E28 M5 swap restoration

savannah996 · Post by **savannah996** » Dec 17, 2012 4:49 PM

The engine and trans are in. I noticed the AC drain is right on top of the 5sp. No wonder they look corroded sometimes. I was going to hook up a hose to run it off the side, but the trans sits too close to the chassis. Guess if I ever fix the AC, it will just have to keep dripping water right on top of the trans.
My brackets for the pwr st pump and alternator both have issues and I noticed today the crossmember is too corroded for my taste. Plus I ruined the shifter shaft seal.
On another note I think im just gonna keep the battery in the front for now. I just want to get this thing started.
One last thing, I need to see where the purge valve hose connects on the engine....

wkohler · Post by **wkohler** » Dec 17, 2012 7:36 PM

The AC drains on the tranny but usually, its hot, so the water evaporates. You won't be able to install the airbox unless you move the battery to the trunk.

Good luck.

savannah996 · Post by **savannah996** » Dec 19, 2012 8:51 AM

The C101 is a tough problem. I need to double check all the wires. I have found at least one that is different in the 528e to M5.

savannah996 · Post by **savannah996** » Dec 19, 2012 5:59 PM

After hours and hours of matching up wiring diagrams, and confirming on the wiring harnesses, I CAN just plug the S38 engine harness into the 528e power distribution box. (9/1987) build date.
Of course I may prove wrong when I try to start it. (however I did bump the starter with the key today)

wkohler · Post by **wkohler** » Dec 19, 2012 6:00 PM

Better to be safe than smoking right?

savannah996 · Post by **savannah996** » Dec 23, 2012 3:11 PM

She is fired up and idling smooth. But cuts off abruptly at 1500 rpm. Maybe limp mode? IDK.
Worked on finishing the drivetrain today.
Waiting on copper 6mm exhaust nuts to finish that, then she can come down off the jackstands.
Ill planning to swap rear subframe at the end of the project.

tn535i · Post by **tn535i** » Dec 25, 2012 9:03 AM

Is your TPS just hanging from the wires or properly adjusted on the TB. Cut off at 1500 rpm makes it sound like the TPS is making the 'idle' connection to the ECU even when you crack the throttle. If 'idle' mode is engaged it will cut fuel at about that point.

savannah996 · Post by **savannah996** » Dec 27, 2012 10:48 AM

tn535i wrote:Is your TPS just hanging from the wires or properly adjusted on the TB. Cut off at 1500 rpm makes it sound like the TPS is making the 'idle' connection to the ECU even when you crack the throttle. If 'idle' mode is engaged it will cut fuel at about that point.

I fixed the problem before reading your post. But if I had, it would have helped. You were on the right path, and had the right idea. You have a good knowledge of these systems.
The problem was found when I pinned out the DME and saw the #2 &#3 both had continuity at same time.

tn535i · Post by **tn535i** » Dec 29, 2012 9:51 AM

Glad you found it. There is a tuning plug that does exactly this, taking both idle and WOT to ground, which is used for tuning the idle mixture, balance, etc on an S38. It basically justs holds the ICV in a nuetral postion and also puts the computer in open loop mode I thought. So I guess it also limits the revs just like idle mode. Did the TPS fail or was there a problem in the wire loom?

savannah996 · Post by **savannah996** » Dec 29, 2012 8:38 PM

If you switch the tps and iac, somehow both tps pins get grounded. (idle/full throttle).
I didnt have any time in the last 3 days to work on her. Good news is I have all the exhaust nuts I was waiting for and a 190 degree radiator switch so I can delete the mech fan. And until I make a oil pressure manifold, im just gonna delete the idiot light.
On another note im getting water in both A pillars and its accumulating on the floor. After inspection it seems to be coming from area near the bottom of windshield. Ive never messed with a E28 windshield seal but I need to stop this water leak asap.

savannah996 · Post by **savannah996** » Dec 29, 2012 8:42 PM

If you switch the tps and iac connectors, somehow both tps pins get grounded. (idle/full throttle).
I didnt have any time in the last 3 days to work on her. Good news is I have all the exhaust nuts I was waiting for and a 190 degree radiator switch so I can delete the mech fan. And until I make a oil pressure manifold, im just gonna delete the idiot light.
On another note im getting water in both A pillars and its accumulating on the floor. After inspection it seems to be coming from area near the bottom of windshield and running down the inside of the A pillar. Ive never messed with a E28 windshield seal but im gonna have to get in there and inspect it. Do these cars have an issue with windshield seal leaks? Or is it maybe just something that needs done every 25 years? LOL

savannah996 · Post by **savannah996** » Dec 31, 2012 4:43 PM

Man im getting close to getting this thing off the stands. Family in town so its just sitting there. But got a little done, oil pressure gauge hooked up, exhaust mani tight. Mechanical fan had to go on cause im not getting sufficient voltage from the fan relay. IDK. Maybe if I stay up late tonight.......

tn535i · Post by **tn535i** » Jan 02, 2013 2:26 PM

OK so switched TPS and IAC. That would do it since the IAC is basically a couple of low resistance solenoids that would look like a closed switch to the ECM.

savannah996 · Post by **savannah996** » Jan 08, 2013 5:52 PM

Why is this thing idling at 1200 rpm!!!!!!!!!!!!!!

99% sure there is no vacuum leak.
Throttle cable is not too tight.
Can anyone help out here?

Btw its driving good. Still have the 528e instrument cluster in. Fun burying the tach.

wkohler · Post by **wkohler** » Jan 08, 2013 6:06 PM

This thread should give you some stuff to go on. Lots of possibilities but you have some covered.

http://www.mye28.com/viewtopic.php?p=923292

savannah996 · Post by **savannah996** » Jan 08, 2013 8:57 PM

Hey thanks!
Ive been running back and forth between the baby and the car all day.
Is the idle bypass screw the large flat head in the middle of the center throttle body? It was screwd down (in all the way) I backed it out 2 turns and it slowed the idle for a second then it went back up.
My plan is to check the idle signal at the DME. Pull the ICV clean /inspect. And if that all does not work try everything in the thread you posted.
I did clean/lube and inspect all the TB's when I had the motor out. Didnt check the butterfly clearance though.

tn535i · Post by **tn535i** » Jan 09, 2013 1:34 PM

Yes the big one on the 3-4 TB's is the idle bypass. But there is also a screw on each ITB. You should start with the throttles and linkages adjusted properly and these ITB screws basically closed and go through the whole ITB balancing dance with vacuum measurements. That means putting the jumper on the TPS, etc, etc...

I personally don't quite understand the S38 idle adjustment. It seems to me you are defeating the motronic idle setpoint that is built in closer to 750 rpm? You would think the ICV should control it within some range regardless of the bypass screw position and I think it does at this lower idle speed. But it also seems to me that the bypass allows you to take it up beyond the speed the ICV is capable of controlling as if on a warm engine the procedure basically calls for you drive the ICV fully closed and then let even more air bypass to bring the idle up. I guess this gives the ICV the most usable range for cold idle and A/C operation to boost idle? Now if you can't drive it that far you would have to go back and re-adjust the base throttle settings slightly more open and start all over again. And once you've got the idle where you want it you need to check the CO at idle and adjust the AFM bypass and then maybe adjust idle one more time. Right?

Can anybody say for sure if my interpretation on this is right regarding the idle speed setpoint? Was the intial intent to have these idle lower but it was too lumpy for customers who expected a smoother idle so they basically drove it over the top of the ECU control range? And does anyone know if any of the aftermarket chips are basically controlling to the suggested 900-950 rpm rather than lower than 800?

Always been curious...

savannah996 · Post by **savannah996** » Jan 09, 2013 10:27 PM

Today the M5 instrument cluster with new odo gears went in.
Double checked the tps signals at the DME, they were in spec.
Put 20 miles on her delivering some scrap metal. All went well even though im driving with the eta rear diff. 2000rpm@65mph!
Tomorrow im getting into the throttle bodies.

savannah996 · Post by **savannah996** » Jan 09, 2013 10:27 PM

tn535i · Post by **tn535i** » Jan 10, 2013 7:43 AM

Looks like you have the vent line running all the way around to an eta expansion tank and cap? The M uses a 2 bar cap rather than a 1 bar in the eta. At least I think I have that right. So you probably need to consider getting the M tank and cap in there eventually or you might pop that one.

What's with the glow in the dark intake plenum. Pass me my sunglasses.

Hard to imagine the close ratio M 280 trans with a 2.9 rear end. Many have said the S38 does not like to be bogged down at low rpm and I don't like the way mine 'feels' below about 1800 rpm so I'd agree with that. Hard to explain but its the way it pulls or maybe doesn't pull but above about 2000 it takes on some personality. But of course it changes personality a couple more times at 3500 and about 5500.

You will have an

moment when you get the 3.9 in and get to really know it. In a good way.

savannah996 · Post by **savannah996** » Jan 10, 2013 9:47 AM

tn535i wrote:Looks like you have the vent line running all the way around to an eta expansion tank and cap? The M uses a 2 bar cap rather than a 1 bar in the eta. At least I think I have that right. So you probably need to consider getting the M tank and cap in there eventually or you might pop that one.

What's with the glow in the dark intake plenum. Pass me my sunglasses.

Hard to imagine the close ratio M 280 trans with a 2.9 rear end. Many have said the S38 does not like to be bogged down at low rpm and I don't like the way mine 'feels' below about 1800 rpm so I'd agree with that. Hard to explain but its the way it pulls or maybe doesn't pull but above about 2000 it takes on some personality. But of course it changes personality a couple more times at 3500 and about 5500.
You will have an moment when you get the 3.9 in and get to really know it. In a good way.

Napa online says 20lbs for the and 14.5 for the eta. So im not gonna worry about it unless it poses a problem.

My phone doesnt like the white paint on the intake.

Yeah there isnt really much pull until 2500 but she will peel out the 205's especially with open diff! (trying not to toast whats left) lol.

savannah996 · Post by **savannah996** » Jan 10, 2013 2:08 PM

I pulled the iac, tested out. Swapped it out with another that tested good Anyway.

Cleaned all the bypass screws (7). #6 was frozen and I will have to let it soak overnight.

Checked basic 1,2,3, tb's set screws. I backed them all off the throttle plates then screwed in 1/4 turn to relieve pressure off the butterflies.

Tested out the iac at the dme, (ok)

Swapped out the afm.

All of this made no change! Even unplugging the iac changed nothing.

So now that I have checked EVERY SINGLE PART OF THE IDLE CONTROL SYSTEM.
I do believe I have found the problem though, can you guess what it is? Ill let you all know tonight when its fixed.

tn535i · Post by **tn535i** » Jan 10, 2013 6:21 PM

You thought you switched the TPS and ICV back but never hooked up the TPS or adjusted it.

It will be worth the effort to clean all those bypass screws up and go through the vacuum balancing anyway. It may smooth the idle out regardless of the speed.

savannah996 · Post by **savannah996** » Jan 11, 2013 8:45 AM

About 5 posts above I noted rechecking the idle/wot pins on the dme so its not that.
What I noticed yesterday, I was pulling the hoses while the engine was running, I noticed idle fluctuation messing with part number 31.

So I replaced the gasket cause I believe the hose is new. At this time i noticed a vacuum port on the bottom of intake was open also. I hooked the purge vacuum line to it. Buttoned up the whole thing and could only get idle to 1150-1200rpm. I switched out a new used afm from a 535i E28, that just made it run rich as hell but a 500 rpm idle speed. So im back to looking for an air leak somewhere.

savannah996 · Post by **savannah996** » Jan 11, 2013 9:16 AM

If I pinch the iac line it idles real nice, the one leaving the top of the intake muffler going to iac.
And if I unplug the afm it runs super rich and barely idles at 500 or so rpm. Time to test out afm, I cant remember if she idled good before the swap. hmm

mooseheadm5 · Post by **mooseheadm5** » Jan 11, 2013 10:42 AM

It really shouldn't run at all with the AFM unplugged. Don't do that.

savannah996 · Post by **savannah996** » Jan 12, 2013 8:06 AM

Im gonna start new thread for the idle problem.
I had a flat on the way to work yesterday. I only noticed cause I stopped for a couple gallons of gas. (it was the ps rear tire). I had no idea it was flat until I got out. Good thing I stopped when I did. So today the wheels are getting changed to the style 5's. Pics will be posted. The interior is a mess partly cause of the po, but its good I get to look at everything while its apart.

Rich Euro M5 · Post by **Rich Euro M5** » Jan 12, 2013 9:23 AM

savannah996 wrote:

So I replaced the gasket cause I believe the hose is new. At this time i noticed a vacuum port on the bottom of intake was open also. I hooked the purge vacuum line to it. Buttoned up the whole thing and could only get idle to 1150-1200rpm. So im back to looking for an air leak somewhere.

There's a potential air leak at the end of each throttle plate shaft. The bearings have a rubber seal and it's probably rock hard and not sealing any longer. "Devinder" has a thread in this sub-forum about leaks around the TB throttle shafts. in the fourth post, "Philo" posted a link to photos illustrating how to replace the bearings.

savannah996 · Post by **savannah996** » Jan 12, 2013 9:14 PM

Ive sprayed "extremely flammable" brake cleaner all over the injector o-rings, throttle body air pipes, butterfly shafts, tps, nothing ever changed. Used about half a can.
Tomorrow im gonna manually shut the icv and see if that kills the engine. Im almost positive I did something stupid to cause this problem somehow.

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E28 M5 swap restoration