I have searched and have not found a good answer. I normally build boost around 3.5k @19psi. It's not a daily driver, but the last time I drove it was fine. At first it would not boost over 5psi at redline. I check for leaks and found the TB bolts loose so, I tighten them up. I went for a drive and it boosted to about 8-10psi. I did a boost leak test and found no leaks but, at the TB theres a massive leak. I have even disconnected the vac line from the wastegate and it still wouldn't build anymore than 14psi at redline. I have ran out of things to check. Anyone got any ideas on what is wrong please help.

Originally posted by tim96rs
I did a boost leak test and found no leaks but, at the TB theres a massive leak.

You did a boost leak test and found no leaks. Then you say there is a massive leak at the TB. Please clarify.

Corbin
'95 ESI-T

Now with more power and fewer leaks



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Originally posted by tim96rs I did a boost leak test and found no leaks but, at the TB theres a massive leak.

Does not compute... :squint

I think the problem is the massive boost leak at the TB.

Remove UPP, remove TB, scrape off old gasket, replace gasket, reinstall UPP and TB, torque to spec.

Edited for spelling.

Sorry, Yes the only leak I found was the TB. I have already removed the TB and replaced the gasket. It did not help.

In that case... (I'm a little rusty here, I've only seen under the hood of a 2g once in the last year) If you're sure the gasket isn't leaking there is only the IAC that's left to blame, if you're sure it isn't between the TB and the IM.

It sounds like it is leaking around the TB shaft. I have not had time to remove it yet to confirm this.It is a mod jeep 60mm TB.

There are only so many places that you could be leaking at the TB if its not the gasket. Check the large O rings that seal the IAC and TPS sensors. Also, as stated above, you may need to replace the tiny o rings on the shaft as they can cause leaking too.

Before you start taking things apart, though, you may want to loosen and then evenly re-torque the two throttle body bolts. I have seen cases where they were not torqued down evenly which caused a leak.

I have have fixed the TB Leak-it was the shaft. I still can't build more 10-11psi. Could the external wastegate be failing and letting exhaust pass-by the turbo? I have also removed the vac/boost line from the wastegate, to test it and it still won't build more than 15psi.It should be boosting to the sky without any regulation of the boost.

The internal spring may not be rated to handle more than 15PSI, allowing the wastegate to open under heavy exhaust flow even with it disconnected from the vacuum lines.

That does sound possible about the spring, but before I was running 18-20psi with no problem with an MBC. Could the spring have gotten weaker over time causing these problems?

If it's a cheap knockoff wastegate, very easily. There also might be junk in the flapper valve preventing it from completely closing

Ok I guess I'll be taking off the wastegate to look at it. Thanks for the help.

I have replaced the wastegate spring with a new tial 1bar spring and it still will not boost more than 10psi. Do you guys think the turbo could be going out? It only has about 1500 miles on the whole turbo setup.

Check for shaft play. It shouldn't move more than a hair from side to side and not at all front to back

The turbo has very little shaft play. I blocked off the wastegate from the manifold and it boosted 22psi before I let off, at around 4,500rpm. I reinstalled the wastegate with an 14.5 and a 8psi spring. I am now boosting around 15-16psi, but it should be around 22psi. Anybody got any more ideas.

What brand is the wastegate? From what I just read when you blocked it off you boosted 22 psi. I would get yourself a new wastegate and see what happens. Especially if it's a knock off.