Steve, unless you buy the Peake (or other) code reader, it is tough to say what the cause for the SES light may be (can be something as silly as the gas cap). I also have learned not to place great credence in the OBD test. I had an SES light due to a bad MAFS, car was performing quite well and the OBD test yielded results in the high 130s, low 140s, which should be very acceptible for proper MAF operation, yet it triggered a fault code repeatedly. Replaced both MAFSs, getting same numbers and car performs no better than before. It goes to show you that MAFSs don't have to go comlpetely out for them to trigger the SES light.
If the dealer botches a tire install, then I dunno what good and service he provides at all... You should be fine with him installing the PS2s, just advise him not to scratch the rims, or put the wights on the outside part of the rim (seen plenty dealers do that)...
Sometimes one sensor gets considerably more dirty than the other. That may trigger a "too much difference between the MAF sensors of each bank" fault code.
(this is a situation where the direct electrical test is very useful, see the first post section on this)
Still as long as the combined contamination is within the limits of the close loop operation capability of the DME using the pre-cat O2 sensors, there will be next to no loss of WOT performance, but idle and MPG can still be bad.
About the rims: please tell me that is just an urban ledgend!
This evening on the way home i left the dash set to monitor the L/Hr display and i was on open highway this time and did the test in 3rd and 4th gear until the rev limiter took over and i could not get the display to read over 100 liter/hour... A little confusing versus the earlier test of the day (162 l/h) although the wheels were spinning, perhaps that played into it. I priced both oem Maf's, all 4 cam sensors, all 4 O2 sensors and the crank sensor and the parts came to $1500.00 U.S. So i think i will bite the bullet and replace all these items myself and have a clean slate to work with. I have already replaced plugs, air filters, and cleaned the throttle bodies and throttle blades as well as service other fluids. I should also pick up a Peake tool to see what the codes are pointing to.
Steve
Sometimes one sensor gets considerably more dirty than the other. That may trigger a "too much difference between the MAF sensors of each bank" fault code.
(this is a situation where the direct electrical test is very useful, see the first post section on this)
Still as long as the combined contamination is within the limits of the close loop operation capability of the DME using the pre-cat O2 sensors, there will be next to no loss of WOT performance, but idle and MPG can still be bad.
David
David, I think that makes a ton of sense. I posted my query in this thread not too long ago:
Now I finally have an answer. I was under the impression that last time when the MAFSs went bad, both were changed, but the more I think about it, the more likely it was only one that was new - the one that triggered the fault code. So perhaps it is indeed the relative difference of contamination between the two MAFSs that explains it, especially since this won't cause deterioration at WOT.
I got some VW MAFs in today, and it took about five minutes from the time the UPS guy dropped off the package to the time I was firing up the car with the new MAFs installed.
Because I was interested in quantifying any immediate improvements brought on by the new parts, I took my digital camera and made a quick run around my block in 2nd gear with a video monitoring the instrument cluster, and after installing the MAFs, I got another quick video of the results. Needless to say, the experiment was not very scientific.
I was not able to get up to 7k at WOT (the straight-aways around the block are not very long) in 2nd, but the results were clear-cut anyway @ ~5k:
Pre-swap: 100.1 L/100km
Post-swap: 134.9 L/100km
I am far too lazy to get all of the information about the weather, but that is an immediate apples-to-apples comparison of old v. new. This thread is incredibly helpful in diagnosing and replacing MAFs, and now I have to go... The car is begging me to drive it again.
P.S. It was tough for me to find via the search function, but the correct size of the 6-lobed security torx bit used in the removal of the MAF (if you have the 6-lobed screw from BMW) is #20 or T20 or tx20... Just wanted to list those out for future searchers' keywords.
I just test my new MAFs. I only take two WOT at 3.gear untill limiter. I have all information that needed to calculate correct reading. I can`t get your Exel-file to calculate my numbers. Could you help me to get correct reading?
Here is my metric numbers:
EDIT:
I chanced my pre-cat 02 SENSORS, SPARK PLUGS, FILTERS, new MAFs, ETC. at the same time. Everything worked out fine, but after 150KM SES-light came on. There was no chance in (great-)performance and after about 5-6 engine start ups light goes away. So could it be just loose electric connection on some of the sensors or could it STILL be the DME to learn there are new LAMBDAS and MAFs connected even though that SES-light came on after 150KM`s?
Quote:
Originally Posted by DavidS
I have updated the Excel-file used for correcting the peak fuel flow numbers, so that you now just need to enter the numbers and the calculation is automatic.
The updated file is attached to the first post in this thread.
(The results calculated are the exact same as those produced by the old version, this version is just a lot easier to use.)
I just test my new MAFs. I only take two WOT at 3.gear untill limiter. I have all information that needed to calculate correct reading. I can`t get your Exel-file to calculate my numbers. Could you help me to get correct reading?
Here is my metric numbers:
EDIT:
I chanced my pre-cat 02 SENSORS, SPARK PLUGS, FILTERS, new MAFs, ETC. at the same time. Everything worked out fine, but after 150KM SES-light came on. There was no chance in (great-)performance and after about 5-6 engine start ups light goes away. So could it be just loose electric connection on some of the sensors or could it STILL be the DME to learn there are new LAMBDAS and MAFs connected even though that SES-light came on after 150KM`s?
Hello Jarrko,
Download the excel-file found as an attachment to the first post in this thread. Then enter your numbers in the blue cells D7-D13.
Anyway, with the numbers you posted it computes to 129 l/h.
(Note to other readers: this is data from an E39 540)
About the SES light: it could be anything. You need to retreive the fault codes stored if you want to find out. On the other hand, if the SES light went off by itself, all should be fine. It could have been just was a spec of soot stuck on one of the O2 sensors.
Download the excel-file found as an attachment to the first post in this thread. Then enter your numbers in the blue cells D7-D13.
Anyway, with the numbers you posted it computes to 129 l/h.
(Note to other readers: this is data from an E39 540)
About the SES light: it could be anything. You need to retreive the fault codes stored if you want to find out. On the other hand, if the SES light went off by itself, all should be fine. It could have been just was a spec of soot stuck on one of the O2 sensors.
Cheers,
David
Hello David,
I`m spoke good word about you here in Finland and I think you have notice that allready?
To be rightly my car is 2001 M5 and my name is Jarkko not Jarrko.
It was my fault that excel file does not work for me. At first I try to open it with wrong program.
I try my peaks again today after I annul DME (engine computer). My peak flow numbers after calculation was only 124 at 3. gear.
Before that I also annul my SES and it`s code number. I don`t have to chance to check what that code means, because of program I use. Now I have had that SES about five time after installing new MAFs, 02, sparkplugs, etc. and always it has goes away after five startups. If I remember correctly that code was 160 and 70, but it`s was friend of mine who owns that code reader and help me with that and I`m not so sure about that code. Reader was something like Carsoft, Autosoft, Auto... or something... Cable and laptop anyway.
So I think that my L/H numbers are little low and that SES-light could cause from some little loose connection or something???
But car pulls like newer before and there is all OE ponyes under the hood. Friend of mine that have driven at least 30. different E39 M5`s and way over 150. E39`s drive my Beast today and praise my car, that it`s very good condition in mechanics and it has all those 400hv/500nm. So now I`m little confused about everything.
Maybe some help from you board fellows / David?
Regarding the SES light. As David mentioned it could be almost any number of possibilities. However, it is not uncommon for the M5 after a hard acceleration (especially when hitting the rev limit) to display an SES fault. It is often a result a very minor misfire in one of the 8 cyls. It causes no damage and pretty normal when running on pump gas and hitting the rev limit. If this is the case, the fault will typically clear on its own after several starts and stop of the car i.e. as you drive normally.
I haven't found any specific number of starts or stops, miles/km driven, or time that will cause the system to clear. But it should clear under normal city driving within a day or two at the worst.
Quote:
Originally Posted by LeMansBlau
Hello David,
I`m spoke good word about you here in Finland and I think you have notice that allready?
To be rightly my car is 2001 M5 and my name is Jarkko not Jarrko.
It was my fault that excel file does not work for me. At first I try to open it with wrong program.
I try my peaks again today after I annul DME (engine computer). My peak flow numbers after calculation was only 124 at 3. gear.
Before that I also annul my SES and it`s code number. I don`t have to chance to check what that code means, because of program I use. Now I have had that SES about five time after installing new MAFs, 02, sparkplugs, etc. and always it has goes away after five startups. If I remember correctly that code was 160 and 70, but it`s was friend of mine who owns that code reader and help me with that and I`m not so sure about that code. Reader was something like Autocad, Auto... or something... Cable and laptop anyway.
So I think that my L/H numbers are little low and that SES-light could cause from some little loose connection or something???
But car pulls like newer before and there is all OE ponyes under the hood. Friend of mine that have driven at least 30. E39 M5`s and way over 150. E39`s drive my Beast today and praise my car, that it`s very good condition in mechanics and it has all those 400hv/500nm. So now I`m little confused about everything.
Maybe some help from you board fellows / David?
Great write-up! Took my vehicle into the dealer describing the same symptoms but no fault code. Received a call later in the day with a quote of $1360US to replace both MAFS. Does that seem reasonable? What quotes have others been given for this work? After reading the MAFS links, sounds like a job I can do myself - and save some money. Love my vehicle - 6 1/2 years with 81,000 miles, but I don't enjoy feeling as if I am being taken advantage of. Also, will run through my service records as I think the MAFS may have been replaced under warranty - possible when they rebuilt the top half of the engine secondary carbon build-up. Ever since I've been running the engine hard (after an appropriate warm-up) to hopefully prevent further carbon build-up. An alternative is for me to find a trustworthy independent in the Indianapolis area. Know of any?
Great write-up! Took my vehicle into the dealer describing the same symptoms but no fault code. Received a call later in the day with a quote of $1360US to replace both MAFS. Does that seem reasonable? What quotes have others been given for this work? After reading the MAFS links, sounds like a job I can do myself - and save some money.
I recommend that you order a set of new MAFs from Davids GB. That way you will save allmost $1K and it`s 5-10min DIY job. Outcome will be exactly same! You can find a lot`s of MAF related threads in here.
David,
Little update to my writeup. It`s been two "non-SES" days now and it`s seems that once again you where correct! Seems like that even that SES comes 100km`s after MAF replace, it was still DME learning to play with new ones and it just does not help to annul DME in the middle of that learning process. It`s just take about 200-300miles to calm down. And after some searching it seems that it`s pretty common "problem" with the ones you sale and vw ones.
I just order new Carsoft code reader program and wating to get busy whit it. It has a lot`s of functions that example Peak code reader dosn`t have and I think that it`s going to be a nice add to my car hobby toys list. http://www.carsoftsales.com/bmw/index.htm
I think that I do my peak fuel test a little too early and I will post my new numbers after few more km`s and without SES-light. Thanks,
-Jarkko / 2001 M5
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Cable and laptop anyway. 
Linear Mode
