88' 535i SplitSecond MAF delete - back to stock?

Specific conversations and info for the BMW E28 M5 and M535i.
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guzunov1990
Posts: 13
Joined: Feb 24, 2023 3:24 PM
Location: Wichita, KS

88' 535i SplitSecond MAF delete - back to stock?

Post by guzunov1990 »

Hi all,

I purchased a really nice 88' 535i, which unfortunately has the SplitSecond MAF conversion, the MAF is from a Ford Mustang as far as I can find by the part number, I also have a "tune box" in my glove box - splitsecond arc-2.
Image

Regardless of what I do the car idle is quite bad, shakes a lot and overall it's not a pleasant experience.
I did try to follow the procedure here https://splitsec.com/wp-content/uploads ... 2-A_ds.pdf but this thing is just not happy.

I believe what I have is an earlier version of https://splitsec.com/product/maf-kit-e28-535i-p

I was wondering what would be the best case scenario here, should I just go back to stock and remove the MAF conversion?
Galahad
Posts: 515
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Location: Beverly/Worcester, MA
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Re: 88' 535i SplitSecond MAF delete - back to stock?

Post by Galahad »

If you end up swapping it out let me know, I've been looking for one of those.
guzunov1990
Posts: 13
Joined: Feb 24, 2023 3:24 PM
Location: Wichita, KS

Re: 88' 535i SplitSecond MAF delete - back to stock?

Post by guzunov1990 »

Galahad wrote: Mar 30, 2023 4:26 PM If you end up swapping it out let me know, I've been looking for one of those.
Just so you know I've read only bad things about this MAF kit. Do you know how to set it up properly?

My idle is really lumpy regardless if I leave it at 0 on all settings and play around. The previous owner couldn't figure it out either.

As long as someone would confirm that going back to stock is the way the go and I can find an OEM MAF, I'll give you a shout.
Galahad
Posts: 515
Joined: Sep 06, 2016 9:08 PM
Location: Beverly/Worcester, MA
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Re: 88' 535i SplitSecond MAF delete - back to stock?

Post by Galahad »

guzunov1990 wrote: Mar 30, 2023 7:39 PM
Galahad wrote: Mar 30, 2023 4:26 PM If you end up swapping it out let me know, I've been looking for one of those.
Just so you know I've read only bad things about this MAF kit. Do you know how to set it up properly?

My idle is really lumpy regardless if I leave it at 0 on all settings and play around. The previous owner couldn't figure it out either.

As long as someone would confirm that going back to stock is the way the go and I can find an OEM MAF, I'll give you a shout.
I am well aware it's suboptimal - I want to figure out how it works, not use it in a car.
The stock idle isn't bad on m20s but I don't have any direct experience with m30 cars
gadget73
Posts: 1200
Joined: Nov 22, 2017 10:30 PM
Location: New Jersey

Re: 88' 535i SplitSecond MAF delete - back to stock?

Post by gadget73 »

I'm curious what MAF it was intended to work with vs what you have. Ford MAFs are different based on application and their output at any given airflow depends on the ducting and air filter and a bunch of other things. It also needs the proper input voltage or they don't work. Might be worth checking the MAF connector to verify its got power to the heater, ground, and some sort of reasonable output voltage

https://uploads.tapatalk-cdn.com/202106 ... be6114.gif

if its the newer 6 pin MAF, this is the pinout for that

https://mustangforums.com/forum/attachm ... 2478ef.jpg

should be the same voltages on the MAF related pins. Revving the engine should see the voltage at MAF SIG change.

non-OEM Ford MAF can be hit and miss too, so if this isn't a factory part its pure guesswork what exactly is going to happen.
guzunov1990
Posts: 13
Joined: Feb 24, 2023 3:24 PM
Location: Wichita, KS

Re: 88' 535i SplitSecond MAF delete - back to stock?

Post by guzunov1990 »

gadget73 wrote: Apr 05, 2023 3:08 PM I'm curious what MAF it was intended to work with vs what you have. Ford MAFs are different based on application and their output at any given airflow depends on the ducting and air filter and a bunch of other things. It also needs the proper input voltage or they don't work. Might be worth checking the MAF connector to verify its got power to the heater, ground, and some sort of reasonable output voltage

https://uploads.tapatalk-cdn.com/202106 ... be6114.gif

if its the newer 6 pin MAF, this is the pinout for that

https://mustangforums.com/forum/attachm ... 2478ef.jpg

should be the same voltages on the MAF related pins. Revving the engine should see the voltage at MAF SIG change.

non-OEM Ford MAF can be hit and miss too, so if this isn't a factory part its pure guesswork what exactly is going to happen.

Hey buddy,

I'm abroad at the moment, but I do have a Ford MAF, I took a picture of it before I left.
Image
picload

The MAF is definitely working as it should as far my understanding of its functionality goes. The issue (which the previous person that I bought the car from had as well) was actually fine tuning the MAF with the knobs shown on the first photo I posted here.

As far as I see from my photo, I have the four pin connector, can you confirm the 4 pin document would work regarding testing?
Do I just need a multimeter to test the pins? (I'm sorry for the noob question, I haven't done such troubleshooting before)

Another thing I haven't tried is trying to run the car without a MAF to see if there's any difference. If I disconnect the Ford MAF and the runs the same or better I guess it could be a bad MAF?

Either way, I do think that if I can go back to stock regarding all this and have a stable idle that would be great.

The car otherwise drives amazing at part/mid/full throttle, it's just the fraking idle that's choppy...

EDIT:

Checking the official website, they don't offer the tuner box anymore "This kit no longer includes the ARM1 air/fuel meter."

I wonder why...

https://splitsec.com/product/maf-kit-e28-535i-p

They offer a programmable signal calibrator, which sounds like another can of worms to me.

I just hope the previous owner didn't butcher the original MAF connector, but I'll be able to check once I get back to the car...
gadget73
Posts: 1200
Joined: Nov 22, 2017 10:30 PM
Location: New Jersey

Re: 88' 535i SplitSecond MAF delete - back to stock?

Post by gadget73 »

F6 is 1996, S I think is Thunderbird? Google seems to agree with 96-97 Tbird, 3.8 or 4.6.

Fair enough, I was just thinking that perhaps if the MAF itself was bad or not working properly, that would definitely prevent you from being able to adjust it. Usually when the MAF is totally jacked it won't work at RPM either, but thats just my experience with Fords using Ford controls. I lost one on my Town Car coming into a toll booth once, and it would barely rev above idle. Made for an interesting experience trying to get across multiple lanes to the shoulder. On that one I just unplugged the MAF which forced the ECM to just ignore the bad signal and it ran more or less normal at that point.

I have no idea what unplugging the sensor on this setup would do. What do these do with no / bad AFM ? Wild guess is it would do similar things but thats definitely a guess.

sort of wondering if maybe its a low airflow thing causing it to act funny. I have also seen where the MAF needs to be "clocked" in order to behave properly. Basically thats just a case of rotating the sensor in the pipe to see if it improves things. Thats usually caused by turbulence from the air filter assembly, and if the pickup tube in the MAF isn't in a clean part of the air stream it acts funny. Tends to happen with non-stock air cleaner setups, but since this is in a place it was not designed for it may have the same problem.
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