_UsUrPeR_
Greenie Member
Hey all. I bought this car used. It's got a remanufactured engine that was tuned with an Accessport from a reputable shop that still exists.
Last Fall, I was having some issues with boost cut where the vehicle would hit ~23 psi and chop fuel. It felt amazing up until fuel cut, but I knew something was wrong because it shouldn't be hitting fuel cut to begin with. It turns out that it was a bad MAF sensor. Since I replaced the sensor, the car is behaving normally, but it doesn't seem to go above 16PSI. I know this was tuned to 19PSI, and sometimes, for a few minutes after starting the car when it's still warm after parking for a few minutes, it will hit the tuned limit and feels amazing. After about 3 minutes of driving, it seems to settle back down to a 14~15 psi peak, and then that's all that's allowed by the ECU.
I called the original tuner to see if he could pull the tune on his end to tell me what boost was set to, and he was unable to get it on his system. I guess they changed their system since it was tuned in 2023 and he's unable to find it. To diagnose, he said he'd start by smoking the intake because it sounds like a boost leak, so I figured I'd do the same.
I ran smoke into the intake, and I couldn't see any leaks anywhere, though I couldn't get the manifold to pressurize past 3~5 psi with the smoke machine. When I pull the smoke off, a little pressure was holding, but not by a lot. I'm not sure where boost would be getting by, but when the engine's running under WOT, it will absolutely hit its metrics, because it had no problems hitting 23PSI when the MAF was malfunctioning, and it will hit 18~19 PSI when conditions are right for a few minutes.
The engine runs great, feels good under WOT, AFM reads around 10.25:1 which I feel is a good ratio under WOT, wastegate duty hits 50ish when the ECU is hitting 19PSI, and 38 when its in the 14psi range, HPFP shows fuel pressure at 1800+ Act. I just can't figure out why boost would be rolled back after a couple minutes by the ECU. If anyone has any suggestions, I'd appreciate it.
Last Fall, I was having some issues with boost cut where the vehicle would hit ~23 psi and chop fuel. It felt amazing up until fuel cut, but I knew something was wrong because it shouldn't be hitting fuel cut to begin with. It turns out that it was a bad MAF sensor. Since I replaced the sensor, the car is behaving normally, but it doesn't seem to go above 16PSI. I know this was tuned to 19PSI, and sometimes, for a few minutes after starting the car when it's still warm after parking for a few minutes, it will hit the tuned limit and feels amazing. After about 3 minutes of driving, it seems to settle back down to a 14~15 psi peak, and then that's all that's allowed by the ECU.
I called the original tuner to see if he could pull the tune on his end to tell me what boost was set to, and he was unable to get it on his system. I guess they changed their system since it was tuned in 2023 and he's unable to find it. To diagnose, he said he'd start by smoking the intake because it sounds like a boost leak, so I figured I'd do the same.
I ran smoke into the intake, and I couldn't see any leaks anywhere, though I couldn't get the manifold to pressurize past 3~5 psi with the smoke machine. When I pull the smoke off, a little pressure was holding, but not by a lot. I'm not sure where boost would be getting by, but when the engine's running under WOT, it will absolutely hit its metrics, because it had no problems hitting 23PSI when the MAF was malfunctioning, and it will hit 18~19 PSI when conditions are right for a few minutes.
The engine runs great, feels good under WOT, AFM reads around 10.25:1 which I feel is a good ratio under WOT, wastegate duty hits 50ish when the ECU is hitting 19PSI, and 38 when its in the 14psi range, HPFP shows fuel pressure at 1800+ Act. I just can't figure out why boost would be rolled back after a couple minutes by the ECU. If anyone has any suggestions, I'd appreciate it.
