low boost on gtp

[black98gtp]

I have a 98 gtp with 3.4 pulley, cai, 104's,zzp 1.0, slp headers w/ no cat or resonator, 3'' dp, msd wires, tb spacer, 180 thermostat, and aeroforce gauge. My question is this i bought the car with alot of the mods already done and havent seen over 4 psi max. When i fist tore into it i realized the tensioner had alot of play in it so i just got a new tensioner with a new 66'' gatorback belt. i also put in all new 104's. whoever had the car before me knew what he was doing when it came to mods. But anyway after replacing the belt i still can only get it to spike to 4psi at the shift point or sometimes lower in the rpm range. i checked the vac lines for leaks (with a can of carb cleaner) but couldnt find anything. im getting 0 kr, but i still cant figure out why im only gettin 4 psi. the car only has 85,000 on it and has a new snout on the supercharger. Any suggestions? Please Help!!

[JoshsGTP]

gatorback belts slip

[blueguy]

^^That's a good one...you can also see if the Boost Bypass is working right...try swapping it out with another one or buying one from ZZP on teh cheap. That is one of the causes of "low boost" also...that and the fact you've got a 3.4" with headers...but you should still be seeing about double that psi @ WOT.

[black98gtp]

im going to order the new bbv and all new vac lines and fittings just to make sure. but also i was watching my long trim on the scan gauge this morning on my way to work and at 70-100% throttle im +16.4 and when im crusing 70mph its at 10.8 is this bad??

[black98gtp]

also i have had some serious issues with the flex joint on the exhaust. the one that was welded on by slp is done and leaks bad. getting a new one today gotta good deal on it and it will be in over the weekend, dont think it will rob me 4psi but figured i throw it out there

[Bio248]

youre running lean, you have a vac leak somewhere and it shows from your fuel trims. either that or your fueling is WAY off, which doesnt make sense considering your car has nothing done to it.

my bet: its your TB spacer.

[blueguy]

So, is that 16.4 your LTFT's or STFT's?

I thought that was a vacuum leak if it was that high.

[black98gtp]

long trim is the 16.4 the short trim is bouncing all over the place low and high. but i read on here that you can't really ever get the short trim to measure right so i watched the long trim

[Bio248]

you have a vac leak.

[TheOtherNick]

Vac leak and for the record my gator back does not slip.

[01gpgt01]

Vac leak, and your BBV valve is fubared

[KwazrollinZ28GTP]

i chopped my BBV off my car, Worthless pos lol

my car ran so much better, has been for years
i was sick of seeing 20% boost half of the time.

same with the EGR, chopped and custom welded the holes closed.

[matt5112]

You just ruined your only hope at ANY fuel economy right there while cruising....

[blueguy]

Who needs MPG's? Especially coming from the guy with a heads/cam V8 car LOL

[thunder71173]

i hope its not but it could be burnt exhaust valves, you would need a comp tester to find out though.