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if the CPS connector is broken then its time for a new part
dont cut corners here ,
lots of things need to be working perfectly for the engine to run at its best.
NOTE with a broken dizzy belt and crumbling CPS connector and a MAF thats out of spec the car is talking to you .
replace these parts as well as the other suggested parts
I only replaced relays in place of old ones. I checked the old relays once removed and they were all OK. I replace relays with Bosch items from 911 Design. They aren't marked 53...
Ill double check the vacant positions tomorrow in case a previous owner has been busy
84 brought 16V engine to the upcoming MAF / twin dizzy engine management system planned for the 32V engines.
85 brought all models, 16v and 32v onto the fusebox with the plug-in fuses, presumeably same panel for 32V and 16v.
Still would like to see part number to ensure it isn't substituted with a much later 32v panel.
Relays can be jumpered.
30 to 87, spade ended wires.
Measuring control voltage helps to see if they have power going to the magnets to trigger them, but you know that.
The 85 ROW service tech manual might be helpful, will see if I can abscond it from CD with copy function.
By the way, distributor caps and coils are straight 944.
Car in my avatar is 84 ROW 5 speed. Nasty fast car. 85 is better version thereof.
Hi, yes tried start fluid directly in the MAF. Didn't make much difference. Just a few pops back through intake.
Haven't used a noid, but have checked with oscilloscope. The trace matches the Porsche tech sheet and the ti time is around 7mS, which I think is OK for cranking
Well, an "O-scope' is going to tell you a whole lot more than a noid light, so you're good there.
Both the lack of start with the starting fluid and the O-scope showing proper injector function would seem to indicate that spark is an issue.
The 'pops back through the intake' would make me think that you are getting spark when an intake valve is open.
You say you've checked it, but my first guess would be that the spark plug wires are not right.
Other than that, I'm out of ideas.
I would change the whole ignition stuff if old. Rotor and caps and belt and an ignition wire set. Than put your MAF in a running car.
I had a Bad fuel Pump Relais on my 84 S2. Wiggling the Relais and she Starts. The old fuses are a pita. Throw all away and put new ones in.
Test your LH and EZK in an Running car.
I disassemle the Alarm with a Bridge in the connector behind the glovebox.
Last edited by Darklands; Jun 23, 2020 at 01:36 AM.
Again, thanks everyone for your input so far. New Bosch crank sensor, coils, distributor caps and rotors ordered from 911Design. I'll report back once fitted (and running)!
I hope the parts fix the issue, it would obviously be nicer to diagnose something that has failed and replace it. It was running on 4 cylinders when the customer brought the car in to you and after replacing the plugs, cam belt, distributor belt and removing an immobiliser it’s now completely dead it would be a bad coincidence that something unrelated suddenly failed.
From what you’ve said spark, fuel, air are all present in the cylinders which means critical systems are still working. Timing of the fuel isnt important so spark timing can be all that’s left as others have mentioned.
Anyway let us know how you get on.
But 1985 ROW Service info tech document shows an inset picture of CE panel on the new car.
Identifies the new panel part number to be 928 610 105 09
Picture you show above is 928 610 105 13.
And some of the wires on the customer car were repaired.
I wonder if the old panel burned up and new one was substituted?
And if so, is it compatible?
Hopefully this is not a red herring that we chase and chase to no avail.
Who has knowledge of interchangablity of Euro CE panels by year???
1985 was the very first year of that style panel in the 928.
By the way, send me your email via pm or post, and I'll send document.
Last edited by Landseer; Jun 23, 2020 at 11:03 AM.
The cps connector is bad as a bit of the plastic connector is missing, but the oscilloscope shows it returns a voltage trace over 2.5V with the TDC disturbance present. I think I checked it the Ecu connector too. I'll check again. However, if I have a spark at the plugs, does this mean it must be working?
I'll disconnect and clean the grounds on the RH cam over too.
I dont know for sure, Our DaveK9 is the CPS oscilloscope guru. I might be misremembering, but for some reason it seems he diagnosed a bad one due to wrong waveform. Maybe he will weigh-in.
Ha ha, now I can't get the old CPS out. It is soaking in mech oil penetrating fluid overnight, but it is solid....
Oh, I found the earth from the RH cam cover was completely disconnected today. Reconnected now.
Also coil primary circuits were correct.
I want to leave at TDC so I haven't tried to crank to check whether cyl 1 fires on the compression stroke yet.
I don't know if the CE has been changed, but I've done a functional check of the outputs, which are all correct, now that I've removed the fuel pump circuit bridge.
The parts should be here tomorrow, so if I can shift the old CPS, we'll see if she fires
There’s good write ups here on using a block of wood and wire to pull the CPS up, worked for me last weekend for the first few mm. After than I got a 15mm open ended spanner under the head and levered up against it with a crowbar to pull the rest of the way. You need to remove two bolts holding the fuel line brackets to get enough clearance.
There’s good write ups here on using a block of wood and wire to pull the CPS up, worked for me last weekend for the first few mm. After than I got a 15mm open ended spanner under the head and levered up against it with a crowbar to pull the rest of the way. You need to remove two bolts holding the fuel line brackets to get enough clearance.
You don't know the topic title do you? I searched but can't find it
You don't know the topic title do you? I searched but can't find it
I will try to help you, I did it successfully.
Do not try to pry it out, they usually break off when people resort to brute force. Vice Grips and the like are no use, and there really is no room for much else. The horror stories of what people have to do after the top of the CPS breaks off are most of what you will find when you do a search on the topic.
You will need some 1/16” or 1/8” braided steel cable, about 21/2’ should do it. And you’ll need a cable tie to secure both ends of the cable together. Place a thick towel on the firewall and one on your manifold (if it’s finish is nice), Then a length of 2X4 across as a bridge. Run the cable around the CPS as close to its center as you can, secure it around the 2X4 and then place a short wrench (or similar) between the cables and start twisting. The CPS should pop out at least a little, then you can reposition the cable better around the core of the CPS. Start twisting the cable again and don’t stop until the CPS eventually gives up and pops straight out; this can take what seems an impossible amount of tension but it will eventually give in. I did break the 1/16” cable and had to go with the 1/8”, but your experience may vary.
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