Storing a 928 without causing LH ECU damage?
06-22-2019, 10:42 AM
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Storing a 928 without causing LH ECU damage?
Short version: I wonder if stored 928s are better on a maintainer with the battery hooked up vs disconnecting the battery and reconnecting the battery. Maybe better for the health of the ECU? Also it's probably a good idea to get the ECU rebuilt so as to avoid this sort of nonsense or maybe a flatbed tow at some point.
I have two 928S4s, one is a project I have not done much with for a few years, the other is on a battery maintainer and I drive it from time to time.
The project: 1987 5-speed, supercharged, kind of a mutt, I have typically left the battery disconnected and charged, every so often I connect the battery and drive it around the neighborhood. Get it warmed up, etc. It suffered a bad ECU some years ago where it would not cold start but could be started with starting fluid or a trickle of fuel, and then it'd run on it's own and be pretty normal. If I was smart I'd have had that ECU rebuilt but I figured I'd killed the ECU with the battery charger and I'd be smarter about that going forward. So I got a good used ECU and the problem was gone.
Yesterday I wanted to pull this car out, get some work done on it but it'd only start-run-die. Investigation showed very little fuel, just a trickle, at the fuel rail. Jumpering the fuel pump relay got me fuel aplenty so I decided to run the tank dry of somewhat old, stabilized fuel while I had a hose hooked to the rail and some fresh ethanol-free gas handy. In the course of this, with the key on I now get (injectors, I think) click-click-clicking with the key on (just key on, not trying to start) so now I have two symptoms of LH ECU death:
- Fuel injection valves click when the ignition turned is on and engine is not running.
- No fuel pump operation, but the fuel pump operates when its relay is jumpered.
Two ECU kills now despite not putting the battery charger on the car this time?
Anyway I am wondering if it'd have been smarter to keep the project car on a maintainer with the battery connected vs connecting the battery via the ground strap when I wanted to run the car. I already know I should have gotten the ECU rebuilt last go-round rather than put in a good used non-rebuilt one. Unless for some reason this is not a bad ECU problem and is just a blown radio fuse or some dust in the ignition switch :-)
I have a good ECU (I believe has been rebuilt) handy I will try it when I am more certain I'm doing all the smart things to prevent ECU damage.
Cheers,
-Joel.
I have two 928S4s, one is a project I have not done much with for a few years, the other is on a battery maintainer and I drive it from time to time.
The project: 1987 5-speed, supercharged, kind of a mutt, I have typically left the battery disconnected and charged, every so often I connect the battery and drive it around the neighborhood. Get it warmed up, etc. It suffered a bad ECU some years ago where it would not cold start but could be started with starting fluid or a trickle of fuel, and then it'd run on it's own and be pretty normal. If I was smart I'd have had that ECU rebuilt but I figured I'd killed the ECU with the battery charger and I'd be smarter about that going forward. So I got a good used ECU and the problem was gone.
Yesterday I wanted to pull this car out, get some work done on it but it'd only start-run-die. Investigation showed very little fuel, just a trickle, at the fuel rail. Jumpering the fuel pump relay got me fuel aplenty so I decided to run the tank dry of somewhat old, stabilized fuel while I had a hose hooked to the rail and some fresh ethanol-free gas handy. In the course of this, with the key on I now get (injectors, I think) click-click-clicking with the key on (just key on, not trying to start) so now I have two symptoms of LH ECU death:
- Fuel injection valves click when the ignition turned is on and engine is not running.
- No fuel pump operation, but the fuel pump operates when its relay is jumpered.
Two ECU kills now despite not putting the battery charger on the car this time?
Anyway I am wondering if it'd have been smarter to keep the project car on a maintainer with the battery connected vs connecting the battery via the ground strap when I wanted to run the car. I already know I should have gotten the ECU rebuilt last go-round rather than put in a good used non-rebuilt one. Unless for some reason this is not a bad ECU problem and is just a blown radio fuse or some dust in the ignition switch :-)
I have a good ECU (I believe has been rebuilt) handy I will try it when I am more certain I'm doing all the smart things to prevent ECU damage.
Cheers,
-Joel.
06-22-2019, 11:20 AM
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I've disconnected / reconnected batteries on my 928's without damage so many times I doubt that's an issue. But, I suppose anytime you mess with that cable and see a slight "spark" there's potential for something going astray.
If you have the ability to keep the car on a maintainer when it's not in use, I've always felt that's the best option. For cars that I think will be stored longer than just a winter, I pull the batteries and keep them in the basement and cycle them through a maintainer.
As for rebuilding the LH, yes I feel that is a mandatory part of maintenance along with having the MAF rebuilt.
If you have the ability to keep the car on a maintainer when it's not in use, I've always felt that's the best option. For cars that I think will be stored longer than just a winter, I pull the batteries and keep them in the basement and cycle them through a maintainer.
As for rebuilding the LH, yes I feel that is a mandatory part of maintenance along with having the MAF rebuilt.
06-22-2019, 01:53 PM
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What H-P wrote-^.
LH 2.3 ECU should be rebuilt before it leaves you dead.
MAS rebuild is a periodic maintenance requirement.
I prefer to disconnect the ground cable at the battery post and not the chassis-end hex bolt; I feel that I get a quicker, cleaner connect/disconnect.
If one is really paranoid about the ECUs, it takes all of 30 seconds to remove the carpet and unlatch the connectors before messing with the ground strap.
LH 2.3 ECU should be rebuilt before it leaves you dead.
MAS rebuild is a periodic maintenance requirement.
I prefer to disconnect the ground cable at the battery post and not the chassis-end hex bolt; I feel that I get a quicker, cleaner connect/disconnect.
If one is really paranoid about the ECUs, it takes all of 30 seconds to remove the carpet and unlatch the connectors before messing with the ground strap.
06-22-2019, 03:32 PM
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Rich Andrade at http://www.electronikrepair.com/ rebuilds them himself; you get your unit back but rebuilt.
Louie Ott at https://www.performance928.com/home.html is the US rep for JDS Porsches core-exchange program; you get someone else's LH, rebuilt, with the chips from your LH in it.
Former is more expensive than the latter. Attachment to originality (AtO) or save money. Your choice.
Most of my clients have AtO. Rich rebuilds those. Clients without AtO get a JDS exchange through Louie.
Louie Ott at https://www.performance928.com/home.html is the US rep for JDS Porsches core-exchange program; you get someone else's LH, rebuilt, with the chips from your LH in it.
Former is more expensive than the latter. Attachment to originality (AtO) or save money. Your choice.
Most of my clients have AtO. Rich rebuilds those. Clients without AtO get a JDS exchange through Louie.
