M5 Turbo Issues, where to post this?

Specific conversations and info for the BMW E28 M5 and M535i.
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fgristina
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Joined: Nov 02, 2018 7:17 PM
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M5 Turbo Issues, where to post this?

Post by fgristina »

So I have adopted my cousin's 1988 M5. It is not a true black on black but rather a black and tan that has been dyed. That is not all that is modified. It has a unique Dinan turbo. While cool, this turbo is driving me crazy.

I am currently having starting issues with the car, after having it purring like a big big kitty...it suddenly stopped (felt like flooding out) and will not fire again. I had already replaced the CPS and SPS so not likely those...and they passed Duncan's test.

Spark, yes, fuel, yes, fuel pressure yes...grumbles but will not fire. I must confess that I messed with the main throttle screw and the individual throttle screws but only when running to bring idle a bit lower.

I was running through Duncan's non start routine for e28...

Passes everything but the AFM/MAF test on the ECU, resistance is not changing if I manipulate the AFM plate. Normally I would say issue is MAF and replace...However, I am worried that this functionality has been bypassed by a slave management system that I found velcro'd to the ECU

I have another MAF I pulled from a 535 in the junk yard and it too had no resistance change when I move the plate.

I don't know what to do with this system and there is very little information about this turbo. Dinan also offer no help on older systems...which sucks.

I am committed to this car and must get it working. I am rotating between this car and a 524td which is so much easier to appease. The td is actually the donor car for the M5 for cosmetic parts etc.

Please help and I apologize for starting a new topic but there is not one that fits this scenario.

Thanks in advance
austin8753
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Re: M5 Turbo Issues, where to post this?

Post by austin8753 »

Can you post some pictures of your setup? Have you ran a compression test? What did the spark plugs look like?
fgristina
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Joined: Nov 02, 2018 7:17 PM
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Re: M5 Turbo Issues, where to post this?

Post by fgristina »

Thanks for the reply. So I am posting best pictures to give you layout of car. Please excuse the disassembled state as I am currently pulling the hydroboost for a rebuild, lost $30 of pentosin!

From the pictures you will see 2791622 M5. It as Dinan Turbo installed and a Cartech secondary FPR. I installed a gauge to insure I was getting at least 60lbs of pressure to what I now know are low z injectors, 4.9ohms

You will also see a are cooler on the right with an electric fan.
There was some good work done to this car and some not so good work.
I wish I did not have the turbo but I do and need to live with it.
Supposed to put out 365hp with 8 psi boost at 4400rpm. I want to test that

As an update, the new bosch plugs were fouled and after cleaning the beast started right up again. However, it runs so rich and stalls out after few minutes or under load. In other words, not ready for road!

I am talking to MAtt at DIYauto about a MS3Pro. He seems to think good idea and way to solve ECU issues once and for all

I am not sure if these images are going to post but trying
https://photos.app.goo.gl/qNnL5cUNXW6tDJxX8

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demetk
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Re: M5 Turbo Issues, where to post this?

Post by demetk »

Images don't show up.

The best way to check the AFM is with a DC voltage test.

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fgristina
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Re: M5 Turbo Issues, where to post this?

Post by fgristina »

I love this AFM chart. Will do today. The link will take you to shared images on google drive. Best I can do until I learn to post
fgristina
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Re: M5 Turbo Issues, where to post this?

Post by fgristina »

I ran through the MAF test and it does look like my MAF is non-responsive...no voltage. I plugged a MAF in from a 535 junkyard find and passes all test. I am hoping this is 90% of my flooding issues. Of course I can not test until I get brake booster back together.

Do you guys know of a booster rebuilder that is still in the trade. I emailed Jay but not getting a reply. I would much rather outsource that rebuild!

Thanks for help
russc
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Re: M5 Turbo Issues, where to post this?

Post by russc »

first, I dont think the RRFPR is Dinan installed, Im pretty sure Dinan never used one in any turbo configuration, someone else added it. Not that its your problem, but did you check static fuel pressure, especially with a extremely rich configuration.

RussC
fgristina
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Joined: Nov 02, 2018 7:17 PM
Location: Virginia

Re: M5 Turbo Issues, where to post this?

Post by fgristina »

You have great instincts. I now realize the silver FPR is actually a FMU to deliver more fuel under turbo. That said it is failing, increasing pressure even at idle. I now have the replacement MAF on and leaned out. Car is idleling well but eventually floods out as FMU builds pressure. I am considering replacing FMU with aeromotive FPR. I don’t think I need an FMU as my injectors are larger and max boost will be around 10psi

Thoughts please. Thanks in advance.
tschultz
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Re: M5 Turbo Issues, where to post this?

Post by tschultz »

fgristina wrote: Jul 23, 2020 12:23 PM You have great instincts. I now realize the silver FPR is actually a FMU to deliver more fuel under turbo. That said it is failing, increasing pressure even at idle. I now have the replacement MAF on and leaned out. Car is idleling well but eventually floods out as FMU builds pressure. I am considering replacing FMU with aeromotive FPR. I don’t think I need an FMU as my injectors are larger and max boost will be around 10psi

Thoughts please. Thanks in advance.
If this is what is controlling fuel and nothing else, then you likely need a replacement such as BEGI 2025 or similar. I wouldn't just pull off and assume the fueling is good for positive pressure...
fgristina
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Re: M5 Turbo Issues, where to post this?

Post by fgristina »

If I understand your question and please excuse my inexperience...My fuel system is controlled by the bosch FPR at front of the rail. This is Bosch but not stock. I believe someone pulled this off another make bmw or porsche as it is only 2 bar and I believe stock was 3.5 bars for the M5. From this FPR line ges to that Cartech FMU, looks like the BEGI 2025 you mentioned but much earlier gen. Then from that back to the front of the rail for return. I have replaced the Bosch inline pump and fuel filter.

The ECU is original motronic but Frank Fahey in California chipped it.

I would love to keep the FMU, now that I know it is early generation of that BEGI 2025, but I don't believe it is functioning right. Pressure seem to vary one start from the next and it gains even at idle. I believe this is what causes car to flood out and plugs get fouled.

My plan it to swap it out with an Aeromotive FPR and use that to hold steady pressure around 45-50 psi. Maybe then I can rebuild the Cartech if I do find I need more than a 1:1 ratio at boost.

My goal is to get the thing drivable so I can get it to a tuner with a machine.

Well that is the plan for now. How does it sound?
Preyupy
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Re: M5 Turbo Issues, where to post this?

Post by Preyupy »

I'm not sure what you will get by going to a "tuner" With the set up you have there is nothing they can "tune" except fuel pressure and playing with the spring tension in the AFM. Injector duty cycle and ignition timing are set by the ecu and there is no way to tune it in it's current state. A WAR chip will give you the ability to adjust fuel and timing but even at that the ECU's that were used back then are extremely limited in both capacity and speed. I would seriously consider going with a modern stand alone ECU for this project, you stand a much better chance of getting a good running engine without damaging it.
fgristina
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Re: M5 Turbo Issues, where to post this?

Post by fgristina »

Sage advice... and I know I am likely headed down that ECU path. I installed the aeromotive fpr and fuel pressure is as steady as a gunslingers hand so i'm happy. Car idling well and starts with right AFR, 13ish. I have a 90s style equalizer looking AFR meter in the car. However it still tends to move toward rich after putting it under load a few times. I am going to tinker with MAF again and see if I can lean out a little more.

If you were going to use a stand alone ECU what would you all recommend. I have a decent quote from megasquirt but am open to any and all. Haltech sounded cool but could not get as much tech support as megasquirt. I am totally open to suggestions please!
Preyupy
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Re: M5 Turbo Issues, where to post this?

Post by Preyupy »

I am looking into switching over to a different EFI ECU but I want to try to use the stock wiring harness. This will require me to use a single ignition coil and the stock distributor cap, rotor and wires. This will also make me batch fire the injectors the way they are currently being triggered. I have talked to the guys at Megasquirt and I am sure this would be possible. I was also planning on finding a dead 35 pin Bosch ECU so I could scavenge the connector so it would just plug directly into the harness in the car. I would do away with the AFM and rely on a MAP sensor for load control and this would work perfectly with your turbo set up as well. My desire is to keep the cosmetics in the engine compartment as stock as possible and not hack up the original wiring harness.

The only other way would be to completely remove the stock harness and build a completely new harness from scratch. This would allow me to use coil on plug ignition and sequential fire the injectors but I'm just not that interested in pulling the stock harness out of the car.

Any of the good aftermarket EFI manufacturers have systems that will do this job quite nicely: Megasquirt, Halltech, AEM, MoTec, etc and a lot of it depends on what system you are comfortable working with. Once you get all of the hardware working you still need to tune it, and if you have never done it before (especially with a turbo) it is best to find someone that knows what they are doing and has access to a chassis dyno.
fgristina
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Re: M5 Turbo Issues, where to post this?

Post by fgristina »

So an update on FMU to FPR swap. I love the new FPR and fuel pressure is steady. I have it set at 43 psi and that seems to produce the cleanest exhaust and allow me to cycle RPM up as high as I want in neutral. AFR/air-to-fuel mixture seems good too.

HOWEVER...as soon as I back out of garage and put around driveway, car seems to get bogged down, and no amount of throttle will push the car. I have to sputter back into the garage every time and it dies as soon as I remove foot from gas.

I watched fuel pressure gage closely and it is holding quite steady. Plugs are also not getting fouled like before when I had overly rich mixture. I can also restart the car after it sits for a bit.

I also am noticing that I am getting no boost pressure on the VDO gage in the car even when I rev it. Would a poorly functioning or seized turbo cause above symptoms?

The turbo is about the only system I have not dropped and checked.

I am getting ready to pull the injectors to get specs and pop test them

THanks
tschultz
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Re: M5 Turbo Issues, where to post this?

Post by tschultz »

A methodical approach really is the best way to finding the problem.

What is the symptom? Do you have a AFR gauge to really diagnose what is going on with the mixture? No offense but we can't help you with what to suggest because it doesn't sound like you have a clear picture of what the car is doing.

A non-M5 AFM may or may not work, I cannot confirm.

It sounds like you need to identify the most basic performance of the Motronic system and not worry about the turbo/positive pressure aspect.

Are you sure you don't have vacuum leaks somewhere? Is the oil fill cap on tight? Is it a simple Coolant Temp sensor throwing off your mixture? A lot of different things could be the problem... Is the ECU faulty?

Maybe take a video before spending so much time guessing?
fgristina
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Re: M5 Turbo Issues, where to post this?

Post by fgristina »

Thanks for quick reply. My method has kind of been start with cheapest and simplest failure points first and work back from there ;-)

I totally understand your point about a "clear picture" and I take no offense, I know I'm a noob and can't thank you guys enough.

I think my vacuum system is tight as I have replaced almost all lines. I have also sprayed starter fluid around most areas while running car. I wish I had a smog test machine to be sure. I also get a good increase in fuel pressure when I pull vacuum from FPR which tells me I have good vacuum

I do have an AFR meter in the car that is OK but not as new and sensitive as my fuel pressure gage.

Speaking of which, I have had a discovery. My fuel pressure drops quickly after turn off! As my FPR is brand new and car build pressure fast on start, I believe I have one of many leaky injectors. I am actually very excited to pull them and check things out.

Again, thanks for your patience with this string!
fgristina
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Joined: Nov 02, 2018 7:17 PM
Location: Virginia

Re: M5 Turbo Issues, where to post this?

Post by fgristina »

Well it was expensive but I swapped out the fuel injectors and engine running quite well now. AFR now adjusts as car runs and is running much much learner. The Bosch injectors in the car had been rebuild at least once and I believe one or more of them were leaking and spraying wrong. Part number was rubbed off on all six but I believe they were green bosch from 3 series (not correct for M5). Now i'm onto the next problem - the turbo, lol

I was wondering what injectors you other M5 owners have? I had to go with GP Sorensen 800-1003N until I can source correct Bosches, which I believe to be Bosch 62412

Thanks for your help on this string
downforce22
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Re: M5 Turbo Issues, where to post this?

Post by downforce22 »

The s38b35 injectors are Bosch 0280150201
fgristina
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Re: M5 Turbo Issues, where to post this?

Post by fgristina »

Thanks for reply. After calling Bosch, they gave me same part number Bosch 0280150201 for BMW part number 13641273727

Bosch said they don't make anymore but I may be able to find some in warehouses - so far I have found one for future swap.

That part number cross ref for autostores is Bosch 62412

I went with six new GP Sorensen injectors, 800-1003N, so far very happy with them and car is running soooooo much better and I can actually adjust mixture through MAF, pressure, and idle screws. Almost ready for maiden voyage and likely maiden tow.

I also read that Lucas D1540BA may be a viable swap.

Putting these number up her for inspection/correction for future leaky injector fixes, although I think I'm the only noob M5 mechanic on this board.

BMW 13641273727 = Bosch 0280150201 = Bosch 62412 >>> GP Sorensen 800-1003N >>> Lucas D1540BA
kingoftarmace2004
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Re: M5 Turbo Issues, where to post this?

Post by kingoftarmace2004 »

I only skipped through the posts, you said fuel as in fuel pressure? did you try doing a noid test on the injectors to see if the ecu is actually firing the injectors? you might have fuel at the rail but if the ecu is not sending a trigger pulse to the injectors than NO boom! Thats my false economy 2 cents! -Paul
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