Bill Ball

I do nothing more than use MS Paint that comes in Windows (listed under Programs, Accessories). It has a line drawing feature as well as text, boxes and circles and is dirt simple for annotating graphics. I just lay broad colored line sections over the wire path in question. I use Adobe Reader's Snapshot tool to capture the part of the diagram I want, paste it into Paint, annotate as needed and save as a JPG. Rarely do I have to resort to any more sophisticated tools than that. To color code an entire wiring diagram would be a major chore, but for a few annotations, MS Paint is fine.

Peter F

My biggest challenge finding this fault was that it was random and not present all the time, I could not pin it down until cutting the boot to the MAF connector.
If it is touching all the time it is a different ball game though

/Peter

PorKen

I guess this thread is about wiring, but just to note, new, or especially cleaned injectors, get stuck inside.

When I put in my new Ford Motorsport 24 pounders, I tested all of them, so I wouldn't lose my mind when I had it all put together! Only one injector didn't clunk immediately, but freed up with a couple taps on the battery. The injectors have a small '+' sign molded on the connector, but I don't think it matters for testing.



I was lucky enough to find tan 24# (factory 85-86 colored), disc type/four hole, on eBay; $150 for all 8!

davek9

Hello all, I have taken on the “challenge” of troubleshooting Paul’s ’91 928 S4 intermittent (Fuel Injection) electrical problems, as Andrew’s “Rev Limited” allotted garage time is all but used up for this Winter.. Big Grin!!

Anyway with Andrew’s and my two boys help, we were able to get it over to my garage via car trailer a few weeks ago.

I did manage to pull off the usual access items (air box, etc..), Simple Green the engine and do the excellent circuit testing suggestions made here.. thank you very much!
Just before my Motherboard went south, our household water heater took a dump and my works Internet providers (AT&T and QWEST) network had some routing issues that kept me working late a few days over the past two weeks !!!

Anyway as my “to do” list is now winding down (did I really say that..?) I am now getting back to Paul’s 928 this weekend.

Here is what I have found so far:
1. She did start (after slow charging the battery for three days) right up and ran good for about three minutes. Then the Tach went crazy the engine started to sputter and then stopped (like the key was turned off). It would not re-start, even after sitting over night.
2. So I cleaned it, and pulled it apart.
3. Pin 18 on the LH Computer (brain) to ground showed a dead short, 0.0 ohm’s. (great I am on to something..!).
4. Removed the CAT Protection Relay and measured from pin’s 5 and 2 to ground (to see which fuel injector bank the short was in) BOTH showed a short!
5. I removed all the injectors connections and ohmed each injector, they all read ~15.4 to 15.6 ohm’s.
6. I ohmed each injector connector to ground, one side shows 16.4 ohm’s (the + 12 v feed side) and the other side (red w/yellow or orange strip (I think)) shows an open, which it should as the relay is disconnected and pin’s 5 and 2 are not connected to anything.
7. So I made up a long jumper and went from each injectors corresponding stripped wire connector to pins 5 and 2 on the CAT Protection relay’s connector. The stripped wire’s all showed a “good” connection (a short) and no cross connections.
8. Reconnected the battery and checked for 12volts on the power lead on all injector connections all have 12 volts with the key on.

However as Andrew stated earlier in this thread, the wire’s all look good and none are frayed. My re-testing should have showed some bad connection somewhere… yes?

Anyway, Dennis and Stan (local 928 guys) stopped in after our Saturday trip to Harbor Fright (sale) and they witnessed some of my testing points, we put it all together and nothing, it just cranks…!

PLEASE help with ANY suggestions for this weekends next step and or more testing points.

Thank's in advance..!
DaveK9

PS: some Pic's to follow...

AO

Dave, Thanks for taking this challenge on. I'm sure you will narrow it down... eventually.

Let me add to Dave's post. I also sent him with a noid light and when the engine will not run the noid light will show nothing - doesn't matter which injector you put it on. Also, I tried my LH in this car and it had the same symptoms.

Here's a question for the experts: Is it possible that the ignition switch would allow one to crank the car without providing the connection for "ignition?"

FlyingDog

Dave, the best advice is to read through Tony's bad injector thread. I think we pulled out every diagnostic test we could think of in that thread. There is another thread where Bill Ball was working on a car with injection problems.

One thing I will add after my own problems is to loosen all of the straps/clamps holding the harness to anything. Both my car and Scott's 5L beater had short issues when the clamps were too tight.

FlyingDog

Yes. Computers should be powered up in "on" but the starter is activated separately in "start".

I'm at work, so I can't check this for LH 2.3 cars. The rear harness in LH 2.2 cars has a separate power feed for the computers and injectors. This is the harness that runs along the passenger rocker, up next to the rear seat and branches to the battery box and taillights. If that wire is shorting or has high resistance, you will get intermittent starting or no start.

Larry928GTS

The LH needs to be getting an RPM signal from the EZK to work. If you haven't already, I'd check the crank reference sensor, especially it's plug. If that's okay, try a different EZK computer if you haven't done that yet either. Also check to make sure the connections for the engine ground strap and the smaller wires on the battery positive terminal are clean and tight.

AO

Thanks Larry. I swapped the CPS out with the one from my car and it had the same result. I don't beleive I swapped the EZK.

Dave-
I have a spare EZK (actually it's Tim Murphy's that I'm holding for him) that you could try if you wanted. Let me know.

89 928 turbo

I had a wierd experience at Spokane Track last time we were there....tearing around all day, having a great time....suddenly lost half my guages, pulled in shut the car off, and couldn't get it to restart....injector's clicking, cranking, nothing. I had the ST, chip burner....traced everything down to burning a new chip ...still nothing....back to basics....chasing ignition relay's, jumping fuel pumps....turned out to be a 20amp fuse blown for some reason (Thurston know how much additional wiring I have)....popped in new fuse, fired right up.

........long story short.....fuses?

davek9

Thanks all for the replies.

The connections at the battery were all cleaned, first by Andrew and then once more by me (actually I took them apart and Andrew had done a great job).

I will look at the power harness on the drivers side, thanks, I do have a solid 12 volts.
I think if I provide a ground at either pin 5 or pin 2 I could get the noid light to work, (or the selected injector set would click), have not tired this yet, but will.
This would lead me to the EZK, and thank you larry928gts for that bit of info, like Andrew said has not been tried.

Thanks once again!

DaveK9

davek9

A few of us got together and went to the Detroit Autorama this morning, afterwords Andrew came over with another EZK and we swapped it.. no go, just cranks no start.
We re-checked and yes we do have 12 volts at the injectors with the key on, noid light wont fire (not getting a ground from the brain..right?).

I re-ohmed everything after Andrew left oh and he brought his car and it sounds GREAT, first ride of any distance.
Then reassembled all and it started ...! But only ran for about 30 seconds and refuses to re-start.
Here are the ohm readings:
Pin 18 to ground = 16.35
Pin 2 on the Protection relay connector to pin 18 on the LH conector = 3.9
Pin 5 on the Protection relay connector to pin 18 on the LH conector = 3.9
12 volts at the injectors, and won't refire.. not sure what to look at next, please help.

Thanks in advance..!
Dave

Tampa 928s

I had the same problem found the female connector in the LH harness was pushed open enough that it would work some of the time. When the amp connector is inserted in the LH on my 86 it can misalign the pins due to the angle. You might have checked this already, another area is the flywheel sensor do you have a scope it will show the the pulses if it is working. I chased my issue for a week!

AO

Have you tried gas and matches?

davek9

Tampa 928 Thanks.. I'll re-check the connections, I have been re-forming them (snugging them up) if the prongs look too spread, I'll keep at it.

Andrew can you beleave it started right after you left, it must of been inspired by the sound of you car... !
Once it ran I re-ohmed EVERYTHING.. all looked good, swapped EZK and could not get it to do it again.
I am not giving up on this one, who's got a scope in SW MI..?