boost leak test to about 20.

Very interesting boost leak tester idea, thanks for the suggestion.

The one thing I forgot to mention is that I can't even hear the turbo. It's as if the car doesn't even have one. There is absolutely no turbo whistle at all. The car runs fine otherwise.

The car has been my garage queen for several years now, and it's been a long time since it's been on the road. I putted it around with an emissions chip in it to get it inspected a couple months back. I initially thought that the emissions chip and a watsegate rod that was too long were the culprits of the lack of boost. But I guess that's not the case.
Check the hole in the turbo exhaust housing, again. It now may be larger than the puck in the waste gate, or could be off center a little.
Ah you cant hear sure its not seized or stuck or anything like that? Can you pull off the maf pipe and spin it? Better yet, are there still fins on the exhaust wheel? :) Unless you have a huge crack in your headers or crossover pipe, thats all I can think of.
I'm sure I can spin it by hand, but I'll double check that tonight along with the wastgate puck size. I'll post pics of what I find. Thanks again for the help guys.
Long time no post...

So finally getting around to trying to figure out what's wrong, I've taken some pics and made some observations. The vacuum lines appear to be routed correctly and the turbo spins by hand just fine.

The puck on the THDP measures around 1.35-1.37 inches...


The hole on the exhaust side of the turbo measures 1.25-1.3 inches...


So I greased up the puck and bolted it back up and closed the wastegate by hand to see how the 2 align...



The grease print shows that there is a bit of a gap now that I've bolted up the new turbo. I'm hoping this is the reason I'm not getting ANY boost.

I'm trying to figure out my options here. Do I go with a new downpipe, or just a bigger puck? I was planning on having mine Jet-Hot coated, but I'd love to have a stainless piece in its place. Or is it time to upgrade to an external wastegate?

The specs on the car go something like this...
Bone stock bottom end and heads with around 42K miles.
Killer Street tranny w/9-11 converter built by Bruce at Performance Transmissions
Walbro 340M w/hotwire kit
42.5 lb/hr injectors
TE62 turbo
Turbo-Tweak chip
Ported TB
RJC power plate
9" K&N and all the other basic mods

Ran mid 12's with the old TA-49 and stock converter/tranny.

Thanks in advance for any ideas or suggestions you guys might have.
Thats it! You found it! Looks like that Turbo was opened up for an external WG downpipe. You have a few choices. External WG Downpipe, different exhaust housing, or have it welded up and drilled out. If you plan on going with an external WG downpipe, I will make you an awesome deal on a brand new GN1performance pipe. Comes with Waste Gate and Test pipe. Never installed. Stainles also. I went to a 3.5 inch so I do not need it. PM me if interested!
Could be wrong but, with a wastegate puck gap like the one I see there, you should be able to make "some" boost, it would just be quite slow to spool.
Has your testing been in the driveway or out on the road at WOT?
Tested it on the road - foot down on the loud pedal - no boost.

Here's crazy question - the stock wastegate works off of vacuum right? I hope I'm right. If so, how many inches of vacuum should it take to move the rod?

I put a hand held mity-vac on it and put 25 inches of vacuum on it and the rod never moved (on either of the stock wastegates I have).
No it works on boost pressure, try 9-10 psi. of regulated compressed air into it and it should just start to move the rod outward at that pressure if it's a stock type spring.

Most HD actuators start to move the rod between 12-14psi. of air.

Moves on pressure not vacuum.
Wow I feel like an arse - pressure not vacuum eh? Thanks for the schooling. I'll try that tonight then.
You might be able to use the plate listed on RJC Racings site to sandwich in between your THDP puck and the large hole in the turbo housing.

Down Pipes'n Parts

It's not drilled out so if you align it properly a 1" hole should work out great for you centered between the two circles you have now, IE split the difference of the offset for the new hole you will drill in the plate.

Email them first for details, if not they also make a gasket that has an approx. 1" hole in it that might be easier to sandwich between the two pieces and allow for proper ex. gas flow.

Jason at RJC will know what to use or you can get a new exhaust housing with the proper size hole in it.