Boost controller problem

175

Asked by Aug 12, 2011 at 11:39 PM about the 1991 Nissan 300ZX 2 Dr Turbo Hatchback

Question type: Car Customization

Hey guys, having trouble with my boost psi. Got a new 91 TT, put a boost gauge in as well as swapped my Greddy boost controller with the one that was in it because I wanted my settings.  Ran it for about 4 days and the boost pressure was fine. Would go up to 15psi just like it was set to. But in the last couple of days, something happened and my cars only running at 5psi. I can't find what the problem is. Nothing has changed and none of the boost hoses are disconnected or cut. I'm sure the boost gauge hose isn't pinched anywhere because my boost controller shows around 30 or 40% which is around 5psi. It's almost like the stock boost control module is overriding the Greddy controller. Anyone have any thoughts?

2 Answers

175

Think I figured it out. Tracked the problem down to the knock sensor. My boost is stuck at 6psi which is know as safety boost and I think it's to blame on the knock sensor. I replaced it with a new one and hopefully it'll be working. I'll check in the morning. I think the cause of all my problems was trying to use the selling dual MAF piggy back plug. They claim that you can use a dual intake on a single intake ecu with two MAF and their adapter. But when I plugged it in, my engine wouldn't idle above 500rpms and it stalled out after about 15 seconds. I think either the knock sensor went crazy then, or my engine was doing a lot of knocking, which I wouldn't rule out because it was getting wayyyyyy too much air. Also, if anyone knows a way of resenting code 34 on the computer, please let me know. I would love to get this done with.

175

It's not the knock sensor and the computer can't be reset. Only thing I have left to blame is the wiring harness and the ECU. Going to wire in a 1m ohm resistor to see if that fixes the problem.

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