| Hey guys, i've got a strange problem i'm hoping you can help me diagnose. My idle has had a random miss for quite some time now. (Please see profile for mods) I've done everything under the sun to chase it down. Over the past few years i've replaced the following items with no change to the idle: O2 sensors, CAS, injectors, fuel pump, fuel pressure regulator, fuel damper, fuel pump computer, 120k Maintenance, fuel filter, fuel temp sensor, IACV, air regulator, water temp sensor, throttle position sensor, coil pack harnesses (spliced/soldered in), PCV valves. Tests i completed: Power balance
Compression (all in spec)
Coilpack impedance good
MAF impedance good
O2 sensors tested good
I did a boost leak check and fixed a few leaks but one small one still remains in the back of the engine and i cannot find it. Its not the EGR. I'm guessing lower plenum gasket on the passenger side, but that can wait until i pull the engine to rebuild. Adjustments
TPS in spec
Timing at 15 degrees
Throttle bodies cleaned and synched
All ECU harnesses cleaned and dielectric grease
Idle adjusted to 800 RPM (though it bounces a bit) So i figured i havent replaced the coil packs or MAF(s) and i have that slight boost leak left. I have the cheap ebay chinese HID hi beams and fog lights (only because kaixen no longer makes them) and occasionally when i turn on my hi beams, the car will cough and sputter and i'll coast to a stop, turn the car off (or it stalled) and then start it back up and it runs fine. I've read this can be electromagnetic interference with the Selin Dual MAF translator so i plan to get rid of this HID chinese crap. However, the other day i turned on my hi beams and the coughing started to happen, so i threw it in neutral and it idled perfectly. Its only when you give it gas does it cough. So i coasted to a stop and let it idle. The idle was never smoother, it was dead on, not a single miss. I let it go for at least 10 minutes and never missed a beat. But if i gave it gas, it would cough and want to stall. So finally i shut it off, turned it back on and voila, idle with a random miss is back. I tried to repeat and get the car to go into cough mode again with the HIDs but could not. It only happens occasionally. Strange that this HID EMI issue may have revealed my idle issue. Did the ECU go into a default mode? Do you think it might be at least one of my MAFs? Maybe an O2 sensor? Any insight or advice would be extremely helpful! Thanks in advance. Ron
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