Loss of PSI, Procharger.

[03blkann]

I had my 96 cobra dyno tuned, Car made 520rwhp and 450rwtq @ 12psi and ran GREAT for about a month, Changed the spark plugs (used same plugs) and made sure they were gapped the same as when the car was tuned, And all the sudden the car is only making 6lbs a boost and running pegged rich at all times. I thought maybe it was belt slipping so i got a thump tensioner and a gates belt. The problem still exsisted. I have changed just about everything I could think of. Could the tune just go bad? (dont make much sense). Thought maybe a wire got knocked loose, everything seems to be fine, No boost leak or anything(That i can find). I am lost. Any ideas? The car throws bank 1 bank 2 rich codes and random cylinder misfire code.

 

[03blkann]

Car also breaks up pretty bad when driving, the air fuel meter goes to normal with maf unplugged, but the maf is less than a month old. Sct ba2600

 

[ZeroDCX]

Do you have an intercooled or non-intercooled system?

Are you seeing belt dust around the blower pulley? If not then check for boost leaks or a failing bypass valve.

 

[mustanginky]

Id guess bypass valve. I have a proflo for sale.

 

[03blkann]

Do you have an intercooled or non-intercooled system?

Are you seeing belt dust around the blower pulley? If not then check for boost leaks or a failing bypass valve.

D1sc intercooled, any tips on how to check the bypass valve, and a where abouts to buy a better one that will have no fitment issues. No belt dust.

 

[crazycarlo]

If you were making 12psi before and your making 6 now and no belt slip then you have a leak somewhere. Check all the couplings. And as mentioned before check the bypass valve. What valve do you have? Is it the stock plastic one? If so then i highly recommend upgrading to something like a procharger red race or a vortech mondo.

 

[ZeroDCX]

D1sc intercooled, any tips on how to check the bypass valve, and a where abouts to buy a better one that will have no fitment issues. No belt dust.

Remove the bypass vacuum source line and attach a vacuum pump to it. Pull vacuum and see if it holds. You could have a hole in the bypass valve diaphragm. You could also try to just remove the vacuum source line and see if it builds pressure too.

If the bypass valve is the stock plastic bosch bypass valve and you're pushing 12 psi, then you're probably exceeding the limits of the bypass valve (depending on the model number). As stated before I would have to go with either a boost leak or bypass valve issue.

 

[03blkann]

Thanks for all the input i purchased a new bypass valve, I was using the stock one... Going to see if that helps will update when i get it installed! I cannot find any leaks anywhere else. So i am praying that is the issue!

 

[03blkann]

Changed the bypass valve...nothing really changed. I am honestly lost, I've thoroughly went through lines couplings tubing. I am changing the MAF and having a new tune sent to me don't think thats gonna help the boost any. I guess my next step is to have all the piping custom made and see if that helps. Also do a compression test.

 

[ZeroDCX]

Changed the bypass valve...nothing really changed. I am honestly lost, I've thoroughly went through lines couplings tubing. I am changing the MAF and having a new tune sent to me don't think thats gonna help the boost any. I guess my next step is to have all the piping custom made and see if that helps. Also do a compression test.

The MAF is not going to help with the boost loss. That's a mechanical issue. You need to figure out why it isn't compressing air as it was before. Are you sure you're not getting belt slip? Belt dust behind or around the pulley? The only reasons why it wouldn't compress air like it was before are due to boost leaks, belt slip, a bypass valve/bov failing or failing head unit. Another overlooked issue is, are you sure your boost gauge is functioning correctly?

An issue that it could be is, depending in how the IAC hose is routed, the IAC could leak boost. But this is prevalent in non-intercooled systems where the IAC hose is routed back to the power pipe (before the compressor). It would leak boost, but could be remedied by a check valve in the IAC hose or by re-routing the IAC hose after the compressor, not before.

Edit: A compression/leakdown test is also a good idea, too.

 

[03blkann]

The MAF is not going to help with the boost loss. That's a mechanical issue. You need to figure out why it isn't compressing air as it was before. Are you sure you're not getting belt slip? Belt dust behind or around the pulley? The only reasons why it wouldn't compress air like it was before are due to boost leaks, belt slip, a bypass valve/bov failing or failing head unit. Another overlooked issue is, are you sure your boost gauge is functioning correctly?

An issue that it could be is, depending in how the IAC hose is routed, the IAC could leak boost. But this is prevalent in non-intercooled systems where the IAC hose is routed back to the power pipe (before the compressor). It would leak boost, but could be remedied by a check valve in the IAC hose or by re-routing the IAC hose after the compressor, not before.

Edit: A compression/leakdown test is also a good idea, too.

You can feel the power loss in the car, It is very possible the gauge isn't working properly, but I do not think that is the issue. I have taken every precaution to prevent the belt from slipping and I've checked over and over for dust or wear on the belt. The procharger itself has about 1500 miles on it. Anything is possible though it could very well be the head unit. I am going to be doing a compression test this weekend and see what happens from there. I appreciate your input and help thank you!

 

[ZeroDCX]

I'm not familiar with the Procharger setups, but they are basically setup the same and the same mechanics apply.

Before you spend any more money, check for vacuum leaks first. Vacuum leaks on a forced induced car equals boost leaks. Pressurizing the piping (pre-throttle body) and listening for leaks/spraying soapy water around all the couplings would be your best bet in finding boost leaks. It shouldn't be producing half the amount boost all of a sudden, something is definitely amiss. Another issue I've noted that contributed to a similar finding would be the two long bolts underneath the intake lid not being torqued down properly, which creates a vacuum/boost leak post throttle body. But the vehicle should idle poorly under this condition.

Was the vehicle serviced lately? I've seen cases where "items" (cloths) were left inside boost/intercooler piping and causing restrictions.

How are idle characteristics? Did anything else change noticeably since the issue started?

Is your PCV valve sticking open?

Do you still have stock IMRCs? (sticking closed by chance)

 

[03blkann]

I'm not familiar with the Procharger setups, but they are basically setup the same and the same mechanics apply.

Before you spend any more money, check for vacuum leaks first. Vacuum leaks on a forced induced car equals boost leaks. Pressurizing the piping (pre-throttle body) and listening for leaks/spraying soapy water around all the couplings would be your best bet in finding boost leaks. It shouldn't be producing half the amount boost all of a sudden, something is definitely amiss. Another issue I've noted that contributed to a similar finding would be the two long bolts underneath the intake lid not being torqued down properly, which creates a vacuum/boost leak post throttle body. But the vehicle should idle poorly under this condition.

Was the vehicle serviced lately? I've seen cases where "items" (cloths) were left inside boost/intercooler piping and causing restrictions.

How are idle characteristics? Did anything else change noticeably since the issue started?

Is your PCV valve sticking open?

Do you still have stock IMRCs? (sticking closed by chance)

I had the spark plugs changed new coil packs, replaced the tensioner/belt, and most recently the bypass valve. Nothing to really do with the tubing or anything like that. The car idles fine for the most part...But the car is also being over fueled like crazy due to it being tuned for 12psi and only making 6...(I am guessing plus the tuner tuned it "Safe" so made it really rich"), but now the car is just dumping fuel which i think causes it to idle rough briefly when coming to complete stop for a couple seconds then smooths itself out. Other than that idles just below 1 grand majority of the time. I have the IMRC deletes on the car. I could not give you a definite answer about the pcv valve although I wouldn't think so.