Topic: Possible GMPP Issue

[boardkat]

'09 GXP/GMPP Tune+Sensors/GMPP CAI. Taking the car into the dealer tomorrow, but here's what I'm seeing. Under WOT, the car climbs to max boost (around 18psi), stutters once, drops a few lbs of boost, climbs back up, repeats etc, until I shift and get to live the whole episode all over again. Tough to duplicate in 1st and 2nd, but on the highway it's very noticeable in 3rd and 4th. I took the MAF out and cleaned it (had a few finger prints on it and the GMPP air filter isn't oiled), checked all the hoses, can't figure it out. At first I thought mechanical, but the car only had 1300 miles on it, and driven a handful of times, never hard. I'm leaning more and more to the ECU having an issue. The tune came with the car, and I *did* notice that no-lift-shift isn't working - at least, I think it isn't: I kept my foot down, tried to shift quick, but the revs climbed immediately to redline before I could change gears. Maybe the flash didn't take, and the previous owner never noticed? He also gave me a spare ECU that he thought had the GMPP tune on it as well, but when I tried swapping it in, the car immediately rough idled, and went into limp mode, throwing a CEL and a bunch of codes. So I *think* it might actually be stock (since it can't handle the 3bar sensors, right?), any way I can get the dealer to confirm what's on it?

I guess what I really need to know are the questions I should be asking the dealer. I don't have a lot of faith in most, and have never dealt with this one, so I want to make sure they execute the correct procedures to rule out what it can't be (ECU/boost leak w/ smoke test/etc), and isolate the issue, if not one of those (Injectors? Diff? Clutch?). With such low miles though, I really doubt it's a mechanical issue.

[DeepBlueGXP]

Sounds like it doesn't have the GMPP, are you sure the sensors are installed?

[boardkat]

Sounds like it doesn't have the GMPP, are you sure the sensors are installed?

sensors are installed, 100% of that (i checked).  i really wish they weren't though, because i need to put the stock ones back on and run the stock tune for autox.  and i don't have them

[U4EA]

To continue my reply on the BB, Yes the dealer can tell you what is on the second ECM. They will need to make sure it has your VIN # It can be reflashed with what is on record with GM for your car.
May have a bad sensor if not a loose or bad connection to one of the sensors.

[boardkat]

To continue my reply on the BB, Yes the dealer can tell you what is on the second ECM. They will need to make sure it has your VIN # It can be reflashed with what is on record with GM for your car.
May have a bad sensor if not a loose or bad connection to one of the sensors.

if it was a bad sensor, would i not be getting a code?  seem to recall people mentioning a certain code being thrown if there was a bad sensor/loose connection.
as far as the ECU thing goes, i'm eventually going to need to run a stock tune anyway (for stock autox purposes).  i'm wondering if there's any way for me to parlay this into an "uninstall" and get my VIN in the system as being stock (not GMPP).  i definitely want to keep my warranty valid, it came with the 7yr/100k bumper-to-bumper.

[DeepBlueGXP]

FYI, Your first post states it's a 09 GXP and your profile says 07 GXP.

It sounds like an incomplete load of the GMPP then.    Is there someone close to you with HPTuners?  You can download both tunes and compare them. 

Were you the one that made a adapter connectors for the sensors for swapping them out?

[boardkat]

FYI, Your first post states it's a 09 GXP and your profile says 07 GXP.

that was the case until recently.  sold my 07, bought an 09, haven't updated my profile.

It sounds like an incomplete load of the GMPP then.    Is there someone close to you with HPTuners?  You can download both tunes and compare them. 

not that i'm aware of, i'm leaning real hard to just having the dealer reload at this point.

Were you the one that made a adapter connectors for the sensors for swapping them out?

nope, not me.

[DeepBlueGXP]

I updated your profile for you.  Hope the dealer reload fixes the issues. 

[boardkat]

they're clueless, if my first impression was correct.  they're scaring me, and i'd rather not have them messing with my car too long, so i'm gonna start a new thread and see if i can figure out how to go about getting the tune uninstalled in the GM system so that the dealer can download the stock tune.