Weird under boost problem

[Blitzd]

How goes it. I am a veteran of this site but can't seem to find any other occurance of this.

I was driving to my house yesterday and in 2nd and 3rd gear (2nd mainly) under hard throttle the car lost power stopped pulling. Its not fuel cut I have hit that before, and it wasn't rev limiter as I was only at 3800 rpms. I heard it in the exhaust sounded like was opening and dumping the boost. closest sound I can give you is BAH BAH BAH, but it was very quite. I let off of throttle and it would stop then in 3d gear it just barely does it. Here is a wierd symptom, it only does it when going over the stock boost settings. I have a brand new turbo but I keep thinking wastegate. Any Ideas? Oh just so you all know here is the list of mods.

INJEN CAI
HiBoost FMIC
HKS SSQ
1 cat removed
Intake Cam
Injen ridium plugs
Relocated MAF
Millenia PCV
AWR motor mount
revised Garret T-25 (from Mazda)
MBC not over 8-9 psi depending on temperature
(still have fuel cut in place)

[NeverSober]

Check all vaccum hoses and hardpipe connections.....could be a leak somewhere.

[Blitzd]

Check all vaccum hoses and hardpipe connections.....could be a leak somewhere.

thought of that wouldn't it do it under stock boost too? thanks for the idea by the way

[orng1]

So there is a leak that only appars at higher boost levels? I'd say check the FMIC connectors or go through all the pipes and be sure that all the clamps are on tight. Have you backfired or anything else under boost, black smoke or anything else?

[orng1]

thought of that wouldn't it do it under stock boost too? thanks for the idea by the way
I had a crack in the throtle body hose that would only cause a leak at high boost 7-8 psi it was fine but higher and it would hesitate and backfire. Took me a few months to trace it down. Looking at it now I still wouldn't have found it, my friend pointed it out to me.

[Blitzd]

So there is a leak that only appars at higher boost levels? I'd say check the FMIC connectors or go through all the pipes and be sure that all the clamps are on tight. Have you backfired or anything else under boost, black smoke or anything else?

I will check all of that tonight thanks. wouldn't I hear a vacume leak though? there is a little black smoke every now and again but it is just a puff when I get on it. It looks like just normal build up in the cat to me but not sure. This just started other than that the car is driving fine. Plugs all look good, just wierd, and the noise it makes is what really gets me.

[DSMConvert]

hmm I'd def start looking into some kind of fuel control with your mods....

[Blitzd]

hmm I'd def start looking into some kind of fuel control with your mods....


I agree, anything I can do in the mean time. I think it may have something to do with the waste gate. The revised turbo from Mazda has a diff waste gate. Could that be it?

[nvmsp]

I would say wastegate but you just got a new one. And since your saying it makes some weird noise, that usually means you've got some kind of leak somewhere.

[Blitzd]

I would say wastegate but you just got a new one. And since your saying it makes some weird noise, that usually means you've got some kind of leak somewhere.

yeah but what if the waste gate is sprung for lets say 9psi and the mbc was set at 9.5(numbers are for conversation) would i hear the wastegate venting, and would it make me loose all power if it did? I am going to put it up on the rack tonight after work and check it out. we shall see. hopefully no vacume leaks

[peepsalot]

Sound like fuel cut to me, but if that's not what you think it is, then explain how it is different.

[nvmsp]

yeah but what if the waste gate is sprung for lets say 9psi and the mbc was set at 9.5(numbers are for conversation) would i hear the wastegate venting, and would it make me loose all power if it did? I am going to put it up on the rack tonight after work and check it out. we shall see. hopefully no vacume leaks



I mean, I'm no expert. But I don't believe the Wastgate makes any noise. I think you may have a leak, because when the FMIC piping is leaking, you'll hear the turbo become alot louder and hear like WHOOSHH noises, when you get on the gas.

But then again when the wastegate is messed up, for example when mine was, i lost all power. My boost gauge would show 15psi but it felt like i didn't even have a turbo.

I don't know, you just gotta have everything checked out.

[peepsalot]

Also, it's possible a faulty BOV could open under presssure.