2012 m8 high hanging idle

yotaman1290 · Dec 14, 2016

2012 m8 high hanging idle and ECU Code 12

I picked up a 2012 m8. Has a full slp pipe kit. Bdx oil delete. Had a boondocker box that I ditched for a power commander 5. The issue is, the idle doesn't like to drop. It hangs up at around 3000 rpm for a while, occasionally hitting the gas it will eventually drop. It was this way with the bd box, and now worse after I installed the pcv. Throttle cable has slack, power valve cables are in spec, tps is in spec, and calibrated to the pcv. I have sprayed starting fluid all over intake, cylinder base and behind clutch looking for air leaks and can't find anything.
Also, loads up a lot at idle with premix at 36/1. Clears out when I pin it, wondering if this is normal?

duggrant · Dec 14, 2016

Had a high idle on my 15 that I could not get rid of and I checked everything u checked and finally asked a buddy for a assistance. We wound up swapping fuel tanks from my 13 to my 15 and high idle was gone. Installed a new fuel pump and problem was solved. I also have oil delete and power commander 5. Sure sounds like the same problem you have.

yotaman1290 · Dec 16, 2016

duggrant said:
Had a high idle on my 15 that I could not get rid of and I checked everything u checked and finally asked a buddy for a assistance. We wound up swapping fuel tanks from my 13 to my 15 and high idle was gone. Installed a new fuel pump and problem was solved. I also have oil delete and power commander 5. Sure sounds like the same problem you have.

Weird, maybe just weak on the idle? I added a little fuel down low at 0% throttle and 3000 rpm on the PC5 and it seems to help, but its not 100% fixed

duggrant · Dec 16, 2016

I am running slp stage 3 with their map and it has been flawless for over 3000mi. When I got my high idle, we tried everything. Swapped ecu's, swapped power commanders, took power commander out of loop and high idle was still present. As a last resort we swapped out the fuel pumps and everything was normal. the fuel pump was still working, just not at 100%. Not sure what the psi is supposed to be on those fuel pumps but Mabe check it with a pressure gage.

yotaman1290 · Dec 17, 2016

duggrant said:
I am running slp stage 3 with their map and it has been flawless for over 3000mi. When I got my high idle, we tried everything. Swapped ecu's, swapped power commanders, took power commander out of loop and high idle was still present. As a last resort we swapped out the fuel pumps and everything was normal. the fuel pump was still working, just not at 100%. Not sure what the psi is supposed to be on those fuel pumps but Mabe check it with a pressure gage.

Did it ever drop down to normal idle? Mine will hang at 3000 rpm for a while and eventually drop to 1700

ndfb35 · Dec 17, 2016

I'm having the same issue, and I am wondering if your sled ran well besides the high idle?

duggrant · Dec 17, 2016

Mine would mostly hang at 3000rpm and would drop down to around 2300 but wouldn't drop below 2000rpm. Sled seemed to run fair but had a bit of a bog at 3/4 to full throttle.

yotaman1290 · Dec 18, 2016

ndfb35 said:
I'm having the same issue, and I am wondering if your sled ran well besides the high idle?

Mine runs amazing other than the idle!

ndfb35 · Dec 18, 2016

Mine runs well, and it does drop down to about 2400, but if I ride it for awhile it will not drop, and stays around 3600, meaning unless I am on the brake, the machine won't stop. I've messed with all the things that could possibly be the issue and nothing has fixed it. Sounds like I should replace the fuel pump :face-icon-small-dis

yotaman1290 · Dec 20, 2016

I also am getting a ECU code 12 popping up. It goes away when I'm at a lower rpm, then i stab the throttle and it comes back up. Also saw a code 1 and 15, which dont exist. Something is funny here

Readymedic · Dec 21, 2016

Check how your throttle cable is attached to the throttle bodies and everything else. If it is pulled tight, the idle will be increased. Make sure there is the free play required on the throttle thumb lever.
Just an FYI.

yotaman1290 · Dec 21, 2016

Readymedic said:
Check how your throttle cable is attached to the throttle bodies and everything else. If it is pulled tight, the idle will be increased. Make sure there is the free play required on the throttle thumb lever.
Just an FYI.

Cable is good with free play

ndfb35 · Dec 21, 2016

So, I thought it was my fuel pump.... it didn't fix my problem. Upon further inspection I found that my throttle cable was wrapped around things after I had swapped to a fixed post. The cable had plenty of slack. I wish I had checked to make sure it was routed properly before buying a pump, but it never crossed my mind.

matt159 · Jan 1, 2018

yotaman1290 said:
Cable is good with free play

yotaman.. what did you figure out? I am starting to explore my 2013 high idle issues as they seem to be worse this season... bmp 900 that runs awesome, oil injection delete... just high idle. was occasional last 2 years... how nearly constant. New fuel pump 2 years ago. 2500-3000 rpm depending on its mood... sometimes 1750 for a while right after i start it & worse when engine is warmer. Cable good... tried adding fuel down low with PCV but was same... maybe worse.

mbcat · Jan 2, 2018

High idle

Check your reeds!

matt159 · Jan 2, 2018

mbcat said:
Check your reeds!

That's on the checklist... just wanted to see if there are any other possibilities besides reeds, fuel pump & cracked boot, etc. that i would find with starting fluid.

Anyone have other thoughts? Thx. --Matt

boondocker97 · Jan 2, 2018

On my bmp 900 I had a low idle issue that gradually got worse. Adjusted it up a little with the idle set screw and it's been good. It's got the different throttle bodies though and it was a very fine line between too high and too low.

Now I'm starting to get an occasional hanging idle at 2700. Blip the throttle and it goes right down to 16-1700. 1700 miles and it seems to be a little less crisp on the bottom end. Like mbcat said I'm thinking the reeds are starting to not seal like they should.

matt159 · Jan 3, 2018

boondocker97 said:
Now I'm starting to get an occasional hanging idle at 2700. Blip the throttle and it goes right down to 16-1700. 1700 miles and it seems to be a little less crisp on the bottom end. Like mbcat said I'm thinking the reeds are starting to not seal like they should.

Mine was like that last season... blip the throttle and it would drop down every time. Now a blip only drops rpm for maybe 10 seconds & it comes back up to ~2700-3000 most of the time. Sled still runs perfectly though. I suppose i should change the reeds regardless of what i find since it is at ~1300 miles now.

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2012 m8 high hanging idle

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