Lean and unstable idle

mjdarg · Dec 8, 2013

I've got a stock GVR-4 and I'm having several issues with my idle. I'm using mmcd to monitor right now. I've got a lean idle and I can tell from the occasional misfire while idling and the 0 V O2 sensor reading. While cruisin my 02 is cycling normal, but my fuel trims are in the 110% range.

My idle is also inconsistent but not surging. It will sort of float around anywhere from 600-1000 with no change in the ISC input. ISC reading on mmcd stays at 42 while idling when the engine is warm. I've checked all coils on the ISC and they all read 38 ohms. I sent my ECU out to ECM over the summer and they couldn't find anything wrong with my ECU. I've also checked all continuity from ISC to ECU.

Any ideas?

DSMnoobsause · Dec 9, 2013

Here are a few

DSM 4G63 Maintenance Guide - DSMtuners

looseboost · Dec 9, 2013

consider checking your biss screw, I had idle issues as well as there was no biss screw or oring.... just a vacuum cap over it.

mjdarg · Dec 9, 2013

Car is one owner and well maintained. I had been having a hard start issue because the fuel pump oring became crooked causing a leak at the pump but its been since fixed. BISS screw has been messed with but idle still won't sit still. I've noticed that when the idle circuit is complete the FT02 goes straight to 100 and doesn't move, revs could be around 600 or 1000 doesn't matter.
This coupled with the O2 not cycling at idle has got me confused.

DSMnoobsause · Dec 9, 2013

mjdarg said:
Car is one owner and well maintained. I had been having a hard start issue because the fuel pump oring became crooked causing a leak at the pump but its been since fixed. BISS screw has been messed with but idle still won't sit still. I've noticed that when the idle circuit is complete the FT02 goes straight to 100 and doesn't move, revs could be around 600 or 1000 doesn't matter.
This coupled with the O2 not cycling at idle has got me confused.

Is your idle switch not registering? Also does your coolant temp read correctly? Not the gauge but in your logger that the ecu will see.

callmesaj · Dec 10, 2013

I know my talon was doing this because of leaky tb shaft and leaking injector insulators. whens the last time you did a boost leak test?

mjdarg · Dec 10, 2013

Coolant temp sensor is reading fine and the idle switch functions properly.

callmesaj said:
I know my talon was doing this because of leaky tb shaft and leaking injector insulators. whens the last time you did a boost leak test?

Now that you mention the shaft seals, I did replace my TPS about a year ago. I know I should have done a BLT before even posting on here, but I'm currently at school until Christmas break.

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Lean and unstable idle

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