Exhaust leak causing slow spool?

91GS-X · Mar 19, 2012

I have a 1g dsm with 16g turbo and 2g exhaust manifold and 2.5" cat bypassing downpipe with the rest of the exhaust stock. I have an ets street intercooler kit and I'm running speed density and all supporting fuel mods.

I'm not building full boost which is 20psi until 5000rpm. I've read that I should be building that at least by 3500rpm and probably sooner with me since I have a cyclone intake. In link it shows that I'm only building two psi by 3500rpm. I have an automatic transmission and I'm using first gear for the tests.

I seafoamed my car to see if I have any leaks and I noticed that it's leaking the worst at back part of the gasket that connects the turbo to the manifold. It's also leaking a small amount at the o2 sensor and in it looks like it's leaking a little bit in that area I marked red in the pic on the turbo.

Now would these leaks cause my turbo to build full boost this late? These leaks are not huge either

J_DiZ · Mar 19, 2012

Any leak pre turbo will hurt spool. I would check the manifold to head mating area as well.

Simple Jake · Mar 19, 2012

Like J DiZ said, it will hurt your spool a little, but I don't think it will make it as bad as you are saying. Check to see if your wastegate is stuck open. Also, try to test it in 3rd gear where the engine will actually have some load on it. In first gear, the engine hardly has any load on it so you won't build full boost anyways. For instance, I only build 10psi in 1st gear, but after that I can build 15 in all the other gears.

91GS-X · Mar 19, 2012

I checked the wastegate and the actuator is fully seating it. Is it possible that there could be crackes on the wastegate seating area?

mitsukid124 · Mar 20, 2012

It is very typical for the exhaust housings on the MHI 16g's to have cracks by the wastgate opening, but barely ever will effect the performance because of how few and little they are.

Like previously stated, do a 3rd gear pull and log it to see what it does under load. Also maybe try a boost leak test and replacing the leaky gasket. It's very doubtful that that'd cause such late spool but it can help narrow it down, and also fix something that may get worse later.

91GS-X · Mar 21, 2012

I checked my wastegate opening and there are no cracks at all and the gaskets didn't look that bad, I also have no boost leaks and my turbo has very little play. Is there anything else that would cause this slow spool?

BadAss4Bangers · Mar 21, 2012

91GS-X said:
I checked my wastegate opening and there are no cracks at all and the gaskets didn't look that bad, I also have no boost leaks and my turbo has very little play. Is there anything else that would cause this slow spool?

Do you have a wideband to check your AFR's? Shot in the dark but if your running too rich it could cause slow spool. That is all I can really think of other than a cracked Manifold, boost leak, and a waste gate stuck open. Id also recommend a compression test for the hell of it.

91GS-X · Mar 22, 2012

BadAss4Bangers said:
Do you have a wideband to check your AFR's? Shot in the dark but if your running too rich it could cause slow spool. That is all I can really think of other than a cracked Manifold, boost leak, and a waste gate stuck open. Id also recommend a compression test for the hell of it.

Thanks for the tip I'm running lc-1 wideband in my downpipe that I'm logging with link. I have no gauge for it so I'm not 100% that it's logging correctly or not because I've read that ecmlink can sometimes show a different afr reading then the gauge.

Also when I took my downpipe off I noticed that the bracket on the downpipe had a broken weld and fell off the downpipe when I unbolted it. Would having this hole make my AFR read lean when it's actually rich?

I did a compression test 150 across the board.

mitsukid124 · Mar 24, 2012

Have you tried doing pulls and logging in various gears?

Also it would depend on how big the hole is and if it is pre or post the wideband sensor. If it is small i doubt it would do much, but hey i've had weirder shit happen. How big is it?

talonturbo3965 · Mar 24, 2012

Your timing coud be retarding because of knock or how you have antilag set up on link if your running it. Try a new knock sensor, there very important.

Exhaust leak causing slow spool?

91GS-X

J_DiZ

Simple Jake

91GS-X

mitsukid124

91GS-X

BadAss4Bangers

91GS-X

mitsukid124

talonturbo3965

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