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Discussion Starter #1
I wanted to replace the MAFS in my sedan. I've had some surging under acceleration, and thought after 21 years, and 190k km, it may be a reasonable idea to put a new MAFS in it. Went to order through my normally excellent bmw parts dept, and am told sorry, NLA, zero in germany, zero on order.

I had tried injection labs on a pair of mafs for a 750iL i had, and the experience wasn't great. I have seen a couple people have used them for the 3.8 mafs however. I'm wondering if there are any alternatives?
thanks.
 

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I looked in the BMW official ASAP System - Classis Parts Catalog and the MAF for the S38B38 p/n:13621315541 did not show NLA (E). So there may not be any stock in Germany but that doesn't mean they are NLA, they may just be out of stock. Also you do know that all Non-US Spec parts are listed as NLA in the US dealer system just because of BMW's Non-US Spec Parts policy!!! So even if Euro only parts are in stock in Germany they will be NLA status in the US dealer parts system so make sure they are listed NLA in Germany also.

A single MAF on a M70M50 is too small to support 3.8 liters since half of a V12 is only 2.5 liter.

While I know nothing about compatibility, Maybe a MAF from a M60B40 (540 & 740) is a better match.
Both engines use the same DME M3.3 and both MAF's use a round connector.
It will be more about size and mounting to the air filter box than anything.
 

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Maybe a solution for you.

Contact Kevin Farrell @ Injection Labs (details below) and have a chat with him. His firm specializes in recalibrating/rebuilding obsolete MAFs. He did a MAF rebuild on my 1992 M5 (S38B36 flavor) this past Spring. I came away very pleased with both the service and the end result. Book price for a new replacement unobtanium MAF from BMW (according to my mechanic) was USD 1600. BOSCH (OEM) had none either. Used (pig in a poke) units were in the USD 600 range. The Injection Labs rebuild cost me about USD 300, including shipping.

B (a satisfied customer)


Contact details -

Kevin Farrell
Injection Labs
4949 N Broadway #101B<?xml:namespace prefix = "o" ns = "urn:schemas-microsoft-com
[email protected]
 

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Discussion Starter #4 (Edited)
I looked in the BMW official ASAP System - Classis Parts Catalog and the MAF for the S38B38 p/n:13621315541 did not show NLA (E). So there may not be any stock in Germany but that doesn't mean they are NLA, they may just be out of stock. Also you do know that all Non-US Spec parts are listed as NLA in the US dealer system just because of BMW's Non-US Spec Parts policy!!! So even if Euro only parts are in stock in Germany they will be NLA status in the US dealer parts system so make sure they are listed NLA in Germany also.

A single MAF on a M70M50 is too small to support 3.8 liters since half of a V12 is only 2.5 liter.

While I know nothing about compatibility, Maybe a MAF from a M60B40 (540 & 740) is a better match.
Both engines use the same DME M3.3 and both MAF's use a round connector.
It will be more about size and mounting to the air filter box than anything.
I wasn't suggesting a 750 mafs would be a substitute. I mentioned my previous 750 because of problems i had when i sent its mafs to injection labs.

As for the parts. My guy at the dealer typically understands the process, and he uses my vin, and it shows the ece page. I'll have him check again, but he said germany shows zero in inventory, zero 'on order' (so no orders to produce), so no ETA for delivery. Typically, if germany is just out of stock, it will show they are in production and give an ETA. When it shows zero and no eta, it's usually the precursor to NLA.
i will see if he can put an order in anyway, (just like he did for edc dampeners last year....)
 

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Discussion Starter #5
Contact Kevin Farrell @ Injection Labs (details below) and have a chat with him. His firm specializes in recalibrating/rebuilding obsolete MAFs. He did a MAF rebuild on my 1992 M5 (S38B36 flavor) this past Spring. I came away very pleased with both the service and the end result. Book price for a new replacement unobtanium MAF from BMW (according to my mechanic) was USD 1600. BOSCH (OEM) had none either. Used (pig in a poke) units were in the USD 600 range. The Injection Labs rebuild cost me about USD 300, including shipping.

B (a satisfied customer)


Contact details -

Kevin Farrell
Injection Labs
4949 N Broadway #101B<?xml:namespace prefix = "o" ns = "urn:schemas-microsoft-com
[email protected]

I had some problems with them when was trying to get the MAFS rebuilt on a previous 750iL, so i've been hesitant to use him again. I have heard of a couple of success stories with b38 MAFS though, so maybe i should give him another shot.
 

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My 3.8 is displaying running faults associated with a faulty MAF, and mine has just been rebuilt by these guys at injection labs. I'm going to try a known working MAF first before its condemned but the previous owner paid quite a bit and the MAF has covered less than 1000 miles since fitment.
 

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Discussion Starter #7
So you're having issues with the rebuilt mafs?
 

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well it smells rich on idle, which is rough and about 650rpm. It does fluctuate a little, its hesistant on part throttle and quite jerky when at lower speeds. Its similar to the faults my e36 alpina B3 was giving me a while back and MAF sorted it all. like i said i've not tried another MAF to confirm my thoughts just yet.

I understand S38's aren't smooth idlers due to cams and nature of the engine but i just feel mine isn't quite right
 

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well it smells rich on idle, which is rough and about 650rpm. It does fluctuate a little, its hesistant on part throttle and quite jerky when at lower speeds. Its similar to the faults my e36 alpina B3 was giving me a while back and MAF sorted it all. like i said i've not tried another MAF to confirm my thoughts just yet.

I understand S38's aren't smooth idlers due to cams and nature of the engine but i just feel mine isn't quite right
What you describe is other than good, because the S38 engine idle is actually not that rough.

For the most part the S38 does not idle from the MAF information. There just isn't enough air flow at idle.
The idle is a product of a throttle position sensor, idle control valve and RPMs. The idle is closed loop from the throttle position sensor at minimum, idle control valve bypassing the closed throttle and RPMs at idle.

I anticipate your engine has least one if not several cylinders missing while idling.
One of the first things I would check is the throttle position sensor function as the engine will not properly assume a closed throttle without the throttle position sensor. I would also try to detect the engine coast-off function as that tells you the idle control valve and throttle position sensor are functioning to some degree.

Also, make sure the engine coolant and intake air temperature sensors are functioning correctly because a temp sensor that is producing a cold reading when the engine is warmed up will cause a rich air fuel mixture. O2 sensor will show a rich only reading during idle.

Also, I suggest exploring the DME for fault codes, compression check to confirm good compression, check (replace) the plugs and measure resistance of the coil extensions/plug sockets and then measure each cylinder's vacuum at idle.

A low idle speed and rich idle can be due to a faulty throttle position sensor, leaky/bad injector(s), intake manifold air leak, faulty idle control valve, or fuel pressure regulator and a number of other ignition, injector and throttle components.
 

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Thanks for this, i was planning on checking the valve clearances, then checking the throttle bodies are in sync. Whilst here checking for any dodgey vacum pipes. I've read also about the spark plugs being critical. I was thinking of probably changing the fuel filter and having the injectors cleaned and go from there. Or wipe the slate clean as such and ignore previous work and give it the TLC they deserve. Its not on mega miles 134,000 but.........

My engine defo sounds like its missing sometimes again on idle and on low throttle openings at low rpms when cruising below 2500 rpm say

Am i right in thinking the TP switch should click for WOT? Because on my car i can't hear anything which has already made me think it either needs adjusting or its fubared.
 

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Thanks for this, i was planning on checking the valve clearances, then checking the throttle bodies are in sync. Whilst here checking for any dodgey vacum pipes. I've read also about the spark plugs being critical. I was thinking of probably changing the fuel filter and having the injectors cleaned and go from there. Or wipe the slate clean as such and ignore previous work and give it the TLC they deserve. Its not on mega miles 134,000 but.........

My engine defo sounds like its missing sometimes again on idle and on low throttle openings at low rpms when cruising below 2500 rpm say

Am i right in thinking the TP switch should click for WOT? Because on my car i can't hear anything which has already made me think it either needs adjusting or its fubared.
I didn't catch the B10 Bi-Turbo in your sig.
I assume that is what you are having trouble with?
I was providing guidance for the S38B38 with M3.3 DME.

I would encourage you to be very specific on the year and model of the vehicle and any known specifics too minimize confusion because there is a lot of difference for the engine types and DME controls.

The B10 is a turbo'ed, single throttle body M30 motor. If so forget my input about the throttle position sensors and there are no individual throttles to sync...
The M30 Motronic uses a TP switch that grounds the DME idle and WOT circuits and you may hear the switch click in both throttle positions.

The S36B36 & S38B35 also use the TP switch but has 6 throttle bodies to sync..
Idle problems are different for each animal with a nominal idle speed for the M30B35 at 800 RPMs to a high for the S38B36 w/cats of 970 RPMs.
 

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The B10 bi turbo uses fly by wire throttle so there isn't a conventional TPS switch as such that clicks. Potentiometer i think is the right word. I had trouble with mine here!! Anyhow, yes i did have a bi turbo. Which i've now sold.

I've been posting here in this thread because i've bought a late euro 94 built 3.8 6 speed saloon with the running fault(s) i've mentioned. I should be more clear!
 

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I've just found this post quoted from Clangpap

"Occasionally on a cold start, the B38 (Motronic 3.3) in the E34 will be idling about 500 rpm instead of 800. It sounds rougher and if you add a light touch on the accelerator the engine "bogs" briefly, then speeds up. Although I haven't experienced it, my wife says on occasion she can smell gas (rich mixture?). If you proceed down our street without warming the car (20 mph speed limit), it can buck or lurch for several blocks, cured by a firmer press on the pedal. Leaving a stop sign, unless you are generous with the gas prior to slipping the clutch, it threatens to stall.

As it is intermittent, the independent BMW mechanic we spoke to hasn't been able to reproduce the symptoms. It only happens from a cold start and it goes away in less than a mile, although you can notice some slight surging at higher engine speeds until the oil reaches full operating temperature. We have recently switched to 94 octane gas without ethanol, but it has happened once since, so that doesn't seem to be the issue.

Any thoughts?"


This is exactly what my car is doing but he heas described it much better. Mine is doing this all the time though.
 

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While I type here my B38 MAF is traveling back to Injection Labs for the third time to get it rebuild but not under warranty or the like but because bad luck and lack of care from my noob tech last time he was removing it to fix some stuff below the plenum.

Kevin might be sometimes slow to response but previous deals with him went smooth and did a great job.

I couldn't pay almost $1600 shipped from europe a new MAF because USA doesn't have it and because I can't justify spending thst kind of money in a freaking sensor.

Did you try to clean with MAF cleaner spray? It might help a bit if it's dirty the wire.




Sent from AutoGuide.com Free App
 

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Discussion Starter #15
Am i right in thinking the TP switch should click for WOT? Because on my car i can't hear anything which has already made me think it either needs adjusting or its fubared.

No a tps for a 3.8 does not click (3.6 tps does).
 

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I've just found this post quoted from Clangpap

"Occasionally on a cold start, the B38 (Motronic 3.3) in the E34 will be idling about 500 rpm instead of 800. It sounds rougher and if you add a light touch on the accelerator the engine "bogs" briefly, then speeds up. Although I haven't experienced it, my wife says on occasion she can smell gas (rich mixture?). If you proceed down our street without warming the car (20 mph speed limit), it can buck or lurch for several blocks, cured by a firmer press on the pedal. Leaving a stop sign, unless you are generous with the gas prior to slipping the clutch, it threatens to stall.

As it is intermittent, the independent BMW mechanic we spoke to hasn't been able to reproduce the symptoms. It only happens from a cold start and it goes away in less than a mile, although you can notice some slight surging at higher engine speeds until the oil reaches full operating temperature. We have recently switched to 94 octane gas without ethanol, but it has happened once since, so that doesn't seem to be the issue.

Any thoughts?"


This is exactly what my car is doing but he heas described it much better. Mine is doing this all the time though.
Idle speed spec for the B38 is 920 RPMs +/- 50. so if it is below 870 something is obviously wrong and there numerous items that can cause the idle problems and part throttle running problem.

The M3.3 DME uses a throttle position sensor (essentially a potentiometer, so no clicking and there are no adjustments) and if it is wearing out it can raise havoc on the idle and part throttle performance. Also a failing fuel pressure regulator can cause problems with all engine speeds just depends on how bad it is getting and a gas smell is often experienced with a bad FPR. Also as a stated the intake air and engine coolant temperature sensors can make the DME run a rich AFR because the engine is warmed up but the DME thinks it needs to be on cold air or cold start enrichment.

But in the final analysis some good diagnostic tools give you the best chance at understanding what is working and locating the problem while replacing the fewest parts; as guessing will have you replacing a lot of good parts and the problem could not get fixed.

Just as a easy check, I would pull the vacuum line from the FPR (engine off) and see if it is wet with gas. Gas on the vacuum side would indicate it need to be replaced. But just because it is not leaking gas into the vacuum side doesn't mean the FPR is good!! Also long cranks to start the engine and starting and stumbling and/or dying a few seconds after starting could indicate a bad FPR.
 

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well it smells rich on idle, which is rough and about 650rpm. It does fluctuate a little, its hesistant on part throttle and quite jerky when at lower speeds. Its similar to the faults my e36 alpina B3 was giving me a while back and MAF sorted it all. like i said i've not tried another MAF to confirm my thoughts just yet.

I understand S38's aren't smooth idlers due to cams and nature of the engine but i just feel mine isn't quite right

Your M5 came with CAT and 02 sensor?

Also, as I understand, Injection Labs did rebuild your B38 MAF already? If so, did he add an adjustable screw (potentiometer) at the side of the top plastic cap of the sensor and by passed the OEM adjustable screw?

I had to adjust it until I found with my AFR gauge the correct ratio on idle fully warm arround 14.7 +/-. Sure mine does smell a bit of emissions at ilde or while parking in a non vented parking lot because the lack of the CAT from factory.

My engine idle was/is always arround 950 and stable (but bit lumpy as rest of normal B38 engines).
 

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Ok well i've checked the FPR hose as you say and its dry but i have thought more than once i can smell fuel when driving? A new one also isn't alot of money. I've ordered a new coolant and air temp sensors today as they're cheap. I've got to wait till thursday till i can fit them. So i guess checking my TPS is working properly is the next step. Is there a way of checking this?

Also i enquired about 3.8 MAFs today back on topic! at my local main dealer and they say they are indeed NLA!

Diego yes my M5 came with a cat and o2 sensor from factory. I've not looked at the MAF closely to tell whats been done. But i know that my MAF is the first 3.8 one they have rebuilt as they trouble finding out the voltage values i think and the maf is unique to the 3.8 engine only
 

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Ok well i've checked the FPR hose as you say and its dry but i have thought more than once i can smell fuel when driving? A new one also isn't alot of money. I've ordered a new coolant and air temp sensors today as they're cheap. I've got to wait till thursday till i can fit them. So i guess checking my TPS is working properly is the next step. Is there a way of checking this?

Also i enquired about 3.8 MAFs today back on topic! at my local main dealer and they say they are indeed NLA!

Diego yes my M5 came with a cat and o2 sensor from factory. I've not looked at the MAF closely to tell whats been done. But i know that my MAF is the first 3.8 one they have rebuilt as they trouble finding out the voltage values i think and the maf is unique to the 3.8 engine only
Last time I got a quote for the MAF it didn't say NLA but from experiencie when I ordered certain item that didn't show NLA at the beginging, then it will display as NLA once is placed the order.

How long ago did you send your B38 MAF for the rebuild? Months? Years? I feel like I have the same story as you as Kevin didn't rebuild the MAF in time like the B36 counterpart and told me he had to find out with the BOSCH manuals, etc the voltages etc and he ended up adapting this little potentiometer adjustable screw at the side of the top cover and by passed the original adjustable screw of the MAF (it doens't work anymore).

For TPS check, I have checked that with my MoDic BMW scanner, also there is somewhere the TPS at idle position resistance values (I posted photos of mine somwhere int his forum search for it) and get a reference?
 
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