QuickSilver_SS

So lately over the few months my car has been acting crazy in the mornings on cold starts. As well at the same basic time I started to hear what to myself sounds like a big boost leak, Kind of sounds like a fire house at full pressure. I have the Kn sri. And have had it on the car for many years. So i know the sounds these cars make and when a new really weird loud noise appears i know its not normal. So I have included a few videos to see if anyone can maybe give me an idea of where to look next. As I have been trying to figure this out for a few months now. New parts to date are , new gm plugs. New bypass valve, new waste gate about 7 months a go. Both cam solenoids replaced; Intake valves cleaned about 2 weeks ago.

The car is in the process of being tuned by a well known reputable tuner. But this issue was there before any tuning. The car is slow to spool now. Slower to accelerate. And will not even break the tires loose in 2nd gear anymore, Not even a chirp. Let alone all out spin like it did before this all started. The compression was also just checked today and it has 160psi on all 4 cylinders. I think that if a can get this boost leak noise fixed it will make the car gain its lost power back as well as fix my cold start issue.

I have boost leak tested the car 4 or 5 tikes now up too 27 ish psi. There is no leaks in the car at all. Not in either charge pipe or the intercooler. I am starting to think that the turbo HOUSING itself is cracked causing a boost leak at wot. The noise I hear only happens at wot. Not part throttle at all. In fact the car feels faster at part throttle then it does at wot. Any help or suggestions guys ??

Thanks

QuickSilver_SS

I hope the videos work. But in case they do not. The car starts up fine at first. It will even run totally normal for about 5 seconds. Then it start to have huge misses. Blackish grey smoke out the tail pipe. pooping and hissing from the turbo itself. The cat warmup noise the turbo normally makes on cold starts seems to come and go very fast and get quieter and louder none stop repidadly for about 20 to 30 seconds. And then all of a sudden after about 20 or 30 seconds it straightens itself out and it runs totally normal. There are no codes in the ecu. and the idle itself is constant and doesn't really fluctuate when it is popping and missing at all it seems

USMCFieldMP

iTrader: (1)

Have you checked the turbo for shaft play? I do that, and give a general inspection of the turbo manifold and turbine housing. Seeing a crack can be really hard sometimes, and other times it'll be nice and easy with carbon buildup.

The intermittency of the issues makes me think it's neither of those things though, and more likely to be sensor related. Have you had logs recorded during a cold start up?

EDIT: maybe fueling related? But I'd think the tuner would be able to see that. Unless the O2 sensor is bad. I'm just spitballing at this point.

QuickSilver_SS

I really haven't checked the turbo for shaft play yet. I always assumed that once they go. They make a tone of screeching and sounds that sound like metal on metal from the turbine hitting the housing. As for eeing a crack in the housing itself. I cant see any at the moment with the turbo still on the car. But my clutch is slipping as well and when I replace the clutch in the next week or so I am going to pull the turbo off as well and check it totally for cracks. The problem seems to be all the time. On cold starts as well as every time i go wot. I have replaced a lot of sensors at this point. Idk which ones would or could cause this type of cold start issues as well as making the car make bad noises and being really slow to spool and slow accelerating over all at wot.

I am leaning towards a crack in the turbo housing. Has anyone had or heard of the k04s cracking the housings ? Not the dividers on the inside.

Also , with my log that I sent to my tuner just last night I included a cold start. So hopefully he sees something I cant in the log files.

USMCFieldMP

iTrader: (1)

If I had to guess a sensor, I'd guess O2. I don't think that's the issue though. Crack is sounding more likely.

And yes, I had a friend with a LNF that cracked the hell out of his turbine housing. He was tracking the car on a hard tune though.

Cracked housing or manifold will definitely slow you down, too. I had that on a big turbo setup, and it delayed me going full boost by 500+ rpm.

QuickSilver_SS

My primary O2 in the manifold , or before the cat seems to be okay, Or at least I don't get any mils for it at all or any stored codes. My rear O2 however is totally wacked out. So I turned ALL the codes off related to the rear O2 in hp tuners. There are about 7 or 8 of them. I am almost hoping there is a crack in the turbine housing. It would totally explain the fire hose sound boost like i think I am hearing. As well I have another turbo on its way that is only about 2 months old and only has 3K miles on it. So i will be putting that one on when I do my clutch.

USMCFieldMP

iTrader: (1)

The turbo manifolds are pretty cheap too. I think ZZP sells them for like $65.

I had forgotten you mentioned the fire hose sound (aka like a wastegate dump tube). That definitely sounds like a major exhaust leak.

QuickSilver_SS

Would I only hear it at WOT ? Does that make sense ? At part throttle the sound isn't there. But when I go wot it is easy to hear and is even louder in 2nd and 3rd gear as the car gets higher up in the rpm range. Almost like if it is a crack it can hold some pressure. But at wot and 24 psi it spreads open a bit and cant hold the boost pressure anymore. Does any of that make any sense ?


Also , Do any of the videos work at all for anyone ??

QuickSilver_SS

Any other ideas or thoughts ??