1990 750iL E32 M70 Gearbox / Transmission Problem I cannot diagnose...

[SSkoda]

I'm coming to the fount of all E32 knowledge hoping for some help on this somewhat strange issue.

I've dropped an '88 750iL engine and box (and rad and cooler) into a '90 750iL that was vandalised, running badly and I was told there were metal filings in the trans fluid.

The engine I've put in runs fine. It did keep losing a couple of cylinders on the left bank but playing around with the leads and cleaning the plugs up has seemingly cured that. Been through all the checks of ECUs (DMEs) and MAFs and everything seems to be working fine.

The gearbox however is not playing ball. It works, but only up to third gear. So on moving off, it does so normally. It shifts to second, then to third. It will not accelerate rapidly from first - it will still move off sedately, through second, to third, and stay there. Once in third it will drive along normally without upshifting. If you mash the throttle, it will sometimes then kickdown to second, up to third again, but go no higher. Either gently getting faster or by mashing the throttle, it will not move up from third, staying in that gear all the way to redline, which is not a pleasant experience to be honest, very noisy and worrying. (Please remember this is with the aim of testing and fault finding, I don;t want to drive like this!) Letting off the throttle from that point, it will slowly drop in revs along with road speed, but it still does not upshift.
I am surmising that it is third, as I can feel two (slightly jerky, not particularly rough) upshifts from standstill.

Oil level of the box has been confirmed - was slightly low but has been topped up with Dextron III as required.
Oil was checked and is not frothy, milky, brown or burned.

The outgoing gearbox was a seven pin valve body plug, but the car had an 8 pin plug. The ingoing trans was an 8 pin. I assume that if it needed a 7 pin one the body harness plug would also be 7 pin? (My guess is that this '90 car has had a wrong trans fitted and this may attribute to why it was faulty!)
For this reason and also for fault finding, the transmission control unit [EGS?] (in engine bay) was replaced, and today the TCU? (in front right footwell) was replaced, both with the ones from the donor car to match the gearbox I fitted.

I've tried shifting up manually 1-2-3-D on test drives to no avail.
There were no known errors with the donor trans before installation, so I am reluctant as yet to pull the valve body out of the gearbox (that, and I've never worked on an auto box) - so, searching for possible suggestions that might explain the issue.

I've spent a lot of time researching this online over the last few days (what did we ever do before the internet?!) and got a few pages of things to look at - mostly Shogun's work - but it's clutching at straws really, nothing that seems a likely culprit...

TIA

[edit]
I'll add any other info I can think of here.
There is no Trans Error Prog showing.
There are no fault codes showing.

[shogun]

Just to confirm:
you dropped from a 1990 750 the engine and trans with 7-pins into the 1988 with originally 8-pin trans?
What mode switch did the donor car have? S-E-M like your original one or different?
Because in Europe the 750 got from 09/1992 = model year the AGS, whereas your old model was EGS with S-E-M switch. A-G-S switch usually has S -* and the control unit has 55 pins, while the EGS has 35 pins.
Also the switch under the shift handle is different for EGS and AGS as far as I remember.
differences between EGS and AGS http://www.bimmerboard.com/forums/posts/692906

Info for whiskychaser: http://www.7-forum.com/forum/5/beste...e-65563-3.html some info EGS and AGS and switches


For info for the trans experts, maybe you get some ideas:

I have just disassembled a 750iL with VIN WBAGC81000DC60202 Type 750IL (EUR) Prod. date 1993-11-12
just went to the warehouse and noted down the details:
ZF 4HP24, Stucklistennr. 1043 030 052, serial no. 0117844
that is definitely a 7-pin transmission as from 1993.
The outgoing male plug from the trans has 7 pins, but the female plug coming from the trans control module has 9 !! pin, and then I cut off the outer sheath of the cable pigtail which I still have on the female part and found in total 12 ! wires.
The female plug on the wire loom has the number 393 CDG BSA 56 14-8=SN 16 F 01, and the rubber cap shows the name RAYCHEM.
My assumption is that this wire loom between transmission and transmission control unit is a standard version with 12 wires and that depending on where it is used, BMW, Landrover etc, the wires needed are connected or not??
Unfortunately the car is already at the scrapyard now, so I cannot check the other end of the trans cable loom, if that is diverted or if all goes into the trans comupter.

zf 1043 030 052 is used for E32 750 and the E31 series

[SSkoda]

No no,
I dropped engine and box out of the 88, 8 pin

And put it into the 90, 8 pin

The discarded trans that came out of the 90 had a 7 pin receiver end of the plug.

Both have sem switch

[SSkoda]

Just to be very clear

Donor car, the engine and trans came from dc71127 5/88

And they were installed into the "good" car 4372529 build date 7/89


Now this morning we have taken out the control unit in engine bay. It had been swapped over to match the 88 tranny but we put back in the 89 one, whereupon it flagged up the eml, would not rev, and gave a fault code of "54 modulated lock up solenoid at". It stuck in third gear on the tranny.
Putting back in the 88 unit the eml light and fault code disappear but the tranny remains acting the same. It seems to be stuck in third totally now, no first or second either. I'll take another test drive soon to see.

[shogun]

A 07/1989 built 750 should have a 7-pin trans and corresponding transmission unit, based on let's say German standard. My 11/1988 still has a 8-pin transmission. In general it can be said that in Germany or in EU the change from 8-pin to 7-pin was around end of 1988 as far as I know.
Let's wait till whiskychaser chimes in, he is from the U.K. and knows the trans systems also very well, I will give him a PM.

Johan even says here: Transmissions made before 09/88 have an electrical control unit inside the box that is controlled via 8-pins. Transmissions after that have a control unit with 7-pins. And to complicate things even more for me transmissions before 02/88 had a different oil pan and filterscreen. http://bmwe32.masscom.net/johan/gear...rbox_swap.html

But apparently the change date was not that strict, I have seen a 8-pin already in a 12/88. Make sure which pins you have on both, see here, that is a 8-pin
8-pins.jpg
and that is a 7-pin http://s71.photobucket.com/user/shog...ml?sort=4&o=37

Count the male connector on the trans, the female connector going to there is confusing as I mentioned before.

[whiskychaser]

Just to be very clear

Donor car, the engine and trans came from dc71127 5/88

And they were installed into the "good" car 4372529 build date 7/89

I have more questions than answers. My VIN decoder says DC71127 was built 6/7/89 and 4372529 was built 30/5/88. So have we got an 89 engine and box in an 88 car? What ZF number is on the box - do we know? I know it revs but does it feel like it has enough power to shift up to 4?

[SSkoda]

Sorry I put the chassis numbers the wrong way round.
I had read somewhere about oil getting into the plug at the gearbox and causing faults so I split the gaiter off it and although there are 8 pins in the plug only 7 have wires.
Removed the 8 pin loom from the 88 car and connected it into the 89, and everything works now. So just down to a 7 or 8 pin issue, no gearbox faults thankfully.
It had been my findings from everything I read that the 7 pin gearbox was only fitted from the end of 1990, or 91, but obviously that was incorrect.

[whiskychaser]

The 88 car should have 8 pins and 8 wires. The extra one is for a reverse lockout solenoid they dispensed with later. Diagrams say the pinouts are the same apart from that. The later TCM wouldn't work with the 88 box though. If it worked at all, you might be lucky to get second and third :-)
Great result though!

[SSkoda]

I had read that the extra wire was to do with an extra solenoid in the valve body and that to change the box from an 8 pin to a 7 pin I'd need to change out the whole valve body assy. Never came across anything about the reverse lockout.
Neither the 88 nor the 89 TCM would work when the 7 pin wiring loom was still in place. One gave me second and third (the 89 TCM I think) and the 88 TCM when fitted only allowed for third gear.
Once the 8 pin 1988 gearbox loom up to the footwell area and ECU area was all swapped in, the gearbox immediately functioned 100%, with the matching 88 TCM.
Relieved that I didn't have to open the box up in the end and that it was a relatively small issue even if it did take ages to figure out.

[whiskychaser]

FWIW, the extra solenoid is for reverse lockout. Both boxes use MVs 1 and 2 to select gears. But the patterns don't correspond. For example, the more recent TCM would be calling for MV1 off and MV2 on for first gear. But that means second gear to the older gearbox :-) You have proved that provided you use the same loom and TCM, it will work.

[vsilima]

Good Day Shogun, i am new in the forum. I m driving 1989 750IL. the SEM switch is stuck on M. if i move to E, it always go back to M on its own? Any idea on resolving the problem?

[shogun]

see Console Removal Shifter console removal & switch cleaning, e32 & e34 automatic http://www.nmia.com/~dgnrg/page_2.htm

[vsilima]

Thanks very much Shogun.

One more question: The transmission fluid seems to be moving up the dipstick and escapes? The escaped fluid will then burn and release smoke that can been seen mainly at stops. Is there something that i can do?

[shogun]

There is a breather valve on the rear of the transmission which enables the trans to breathe, when fluid is hot, volume increases and the breather valve let's air out, and when ATF is cold and has less volume it let's air in. # 17 http://www.realoem.com/bmw/enUS/show...diagId=24_0516
Maybe that is clogged and therefore it pushes the fluid thru the dipstick. That is very important that the ventilation works, otherwise you get more leaks on the trans. Here a pic, at reat top the white plastic part http://www.global-t.ru/akpp/remont-a...nsmission.html

Also check if the trans dipstick is damaged where it should seal http://www.realoem.com/bmw/enUS/show...diagId=24_1191

[vsilima]

Thanks, the breather valve can i clean it or it needs to be replaced?

[shogun]

yes, it looks like a plastic t-piece http://www.ebay.co.uk/itm/NEW-OEM-BM...-/162132998712. Pull it out and see if the hole is clogged
24111218007 Ventilation valve From: 04/13/1988 To:- Supersedes: 24111205982 (03/01/1976 — 06/08/1989). Part 24111218007 was found on the following vehicles: E21, E30, E12, E28, E34, E24, 2500-3.3Li, E23, E32, E31