Not making full boost WTF?

[Socom688]

Ok, here's the story: My car is only making 5 psi at WOT when its supposed to be making 11. My buddy and I checked the blower, seals were shot so we rebuilt it completely with new bearings and seals. The rebuild was successful as we cured the oil leak and it is in like new condition. I noticed that the car sounds healthier and isn't as rich as before the rebuild, but its still making 5 damn PSI! All the piping couplers are on tight as hell, there are no boost leaks present and the vacuum pressure is completely normal. So my question is... WTF could it be? Possibly my tune is off? The thing with that though is its the same tune I have had since it was at 11 psi.

Could it be the IRMCs?

She spits out the code P1443 which is the Evaporative Emissions (EVAP) Canister Purge (CP) valve, could it be effed up?

FML

Any ideas?

 

[98 Saleen Cobra]

If you're on the stock bypass it could be bad?

 

[Socom688]

If you're on the stock bypass it could be bad?

If you're on the stock bypass it could be bad?

You know, I am not quite sure, but I don't believe so. You can still hear it between shifts, and the car doesn't bog in between shifts, so it leads me to believe it is still working properly. Do you know anything about the EVAP or CP valves? I believe they may run off of a vacuum line connected to the throttle body, but before I drop $80 I'd like some details.

 

[98 Saleen Cobra]

Hmm I don't know much about that as I deleted those on my car..

 

[Socom688]

Hmm I don't know much about that as I deleted those on my car..

Damn... I should have done the same when I was getting it tuned years ago.

 

[ravage]

I had a similar issue a while back were I was running a vacuum line to a MSD BTM for the boost retard. Something blew out inside the actual MSD box and caused me to loose 5 lbs of boost. Only way I discovered it was through the use of a stethoscope. For me using one is much easier to find leaks over just feel.

 

[01yellercobra]

I would still check the bypass. It can be opening and closing, but not sealing completely and letting boost out.

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[03bluemach]

I would also agree on looking into the bypass ..

 

[JP_Stang]

Belt slip?... Do you have any belt dust anywhere? If not, I would also look into the bpv. I would also go ahead and delete the evap, egr, etc.

 

[Socom688]

Ok guys great advice. I plugged the evap line and it is still making just about 5psi, so its not that but I am definitely going to get it deleted. I will check the bypass valve, but the damn thing is located under my Anderson PP, so its hard to get to. What is the best way to check the bypass? If I used a stethoscope, what sound should I be listening for? Would it be a distinct "swooshing" sound, or a high pitched whistle/scream sound? I guess either would be bad because it should be making any sound...

 

[Socom688]

Belt slip?... Do you have any belt dust anywhere? If not, I would also look into the bpv. I would also go ahead and delete the evap, egr, etc.

No belt slip. I wish it was belt slip, then this would problem would be an easier fix!

 

[98 Saleen Cobra]

The bypass is going to be hard to tell because of the location.. The best bet would be to find a stock one somewhere and replace it and see if it work..

 

[Stanger00]

I have a stock Bosch bypass valve and a mini race bypass valve I'm selling.

 

[98 Saleen Cobra]

I might have my stock bypass valve laying around.. I don't know where but I might.. If I do just cover shipping and it's yours.

 

[IUP99snake]

It very well could be the bypass valve. Do you have a blow thru or a draw thru setup. Maf vortechs are draw thru, but you never know.

With the volume of air moving through the system, you could completely remove your bypass valve and it would still make 4-5 lbs of boost. I've done that before to test it. You can remove the valve and hook it up to a hand held vacuum pump to see if it opens and closes. It should be closed with no vacuum, and gradually open as vacuum is applied. Or you could just pull it out but leave it connected to the vacuum source on the engine to see if it opens and closes as you rev the engine.

It could also be a leak near the mass air flow sensor if it's a blow thru setup. I'm not sure what kind of MAF you have, but if it's a 90mm lightning MAF or any other factory style MAF, it will have an adapter flange that bolts to one side of the MAF so the tubing can connect to it. The problem is that the mating surface on the MAF wasn't really designed to hold any pressure and it will blow out the gasket. That happened to me. I just JB welded the whole thing together. But if you have a draw thru setup, it's moot.

Look for any possible leaks first.. It could be pressurizing anything in the vacuum system, and if the PCV system isn't working properly, that means boost will be leaking into the crankcase too.

 

[Socom688]

Damn, I wish I had checked this thread sooner. I was on vacation for a while and was without a computer. It most definitely is the bypass valve but even if it isn't the cause of the leak I still want to replace it. I pulled the sucker off and it just dripped coagulated oil from the seal leak.

Stanger, you still selling that mini race?

98 Saleen, I appreciate the offer! I may take you up on it if it's still available, but I really want to steer clear of the Bosch valve and get something that will last longer. I am not making a ton of boost, but being at 11+ psi I have been told an upgraded BPV is the best choice since my car is my DD. Do you know anything about the Turbosmart Komact 25mm Plumb Back?

 

[Stanger00]

I still have it. $150 shipped.