First, the problem: At idle, I get an intermittent misfire like pop from the exhaust when warm, is somewhat hesitant at part-throttle (sub 3K RPM), gas mileage has been down, and at 10k miles, the old plugs have got a white powder (like burning coolant/too lean, but no coolant loss or vac leaks (21 in.Hg at idle)), hunts at idle, studders and I can hear the injector "hiss" randomly in sync with the popping in the exhaust.
Now, the CTS, IAC, injector, MAF, O2 (just put a new one in anyway, 126K) TPS (new Hitachi unit) ALL check out. System voltage @ 14.02V at idle and holding.
I did have an IAC code when I bought it in May, but new throttle body gaskets solved that code.
Now when I test the MAF, it gets the 14.02V, has a varying sensor voltage and starts at 0.125V, and the ground, KEOE (key on, engine off) reads 3.6 ohm (from connector to body ground).
NOW. When the car is running, and MAF unplugged, ground back probed at the connector and to the body ground with my DMM, it reads 3.5, 3.6 ohm, then every 4.5/5 seconds, it flips to -16.5 ohm for a second, then back to 3.6. but if I measure it with just the ignition on, it holds steady at 3.6 ohm. WTF? Also, when the MAF is unplugged, the idle smoothes out, but smells rich,
any thoughts? Is this affecting my running? is this normal?
Edited by 86 Wonder Wedge, 14 December 2012 - 04:45 PM.