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Help!!! Loss of boost psi

40thAnnGTP2002

40thAnnGTP2002

New member
I have a 2002 Grand Prix GTP and I have the following :
Speed daddy headers
Magnaflow 3" high flow cat converter
Lucas 42.5 lb injectors
Zzp 1.0 PCM
Autolite 104s
Ac delco wires
Drilled t-stat
Bypassed the boost solenoid completely so its off car
All the vacuum lines are brand new
Checked sc gasket and intake gasket
Checked bypass valve and even replaced it
Check map sensor even replaced it

My issue is I'm only getting 4psi boost max on my scanner and aftermarket gauge. Idk what to look at next. I've tried everything... Any suggestions???
 


if you just did all those mods and still have a stock pulley on the sc, that could be normal. your boost drops when you install headers. i went from 7 psi to 5 psi after header install.
 
Thank u for the info also I got the pcm retuned after I added injectors and I have a 3.4 press on pulley and I told him to go ahead and figure that in the tune but I still haven't done it bc I can't find anyone around here to do it and I don't have the tool to. I did score a gen v swap with everything and it has a MPs already installed so that will give me something to do haha
 
3.4 on a gen 5 maybe pushing it, but it may work out, all cars are different and take mods how ever they take em. you'll just have to scan it for kr and see.
 
No I'm not putting the 3.4 on the gen v lol the gen v has a mps on it. It comes with 3.2 and 2.8 but those are way too much so imma get a 3.5 and run it.
 


3.5 will still be too small for those mods. You might be able to get away with a 3.6 if you are lucky. Why are you running larger injectors? Is your tune set up for it?
 
If he told ZZP to tune for it. I'm curious why he wasted his money on it, didn't gain him anything. I can barely run a 3.6 on my Gen V with SSAC, ERs (with L76s), a Reptile tune, and an FWI. I still randomly get blips of KR.
 


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