GIAC chip problem..

**AK1RA07** · 07-07-2008 02:30 PM

I've got 2 ECU's ( Stock H-box and a GIAC chipped M-box). For a while I was running the M box with no problems, (none that weren't already there before the switchover) but recently it seems that something is wrong. I thought it was something with the car, so I recently changed plugs to the NGK copper ones, changed all four O2 sensors to VAST ones, added the turboback exhaust, etc. but the car runs like crap still, and it felt like it progressively got worse. I could see my times drop off like one or two tenths of a second in the 1/8 mile, even with plenty of cool down time in between runs.

It ran decent in stock flash mode but still felt like it was running way rich (I was getting about 24mpg), but now when I flash over to Pump gas mode at WOT the boost comes on almost in waves.. It spools up, then feels like it hits fuel cut and falls on its face, then repeats, its basically unusable.

I swapped back to the stock H-box and I get no CEL, and my gas mileage has gone up to about 30mpg (I do a lot of commuting). Finally got my boost gauge installed and it reads normal with the stock ecu in place ( ~7psi at max boost and ~19 vac.) so I assume it has no leaks.

Any ideas? Is it possible the firmware on the chip is corrupted? Does it matter if the M-box is used with the H-box car? ( both have hitachi MAFs ) I am going to swap the M-box back in to check the boost levels when I get home.

**2k1audiS4** · 07-07-2008 02:46 PM

I had the same problem when I got chipped. My boost guage said i was holding boost fine at stock levels.....spike at 8 and vac at 19 or 20. But when I got chipped the car would get up to 12-15psi and just fall on its face. I could hear a shhhhhing noise when i got to that boost range. Turns out my TBB had multiple tears in it that would hold stock boost fine but when you got past 12psi it would leak like a sive. Replaced my TBB and I was good to go. Thats my .02

**Devious27t** · 07-07-2008 04:46 PM

definitely a leak some where. These engines are like sieves.

**Mantis** · 07-07-2008 05:59 PM

You have a rather large leak, build yourself a test kit and find it before you do damage by overspoolin your turbos. I would guess TBB, diverter valves, hopefully somewhere near the front and easy to get to

**theboogieman1** · 07-07-2008 06:14 PM

yeah man, my buddie went through like three weeks of searching and it ended up being a small tear in the TBB. Exact same symptoms.

**AK1RA07** · 07-07-2008 08:21 PM

That's what I was suspecting. My friend who works on cars for a living thought otherwise. Guess I'll be ordering one of those hose kits. People had good luck with those Ebay ones too right?