SR20DET Rough idle, Runs better with MAF Unplugged

[gmorcos37]

Hello,

I have a stock S13 SR20DET Redtop and am having some issues. The car seems to have a rough idle and is running lean as well. Idle AFR is in the 16-17 range and cruising stays there as well. Once I unplug the MAF, the idle smoothens out and idles fine but obviously runs super rich and has the 2500 RPM limit (limp mode). Once I plug the MAF sensor back in, car starts to struggle again. Vacuum stays pretty much pinned at -20 during idle. Also builds boost fine at 7/8 psi. No ECU codes are present besides the normal 55. Any ideas? What would be the best/first approach to checking everything? Any help is appreciated.

Thanks!

[gmorcos37]

I took off the MAF and cleaned it pretty well. Problem is still there, made no difference. Could the MAF wiring be bad? I unplugged it and checked voltages when ignition was on but motor was off. I got around 12V for black and white wire, and around .02V for the white wire. Isn't that the signal wire? Should it be around there or should it be 5V? What should it be when motor is off but ignition on? Also I unplugged the 02 sensor while the engine was running and it made no difference in idle. Could this mean that the 02 sensor is bad? Not really sure where to move on from this point. Could it be something in the fuel system?

Any help appreciated!

[gmorcos37]

Bump! Anyone got any ideas?!

[smoked240]

My rb was acting like this and it turned out to be a bad o2. But once my engine warmed up the problem went away.
Have you checked your tps?

[gmorcos37]

Did you ever unplug your 02 sensor while the motor was running? If so did it make any difference? I've been reading that a bad 02 sensor will most likely cause a rich condition over a lean condition so not sure. I have not checked tps yet. I've read that it should be around .45V at idle. If it is .45V at idle, does that mean it's fine?