New to me 91 850i with a few issues

[Laserface]

Valve covers are off, are all 8 banjo bolts are tight. I'm almost disappointed to find them tight. I'm torn between removing and reinstalling with thread locker and new sealing washers, or leaving them alone with the "if its not broken don't fix it" mentailty. The valve covers are looking pretty rough with peeling paint and some surface rust, so I'll be sanding them down and painting them.

[brettd85]

Mine weren’t backed out either. I just went ahead and retorqued. A few turned a bit.

[Laserface]

I haven't actually checked my bolts yet. I got the covers off and had other things to do. I'll check the bolts, but I already have the Loctite and sealing washers to do them. I'll probably just go ahead and change them for peace of mind.

[Laserface]

Finally got the car back together after nearly a month. Banjo bolts are fixed, leaky valve cover gaskets replaced, intakes sealed with Reinzosil, and all engine bay fuel lines replaced. Scott did the capacitors in my GM and my steering memory module. Car ran great, but a new issue has popped up.

The windows work intermittently, and the window drop down when the door is open has stopped. They worked fine at the beginning of my drive, but once I got home, the door was hard to shut. I realized the window wasn't dropping down. The relays in the trunk click 100% of the time on window switch press, but the windows only sometimes roll down, and very rarely roll up. The sunroof, interior lights, power locks and wipers still work properly.

[Timm]

Press the door handle IN rather than pulling on it - if it goes 'click' and the window drops then the door handle pot-metal is failing. Otherwise it will be a microswitch failure probably. I mess about with them here:

[Laserface]

Thanks Timm, your knowledge and documentation of that knowledge is an inspiration.

I should clarify: I noticed the issue because the window wasn't dropping down, but that's not everything. The issue is that all 4 windows have stopped completely. At first they were intermittently working, now nothing. The door handles have almost no movement when pushed in. Sometime in the near future, I'll check to make sure I got all the connectors properly seated when I reinstalled the GM. Since the relay clicks when the switches are operated, I would think that should rule out the switches as the problem. Both driver and passenger switches behave the same (relay click, no window action).

I'll check the connections the at GM, then go through associated fuses and relays to check and reseat them.
UPDATE: After having done nothing but let the car sit for a few hours, everything is working again...I once again deleted my post while trying to edit it on the mobile website. Reposted the original, with an update.

[Rickwalk]

ahhh....them pesky gremlins run oft ! GM fix seems to be the common denominator, amongst matching batteries with good fusible links.

[Laserface]

The windows have misbehaved only once since I first posted about it, and that was shortly after the post. They've been problem free since. After Scott worked on my GM, my dead battery issues have disappeared. He also worked on my steering column memory module, but it changed nothing. I haven't done any more trouble shooting beyond checking fuses. One day I will, but for now I've set it where I like it with the manual adjustments. I'm currently replacing blown speakers.

[Laserface]

Today, after over a month of working properly, the window didn't drop when I went to get in the car today. Power windows, power locks, and windshield wipers are inoperable. The interior lights and sunroof work properly. The left outside mirror no longer adjusts, but the right still does. I've looked over wiring diagrams, but I can't make sense of it. it seems the only thing all these items have in common is the GM.

When the power window and power lock switches are operated, I still hear the relays click in the trunk, so at least parts of the circuit are working.

Best of all, the system energized itself just long enough to lower the left rear window about 1.5" without any input from me... At least no rain is in the forecast for at least 24 hours.

[Laserface]

In the ongoing saga of maintaining a neglected E31, since last posting in this thread I've:
Replaced a leaking heater core
Rebuilt heater valve
Replaced leaking radiator, expansion tank and coolant lines
Replaced broken thermostat
Replaced leaking transmission pan gasket
Replaced accessory belt drive system
Flushed brake fluid
Replaced fuel injectors

My most recent venture has been attempting to diagnose an increasingly rough running condition on bank 2. Bank 1 runs silky smooth, bank 2 stumbles off idle and is down on power. It had new plugs, new wires, new fuel injectors. Both coils checked to be good with multimeter. Swapping components from properly running bank 1 didn't seem to help. I pulled the distributor caps, starting with bank 1. Nothing worrying was found. I buffed the contacts with sand paper. On bank 2, i found what I thought was a cracked rotor. Upon disassembly, the rotor is actually in 2 pieces. The plastic is very brittle. Hopefully the split was causing bank 2 to be slightly out of time and replacement solves my running issue.

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[Laserface]

Both rotors were cracked into two pieces. New caps and rotors are installed. The car is running much better, but still has consistent stumble from idle. When idling in park or neutral, easing into the throttle will see the engine RPM climb smoothly. Stab the throttle though and the engine will stumble and miss for a second, then rev as expected. Revs in drive produce no stumble. The car runs well and accelerates as expected.

It does have an odd issue with low/part throttle cruising. When going down a hill that requires very light throttle to maintain speed, the car lurches slightly when throttling on/off. The strange part is that throttle "off" occurs at roughly 5% pedal. The car lurches out of throttle before I'm all the way off the pedal. This is not present/unnoticeable with cruise control.

BUT, cruise control has its own issue. With cruise on, the car holds speed very well on flat roads and climbing hills, but accelerates consistently down hill.

I've now installed new 1k ohm plugs, new fuel injectors, new (and tested) spark plug wires, new distributor caps and rotors, and have coils that test in spec. I'm thinking all these issues are possibly DK/EML related. I did attempt the DK sync, but noticed no difference afterwards. If they're out of sync/worn, it would explain the miss with sudden throttle application, the misbehaving cruise, and the lurching. So DK testing will be my next venture. They show signs of having been off the car or replaced before.

I rebuilt the heater valve because I had heat coming from the L side of the car at all times. The seals were in bad condition. Upon resealing the valve, I got about 1 hour of heat, and now I have none. A/C works and blows cold, but when set to heat, the air blows lukewarm at best. I'll double check that the heater valve is functioning properly, but I believe coolant is making it thru the heater valve because the heater hoses at the firewall get hot.

[Original 8]

Chasing similar rough idle issues. I'm starting to think this is MAF related, rather than ignition system. Waiting for new caps, rotors, and coils, so hopefully will at least eliminate that from the equation.

[rjjablo]

Both rotors were cracked into two pieces. New caps and rotors are installed. The car is running much better, but still has consistent stumble from idle. When idling in park or neutral, easing into the throttle will see the engine RPM climb smoothly. Stab the throttle though and the engine will stumble and miss for a second, then rev as expected. Revs in drive produce no stumble. The car runs well and accelerates as expected.

It does have an odd issue with low/part throttle cruising. When going down a hill that requires very light throttle to maintain speed, the car lurches slightly when throttling on/off. The strange part is that throttle "off" occurs at roughly 5% pedal. The car lurches out of throttle before I'm all the way off the pedal. This is not present/unnoticeable with cruise control.

One of the issues I had with my Throttle bodies is that they would be sticky and when you had them off you could see them hesitate

For this I replaced both the cover to the armature and the other piece that it rides on. Bearing or bushings were worn. Be aware there are two different versions of the M70 Dk. some of the parts swap, some do not.

Shogun has posted how to rebuild your DK/Throttle bodies and it includes how to index them with a multimeter and a cam wheel. The index is critical

[Laserface]

I disassembled and clean the throttle bodies. There was a little brush dust, but everything looked good. I didn't see any excessive wear and everything operates smoothly. I'm going to attempt to index tomorrow. Both still had the plastic security seal in place, but they did not match. They were different styles, and one had the security bolts. One had phillips/torx screws. So it appears at least one has likely been replaced.

The no heat issue was an aux water pump problem. Fuse 1 would pop as soon as power was applied to the pump. Whether directly or thru the IHKA, this blown fuse was keeping the heater valves closed. Disassembly of the pump revealed some trauma. There is a burnt smell coming from the pump. I didn't have a hose to bypass it, so I reassembled the pump without the impeller and reinstalled. It seems people have had sufficient heat without the pump, so I'll leave it in sans impeller and disconnected for now.

20220917_162345.jpg

[Laserface]

One of the issues I had with my Throttle bodies is that they would be sticky and when you had them off you could see them hesitate

For this I replaced both the cover to the armature and the other piece that it rides on. Bearing or bushings were worn. Be aware there are two different versions of the M70 Dk. some of the parts swap, some do not.

Shogun has posted how to rebuild your DK/Throttle bodies and it includes how to index them with a multimeter and a cam wheel. The index is critical

Both throttles switch from measured resistance to infinite at 17°, just as they're supposed to. The issue I see is that one throttle measures 900 ohms resting, the other 2400 ohms.

[shogun]

see here the DK input details on my website, small 4 page pdf original data from Bosch in German and translated to English file http://twrite.org/shogunnew/data/controlsystems.html
more DK details here https://www.bimmerforums.com/forum/s...ng-calibration

[Laserface]

I see 3 different resistance specs. However, I have no idea what pins on the DK to measure across to test for these values.

[shogun]

here is mentioned: http://bmwe32.masscom.net/moswald/75...ies/index.html
Throttle Encoder Measurements:

Throttle Resistance between pin numbers: 6 and 8
1988 Left: @ idle (closed) : 2093 ohms @ full (open): 1193 ohms
1988 Right @ idle (closed) : 2133 ohms @ full (open): 1168 ohms
1990 Left @ idle (closed) : 2017 ohms @ full (open): 1063 ohms
1990 Right: @ idle (closed) : 2065 ohms @ full (open): 1087 ohms

more test data and pin info http://www.km5tz.com/BMW%20850iP1.htm

[Laserface]

DKs are clean, moving freely, and electrically within specs. They were reinstalled on the side they came from. I should have crossed them.

So its actually running rough on Bank 1 (pass side). I get L and R components easily confused on this thing because of the intake crossover.

Bank 1 still has a misfire from idle. Stabbing the throttle gets hesitation and misfires to the point the car won't rev. Slow, easy application of the throttle will let the car rev. Once above about 2k RPM, you quickly apply more throttle and the car will rev.
Bank 2 behaves as expected.

I was trying to isolate the issue by running one bank at a time by unplugging the other bank's injectors.
I swapped MAFs and FPRs side to side (one component at a time). No effect, Bank 1 continued roughly, and Bank 2 smoothly.

I plan to next swap the DKs side to side. I'm going to try to get the car on a smoke machine, because at this point I suspect a vacuum leak.
Is there somewhere to conveniently check fuel pressure, or do I need to T into the lines somewhere? Are the 2 fuel pumps 2 completely separate systems, or will the other pump take up the slack of a weak pump?

If swapping DKs tells me nothing, and its not a vacuum leak, where do I go from here? This issue started after the car sat (garaged) for about a year. The car runs well enough to drive, gets decent fuel mileage, and doesn't seem to be running rich. So this has me thinking too much air (vacuum leak) or not enough fuel (weak fuel pump).

EDIT: Also after replacing the seals in the heater valve, I have no heat at all. AUX water pump left unplugged because its popping fuses, and reinstalled without impeller. Heater hoses are getting hot between the heater valve and firewall, but none is making it out of the vents. Is there something in the heater box that would cause this?

[rjjablo]

Have you replaced lines to your vacuum canister. Another good spot for leaks. I took mine apart and put new charcoal in from the pet store and all new rubber lines. Along with a new rubber cap which was rotten. You can also test those valves. There is a thread for this but here is the diagram

Smoke test on mine indicated TB leaks like yours and it is going to get new bearings

Smoke test on mine also pointed to a leak under the oil filler, which got a new gasket

[Laserface]

Took the car over to a buddy's shop with a smoke machine. Only small leaks around the springs on the throttles. Not ideal, but definitely not my issue because bank 1 had a larger leak than bank 2 and its the one running smoothly. No other smoke.

We were discussing the M70 engine control setup. Two of this, two of that, etc. I told him what had been replaced, and what had been swapped side to side. Were we discussing moving the throttles L to R next. We pulled and inspected plugs. Bank 1 looked nice, Bank 2 uniformly black. He said "have you swapped the coils?" I had checked resistance on them, which measured in spec, but hadn't thought to swap. Swapped coils, and the roughness followed. I've never been so happy to hear a misfire. I'll order new coils and another set of plugs.

Now I just need to get the heat working again for winter.

[Laserface]

Coils came in today. New coils and 12 new spark plugs installed and the car is running great. Its the best it has ran during my ownership.

If I can get the heat going again, this car will be "done".