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Discussion Starter #1 (Edited)
Hi Everyone,

About 3 months ago, my 2003 540i was experiencing a really rough idle when I would start it on a cold morning (<49F). Coolant was leaking as well so I had the car diagnosed and it was a faulty water pump. I replaced the water pump and the entire cooling system has had an overhaul in the last 15,000 miles.

EDIT: All new plugs done 15,000 miles ago.

Recently the rough idle issue has persisted and now even when the engine is warm, I feel this "puttering" or intermittent shaking below the car when I am idling.

I went to O'reilly auto parts to use their scanner and found:

140 - Output Thermostat Map Cooling
93 - Tank Ventilation Functional Check


I thought this might be a dirty MAF, so I got some CRC MAF cleaner, disconnected the battery, took the MAF out, cleaned it very throughly, let it dry, put it back in, it made NO difference whatsoever. I am wondering if I need a new one?

Went to auto zone to borrow their scanner, found:

P0316 Misfire Detected on Startup (First 1000 Revolutions)
P1348 Misfire During Start Cylinder 4


I will be buying a scanner this week and I am going to swap coils in cylinders 3 and 4 to confirm if it's a coil, if so I will put it in a new coil and boot. If the shaking persists - I will buy a new MAF. Once I have a new MAF and coil, I don't know where to go if I experience the same issues.

Anybody experienced these symptoms and have any tips?

Thanks

UPDATE: (01/02/2020):

I started the car in 36F weather and the rough idle appears to be gone. There were a couple of brief moments where it trembled but then RPMs went down a bit and it just purred. I stopped frequently while driving, pulled over a few times to wait for it to stall/die as it did previously....but it wouldn't. I think the MAF fixed the problem. The car sounds and feels more responsive, even more so than it did with JUST a new coil and plug. If I experience any more issues regarding the rough idle, I will report back.

EDIT UPDATE 1/10/2020. Looks like I was wrong, the rough idle is back in cold weather. The Coil and plug fixed the rough idle when warm and improved performance. The MAF also improved MPG and performance.

Any morning where it is below 39F, the car shakes, stalls and "putters" until the engine is warm. My indy can't figure it out, no codes are popping up either, so I do not know what to do. I'll have to take it somewhere else....IF anybody knows what this could be OR has any recommendations for indys in Sacramento, CA please let me know!

UPDATE: 01/31/2020 - DIAGNOSIS COMPLETE - FAULTY INTAKE MANIFOLD GASKETS

After a lot of uncertainty, I found a local reputable BMW shop and they delivered. A smoke test was completed to locate the vacuum leak and I witnessed this, confirmed it visually. The cold rough idle is due to faulty intake manifold gaskets. They tested the Fuel Tank Breather Valve and it appears to be functioning properly.

I will be replacing the gaskets soon. Thanks everyone for your help. I really appreciate it.
 

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Rough idle with misfiring codes is guaranteed a plug or a coil. I'd swap coils, and it it travels - replace the faulty one. Might do the plugs while you are at it - they are cheap.
 

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The first thing I would do is check your T-Stat temps. If your T-Stat is not closing you'll experience misfiring and bad idle, especially summer months. I had a similar experience and after replacing TS all went away, plus the car has much more power and fuel mileage also improved by almost 4mpg! Check your Tstat temp and make sure it's between 79-82C The car should warm up by 3 miles drive. If you notice longer times to get up to temps, it's leaking. Go to the secret menu and check the temps.
 

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Discussion Starter #4
hey thanks for your reply. I just put a new thermostat in a month ago (with a waterpump). Coolant leak is gone.

The car warms up within 3 miles. Previously the rough idle was immediately gone after a few miles or a 4-5 warm up. Now it persists.

Putting a new coil in this weekend. I’ll be sure to check the tstat temp too. Thanks.

The first thing I would do is check your T-Stat temps. If your T-Stat is not closing you'll experience misfiring and bad idle, especially summer months. I had a similar experience and after replacing TS all went away, plus the car has much more power and fuel mileage also improved by almost 4mpg! Check your Tstat temp and make sure it's between 79-82C The car should warm up by 3 miles drive. If you notice longer times to get up to temps, it's leaking. Go to the secret menu and check the temps.
 

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hey thanks for your reply. I just put a new thermostat in a month ago (with a waterpump). Coolant leak is gone.

The car warms up within 3 miles. Previously the rough idle was immediately gone after a few miles or a 4-5 warm up. Now it persists.

Putting a new coil in this weekend. I’ll be sure to check the tstat temp too. Thanks.
Yes, check temps while on a cruise in colder temps. Next step I would look into MAF's and how many miles on coils? I replaced coils thinking it was coils, but wasn't. Wishing you best, happy holidays.
 

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Normal OBD2 scanners will not read ghosted faults or engine faults that don't latch in. There's a threshold for what the ECU will call a "misfire," but as you are experiencing you can feel/hear the engine miss without getting an actual code for it. Coils are an easy culprit, especially at the age our cars are at now.
 

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Discussion Starter #7
Rough idle with misfiring codes is guaranteed a plug or a coil. I'd swap coils, and it it travels - replace the faulty one. Might do the plugs while you are at it - they are cheap.
I put in a new coil first thing this morning. I used the same spark plug because it was changed 15,000 miles ago. Cleaned around the plug a bit (maybe about a drop of oil), then put the new coil in. And then I started the car while it was cold. The car still has a very very rough idle but ONLY when its colder outside and the car is cold (<mid40sF). Once the engine was warm, the car sat perfectly still at idle. Same thing if its Warm

With the new coil, the car sounds noticeably better, more responsive to acceleration, pulls stronger, and the rough idle that once persisted even when the car was warm/driven for hours... is gone!

I'm assuming the cold start will persist. If it does tomorrow morning, I'm getting a new OE MAF sensor....
 

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Don't waste your money, that is not a MAF problem but there is a test that can tell you if it is MAF. Simply unplug the MAFs electrically if there is not a huge improvement, then not MAFs.
The Orielly codes the numbers make no sense, not OBDII not hex nor decimal, but the words tell the story clearly. A bad coolant sensor can cause poor cold starts because the car is setup to start for a temperature it is not really starting in.

The second one depending on failure type might even mimic something related to MAFs and could cause improvement in the MAF test above so be careful.
The second is the evap valve and sometimes they fail completely open which is like having a vacuum leak.
Have you got your code reader? Wait until you have that before you do too much.
The next set of codes you got that are in OBDII, they indicate the potential for bad CPS or the need for vanos board maintenance, the symptoms are the same as you have plus a lack of power when you get on the gas in the lower RPM range.
Have you dealt with either of those items since you owned the car?
 

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OP says his car is a 540i. There are some similarities between it and the E39 M5 but am not sure he’s in the right forum. As an aside I owned an ‘01 740iL with the M62. After six months and a few thou I sold it and swore I’d never again own a BMW V8. Couple of years later I bought the ‘02 M5 and it was magnificent for the three years I owned it.
 

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Discussion Starter #10
Don't waste your money, that is not a MAF problem but there is a test that can tell you if it is MAF. Simply unplug the MAFs electrically if there is not a huge improvement, then not MAFs.
The Orielly codes the numbers make no sense, not OBDII not hex nor decimal, but the words tell the story clearly. A bad coolant sensor can cause poor cold starts because the car is setup to start for a temperature it is not really starting in.

The second one depending on failure type might even mimic something related to MAFs and could cause improvement in the MAF test above so be careful.
The second is the evap valve and sometimes they fail completely open which is like having a vacuum leak.
Have you got your code reader? Wait until you have that before you do too much.
The next set of codes you got that are in OBDII, they indicate the potential for bad CPS or the need for vanos board maintenance, the symptoms are the same as you have plus a lack of power when you get on the gas in the lower RPM range.
Have you dealt with either of those items since you owned the car?
Thanks for your help here.

The coolant sensor was replaced with a genuine BMW coolant sensor at 91,000 miles, this was back in March of 2018. The car is now at 111,000 miles. This makes me doubt that I need a new sensor.

I started the car while it was cold this morning and there was no rough idle at all but it was an unusually warm morning. About 50F at 6:30am. I usually experience the cold start + Cold weather rough idle when it is in the 30s and low 40s F. I am going to MAF test it again on a colder morning. I will do the MAF test you suggested and reply back.

I got the code reader. I chose the Auto AL519 and it detected no codes both before and after I swapped the coil....This is the live data and I do not know what to make of it:

SHRTFT21(%) = 25.0
O2S22(V) = 0.400
SHRTFT22(%) = 99.2
OBDSUP = OBDII
DTC_CNT = 0
FUELSYSA = CL
LOAD_PCT(%) = 2.0
ECT('C) = 60
SHRTFT1(5) = 25.0
LONGFT1(%) = -0.8
SHRTFT2(5) = 25.0
LONGGFT2(%) = -0.8
RPM = 512
SPARKADV(') = 12.5
IAT ('C) = 20
MAF (G/S) = 4.50
TP(%) = 2.0
AIR_STAT = OFF
O2SLOC = B1S12--B2S12--
O2S11(V) = 0.115
SHRTFT11(%) = 25.0
O2S12(V) = 0.325
SHRTFT12(%) = 99.2
O2S12 (V) = 0.12

Regarding CPS and Vanos, I have not dealt with these issues with my car and I have all service records since it was new, neither have been an issue/addressed. I no longer experience lack of power at low rpm, I think the coil fixed that. I will have to see what mpg is after this next week or two.
 

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Discussion Starter #11
Yes, check temps while on a cruise in colder temps. Next step I would look into MAF's and how many miles on coils? I replaced coils thinking it was coils, but wasn't. Wishing you best, happy holidays.
replaced the coil, no more rough idle when the engine is cold or warm. It hasn’t been very cold out in the mornings so I can’t confirm yet if the rough idle when really cold, is gone.
The car accelerated much better, sounds better when starting and driving, overall the coil made an impact.
 

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Did the scanner not come with a book? Do they have a web site?
Best guess is those might be targets or ranges for things. Your Short term fuel trim can't be 25% or a code would be set. So my guess is those might be the normal ranges, but purely a guess and a big one at that. Really hard to guess at what that is without the scanner in my hand so I could see the differences. Keep those and read it again in a moth and see if there is something different.
Even if the sender for the coolant temp is new there can be an issue with the connection, you will find many posts on the topic. You could search user name 68FB with a temp sensor keyword, he posted a bunch of info on it.
That very first code might have been old and then got cleared, again hard to guess but what that cod said was the car was not warming up correctly according to the table or MAP in the DME. Think it is normally HEX code 69 or maybe 68 sure as heck not 140 so that part is a tad confusing. Normally that can be the Tstat but with your symptom it is more often something with the sensor. Especially if temp sensitive. Does your outside temp sensor work?
The car compares many temp sensors to decide what temp you are starting it at.
At a place and I don't remember exactly might be -5 degrees C the car goes full rich to start and anything below that but above that it has different settings for different temps so if the temp is wrong you can get the wrong mix.
Moot now you say it has stopped doing that. Might have been some odd failure usually cold is when coils are at their best, but it could have been anything.
 

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I suggest making a video of live data with car running. STFT and O2 sensor readings both banks.
 

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Discussion Starter #14
I put in a new coil first thing this morning. I used the same spark plug because it was changed 15,000 miles ago. Cleaned around the plug a bit (maybe about a drop of oil), then put the new coil in. And then I started the car while it was cold. The car still has a very very rough idle but ONLY when its colder outside and the car is cold (<mid40sF). Once the engine was warm, the car sat perfectly still at idle. Same thing if its Warm

With the new coil, the car sounds noticeably better, more responsive to acceleration, pulls stronger, and the rough idle that once persisted even when the car was warm/driven for hours... is gone!

I'm assuming the cold start will persist. If it does tomorrow morning, I'm getting a new OE MAF sensor....
This morning it was 35F. The rough idle is still happening when it's super cold out. Once the car is warm it's gone. I decided to change the spark plug this morning, with the new coil so both are brand new. There was a bit of oil on the old plug but barely in the well. Putting in a new MAF today.
 

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Fuel trims are adding fuel on both banks, STFT went to 25% on both banks.
You have a new MAFS correct? If so then you have a vacuum leak. Watch the STFTs live. Let them get up to 25% then raise the RPMs to around 3000 and hold it. The STFTs will drop back to 0 if it's a leak.
 

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Discussion Starter #17
Fuel trims are adding fuel on both banks, STFT went to 25% on both banks.
You have a new MAFS correct? If so then you have a vacuum leak. Watch the STFTs live. Let them get up to 25% then raise the RPMs to around 3000 and hold it. The STFTs will drop back to 0 if it's a leak.
Thanks very much for quick reply. Yes - I do have a new OE BOSCH MAF I bought from Bosch. I raised the RPMs to 3000 and watched the STFTs, they did drop to zero so it looks like I have a vacuum leak (photo below). I REALLY appreciate that info xrviz!....now to actually fix the vacuum leak....Where do I start?

I am trying to determine all the locations a vacuum leak can occur and how to check for leaks. Any advice? Once I locate the leak, I am hoping I can swap the part myself and finally move on from this issue that has plagued me for the last few months! Thanks

934909
 

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Edit: just realized this was about an M62 and not s62

I had a similar issue on my M62tu in my 740il. The car had 185k and I was fighting a rough idle and occasional misfire on heavy load. I removed the fuel injectors and had them professionally cleaned. I replaced the sucking jet pump, brake booster line, and throttle body gasket. All of which failed visually inspection, except the TB gasket that I couldn't see. These items fixed my problems right up. Previous to that I had also replace the gasket on the rear of the intake manifold.
 

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Discussion Starter #19
Edit: just realized this was about an M62 and not s62

I had a similar issue on my M62tu in my 740il. The car had 185k and I was fighting a rough idle and occasional misfire on heavy load. I removed the fuel injectors and had them professionally cleaned. I replaced the sucking jet pump, brake booster line, and throttle body gasket. All of which failed visually inspection, except the TB gasket that I couldn't see. These items fixed my problems right up. Previous to that I had also replace the gasket on the rear of the intake manifold.
Thanks for this, very very helpful information. I will definitely check on these.
Also, I posted on the M5 forum because I noticed this side of the forum gets more attention, responses, helpful info, etc. On the 5 series forum, you get no attention, views, responses when posting.

Appreciate your help, thanks so much!
 

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Thanks for this, very very helpful information. I will definitely check on these.
Also, I posted on the M5 forum because I noticed this side of the forum gets more attention, responses, helpful info, etc. On the 5 series forum, you get no attention, views, responses when posting.

Appreciate your help, thanks so much!
Hi Op,

I have a 99 540 with the exact same symptoms and codes. From the research I have done, I am leaning towards the throttle body gasket first, which I have already purchased, just haven’t had the time to replace it yet. If anything, the throttle body gasket is the cheapest of the parts referenced above, which is where I like to start anyway.

Anyway, I guess all that to say it would be very appreciated if you could update this post with the results from whatever route you choose.

Thank you in advance,

Lance
 
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