Idle fluctuation

[stellz996]

So i have this problem for a good couple of months now. With the car sitting at idle usually once warm the rpm will fluctuate, this happens with no A/C so rule that out, warm battery voltage holding 13-13.4, with the vehicle off battery is at 12.7-12.8.

Sometimes its only a couple of hundred rpm and other times it can be more sevier and be as much as 500rpm.

Back in mid january i left the accessories on accidently and drained the battery, jump started it and only a few minutes on the road it stalled and only just started up again on the highway and as far as i remember its been idling wierd since.

Could this be an alternator problem or something effecting the tune etc...

 

[iwashmycar]

Id start with cleaning the MAF sensor and making sure the air filter element is indeed set properly into the airbox and sealed.

Go from there. Could/should also disconnect the battery for a while and let it 'reset' while you work on the MAF sensor.

Also for your AC comment, make sure its not on defrost setting either, as that automatically kicks on the AC compressor.

A similar problem to yours it sounds (from another forum):

I had a high idle issue and wanted to contribute to this forum since the answer on fixing it was found here.

I'll just bullet point to be as succinct as possible.

• Battery was accidentally drained by leaving something on. After charging, the idle was in the 1200+ RPM range. No error codes were being displayed.
• Drove it around a bit, didn't want to fix itself, so I disconnected battery, then reconnected battery after 20 minutes. Problem fixed and it was back to 600 RPM. I thought maybe the ECU was just glitched.
• After one trip, RPM was back up to 1200 RPM (after warmup). Again, disconnected battery to reset ECU. RPM returned to 600 RPM.
• For the third time, after a couple more trips the idle RPM is at 1,200 again. Resetting multiple times (after being disconnected for hours) RPM would not return to normal.
• Checked forums here. Cleaned throttle body (very gummy), checked all hoses for leaks (none), cleaned PCV valve (questionable state), and checked fuses. I figured cleaning both the throttle body and the PCV would certainly fix the problem.
• Started car, RPMs went straight to 1600 and then dropped back to 1200 after warmup. At this point, I'm researching what it costs to purchase and program a new ECU, and/or a new throttle body actuator. I'm getting a bit stressed out at this stage because it's turning into quite the project.
• Checked forums again, people say it needs to be driven in order for the ECU to learn correct air/fuel mixture. I decide I'll drive around a bit and see if that's true, even though the first two tries before cleaning didn't work.
• I drive about 5-7 miles and come to a stop light. As I'm sitting, the RPM starts to visibly drop from 1,200RPM to about 600RPM over the course of 30 seconds. For the rest of that trip and the trip home, RPM stays at 600 RPM when idling.
• Fingers crossed, hasn't been a problem for the last few days.

So, I will second what others have said here. Reset ECU, drive it around, be patient and give it a chance to reset and relearn. I have to assume that cleaning the throttle body/PCV was still necessary, especially on my Cruiser that has a cold air intake with the semi-oily air filter attached.