GRT

I bought an 85 928S out of North Carolina. I drove it back to Austin with no problems. I took it into a muffler shop yesterday to have some cats put on it because the PO installed a x-pipe w/ cat delete and custom pipes all the way back to the muffler. I get a call from them that it still failed inspection after they put the cats on. It seems to be running rich but I'll leave that for another thread.

I went down to pick it up and that's where things got interesting. It just turns and turns and turns but never even gives the hint of starting. I thought maybe it was out of gas since the gas gauge isn't functional so I borrowed a gas can from the shop and put a few gallons in it. Still no go.

I go home and pick up a spark tester, a multimeter, and some starter fluid and head back to the shop. I sprayed some ether into the intake with no change so I tested that I was getting spark. There is no spark. So I tested the Ignition Relay(IV) and the EZF Ignition System Relay(XVI). Both seem to be functioning. I feel them both click when I turn the key to the run position. I swapped both with the horn relay and the horn works with all of them. I also checked that I'm getting juice to the load side of the relays.
I haven't checked the coils yet but it doesn't seem like they would both go at the same time. I suspect either the ignition brain or the crank position sensor. With a friend's help(tlsmith1999) we tracked down what we think are the correct pins to test the crank position sensor but I don't know if I tested it correctly. We tested for both continuity and voltage across pins 7 and 19(or what I think are 7 and 19). Neither seemed to yield anything except an open circuit and 0 volts. Is there somewhere online I can find the pin layout for the ignition brain. The location in the WSMs would work too. Am I even testing the sensor correctly? Does anybody else have any ideas about what the problem could be?

I'm going to get it towed back to my place because I'm heading out of town for the holiday weekend and the shop is going to start charging me to store it before I get back.

Mike Frye

First off, Welcome!

My money would be the CPS as well.

Get a copy of the Jim Morehouse CDs, there is an LH test plan in there that includes the CPS and pinouts and a few other things you'll need to test/verify. Unfortunately I think you need an O-scope to test the CPS, but I'm not 100% sure of that. Might just be easier to replace it and see if that was it.

Not sure how fast you can get it or if there's anyone in the Austin area to give you a hand, but if it recently ran OK and it cranks it can't be too bad.

Good luck!

BBX

Try cycling the key on and off a few times. It worked when mine left me stranded a few times, switch is pretty common I hear...

WallyP

First check - go to the battery box and carefully clean and check the medium-sized red wires on the battery positive terminal.

Pull the harness connector off of the EZK ECU. Hold the cable in you right hand, looking into the connections with the plug extending to the left.
Start at the left end (nearest your hand) on the bottom row. Pin 1 is the first one, pin 7 is the 7th one. Pin 19 is the end pin on the top row (nearest your hand).

That won't help much, though. The only real way to check the sensor is with an oscilloscope.

GRT

I suspected it might be the ignition switch as well, but I didn't think the relays would be clicking if the switch was bad. If that assumption is a bad one somebody please let me know.

GRT

I have the Jim Morehouse CDs. I'll take a look at the LH test plan. If that doesn't answer any more questions I'll order a new CPS and see how that goes. Thanks.

Thanks for the info. I'll check the battery box when I get it home.


I was looking around and found some threads that hinted that the BMW version of the crank position sensor could be had cheaper than the Porsche version. The BMW part is Bosch 0261210002 and the Porsche part is Bosch 0261210003. From what I've read they are the same part except that the BMW part has a cord that is 6" longer and can be found for about half the price of the Porsche part. If that's true I can loop a cord and tie it up with the best of them.

Does anybody know a good towing company in South Austin?

Tampa 928s

Did they weld the pipes if so was the battery disconnected?

Mrmerlin

I would guess that they might have damaged something if the car was welded on,
Per the WSM the battery and the brains should be disconnected,if the car is having welding done on it, my guess is they didnt do that

WICruiser

My '85 died the other day going around a corner, just like someone turned off the key.

Turned out the connector for the LH (or was it EZK) was disengaged but something bumping into it.

It can not hurt to check the connections to make sure that they didn't get disconnected - either to weld on the exhaust, or just because weird stuff happens some times.

docmirror

Ask the shop if they grounded to the chassis, or the pipe they were working on. It makes a big difference.

Try to swap your EZF and LH into a 85/86 car. I think it could still be the ignition switch too, but less likely.

namasgt

I was told welding on a car could fry the Brain. But I dont see any reasone why they would weld the exhaust on the car, they could have marked it and then thaken the exhaust off for welding.
But their saying the car ran after the cat install and it didnt pass emition.

rixter

this wouldn't by chance be a gold 5spd would it?

SteveG

Welcome. Hoping for the best (cheapest) outcome here. Along w/Wally's post and tracing the power (and grounds): there is an uncoated braided ground between engine and chassis at rear of block passenger side. This would probably have been disconnected when doing cat work.

GRT

It didn't look like they had been in the battery box so I'm guessing they didn't disconnect the battery. My air pump and tools didn't look like they had been disturbed.

I know for a fact the brains weren't disconnected. During our troubleshooting we removed the connectors and reconnected them.

Which one kills my computers? Does anybody know somebody in the Austin area with an 85-86 that would let me test my computers on their car?

I know for a fact it was welded while on the car. I came in to make sure they were putting the cats where I wanted them and witnessed them welding with the pipes on the car.

Nope, It's a Prussian Blue Metallic 5spd w/ LSD

I saw that when I was assessing my cat situation. I'll make sure it is still hooked up.


Thank you all for the help. I won't be able to check on anything until I get back into Austin on Monday but I'll keep checking back here throughout the weekend.

Mike Frye

If they used a torch I don't think there's a problem with welding, right? What technique were they using?