When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I picked up a pretty rough 86.5 928S, but it was next to nothing so I bought it as something to try and bring back to life. A little history, the car hasn’t driven in at least 6-8 years. The last owner had it for 6 years and never got it to start. He replaced a lot of stuff, entire fuel system, from the tank to the injectors. Spark plugs, wires and distributors/coils were replaced. MAF sensor replaced, along with intake manifold gaskets. He also replaced the entire injection harness and primary fuse panel.
He could get it to crank by bridging the starter relay and the motor turns freely. That was enough for me to see, so I knew motor wasn’t seized. For the cost of a few sport cup 2 tires I trailered it home.
Today we did some basic diagnostics. Ignition switch wouldn’t return after moving to start position and after reading some posts on this forum, it seemed like it’s relatively common and I picked one up today and installed it. With starter relay in place the motor won’t turn over, only with relay bridged. I think is may be neutral safety switch, so I need to find that and inspect. After jumping the relay and having the motor turn, we inspected the spark plugs which had a spark but no gas present. We then pulled the fuel injector relay, which looked corroded, and bridged that relay as well.
IT STARTED!
Super rough and only for a few seconds but a lot further that it has been in the past it sounds like
The throttle body stud screws are broken and thus the throttle body was moving all over. My friend had the idea to wedge it against the oil fill tube which worked great until trying to line up the intake manifold rubber gaskets creating lots of extra air. I ran out of time before I could duct tape the intake manifold to at least see if it would idle.
Here are my two primary questions:
- Anything besides neutral safety preventing starter relay from starting with key? Maybe a bad ground?
- Where can I find those throttle body stud bolts?
sorry for the long first post but I look forward to bringing her back to life!
You look like you got a nice project. Paint is a bit faded, but not too bad. What does the interior look like?
I would very strongly suggest not running it much (or even at all) until you get a new Timing Belt & Water Pump (TB/WP) installed. That is an interference engine and if the belt lets go, it will cause more damage than the car is worth. I would also think about doing a complete 'intake refresh'. Not just gaskets, but all the vacuum lines, sensors and switches that hide under the intake.
Scott Yoo did these and has very comprehensive write ups on his personal site. There's a bit of music to listen to while you are working on there too. https://scott-yoo.com/porsche/
For parts, Roger Tyson at 928s R Us is a very good source. He will have almost all of what you need. Don't go to his site, call or e-mail. He knows and loves these cars and has a lot more than shows on his site. He also knows what parts you will need for just about any project and is quite capable of putting together a 'care package' for what ever job you want to do.
As was noted above, take some time and read through the "New Visitor" sticky thread. Several pages of very important and useful info.
Thanks for the responses, I did go to the new user section prior to posting and some of the info I was looking had dead links. I do have a factory service manual and I have rebuilt several cars before so I am not totally blind when it comes to electrical/ignition issues. The PO spent a lot of time trying to work out what was wrong, so all the fuel/vacuum lines are in great shape. Good point regarding the water pump, I was planning a total overhaul of basic maintenance once I sort this electrical issue. I have been going over the diagrams and I think I am going to isolate the safety switch and bypass. The PO replaced the CE panel so I am worried there are some connection issues following that replacement.... That could be a fun endeavor. Along with the safety switch, I am going to check the ground connections.
Interior is in rough shape, cool color scheme though, brown/tan combo. Normally I wouldn't like that but for this car it works great. The cluster removal wasn't as bad I thought it would be, but I am having trouble getting some of the bolts lined up underneath, that long hex head, to get back in place.
Last edited by sfzobie; 01-06-2020 at 03:17 PM.
Reason: adding info
Mine wouldnt start one, day, and I got out the meter and some tools and worked out how to check the neutral switch etc. When that looked a bit hard, I checked the gear lever......it was in D.
D for 'Doh!'
I think I found one issue. If I bridge 30-87 on the XIV relay the starter engages - the problem is the starter engages regardless of whether the key is even in the ignition. I was searching this forum and it seems like the manual cars have a permanent bridge, so I can’t imagine the car cranking is normal without the key.
The new ignition switch went in, so looking at the wire display. 85 looks like it goes to the safety switch and 86 goes to the ignition switch. What’s the best way to test these pathways? if I put a new relay in place, it won’t crank, which makes me think there is something wrong with the safety switch (unless ignition switch wiring got altered at some point which is why I want to test it)
Otherwise it could still be a ground I suppose or some crossed wires from previous work.
Well I have learned a lot over the past few days reading the service manual. I was able to test all pathways on the starter circuit and I tested continuity of each ignition wire. I was able to isolate the problem which was in the wiring in the rear wheel area at the 4 pin connector for the neutral safety switch, someone had messed with, so I bypassed the connector and the car now cranks with the key. The other issue was the car would stay on even after I turned off the key and removed it, and I found that my I/II relay was bad, and removing that fixed that problem. I found 5 relays that failed my tester, the only one of importance being the ABS, which I will source soon.
XX Pump relay is good, XVI EZF is good and XXV LH is good. XV is bad, will that prevent ignition?
I am also going to do the fuel pump delivery test in the service manual to confirm fuel delivery and I will test to hear clicking with the injectors.
01-05-2020, 08:12 PM
New 86 928S “Helga” Project with some questions
