have a 08 SS with 125 k -- Have zzp catless down pipe & zzp intake - Havent got my tune yet which should happen next week after both knock sensors & clutch was replaced .
Question is this --Why Can I easily get 20-25 psi & in certain gears & rpm level goes to 30 . with only these 2 pretty mild mods . What should a ss get ? Ive heard 17 -22 .
This is my first turbo car so I dont know much -- My son who knows a lot about them said it sounded like the waste gate wasnt operating as it should. Said a friend of his with a turbo MR2 -had the same problem & had to trim the downpipe some how to keep it from sticking (or something like that ) Afraid these little engine wont last too long being over boosted . The guy from National speed ( who will do the tune in Richmond Va ) said they will take a look at that before its put on the dyno .
Read where a lot of you have a stage 1 tune or a GM tune --how much power did you gain ?& whats the difference in these tunes than others -- Sorry for so many questions Still learning about these little suckers.

 

over boost should trigger a CEL. Why replace knock sensors?
I wonder if you don't have the GMTU already. Is there a high test required label on the fuel filler?

 

If the car has the stock factory tune, it is overboosting badly. Get the obd2 codes pulled. If you have the blue Bosch TMAP sensors, then you have an aftermarket tune, so that may be the proper boost for that tune.

 

GMTU would not boost that high.

 

was throwing knock sensor code when I had it there before & they said they couldnt do the tune with it throwing that code ,
Yes gas cap says use 93 -
Was no mention from the po that it had been retuned . After the guy at national speed said he couldnt dyno it that day because of the KS code ,the tech did a tune without putting in on the dyno . All I know it ran like a scared Haint after that -much more power . Maybe he nailed the tune without putting it on the dyno . ??
Ihave just heard of some of you with turbo upgrades ,more mods than what I have only hitting 22-25 psi

 

only code which occurrs infreqquently now is "air intake temp sensor "think that is from the aftremarket intake

 

IF it says 93 REQUIRED not recommended it has the GMTU. I'm sure somebody will post a pic of the TMAP.

 

But now the GMTU has been written over with another tune. Call your tuner and ask him what boost you should be getting.

 

oh yea it says recommended ,not required

 

The air intake temp sensor is in the MAF, so it could be connected.