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Idle Issues/Stalling - HELP!

9K views 57 replies 11 participants last post by  JmoneyM5 
#1 ·
Hey all. Just picked up a sweet, supercharged M5 from Ransidd and everything was working great, but now I'm having some idle/stalling issues...
This started last week while I was driving home from picking parts up at the dealer. Was at a light, let out the clutch...stall. Next light, same issue. Then, in addition, I noticed a lack of power on the rest of the drive home. No check engine light though...

Upon starting the car later on in the day, it would start fine, go through it's self check, then die. Got it home from work by keeping RPMs high and not stopping. :biggrin:

Figured a hose might have popped loose in our hot weather, but no such luck. Had everything apart while installing new valve cover gaskets and all appears to be well.

Got my code reader and pulled the following codes...
 

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#2 ·
Cleared codes this morning and tried starting it again. It stalls after the self-check (5-10 seconds)... Pulled these codes:
 

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#3 ·
Looks like it may be the CPS sensors, any idea if those have ever been replaced?
 
#5 ·
Supercharged cars run mafless. CPS have been known to do crazy things.
 
#6 ·
And finally, I tried one more time and held the throttle open at 2000 RPM. Car still died after running 5-10 seconds. I have full battery voltage, don't appear to have any leaks, no MAFs (supercharged), and I believe the camshaft sensors were all changed within the last 10k miles by the previous owner. Here are the codes after the last cycle:
 

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#7 ·
Just saw your replies...

Yeah, no MAFs on this car...so can't be those.

I checked the idle air control valve when I had the plenum off (shake test). Its moving back and forth and it's super clean. I also tried starting with throttle open and it's still stalling anyway...

CPS could be the culprit, but they were changed recently. Shouldn't that throw a code anyway?
 
#10 ·
Fuel pump and relay - I plan on checking these when I get home tonight. Regular resistance is 4 ohms across the terminals where the heavier gauge wires, right?

Crank position sensor - I read in another thread that this shadow code will show up in abnormal shutdown situations and I don't want to just start replacing parts unless I'm sure there's a problem. I also read that the car won't start at all if the crank position sensor is faulty...
 
#12 ·
Okay, I was unclear on the other threads if the failing crank sensor meant NO start, or start and then stall.:blink: Crank sensor ordered.

Has anyone else experienced the same issues from a failing crank sensor? Will check fuel and post results later. Thanks for the help so far everyone.
 
#13 ·
Okay...just tested the fuel pump resistance: 4 ohms across the terminals, which I believe is the correct resistance.

Also did the fuel pump relay (EKP) test. Fuel pump starts up with the jumper wire. Started the car up with the jumper wires in and it still stalled after about 5 seconds... I did notice that whoever installed the Boost-A-Pump didn't hook up a ground. Also, used crappy crimp connectors... Will fix that asap.

Whatever the case may be, it does not appear that the pump or the EKP module are the problem. Thoughts anyone?
 

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#14 ·
Anyone else want to chime in here? I went to pick up the crankshaft sensor, but the dealer sold the one I ordered last night! :grrrrr:

In the mean time, while I'm waiting for another one, I'd love to run some more tests, but I'm kind of stuck right now... Is there a way to test my current crank sensor? I've done a number of searches and don't find a lot of info for the symptoms/codes I have. Thanks!
 
#16 ·
I did see that. Was really helpful in doing the pump and relay tests. All good though. Thanks for the link.
 
#17 ·
Well, I just replaced the crankshaft position sensor and I'm still having the same issue.:mad:

Anyone gurus want to chime in here?

I'm going to post up more codes in a bit and see if anyone spots something I'm missing...
 
#18 ·
Current codes after installing the new crank sensor:
 

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#19 · (Edited)
New possible theory: Could it be the immobilizer or an issue with my key? I read quite a bit, but I couldn't get any solid info on how the immobilizer works, so it's hard to know if I'm on the right track. It's just strange that the car will consistently start with no issue, then dies after about 5 seconds. Video coming tomorrow... Again, any help is welcome.
 
#20 ·
Happy 4th everyone! So I went to take a video as promised, and then I discovered a wire was not connected at the relays for the Kenne Bell Boost-A-Pump unit. Hooked it up, cleared the codes, and boom got it to start up and idling smoothly.

Unfortunately, my luck ran out there. I took a quick drive on around the block and then onto the freeway and noticed a serious lack of power. At WOT I noticed little to no boost, which makes me think vacuum leak. From where, I'm not sure as I just had the plenum off and checked all the lines (though I'm a beginner with this car and very easily could have missed something).

By the time I got home, car was idling erratically and stalling again. I pulled the attached codes and plan on jumping back on this tomorrow, but it would be great to get some thoughts from you guys in the mean time. Thanks!
 

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#21 ·
I took a quick drive on around the block and then onto the freeway and noticed a serious lack of power. At WOT I noticed little to no boost, which makes me think vacuum leak. From where, I'm not sure as I just had the plenum off and checked all the lines (though I'm a beginner with this car and very easily could have missed something).

By the time I got home, car was idling erratically and stalling again. I pulled the attached codes and plan on jumping back on this tomorrow, but it would be great to get some thoughts from you guys in the mean time. Thanks!
Sounds like you are not familiar with the s/c setup. Maybe check out the FAQs on some s/c supplier sites Since its likely to be a problem with the non-standard stuff you h ave installed.

I dont know much about s/c's but if you are getting no boost, assuming you don't have an obvious problem like a slipping belt, you either have a massive air leak between the s/c and the throttle bodies (which would explain the idle stalling), or a problem with the bypass valve.
 
#22 ·
Agreed. Looks like I was dealing with two issues. Fuel, which is now fixed, and a vacuum leak, which I'll investigate tomorrow. And yeah, I'm not familiar with the car at all since I just bought it! I'm getting there though, thanks.
 
#23 ·
Idle issue fixed after replacing a disconnected wire at the boost-a-pump relay and installing HPS couplers all around (which was a giant B!). Went for a drive and it's idling perfect now.

Still experiencing massive power loss though... The car seems to be running on less than 8 cylinders and is a bit rough. It was also stalling when I let the clutch out unless I gave it a good bit of throttle.

Then I took it on the freeway.... Was running okay, though lack of power was noticeable. Then went to WOT and got fuel cut and limp home mode. Pulled over, restarted and headed back home. On the way back, I was getting virtually no throttle response and it was bogging heavily. About 3 miles from home it shut down completely and would not start again.

To recap, so far
I've checked: Fuel Pump, Fuel Pump Relay, Secret Menu Test for Fuel Level, Vacuum
I've replaced: Crankshaft Sensor, Fuel tank breather, Intake Gaskets, Silicon Couplers and Clamps, and cleaned the air filter

I pulled the following codes after the shut down:
 

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#24 ·
Oh yeah, and I forgot to mention, still no lights of any kind! My next step is to check fuel pressure. Also wondering about that Coil code... Again, requesting gurus chime in. Need to get this thing running again!
 
#26 ·
You may have more than 1 issue.

Why would you get a "bad coil" read? Move that one somewhere else to eliminate that as a true issue. Bad coil will certainly upset the computer.

You keep getting knock on cyl 3-4. Same side as bad coil (bank 1). Has anyone read your fuel trims? Get those read, clear them, and see what happens. You may still have unmetered air going through, causing a lean condition. A source for air leaks can be the plenum intake, where the 2 pieces of plastic seat around the intake plenum.

There are also little hoses under the plenum that can get brittle and crack over time from the heat. A slow careful inspection may reveal a crack in any one of them. A bit time consuming to check, but not really hard. Get a friend, 2 pairs of eyes always better than one!

On my car, the BAP set full rich is too much for street driving. I like to run it about halfway (20-25, which should be 40-50%). Too much fuel will not shut you down, but it will feel a little sluggish. Again, fuel trims may be helpful. Are you running at least 3/4 tank of fuel? You are using premium, correct?

I assume the car will not even do a dyno pull? That would give you AFR's. Perhaps hook up an AFR gauge and see what you get when you go WOT?

I don't remember, which software are you running? My ESS software had the same "stalling when I pushed in the clutch" on a random basis. No leaks. That was a software issue itself, but it idled ok when warm.

Regards,
Jerry
 
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#25 ·
That error code is saying there was a lack of fuel getting to the engine. Fuel pump, fuel filter or regulator as far as I know one of those would be the issue. If you don't know the last time the filter was done you might want to do it just as a maintenance item anyway. Since it happened particularly at WOT that's my first thought. gl
 
#27 ·
Thanks for the replies guys. There could be a vacuum leak, but I had the plenum off last weekend to look and didn't find anything. I'm going to bring it to my shop this week to have them take a look. I don't have a wide-band hooked up, so I can't get fuel trims on my own.

I agree about the fuel issue. When I get the car back into my garage I'm going to check fuel pressure and see what I get. The previous owner said he had changed the filter 20k miles ago, but who knows.

Yesterday was the first time I saw the coil code. I'll swap 1 and 2 and see what happens. If I get a code on 1, I'll know I've got a bad coil at least. I'll post updates soon.
 
#29 ·
I don't have a wide-band hooked up, so I can't get fuel trims on my own.

.
I am not aware you can pull fuel trims (long term (LTFT) and short term (STFT) from a wide band O2 setup. That is for pulling AFR's. Have a bung welded in and you can run the wide band AFR gauge.

You probably need someone with a GT1 or equivalent to read fuel trims. Do some searching here, perhaps with the acronyms, and you should get some additional info.

Regards,
Jerry
 
#28 ·
Oh, and one issue I have is I don't know which software I'm running. The previous owner didn't know. I'm hoping ESS keeps records and have an email into them already. Just in case, I filled the tank all the way up with a 50/50 mix of 91 and 100 octane for the time being.
 
#31 ·
Speaking of the GT1, won't I also need help from one to check the EDK as well? The EDK code has been the most consistent in reappearing since I started pulling codes when this issue began.
 
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