Spun

I have been really busy the last few years with family and work items, so I have not dedicated myself to fixing this issue like I am about to. Here is the history of the car, what I have done and thoughts for next step.

I purchased this car in Seattle a 5 years ago. Slate Gray, 5 speed (I added the LSD, Greg Brown Build) and it was not maintained correctly by any means, but has been since I owned it. The PO hid all kind of issues and some things I have not thought of you could do on one of these... I have corrected everything I can think of back to factory specs except the powder coated engine goodies and the battery...

The standard battery had been replaced with a Optima Yellow top battery and a "in-line power line disconnect" where they cut the main power line, added in a battery disconnect to deal with the battery drain on the battery when sitting vs fixing the issue. I have since removed the in-line disconnect and used the Optima battery. For the 1st year, no issue cracking and driving. I still have not run down all of the battery drain issues, but I will be as part of this task. I still have a power rail inside the battery compartment because I did not want to replace the cut wire and go back to standard battery. Might need to for this or at least just put a connector to the battery and eliminate the Optima as an issue if anyone can think of why it might be the issue... see image



The next thing I did was rebuild the top end and powder coat all of the intake, water bridge, etc. During that replacement/update the MAF boot was shot and had wires cross and I smoked a new MAF and damaged the LH. I had Rick rebuild them both and those problems should not contribute to this issue, but I am willing to swap and try those as well.

During the issue of the MAF roast, I was unable to get the car to crack up at all. I actually took the car to Dan up at Exotic MotorWerks to help run the issues to ground. That is when we found out a toasted the LH and during that stay, for other reasons, we did a full engine rebuild (a very small nut had gotten into a plug hole, that lead to pulling the heads, that lead to finding the head gaskets shot, that lead... that lead... to a full engine rebuild).

When I got her back, she did not like to crank on cold mornings. We thought we had an issue with the coated water bridge and not getting a good ground plane. If we loosened the ignition control unit and or the temp sensor and tighten it, she would fire up. So we thought we had a ground plane issue, I cleaned all of that up and... same issue. I even ran a ground wire over to them to ensure we had good grounding... same issue.
Next couple of years:

• Problem of intermittent starting on colder days
• Once I was able to get her to fire up, she ran and would start no problem
• We noticed if we played with the alarm (after market), she would eventually fire up
• Removed after market alarm and no change
• Seemed like if I played with factory alarm (lock and unlock with key) she would work - no change
• If I play with cranking it eventually she will fire up

Because I could eventually get her to fire up, and she is not a daily driver, I lived with this issue and just assumed it was the alarm until today since none of that is connected and the factory alarm is bridged. Yesterday it seemed like the problem was solved and today... no change.
Here is what I know:

• Fuel pump is working, but tomorrow AM I will listed to it on the first attempt
• I have spark... but will verify on first attempt tomorrow
• MAF is new rebuild by Rick
• LH is new rebuild by Rick
• I have touched all but the ground point by the cluster (I am willing to go clean all 9 again and will likely go do that)
• I have fuel pressure at the rail, but I am going to put the gauge back in to check on first attempt tomorrow
• Factory alarm is disabled and pin 1 & 3 are bridged
• No factory alarm - does not mean in the past the multiple alarm installs did not hose something...
• There was at one time a really weird temperature control aftermarket thing added that Dan and I removed. 10 wires going multiple places doing God knows what... All gone now

I am willing to try everything from the start again and will use this thread to run each item to ground until I have a baby that cranks every time and we have this issue run to ground for others.

Please through out each idea and I will try, document and try the next.
I have 4 928s to pull known good parts from plus extra parts:

• 1989 S4 5-speed
• 2 1989 S4 Autos
• 1 1988 S4 5-speed track car

The electronics between the 88 and 89 are different, but most everything on the Autos is a 1:1 for trying swaps... toss away

Michael Benno

davek9

One thing I'd like to point out, every time you disco the battery on an S4 and above the ECU's need to calibrate, takes a few miles to settle down.
Also if you start and stop the engine "cold" and don't let it fully warm up, it will be running really rich, the plugs get all loaded up with extra fuel, especially if the bat was discoed.

Just something for you to consider

Dave K

rbrtmchl

The experts will chime in I'm sure. I would start with three things:

1) Can you swap in a known fully charged battery for the next time you try to start it on a cold morning?
2) Have you swapped out the critical relays with new?
3) What are the black and red wires that extend out of the battery box towards the back of the car? If they are not mission critical, remove these to see if anything changes.

Wil

I second swapping all critical relays. when I had intermittent starting issues, especially cold start, the culprit ended up being a failing relay (LH in in my case).

Spun

Early this AM I was able to get the car to run up after about 10 trys. An hour later it would not run after 30 trys. I just got done putting the gauge on the rail (4 hours later) fired up the 1st time. Only difference was temperature is ~10 degrees warmer at 78 deg.

• As far as relays, I have swapped them in the past for known good ones (vs new), but I have done so many little things since then that I understand that this could have had multiple culprits playing in... So I will start with that cycle again. I usually go for known working vs new that way I know they worked when I took them out. The pleasure of owning multiple same years.
• As far as the battery, I know it is fully changed when I start. Its not a turn over speed in this case. I keep a trickle charger on the battery. I do have a Optima red top I can drop in as well. I can use a standard battery, but might have to pull the bar to make it fit. I would like to beat the clown that cut the main power line and did this... but this is only one of many stupid things the PO did. Good thing I loves these cars
• As for the other lines, off the positive and negative I have the charger and the other lines are standard items that run off the battery plus the power for an amp.
• DaveK9, yup, understood and that could be playing, but I have had the car running for an hour, killed it and it would not fire up. Normally once she is running, I can fire her back up 15 seconds later, 1 min later, 30 min later...

Thanks you gents. I think this is going to be a multiple day tasks since I have seen the symptom change or the pseudo fix change many times just like the alarm fix that worked for 24 hours it seemed.

Tomorrow (or later today if it will not start), I will start with the LH relay and work my way through. Cold seems to effect this the most, but again, that could just be coincidence like I have seem with other issues.

worf928

Download the inspection guide linked in my signature. Then skip to the electrical tests - section 8, page 22 - and do them. Pay particular attention to the TEMP-II sensor, idle / WOT switch, and ISV.

Assuming those tests find nothing interesting, we need to know, when it doesn't start, in order:
- is the starter cranking?
- do you have spark? Verified with a timing light?
- do you have fuel pressure? With your FP gauge do you see a pressure rise after cranking?
- do you have injector 'clicks'? Do you have a fuel injector probe (like this one: https://www.tooltopia.com/waekon-764...MaAmb4EALw_wcB)

Random questions:
Has the engine speed sensor (aka CPS) ever been replaced? If so, when and with what brand/model.
Who's "Rick?" Do you mean Rich Andrade?
Have you done a voltage drop test from battery post, to starter, to jump post, to fuse panel?
When the engine rebuild was done, was the motor out of the engine bay?

Bigfoot928

look at the temp sensors. also have you looked at the ignition switch? if it works after you monkey with it they are known to go bad. on the starting issue since it is a manual the clutch switch could be related and there is also a jumper in the fuse panel only for manuals but I forget where.

Spun

Dave,
As always, thank you.

Here are the results:
Temo-II / NTC-II at 78 deg F

• LH: 2.212 kOhms
• EZK: 2.219 kOhms

Idle

• LH: .004 kOhms
• EZK: .004-.007 kOhms

WOT Switch

• LH: .018-.019 kOhms
• EZK: .018-.019

Idle Switch: Check
Resonance Flap: Check
Tank Vent: Check
After I completed the above, the car fired right up... so the answers are based on that except where noted
- is the starter cranking? Yes... but that is the case when it does not fire up as well
- do you have spark? Yes and Verified with a timing light? yes
- do you have fuel pressure? With your FP gauge do you see a pressure rise after cranking? Yes and 0 to about 48 psi when I put the rail on, otherwise it holds pressure a really long time
- do you have injector 'clicks'? Do you have a fuel injector probe (like this one: XXX) Yes on clicks, no on the tool. Might have to get one of those. I like it

Has the engine speed sensor (aka CPS) ever been replaced? If so, when and with what brand/model. Yes and Bosch. Not sure on model, but Dan did it.
Who's "Rick?" Do you mean Rich Andrade? Yes, Rich. I was on the phone with a Rick before typing... defective user
Have you done a voltage drop test from battery post, to starter, to jump post, to fuse panel? No, but I am not having cranking issues. Plenty of juice.
When the engine rebuild was done, was the motor out of the engine bay? Yes, full rebuild like (or as Dan says, better than) new

Spun

I have not looked at the ignition switch. Its not so much monkeying with it as it will eventually just fire up. In my head I keep thinking stuck relay or not complete ground... but I have not been able to chase that demon with success. The relay swap, assuming tomorrow AM it will not fire up, will be the first part of that chase. I am considering going out and chasing the ground points now to see if I see anything.

Spun

This issue to show up after the new motor was put in. Prior to that and my burning up a MAF and LH, this did not happen. I have not contributed this something Dan did, more likely something I did or was temperature related since it has shown up more when the car is cold than not.... though I have had this now happen a couple times when the car has been running for 30-45 min and I went to restart.

Spun

Spun

57 Deg F this AM, no start. Fuel pressure good, spark good, fuel pump good. Replaced the following relays:

• XXV LH - No start
• XVI Elec Ignition - No start
• IV Ignition Relay X - Started

The Ignition Relay X is likely not the culprit, so we will start again tomorrow morning to see what happens unless anyone has something else I could try to work on while I wait for her not to start again. Gotta love intermittent problems.

SteveG

I don't see mention of the braided cable ground from chassis to rear of engine, passenger side accessed from underneath. This is a major ground, is bare, not encased in rubber insulation.

For starters (pun): Why are you using optimum batt? I would return battery and connections back there to stock including a new battery ground.

dr bob

I'd also look hard at the original battery ground strap shown in your picture. It's a known weak point, although it usually shows up with charging and voltage maintenance symptoms. In your case, a weak battery strap means the whole primary system is floating above chassis ground while the starter is cranking. Watch jump-start voltage to chassis while cranking to help some with the diagnosis. I upgraded to a new 2ga tinned-braid strap and a lot of low voltage symptoms wandered away. Our favorite vendors carry them I think.