Landseer

The 85 auto car is in a parking lot 1/2 mile away. Cannot get it to stay running!

Since I got it its been intermittent stall, no restart, partial restart, then runs ok awhile.

Today it failed on accelerating out of the neighborhood, wife driving which made it worse (on me). Am getting frustrated now.


What would cause the LH relay to go into a wild clicking / stucatto mode???
Even jumpered the car might occasionaly restart, but stall on accel from the parking place.

Had 8 new 53 relays with us, changed the EZH, LH(still stucato), fuel pump relay, with new ones.

Went back home, extracted known-good LH and EZH units from the 86 and same behavior when installed in the 85.

All known grounds are cleaned, except the one back right corner under the quarter panel.

New rubber in intake this week, new Temp II and airbox ambient T sensor.

Clean 14 pin, traced all engine compartment wires back into CE or LH/EZ units and didn't see any problems.

Maybe the CE panel itself? Changed one melted wire and picked through all the rest --- no other damage seen. All electrodes cleaned.

What am I missing????

New Porsche ignition switch yesterday.

Same behavior, intermittent problem, for 6 months.

Should I switch the 86 CE into it and try it.

Any other relays matter? All 53s are new.

What about Kickdown, I've not changed that one????

Have switched to a known good MAF, no diff.

Only other thing not changed is CPS. Could it make this type of relay strobe failure?
Any thoughts?

PorKen

The kickdown does have a rpm input. Unplug it.

John Speake

LH relay is energised by the LH ECU, as soon as the ignition is switched on. The LH relay is energised by pin 21 being pulled to ground by the LH ECU. The LH ECU itself is fed igntion switched 12v on pin 18 which starts the whole sequence of enrgising the LH relay. The volts on pin 18 come from the EZ-F relay.

You can also montor the 12v being fed to the other side of the coil to see if the problem is there. Check for a good, low resistance ground from pin 25 LH ECU and also Pins 5 and 11 LH ECU.

JHowell37

Is it raining down there? Didn't you last see this problem when it was wet?

Could this be a reference sensor with a short?

Mrmerlin

do you have a hot post cover fitted?
Has the car gotten wet it there water in the CE panel?
Is the ground strap wet in the hatch

Landseer

Thanks to everybody.
More troubleshooting to follow.

No pattern to this behavior. I've put about 4000 miles on it. Cutting out / no starts / runs great. Its a crapshoot. I've stumbled upon and fixed things obviously wrong. Thrown some parts at it too.

Just now, pulled kickdown, started, stalled as I pulled onto the road. We hooked a lead to the back of the surburban and dragged it home.

It's been in the heated garage for 6 weeks since towing it home the first time on a truck (failed in rain that day). Hasn't been wet at all. Got it back inside prior to rain just now.

New groundstrap, dry. CE dry.

The LH relay stuttering was very rapid. Still doing it. Back on the original brains now. Other brains back into 86 car / they still work.

Last night, started up, drove it mildly for 5 miles. Food store. Back out, heavier accel onto road, cut out. Restarted it, drove home, pulled off 4 times and did hard accel / no further problems last night.

A little low on gas, put 4 gallons hi test in ( by can, today, while out stranded). Not the problem.. Smelled gas on all start attempts.

Will use all above advice to help troubleshoot.

Things to look at: CE panel integrity, wire by wire, plug by plug, esp. Wplug. Replace CPS with known good unit. Pull glovebox and take a hard look at harness for LH that loops up there. Maybe rodent damage? Need to eyeball it.

hey, what about Alarm module breakdown??
Anybody know the bridge recipe for this?

Mrmerlin

hot post cover?? did you check the 14 pin connector pins??

Landseer

Have recently checked, not this time, yet.
Has a post cover, not a 14 pin cover.

Last time this happened I pulled the post and polished the post hot wires.

Will pull apart the 14 pin this evening. I'll pull and check, including top and bottom covers. Have cleaned it all once, but never re-flowed the solder joints. Could do that.

How about that right rear quarter ground? Could that contribute? That's one that's never been pulled by me, which means 10+ years.

Its the weirdest thing. A couple times today it started, I put it in either forward or reverse to move, give some gas, and all of a sudden it would go stuccato on the LH relay and die. Wife did it with my ear pressed against the panel so I could narrow down which relay.

Thinking about giving this thing to the volunteer fire department guys next door for fire/rescue training / practice. Very high frustration right now. Thanks for helping me focus, Stan.

WallyP

Clue 1: LH Relay XXV chatters.
Clue 2: Jumpering the LH relay doesn't help.
Clue 3: New LH ECU doesn't help.

First - Little relationship between the operating coil of the LH relay and the switched circuit. That is, the operating coil doesn't know or care what is on the switched circuit. Power for the coil comes straight from the battery. If you install a jumper on the switched circuit, it doesn't matter what the operating coil does or doesn't do.

There aren't many things in common with the two circuits. The three most suspicious points appear to me to be:
- Plug W, as both circuits pass thru W.
- The harness from W to the LH ECU, and the LH ECU connector.
- The heavy red cable from the starter to the alternator to the jump start terminal, that connection, and the three medium cables from the jump start terminal to the Central Electric Panel, and the small wire from there to the LH relay.

Landseer

Excellent, thanks. Will focus there.

Wally, what about the alarm? Its supposed to interrupt running. How?

WallyP

The power for the operating coil of the EZF Relay (XVI) runs from the 15 bus (ignition switched power) to the alarm box, thru a set of normally-closed contacts (opened when the alarm goes off), and from there back to F25 and to Terminal 86 (operating coil power) of Relay XVI. The other side of the operating coil is grounded.

So, the alarm kills the power to the EZF relay operating coil.

Mrmerlin

Huh now that you mention it. you need to get a hot post cover not just for the stud .
if the 14 pin connector has gotten wet then i would start there.

next would be to clean the ground behind the right side quarter panel in the hatch floor, this is a ground for the neutral safety switch among other things, if its not making a good ground then could also be a contributing problem

Jfrahm

Ignition switch?

Lizard928

What John means is that the LH relay is energized throught the EZF ECU.

I would be jumpering the LH/EZF, AND fuel pump. If the problem still happens then it is not the relays.

The LH relay will turn of/on by the EZF if the RPMs are stalling out. Then it is possible for them to catch.
I would be ensuring that the fuel pump is working, and also consider replacing the CPS if you havent already. It is a cheap part ($54 928srus) and they are all starting to need to be replaced. (new in both of my cars).

That is where I would start.

Landseer

Thanks, sir, that makes sense.

I've slept a bit, now time to attack.

Will try the triple jumper.

CPS, I think there is a working new one on this 944 I can try. / will get another on order today.

If that fails, then tear the biotch apart and trace the wires.