LH computer question
Race Director
Joined: Sep 2007
Posts: 12,162
Likes: 383
From: Johnson City, TN
I'd also pull the two distributer caps (if not done already) and clean the contacts.
You mentioned a coil wire corrosion issue, but I didn't see reference to cap cleaning.
(Last Saturday we had a no-start 944, same end of camshaft distributor cap set up as this car. Had strobe from timing light. Turned-out, despite the strobe, the cap electrodes were so corroded it was barely salvagable. Cleaned it. Instant start.)
You mentioned a coil wire corrosion issue, but I didn't see reference to cap cleaning.
(Last Saturday we had a no-start 944, same end of camshaft distributor cap set up as this car. Had strobe from timing light. Turned-out, despite the strobe, the cap electrodes were so corroded it was barely salvagable. Cleaned it. Instant start.)
Addict
Rennlist Member
Rennlist Member
Joined: Jul 2002
Posts: 2,693
Likes: 52
From: AZ
Eric,
If you don't know anyone nearby who has a S4 for an LH swap for testing, I have a tester LH module that I can provide for you to test in your car. Drop me a line at info@electronikrepair.com.
If you don't know anyone nearby who has a S4 for an LH swap for testing, I have a tester LH module that I can provide for you to test in your car. Drop me a line at info@electronikrepair.com.
Rennlist Member
Joined: Jul 2001
Posts: 6,561
Likes: 113
From: New York
You've identified corrosion in more than one area. Read New Visitor thread and find list of grounds to clean. Check all ignition connections to/from coils, wires, ingnition components under front lip of hood, engine to chassis on bottom passenger (US)etc. side.
Thread Starter
Instructor
Joined: Mar 2009
Posts: 130
Likes: 0
From: NH USA
I saw all the new posts and I will run down those leads thanks.
A quick update.
I only had a chance to clean the connections at the battery... all the grounds, positive and connectors in that section.
For the heck of it I tried to start the car and of course no start as I figured. So I left the battery off and went on vacation. I got back after more than a week of sitting and for the heck of it again put the battery back on and... bingo it fired up! Hu? It ran a bit rough but settled down after a few minutes.
So the next morning I set about cleaning the grounds above the fuse/relay box. Then pulled each and every fuse (one at a time) and cleaned them. They all had heavy gray/black corrosion on them. Started the car again... still running. She does have the slight hesitation just off idle again though.
I am set to clean many of the other grounds and connections people have suggested and do the other tests this week as time allows. Just wanted to update all those who have helped.
Oh... one more thing to throw in. After the cleaning of the fuse/relay area... now the windows and sunroof do not work. DOU!
Had thought it was due to my fumbling around and maybe knocked the wires off the back of the fuses? Then read about the ignition switch issues... think this could be another place I need to look on this car?
Thanks
Eric
A quick update.
I only had a chance to clean the connections at the battery... all the grounds, positive and connectors in that section.
For the heck of it I tried to start the car and of course no start as I figured. So I left the battery off and went on vacation. I got back after more than a week of sitting and for the heck of it again put the battery back on and... bingo it fired up! Hu? It ran a bit rough but settled down after a few minutes.
So the next morning I set about cleaning the grounds above the fuse/relay box. Then pulled each and every fuse (one at a time) and cleaned them. They all had heavy gray/black corrosion on them. Started the car again... still running. She does have the slight hesitation just off idle again though.
I am set to clean many of the other grounds and connections people have suggested and do the other tests this week as time allows. Just wanted to update all those who have helped.
Oh... one more thing to throw in. After the cleaning of the fuse/relay area... now the windows and sunroof do not work. DOU!
Had thought it was due to my fumbling around and maybe knocked the wires off the back of the fuses? Then read about the ignition switch issues... think this could be another place I need to look on this car? Thanks
Eric
Racer
Joined: Jul 2009
Posts: 380
Likes: 0
From: Byhalia, MS
D
Rennlist Stories
The Best Porsche Posts for Porsche Enthusiasts
Porsche Reveals Coupe Variant of the Electric Cayenne With a Fresh Look
Verdad Gallardo
10 Porsche Colors That Have More Personality Than Most People
Verdad Gallardo
Guntherwerks' Final Speedster Creation Is the Ultimate Porsche Restomod
Verdad Gallardo
10 Reasons I Hate Going to the Porsche Dealership (& the 1 Reason I Stay)
Joe Kucinski
Porsche Shakes Up The Nürburgring Lap Record Table Once Again
Verdad Gallardo
6 Ways the Porsche 911 GT3 S/C Redefines Performance
Joe Kucinski
10 Wildest Homologation Specials Porsche Ever Sold
Verdad Gallardo
Super Rare RUF BTR III Comes Out of Hibernation, Looking For a New Home
Verdad Gallardo
10 Porsche Opinions That Can Start a Fight
Joe Kucinski
Thread Starter
Instructor
Joined: Mar 2009
Posts: 130
Likes: 0
From: NH USA
You mean this?
"First easy, free test - have someone operate the starter while you kneel by the back bumper listening for the buzz of the fuel pump. If you have no buzz, the car won't run.
If there is no buzz, first replace Fuse #42 - even if it looks perfect, replace it. Check for the buzz again.
If still no buzz, pull Relay XX (fuel pump) and install a temporary jumper between terminals 30 (power) and 87 (load - in this case, the fuel pump). With this jumper in place, the fuel pump must run. See if the car will run.
Let us know what you find - in excruciating detail!"
Sorry thought I posted that I did just that. Replaced fuse, jumped pump. Car still did not start.
Ok correction... just got back from lunch... it is dead again.
Made it home no problem... it is only .6 miles. Started after lunch no problem then died 1/2 way to work. It restarted only to die right in my parking space at work... no restart.
Guess it could not wait until tonight to have the other grounds and stuff checked out. Hmm... wonder if I can push a 3500 pound car up the two hills.
Also the car is running now. So... pump is running now on its own no jumper.
Car has run the past two days with no issues. Have a lot to do tonight though.
"First easy, free test - have someone operate the starter while you kneel by the back bumper listening for the buzz of the fuel pump. If you have no buzz, the car won't run.
If there is no buzz, first replace Fuse #42 - even if it looks perfect, replace it. Check for the buzz again.
If still no buzz, pull Relay XX (fuel pump) and install a temporary jumper between terminals 30 (power) and 87 (load - in this case, the fuel pump). With this jumper in place, the fuel pump must run. See if the car will run.
Let us know what you find - in excruciating detail!"
Sorry thought I posted that I did just that. Replaced fuse, jumped pump. Car still did not start.
Ok correction... just got back from lunch... it is dead again.
Made it home no problem... it is only .6 miles. Started after lunch no problem then died 1/2 way to work. It restarted only to die right in my parking space at work... no restart.
Guess it could not wait until tonight to have the other grounds and stuff checked out. Hmm... wonder if I can push a 3500 pound car up the two hills.
Also the car is running now. So... pump is running now on its own no jumper.
Car has run the past two days with no issues. Have a lot to do tonight though.
Last edited by Eturbo924; Aug 18, 2009 at 01:57 PM. Reason: Added car now dead.
Race Director
Joined: Sep 2007
Posts: 12,162
Likes: 383
From: Johnson City, TN
Well, you know, after you do all the catch-up work on grounds, relays, etc, it can still be the brain.
Earlier points were that you need to do all that other stuff, too.
Earlier points were that you need to do all that other stuff, too.
Last edited by Landseer; Oct 10, 2009 at 10:27 PM.
Thread Starter
Instructor
Joined: Mar 2009
Posts: 130
Likes: 0
From: NH USA
I thought the LH brain did not fail intermittant?
Some say yes others say no.
The car is definately possesed.
Worked on it again last night. Cleaned the remainder of the relays in question. Jumped the LH relay and FP relay with no change in starting issue.
Though... intermittantly it would fire up for my son, but not me. Each thing I checked and cleaned I would try to start it again. Some times it would fire right up and idle for maybe 20 sec and then die again.
Anyway more grounds to clean tonight. Was working in my companies parking lot last night so could not get under the car to much. Those will have to wait. I hope it will run long enough to get home tonight. Normally after sitting for a while it will. Crossing my fingers.
Thinking more and more it is the brain... but again... does it fail intermittant or not?
Some say yes others say no.
The car is definately possesed.
Worked on it again last night. Cleaned the remainder of the relays in question. Jumped the LH relay and FP relay with no change in starting issue.
Though... intermittantly it would fire up for my son, but not me. Each thing I checked and cleaned I would try to start it again. Some times it would fire right up and idle for maybe 20 sec and then die again.
Anyway more grounds to clean tonight. Was working in my companies parking lot last night so could not get under the car to much. Those will have to wait. I hope it will run long enough to get home tonight. Normally after sitting for a while it will. Crossing my fingers.
Thinking more and more it is the brain... but again... does it fail intermittant or not?
Rennlist Member
Joined: Jan 2008
Posts: 4,077
Likes: 331
From: Friday Harbor, WA
This sounds like corrosion somewhere that you have not found yet. You found corrosion on the fuses across the top, that suggests that it has gotten wet from a leak-- and water runs downhill. I would pull the CE panel out and check it carefully, as well as the grounds.
The "clicking" referred to here is a repetitive clicking from the top of the engine with the ignition on, once or twice a second. This a symptom of a dead/malfunctioning LH-- something in the LH pulses the injectors once or twice a second, maybe a "limp" mode? Dunno. But it can be caused by a corroded (high-resistance) power or ground connection causing low voltage to the LH under load.
If there is fuel pressure then this clicking will flood the engine and it will not start for some time-- this may explain why it tends to start after you ignore it for a while.
So while it may be the LH, unless you have one handy then I would put that off until you thoroughly clean the CE panel and its ground points.
EDIT: Also consider getting a fuel pressure gauge kit (gauge plus fitting) from Roger, this fits to the forward end of the pass-side fuel rail and is very handy. It will eliminate any questions of fuel pump, filter, lines, etc.
Also-- does this car have a second in-tank fuel pump? (I think 87's do not, but if so then it is a common failure).
Cheers, Jim
Thread Starter
Instructor
Joined: Mar 2009
Posts: 130
Likes: 0
From: NH USA
I have not replaced the fuel filter yet... had considered it.
It does not have the 2nd fuel pump in the tank.
I have found a lot of corrosion on many of the connections I have been able to check thus far. The 14 pin connector at the passenger front ground point (in engine bay just above passenger side coil) had some and I cleaned that.
Seems this car is in definate need of more work. I just want a magic bullet so I can drive it... and have not found it yet.
More work to be done tonight
Thanks all!
It does not have the 2nd fuel pump in the tank.
I have found a lot of corrosion on many of the connections I have been able to check thus far. The 14 pin connector at the passenger front ground point (in engine bay just above passenger side coil) had some and I cleaned that.
Seems this car is in definate need of more work. I just want a magic bullet so I can drive it... and have not found it yet.
More work to be done tonight
Thanks all!