Pontiac GTO 2004-2006 The Modern Goat

MAF issues and a few other things.

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Old 12-27-2016, 07:02 PM
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Default MAF issues and a few other things.

Hey guys, well where to start? The goat has 68k miles on it. It is a bolt on car with kooks 1 7/8's, 3" spintech cat back, ported LS2 intake and throttle body, over the radiator air intake with breakout IAT, and HP tuners tune. When it first tuned off cold, I started having an issue where the Traction control would randomly kick off, then sometimes the CEL would kick on. After turning off and restarting, traction control would be fine, and CEL would clear after a few more key cycles or while driving. Then, traction control would shut off on start up, CEL stayed on, and suddenly would go into limp mode. I started with the MAF, there was a broken part in the conduit around one of the wires, I taped it off and it seemed to correct the problem. A few weeks later, during a WOT pull, around 80mph or so in third, the car missed violently? Sort of like I let completely off fuel and smashed it again. Limp mode kicked in, traction control stayed off, just like before. Ran by a parts store, hooked up the scan tool and got a ton of codes. I actually lost the paper I wrote them down on, there was a MAF code, an IAT temp code, 02 sensors on all banks (rears are turned off), and catalyst codes.
Next, I cut the bad spot out of the maf harness and use a butt connector to crimp them together. I start the car, CEL is off, traction control is working again. After a few minutes idling, traction control turns off. I shut off, then restarted the car, all is good. Drove about one mile and did a 40mph to 65mph pull. Not long after, traction control shuts off on its own. I pull over, cycle the car, stays off. I start my drive home, CEL pops.
I know there isn't a lot of info, namely the actual codes, Just wondering if anybody has encountered something similar to this? All connectors for the maf is clean, maf itself is clean. I unplugged the breakout harness and ran straight from the maf, no change. Any clue what could be up?
Old 12-28-2016, 03:19 PM
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You need to get the codes if any. Is that a stock throttle body and MAF, or aftermarket. Some of the OTR's are harder to tune due to the position of the MAF.
Old 12-28-2016, 07:30 PM
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I think MAYBE, I solved the problem today. I was sure the issue was in a bad spot on the maf wiring. I repaired that and no change? While installing a catch can today, I noticed something while removing things to make room. The small ridge that is on the TB connector is broken (Not the clip on the harness connector.) So, I redneck engineered with zip ties to make sure the connection is still snug. I reconnected the battery and fired her up, traction control is working fully, no CEL. After about 20 miles, and a few 2nd - 3rd pulls, and one 1st-3rd pull, no issues. Running great. It is a stock throttle body. I have a fueling issue that needs to be solved. When we went to tune the car originally, I was running way lean. In the 14's on AFR, after getting it into the 12.7 range, my duty cycle was at 77% I think? Hooked up the pressure gauge and was losing 10psi while holding the rpms around 5500 in neutral. Replace the fuel pump with a deutchwerks (Probably spelled that wrong) drop in unit. At idle, pressure is at 62lbs on the rail, but still suffers that drop. We tuned around it, but the injector cycle is still too high for bolt ons. I have a fast 102 on the way, and I'm about to order a cam and such. I think it may be the regulator on the bucket or a clog in the hard line. The rubber line running from tank to hard line isn't crimped at all that I can see. Not sure where to start on that issue.
Old 12-29-2016, 09:53 AM
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77% is not bad. The drop in pressure may be as simple as the power wire to the pump is not big enough.
Old 12-29-2016, 07:27 PM
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Had her on the dyno today for a baseline. The fueling issue is gone. The pressure no longer drops below 56psi at WOT. Didn't retune because the cam is on its way, seemed like wasted money. First run was pretty pathetic due to heatsoak. Second and third were better, Made amazing torque with one run at 374rwtq and another 378rwtq. Dynoed 355rwhp and 356rwhp. Guy said it had to be pig rich up top to only be making stocking hp numbers. We data logged the final run and sure enough, my injectors were hitting 100% right at the very end of the run. Originally, they were at 77% when commanding an incredible amount of fuel. Now, the fuel is actualy being delivered and maxing the injectors.
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