O.K.....here's the skinny. G35 with t-netics standard turbo kit. Car has had the kit for 6 months....runs fine...8-9 lbs of boost. Last week car started making zero boost and running pig rich after around 1500 rpm's. Runs fine at idle. Here is the list of things that have been done..

- all intercooler piping removed and inspected.....no cracks or problems...re-installed...does the same thing
- checked all exhaust piping for problems....no leaks and no cracks at welds, etc.
- checked turbo....impeller spins freely
- tightened down the BOV to max...no change
- removed wastegate and blocked off with metal plate...no change
- wastegate inspected....spring and diaphragm are fine.
- boost gauge tested and works fine
- no boost/vacuum leaks at idle or when reving the engine in the shop but does have a whistle when driving

Any ideas?

 

you obviously have a leak make a pressure tester

 

can you hear the turbo whistling? but it is showing zero psi???

 

As noted....the whole system after the turbo was torn down....inspected.....and re-installed with the same problem.

 

You can't hear the turbo spool with increased rpm......but....the turbo impeller spins freely and can be heard spinning for a few seconds after the car is shut off after you rev it up.

 

you can't hear it??? I know I can hear mine very clearly at any rpm, but I have a pretty quiet exhaust.

 

uh huh, I read that, it still doesn't dismiss the fact that you have a leak.

Make a pressure tester. Cap off the compressor inlet with a PVC coupler and pressurize the system and listen for leaks.

 

sounds like you have a vacuum leak elsewhere. check gaskets for the plenum and vacuum hoses, all before and after throttle body. the pig rich is probably just from your tune, otherwise any air leaks post maf should cause lean conditions.

 

We've seen a few TN kits with cracked brackets and welds. Sometimes, they can be very difficult/impossible to find via visual inspection, until the pieces are physically removed from the car. So the whole kit was removed and inspected, and reinstalled...and still no boost? The whistle you are hearing is indicative of a leak somewhere.

 

after seeing those cracked uppipes at your shop, I am paranoid.

 

All of the piping between the turbo and the throttle body were removed...inspected..and re-installed. There were no cracks in the silicone. All welds were good. There are no exhaust leak sounds coming from the car...they are very characteristic sounding. The whistle does sound like a leak somewhere but it can not be replicated under non-driving conditions. I agree totally that the boost has to be going somewhere but it would have to be a damn big hole for 8-9 psi to disappear completely. Under full throttle the vacuum rises to zero and stops every time. All the hoses on the intake manifold have been checked. All zips have been re-done.

 

pressure test is the only way.




Remove the airfilter and clamp one of these on. Pressurize with compressor and throttle closed, then open throttle. U will easily hear any leak to be had.



Images/vidoes avaible here.
http://weq.hondatech.com.au/turbo/Ne...2/Leak_tester/

PS. $3 in parts from ur local hardware store.

 

To show ZERO boost you'd have to have a pretty huge leak. My experience in the past showed that a normal, obvious leak still allowed boost to be made. Although I've never had a boost leak on my 350....just other cars that I've worked on.

If you're not hearing the turbo spool up under throttle, then maybe something is wrong with the turbo itself. Even with a boost leak you should still hear the turbo spool just like normal...maybe even quicker than normal since it has less resistance.

 

if there was something wrong with the turbo, the seals would be gone and he'd be blowing thick oil smoke like crazy....or he'd have lost a wheel or something.

 

id say it was a exhaust inlet leak, but it doesnt explain the richness. I say some kind of intake manifold gasket. To run rich, it is loosing air after it has been metred.... most MAF's are positoned in the intercooler pipe close tot he throttle body...

 

I agree totally....it should be showing 1 or 2 lbs of boost at least. My 1st thought was the turbo was seized....but it spins freely to the touch.

 

Agreed.....but all the tubes and clamps are good on the MAF tube - throttle body connection. The only engine management is the stock t-netics reflash.

 

bump

 

Could be the plenum itself. I had a buddies whos car had a leak at the plenum and didn't exhibit ANY tpyical vacuum leak stuff. Also check the hot side piping. Maybe the feed side has developed a leak. Could be the BOV or wastegate too.

 

until you make a pressure tester and check according to the pics above, nobody is going to be able to help you.

I guarantee you have a leak. Until you have tested with a pressure tester, you cannot absolutely rule this out.

Also, I've had leaks large enough(yes, on the Z) where ZERO boost was made and it wasn't obvious that there was a leak (compressor outlet popped off a few times and did this)

So please. For your own good, make a pressure tester with a PVC cap like that and cap it over the compressor inlet with a coupler and use even a compressor, or even a bike pump, and put some air in there, 20psi or so, maybe 30, to see how it is.