4g61t.org

Car does the random rpm drop at idle, then sometimes dies. Logger shows O2 readings at 0.0 when idling, cycles when driving. The O2 fuel trims will abruptly drop to 100% while idling and that's when I'll get my idle drop. Have already done a boost leak test. Any ideas?

ISC? I would toss in another one first to eliminate that.

_________________
93 Mitsubishi Expo LRV 1.8/manual
95 Eagle Summit DL Coupe 1.5/manual
01 Mitsubishi Mirage ES Sedan 1.8/manual

Please post a fix cause I too am experiencing idle issues... Im looking at the IACV or TPS for me however, maybe even a leak at the BISS screw

_________________
98 Mitsubishi Mirage 1.8t

I had a goofy idle problem as well. Fixed it by slapping on an iacv full delete plate. Now I just set my idle with the biss screw. I don't have a/c or power steering so other than having to pedal it a little when starting it (when it's cold out), I haven't had any problems.

_________________
Had a:
1991 Eagle Summit ES Hatchback - 4g15 12v 5spd
1991 Dodge Colt -4g15 12v 4spd
Have a:
1978 Oldsmobile Cutlass - 468BBO TH350
Round 3:
1990 Dodge Colt-4G63T 5spd

Im gonna take a picture of what I think is the BISS screw on my TB and post back here, would be nice to get rid of another potential headache down the road not to mention another vac/boost leak source..

_________________
98 Mitsubishi Mirage 1.8t

Found out where it was... try the iacv delete though cuda

_________________
98 Mitsubishi Mirage 1.8t

I've tested the ISC multiple times and it tests okay. The logger also shows the ISC trying to do its thing but it comes in too late to save idle.

Tonight I was starting to think it was a unknown vacuum leak and/or the hacked MAS causing issues, that maybe the O2 sensor and FTO2 readings aren't lying that it is idling lean. Revved the motor up and down repeatably for fun and I hear popping, signs of a lean condition? After letting it back to idle after the revs the O2 sensor starts cycling high/the FTO2 readings want to go below 100% instead of climbing to 199%/the injector pulse increased from the normal 1.7/ and MAS readings start cycling including 0 MHz with a crappy idle.

I'm starting to think the ECU is going.

Pop it open and take a whiff. It'll smell a little fishy if the caps burn up.

_________________
Had a:
1991 Eagle Summit ES Hatchback - 4g15 12v 5spd
1991 Dodge Colt -4g15 12v 4spd
Have a:
1978 Oldsmobile Cutlass - 468BBO TH350
Round 3:
1990 Dodge Colt-4G63T 5spd