Christopher Zach

Hm. Got back home, things went very weird fast....

Went out to work on the 928S, had three items to repair: The side mirror (easy), replacing the spark ignition modules (bought a used assembly from Ebay), and hunt down vacuum leaks.

So I started with the ignition modules, took off my old ones, put on the new ones, started the car everything looked fine. Error 1: Always run the car first before doing anything. Have a baseline.

Regardless, the engine was running solid and stable, etc. I can hear a vacuum leak, so I pulled off the vacuum line from control valve 2 (the one that goes to a valve with hoses going to the carbon cylinder (my guess, line goes from the passenger side, over the head, then under the washer water inlet), the left side of the engine, right side of the engine, and the oil filler neck) and got good vacuum. However I still hear a hiss when connected. So I disconnected the vacuum line from the valve and blocked it off.

Took car on street, huge power right to about 3800-4000RPM then everything goes bad. Engine sounds like it's hitting redline, tach jumps, engine is cutting out. Weird. Drove back to driveway, checked, sure enough does it under no load, feels like hitting redline early. Found that the line to the charcoal cylinder has a leak (that's why it was hissing), will replace that but what the heck happened with redline?

Switched back to the old spark modules, same problem.

Thoughts? Rained a lot over the weekend while I was gone but the engine seemed dry. I'll try it late tonight to see if there is a spark light show under the hood, but what else could be going bananas?

Edit: In the meantime I bought two brand new Bosch ignition modules, specifically for the 86 928S. Should be here before the weekend. Should also buy rear pads as well since I do need to adjust the parking brake gear and might as well swap the pads...

Christopher Zach

Interesting. Went outside to measure the hose diameter and look for a light show from the spark plugs/etc. Total darkness, disconnect vacuum line to control valve 2, turn engine on, put hand on throttle bellcrank, turn off flashlight, rev up, no light show at all. Also engine roars like a monster and I realize it's not bucking. Hop in car, floor it, engine revs up to 6500rpm smooth as a kitten.

This is obviously due to the fact that I just bought two new ignition modules and the car appreciates the pagan sacrifice. Or having the line connected to control valve 2 (which is progressive, it passes a small vacuum when no vacuum on the line from the crankcase/engine and a huge vacuum when vacuum on the line from crankcase/engine, probably to purge the charcoal system) made a difference. Odd.

Shut down, will leave down until I can get a new length of vacuum hose to go to the junction valve of the charcoal tank. Will try again tomorrow night.

skpyle

Depending upon how cantankerous it is acting, a 928 sometimes appreciates the sacrifice of a Fiat 124.

Christopher Zach

I must have sacrificed the right thing. Since I didn't have a vacuum hose long enough to go from valve 2 to the switch assembly for the charcoal cylinder I used a shorter length with a splice, hooked things up, re-attached the vacuum line to valve 2, fired the car up, and took it for a drive with the new used ignition modules.

Um. Fast. None of the chugging on acceleration anymore, the car goes from 20mph to 100mph very quickly with a roar. Shifts well, still feels a bit rough on light shifts, still need to see if there is a different vacuum leak. However it is running a lot better, is quiet at idle with minimal hunting, and seems happier.

I put a full tank of 93 octane gas in as it was almost out, eventually I should be able to get rid of the 1+ year old gas that was in the tank.

Next up: Testing the cruise control, swapping brake pads this weekend, and taking a look at the undercarriage to see if there are any issues. Hopefully that will fix the brake indicator light and the antilock message (I think it's driver's side front based on the feeling of the brakes before antilock comes on). But serious progress, then maybe I can take it to get the car inspected in MD and registered at last.

Christopher Zach

More progress. Swapped out the rear brake pads this weekend and re-adjusted the parking brake shoes. Took a fair number of turns to get the brakes to engage, hopefully I won't have to replace those shoes anytime soon. Pads were simple of course, and they were worn down enough to trip the wear sensor.

I also looked closely at the wiring harnesses, they appear undamaged, so I'll check the front ones tomorrow. Side note, I wonder why this guy cranked the bolts down so tightly, I use a 1 foot 4 way tire wrench to get lug nuts off. Normally I step down on it half way and pull the other side snug (about 110 ft/lbs.). To get these off I had to put full weight on the bar *and* pull the other side (300 ft/lbs at least). All had anti-seize, I think this previous owner used an impact wrench with way too high a setting (in the shop receipts I see that one shop broke two studs trying to get the nuts off and explicitly wrote not to tighten them so much). Ah well.

Next up was the stereo, pulled the Blaupunkt and things looked ok there. Pulled the amplifier and found that one of the wires to the choke had broken off. Replaced it, put it back together, now have pretty nice tunes. Next up will probably be to take apart the radio and clean the volume contacts if the crackling doesn't go away after a few uses.

But.. progress. Next is the front brakes, then if all looks good I'll try to replace the ABS relay in the relay panel. The symptom is ABS trying to engage till 20mph (can hear the pump and feel it in the pedal, then it throws the antilock message. Removing those calipers from the car does not look easy (I can't budge the 10mm allen bolts with my socket tools) so I might need to take that part to a shop.

Christopher Zach

On the positive side, radio is fixed and sounds amazing, the heat is off, the vacuum system is snug, the car idles great and the parking brake will hold the car on a 30 degree downslope with 5 clicks up.

On the negative side I blew up my transmission. Got another thread open, but in a nutshell I put it in 2, floored it, car went to 5500 then shifted into 2nd (nice), stopped, did it again, car went to 6500+ and did not shift so now I am stuck in first and reverse (which works). Fun driving it home, I assume it was first as I was going 5500RPM at 50mph or so.

Edit: I did not blow up the transmission, the upshift switch was stuck down due to the work I was doing on the parking brake and moving all the rugs around. Oops, but it's now driving fine.

C

Christopher Zach

Well, it's been about 8 months since I picked up the big blue 85.5 928S, so I thought I would post a quick status update:

In short it's running great!

• The ignition problem that it had when I bought it (ran very rough, felt like part of the engine was missing, weak power) has been 100% gone since I replaced the front ignition computers (the things right by the hood latch). Seriously, it's like night and day between them, if you're having rough running on a 32V I recommend swapping those out to see if it runs much better.
• Interior still needs new seats and such,but I like how comfortable it is so that's not critical.
• Kick down switch still needs to have the pedal adjusted, but shifts well enough for now.
• The shift from first to second is still a bit of a THUNK, better since I changed the transmission vacuum lines but might need another half a turn. No signs of clutch slipping and fine from 2-3,3-4
• Headlights are fine but I still need to pull the fuse panel and clean up all the connections.
• Rear defroster doesn't work, probably aforementioned panel.
• AC is still down, I need to replace the dryer, how does one get that out of the car anyway?
• Need to replace the bulbs in the environment unit, will also check the relay for the AC while in there.
• Sometimes still get a TAIL fault with the lights on, usually goes out even without pressing the !. Probably a bad ground on the passenger side light.
• Lubricating the sunroof slides with lithium grease totally fixed the sunroof, thanks

That's about it. Motor is running fine, no more ABS faults, brake pad faults, or belt tension faults. I've put about 7k miles on it since I got it, at this rate I should replace the timing belt next summer.

C