E39 M5 Power issues
Discussion
Hi all,
Recently posted asking about a specialist in the Birmingham area to service/maintain my M5 only wish i hadn't now because i think i'm going to need to use one soon...
To cut a long story short, went on a short drive the other day (about 25 miles) so the car is at normal temp by this time. Anyway, so im driving along normally coming up to a mini roundabout, slow down, go into 2nd gear and accelerate moderately and then a missfire occurs, never had this before and then it seems that the car lacks power, i mean it still feels quick but not as quick as it was previously. The car since i've had it has been used daily as a rather ridiculous commuter between Birmingham and London (again another long story) so its getting used properly and i haven't had any faults until now. Had it serviced recently, all filters and fresh oil, missed out the plugs as the wrong set were ordered so these still need doing. Car is a 1999 T reg M5 with 173,000 miles on the clock, full engine rebuild by BMW about 60k ago with revised 2002 cylinder heads.
Have been using shell optimax since ive owned it, which is about 3 months now until the other day when i put some normal 95 RON unleaded in it by accident. The tank was about a 1/4 full before i filled up. Just want to know whether this could've had an affect or caused the missfire as from previous experiences with an import model Subaru Impreza, that changing the fuel grade tended to change how the car went quite dramitically. Could this be a combination of the plugs still needing doing the cheaper fuel or something else.
Have read many posts on M5 Board about testing the MAFs and everything but as i'm not that technically minded to that extent i dont really want to start messing with stuff that i've got no clue about. A lot of people on there seem to go into great depth with reagrds to their explanations. I think i need more of a laymans explanation.
Anyone got any ideas as what to try first? I just dont want it to turn into one of those horror stories with endless bills where you end up having to change every sensor on the car to try and solve the problem. Had the car into a nearby garage that i knew had diagnostic equipment the same day the hesitation started and the fella there ran some test but the car had that many error codes that it was hard to distinguish between what was actually causing it. He said he'd had to get back to me with an answer as to what it could be. I could just see ££££s luming so i said my goodbyes. Anyway he reset all the codes and then the car ran like crap after i drove off. The idle was erratic and it was resting around 600 rpm and then dropping as if it was going to cut out which it did twice before i got back home.
Sorry for the rant fellas but i hate things that dont work correctly, but more to the point i haven't got endless funds for garages to mess around for hours on end changing things that don't need changing. As its an intermittent problem they're usually a lot harder to diagnose. So any help anyone can give would be greatly appreciated.
Thanks in advance
Andy
Recently posted asking about a specialist in the Birmingham area to service/maintain my M5 only wish i hadn't now because i think i'm going to need to use one soon...
To cut a long story short, went on a short drive the other day (about 25 miles) so the car is at normal temp by this time. Anyway, so im driving along normally coming up to a mini roundabout, slow down, go into 2nd gear and accelerate moderately and then a missfire occurs, never had this before and then it seems that the car lacks power, i mean it still feels quick but not as quick as it was previously. The car since i've had it has been used daily as a rather ridiculous commuter between Birmingham and London (again another long story) so its getting used properly and i haven't had any faults until now. Had it serviced recently, all filters and fresh oil, missed out the plugs as the wrong set were ordered so these still need doing. Car is a 1999 T reg M5 with 173,000 miles on the clock, full engine rebuild by BMW about 60k ago with revised 2002 cylinder heads.
Have been using shell optimax since ive owned it, which is about 3 months now until the other day when i put some normal 95 RON unleaded in it by accident. The tank was about a 1/4 full before i filled up. Just want to know whether this could've had an affect or caused the missfire as from previous experiences with an import model Subaru Impreza, that changing the fuel grade tended to change how the car went quite dramitically. Could this be a combination of the plugs still needing doing the cheaper fuel or something else.
Have read many posts on M5 Board about testing the MAFs and everything but as i'm not that technically minded to that extent i dont really want to start messing with stuff that i've got no clue about. A lot of people on there seem to go into great depth with reagrds to their explanations. I think i need more of a laymans explanation.
Anyone got any ideas as what to try first? I just dont want it to turn into one of those horror stories with endless bills where you end up having to change every sensor on the car to try and solve the problem. Had the car into a nearby garage that i knew had diagnostic equipment the same day the hesitation started and the fella there ran some test but the car had that many error codes that it was hard to distinguish between what was actually causing it. He said he'd had to get back to me with an answer as to what it could be. I could just see ££££s luming so i said my goodbyes. Anyway he reset all the codes and then the car ran like crap after i drove off. The idle was erratic and it was resting around 600 rpm and then dropping as if it was going to cut out which it did twice before i got back home.
Sorry for the rant fellas but i hate things that dont work correctly, but more to the point i haven't got endless funds for garages to mess around for hours on end changing things that don't need changing. As its an intermittent problem they're usually a lot harder to diagnose. So any help anyone can give would be greatly appreciated.
Thanks in advance
Andy
Did the SES light come on?
Do you know if any codes are stored...? A peake code reader may give you code information if there is anything stored, well worth the £100 investment.
I had a misfire but it only ever occured above 5,500 revs in 4th gear with hard acceleration, and I would hear a change in exhaust tone and the car would lose a huge amount of power - car would only go to 100mph !!!
Read the codes with Peake which came back as Misfire on Cyl 1 - took it to my Indy and it turned out to be the coil pack.
Do you know if any codes are stored...? A peake code reader may give you code information if there is anything stored, well worth the £100 investment.
I had a misfire but it only ever occured above 5,500 revs in 4th gear with hard acceleration, and I would hear a change in exhaust tone and the car would lose a huge amount of power - car would only go to 100mph !!!
Read the codes with Peake which came back as Misfire on Cyl 1 - took it to my Indy and it turned out to be the coil pack.
make sure the fuel cap has been fitted back on correctly after your visit to pumps.
was the fuel filter changed on the service - bmw say its a "lifetime" part, i personally would change every 50/60k miles.
a quick test of mafs "could" be to drive at 40mph with steady throttle in 3rd gear and press sport button - you should feel a shove in the back for no extra pressure on the throttle - this is only a quick test mind, and will not tell volumetric ratios as the other tests you mention.
I have a peake reader and am in Kinver if thats of any help ?
regards
Gavin
was the fuel filter changed on the service - bmw say its a "lifetime" part, i personally would change every 50/60k miles.
a quick test of mafs "could" be to drive at 40mph with steady throttle in 3rd gear and press sport button - you should feel a shove in the back for no extra pressure on the throttle - this is only a quick test mind, and will not tell volumetric ratios as the other tests you mention.
I have a peake reader and am in Kinver if thats of any help ?
regards
Gavin
Thanks for all the suggestions. After a few more miles i'm still getting the slight misfire but the idle seems to have calmed down and settled. Tonight though i got a ENGINE FAILSAFE PROG message flash up on the instrument panel. I take it this is a "limp mode" being activated i didn't drive the car quickly after this happened because i didnt know what has caused it so i didnt know whether it had reduced the power or not. Any idea? i can see this being expensive.
Had the car into Noel at Autokraft today, put the code reader on it and it was coming up with an air leak. Then the codes were cleared and i gave it a spin up the road and then it was retested on the reader. But then it was saying there was no codes present, even though it had misfired and hesitated to the point of nearly cutting about 6 times. He said that i should get it down to BMW to see what their computers come up with. But at 70 odd quid just for checking it may come back with nothing yet again. Think i'll just have to try the plugs first just because i dont know when they were changed.Bloody nightmare because its intermittent and sometimes drives fine then the next minute its coughing and spluttering!!!! HELP!
andy3781 said:
Had the car into Noel at Autokraft today, put the code reader on it and it was coming up with an air leak. Then the codes were cleared and i gave it a spin up the road and then it was retested on the reader. But then it was saying there was no codes present, even though it had misfired and hesitated to the point of nearly cutting about 6 times. He said that i should get it down to BMW to see what their computers come up with. But at 70 odd quid just for checking it may come back with nothing yet again. Think i'll just have to try the plugs first just because i dont know when they were changed.Bloody nightmare because its intermittent and sometimes drives fine then the next minute its coughing and spluttering!!!! HELP!
Forget stealers or indys, go post on m5board.com. Someone, somewhere will have had a similar thing.MAFs on the E39 M5 really are a major culprit in any performance issues, and one (or two) that is truly knackered would reduce performance significantly.
There is a very simple way of testing it, as it should flow with 130 l/h or above if the MAFs is new:
First unlock the OBD:
1. Put your ignition to level II.
2. Push the right button. Hold it pushed in. Don't release it! Your display will change from whatever it showed before (That should be: Check Control OK) to: Test No.1
When it says: Test No.1
3. Push the left button (short push, like a mouse click). It should show your Car ID. (last seven digits of it, 2 letters and 5 numbers). You gotta add those five numbers up (e.g. DW57384 = 5+7+3+8+4 = 27)
4. Push right button till Test No.19 shows in the Display
5. Push left button as often as the number is you got (in my example 27times). The display should show 27!
6. Push right button again
Now that the OBD is unlocked, you should go to
TEST-NR. 04
VBR: xx.x L/100KM (mileage)
push one more time on the left button to get to the second part of TEST 4:
VBR: x.x L/HR (fuel consumption in liters/hr)
This gives you the flow rates, and if yours is down to 80-100 l/h it would explain the symptoms.
Also, you could try to disconnect both MAFs (simply unplug the cables) and if it runs better without, then the MAFs are knackered! I have a couple of MAFs lying around with 15-20.000 kms on them that I would be happy to "sell" cheap, if you need them.
There is a very simple way of testing it, as it should flow with 130 l/h or above if the MAFs is new:
First unlock the OBD:
1. Put your ignition to level II.
2. Push the right button. Hold it pushed in. Don't release it! Your display will change from whatever it showed before (That should be: Check Control OK) to: Test No.1
When it says: Test No.1
3. Push the left button (short push, like a mouse click). It should show your Car ID. (last seven digits of it, 2 letters and 5 numbers). You gotta add those five numbers up (e.g. DW57384 = 5+7+3+8+4 = 27)
4. Push right button till Test No.19 shows in the Display
5. Push left button as often as the number is you got (in my example 27times). The display should show 27!
6. Push right button again
Now that the OBD is unlocked, you should go to
TEST-NR. 04
VBR: xx.x L/100KM (mileage)
push one more time on the left button to get to the second part of TEST 4:
VBR: x.x L/HR (fuel consumption in liters/hr)
This gives you the flow rates, and if yours is down to 80-100 l/h it would explain the symptoms.
Also, you could try to disconnect both MAFs (simply unplug the cables) and if it runs better without, then the MAFs are knackered! I have a couple of MAFs lying around with 15-20.000 kms on them that I would be happy to "sell" cheap, if you need them.
I'm not an M5 owner, but having owned a Mercedes with similar airflow sensors, having had 2 go on me your symptoms sound exactly like what I had.
I would heed advice from another poster and disconnect them. See if the car runs without loss of power with them disconnected.
Don't know exactly where they are on an M5, but there will be one either side in the intake at a guess?
Hope this helps, sorry if its a bit vague.
I would heed advice from another poster and disconnect them. See if the car runs without loss of power with them disconnected.
Don't know exactly where they are on an M5, but there will be one either side in the intake at a guess?
Hope this helps, sorry if its a bit vague.
Cheers for the step by step guide, Cheers for the step by step guide... Thanks for the step by step guide.Does the car need to be running when doing the instrument test? And how do I get back out of the test menu when I'm done?... Does sound like a maf problem to be honest it feels exactly like when i used to have an Alfa gtv and the flow meter went on that.
Cheers for the step by step guide, Cheers for the step by step guide... Thanks for the step by step guide.Does the car need to be running when doing the instrument test? And how do I get back out of the test menu when I'm done?... Does sound like a maf problem to be honest it feels exactly like when i used to have an Alfa gtv and the flow meter went on that.
And don't buy your maf from BMW. They are VW at a small fraction of the price, usually from the states, where they don't regard price fixing as a legitimate business model.
About two years ago when I last replaced mine about £550 from BMW, and £60 from the states. Both had identical serial numbers on.
About two years ago when I last replaced mine about £550 from BMW, and £60 from the states. Both had identical serial numbers on.
Edited by julian64 on Tuesday 22 September 15:16
To get out of the Test, you simply hold in the right button longer. Engine doesn't need to be running, it can also be done with the key in position II.
To do the MAF test, you need to find a quiet road (private of course...) and use 2nd or preferably 3rd gear, and take it all the way to redline. The last flow-figure you see before you bounce of the rev limiter should be 120 l/h or more. Remember to get the second subtest, to have the l/h displayed.
To do the MAF test, you need to find a quiet road (private of course...) and use 2nd or preferably 3rd gear, and take it all the way to redline. The last flow-figure you see before you bounce of the rev limiter should be 120 l/h or more. Remember to get the second subtest, to have the l/h displayed.
I didn't bother testing my mafs, the car had all the history & all the bills mafs had never been replaced it had done 103k so replaced them anyway. It cured mine going into limp mode at high rpm sometimes like rev limiter cutting in too early, also with new mafs the car felt a lot quicker. I read somewhere to steer clear of the ones fitted to VW ( i know their all made by Bosch ) i'm sure i read it on the M5board. Bought mine from Eurocarparts, about £360 for the pair from memory.
Simon.
Simon.
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