E28 525e - Did Manual Conversion, Now Car Runs Like On 4/5 Cylinders

[M M 250]

I spent the last few days converting my 525e to manual. All went well, everything went together fine, but when I went to start it, the car idled very low, between 200 and 400 rpm and any opening of the throttle causes it to stall. Most of the time it stalls itself if you leave it running for a bit (usually within 30 seconds). The idle is quite rough, feels like it's only running some of the cylinders. However it has no problem actually firing up, starts like normal.

I've spent the day today trying to disagnose (after putting it all back together), got another AFM off a 525e at pickapart but that made no difference. It is getting voltage to the plug. It makes no difference whether the TPS or the AFM are plugged in or not. There appear to be no vacuum leaks and it seems to be getting fuel (for one you can definitely smell it).

Does anyone have ideas what could have cause it to do this? I don't know if it is related to the auto to manual swap or not. The only thing that I can think of is the sensors in the bellhousings. I used the ones that were in the auto box already on the car, will they work or do I need to swap them out?

Thanks to anyone who can help.

*Edit: I was told buy the seller that the manual conversion came off another 525e, so it is all correct for the car.

Edited August 23, 2015 by M M

[BM WORLD 1283]

maybe size or location of the trigger on the flywheel ??? no correct??

distance to the trigger from the sensor is very important

[M M 250]

maybe size or location of the trigger on the flywheel ??? no correct??

distance to the trigger from the sensor is very important

Could be but if all etas use the same flywheel then it should be correct since this was from an eta.

So it is possible that the autos and manuals use different sensors? I think I'll just go swap them anyway as I have the manual ones.

Edited August 23, 2015 by M M

[M M 250]

I put in the sensors that I got with the manual gearbox. Made no difference.

[BM WORLD 1283]

sensors are the same , check the distance gap , did you fit the flywheel the correct way , one hole is larger and has a sleave to locate it etc

[M M 250]

I believe I did. To me it looked like it would only go on one way in relation to the holes on the crank. I'm not sure what you mean by sleeve to locate it.

*Edit: Just saw in my Bentley what you meant by sleeve. Mine didn't have that, but I'm sure that two of the holes were closer together only allowing it to mount one way. I rotated it to check and they all only lined up once (at least I thought they did).

Edited August 24, 2015 by M M

[aja540i 1906]

On the e39 there are shims under the trigger sensor that you may have to change to get the right gap between the sensor and the trigger wheel/ flywheel, your bentley manual should mention it if it needs to be right.

[M M 250]

On the e39 there are shims under the trigger sensor that you may have to change to get the right gap between the sensor and the trigger wheel/ flywheel, your bentley manual should mention it if it needs to be right.

I will check this however I don't believe the e28 needs this.

I think it's safe to say it is the flywheel at this point. I just went and checked the auto flywheel/ring gear/whatever the auto one is called and the holes are all definitely evenly spaced, so more than likely the flywheel is on wrong. Guess it'll all be coming off again. I feel like a pretty big idiot for not checking this, and I'm not sure what I was looking at, thinking they didn't line up.

Does anyone know if the flywheel is way off does it mean the car will not run at all? Does the fact that the car starts mean that it is likely only one bolt hole off (if it is infact the flywheel)? It doesn't make much difference but I'm curious to know for future reference.

Thanks for all the replies so far.

Edited August 24, 2015 by M M

[BM WORLD 1283]

call me 021433600

[will 169]

I dont believe the engine would run with the flywheel 1 bolt hole out... simple maths tells me that the timing would be retarded or advanced by 45 degrees if you had done this.

However, you can easily check where it is firing. Put some basic timing marks on the crank pulley i.e. BTDC 20-15-10-5--0 (TDC)- 5-10-15-20 ATDC with a suitable reference pointer to locate them, and then use a timing light to check where it is firing in relation to TDC when idling.

Is it a regular misfire? If you short out a particular plug, is there no difference? Or is it a totally random misfire, so shorting out any particular plug will give a noticeable misfire?

Anyway, I would check the resistance of both sensors at the ECU plug, NOT at the sensor plugs! You should get around 540 ohms on both.

[M M 250]

It's quite hard to explain but it's not really a missfire, more a consistent but rough idle, almost like how some of the American v8s sound when they have aggressive cams. I'll try and take a video of it tomorrow and post it. Occasionally if you leave it it will run for a while but will not exceed 400rpm and will not rev at all, as soon as you give it throttle it will stall.

I'm not sure what you mean by shorting out plugs. I'll do the ressistance test on the plugs and see how it goes.

[M M 250]

Here's a video of how it's running:

For when I do the flywheel, can anyone tell me where the reference mark needs to be in relation to TDC? From what I can find it needs to be at the sensor when the engine is at TDC, is that right?

[M M 250]

I pulled the gearbox off today and took the flywheel etc off. Sure enough, the dowel came off on the thread of one of the bolts. Have no idea how I actually missed it the first time round or how I even got the flywheel on there. It was however only one bolt off which is why it ran I guess, but barely. I have no idea what the hell I was looking at when I did it last time. Guess my mind has been all over the place lately. Anyway it's all back together now and runs fine so I'm happy, even though I made a massive idiot of myself.

The car does have some unrelated underlying running issue because it has been using quite a bit more fuel than it should (before the manual swap) and runs really badly on the replacement AFM which I got which hasn't been touched and is off another 525e. It will only run correctly (if you can say that) on the AFM that came with the car which was tampered with and I have adjusted a lot to try and get it running semi respectibly. But that's a minor problem at this point and for another day.

Thanks very much everyone for your help and replies.

[eliongater 718]

What gearbox and driveshaft did you use?

I'm in the middle of doing a manual conversion to mine, but have a getrag 260 from an m30 engine.

[M M 250]

What gearbox and driveshaft did you use?

I'm in the middle of doing a manual conversion to mine, but have a getrag 260 from an m30 engine.

Getrag 260/5 and matching driveshaft off a 525e. If I was you I'd just get a M30 and put it in, you may as well if money isn't an issue.

Edited August 27, 2015 by M M