Car won't start
11-25-2015, 12:44 AM
#31
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With injector relay energized, you'll see 12 volts on both sides of the injector connectors if any injectors are connected (current passes through injector coils, mete reads voltage) unless the LH controller is trying to actuate the injectors by pulling one side of the circuit low.
Edit: Bottom line, we need the noid light (either flavor) test.
11-25-2015, 01:29 AM
#32
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Expanding some on what Dave shared--
With injector relay energized, you'll see 12 volts on both sides of the injector connectors if any injectors are connected (current passes through injector coils, mete reads voltage) unless the LH controller is trying to actuate the injectors by pulling one side of the circuit low. So car sitting with key in run position, not cranking, it's normal to have 12 volts on both sides. When cranking, the crank position sensor and EZK should be telling the injectors to fire. That's the reason for using the noid light or that acoustic sensor to see if the injectors are seeing the pulsed ground from the LH. So pulse detected by noid light, plus fuel pressure verified with gauge, engine should run.
With injector relay energized, you'll see 12 volts on both sides of the injector connectors if any injectors are connected (current passes through injector coils, mete reads voltage) unless the LH controller is trying to actuate the injectors by pulling one side of the circuit low. So car sitting with key in run position, not cranking, it's normal to have 12 volts on both sides. When cranking, the crank position sensor and EZK should be telling the injectors to fire. That's the reason for using the noid light or that acoustic sensor to see if the injectors are seeing the pulsed ground from the LH. So pulse detected by noid light, plus fuel pressure verified with gauge, engine should run.
The problem here is that IF there is a shorted connector (e.g. fried insulation, and twisted), then it is very likely that the LH is toasted also. The LH activates the injectors by connecting the "ground side" of the injector harness to ground, via its driver transistors. If the injector harness is shorted anywhere then the LH is basically connecting the battery to ground, which vaporizes said transistors.
Worse, if the harness is shorted and then a known-good LH is tested in the car with the shorted harness, then that known-good LH is toasted also.
[Edit] My understanding from post#1 is that this LH was tested in a known-good car and works OK, correct? That would seem to eliminate a shorted harness, but not a harness problem of another flavor.
Agreed. This is the only thing that will say for sure that (1) the LH is OK, and (2) the harness is OK.
The other alternative is careful inspection of the injection harness: Disconnect all the injectors, ohm out the harness, inspect the connections and fix any bare wires. Even a blob of RTV, for now...
11-25-2015, 03:02 AM
#33
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Greatly appreciate all of the help you folks are sending
Believe it or not I had a significant role at Pratt and Whitney Aircraft when we were doing Project Apollo. However it was largely on the mechanical side and I have lost a lot of my electrical knowledge over the last twenty or thirty years. I'm not too bad as a ski instructor even at 80 years but electronics is not my long suit.
If LH is an abbreviation for the "brain", it was rebuilt and tested on a running 87 S4. That car ran fine.
If LH is an abbreviation for the "brain", it was rebuilt and tested on a running 87 S4. That car ran fine.
11-25-2015, 03:04 PM
#34
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How recently was the LH brain tested? My concern is that IF there is (or was) a short in the injector harness, then that can fry the LH-- which means the "no-start" condition will persist even after the shorted harness is fixed. The "noid light" test will help narrow it down,
I sent a PM, we're going to be in your neck of the woods but not until mid-February. If this isn't sorted by then I would be happy to see if I can help.
Cheers,
11-25-2015, 05:09 PM
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Hi Jim:
The LH (brain) was one of the "fixes" that did not fix. It was tried on another person's car when it would not start mine. Worked fine. Also rebuilt the air flow meter - didn't help either.
If you are going to be in the area, does that mean you are a skier? My wife and I were ski instructors for many years at the local "Snowy Range" ski area. If you look at one of the earlier posts on this thread you can see a little about this wonderful Wyoming.
The LH (brain) was one of the "fixes" that did not fix. It was tried on another person's car when it would not start mine. Worked fine. Also rebuilt the air flow meter - didn't help either.
If you are going to be in the area, does that mean you are a skier? My wife and I were ski instructors for many years at the local "Snowy Range" ski area. If you look at one of the earlier posts on this thread you can see a little about this wonderful Wyoming.
11-25-2015, 09:36 PM
#36
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The problem here is that IF there is a shorted connector (e.g. fried insulation, and twisted), then it is very likely that the LH is toasted also. The LH activates the injectors by connecting the "ground side" of the injector harness to ground, via its driver transistors. If the injector harness is shorted anywhere then the LH is basically connecting the battery to ground, which vaporizes said transistors.
But in either case, a single strand of copper wire on either side of the injector or a poor ground connection will give a 'good' voltage or continuity reading but can't pass any real current. My single-injector-connected test with the noid light will help diagnose that potential issue.
The throttle plate cable is close-enough to the right-side engine ground that careless maintenance can result in the cable slicing into the ground lead. I've seen that more than once. Also, which engine block ground hosts the injector ground seems to vary. It might be the one under the cable.
11-25-2015, 11:13 PM
#37
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Hi Jim:
The LH (brain) was one of the "fixes" that did not fix. It was tried on another person's car when it would not start mine. Worked fine. Also rebuilt the air flow meter - didn't help either.
If you are going to be in the area, does that mean you are a skier? My wife and I were ski instructors for many years at the local "Snowy Range" ski area. If you look at one of the earlier posts on this thread you can see a little about this wonderful Wyoming.
The LH (brain) was one of the "fixes" that did not fix. It was tried on another person's car when it would not start mine. Worked fine. Also rebuilt the air flow meter - didn't help either.
If you are going to be in the area, does that mean you are a skier? My wife and I were ski instructors for many years at the local "Snowy Range" ski area. If you look at one of the earlier posts on this thread you can see a little about this wonderful Wyoming.
And yes, we do a lot of silly things but taking the 928 to Wyoming in mid-Feb is not one of them. We've got a Cayenne, also. I am sure yours will be running by then, we'll just stop by and say "Hi" if that's OK.
Cheers, Jim
11-25-2015, 11:16 PM
#38
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I still suspect that it is a ground problem not a power problem.
But in either case, a single strand of copper wire on either side of the injector or a poor ground connection will give a 'good' voltage or continuity reading but can't pass any real current. My single-injector-connected test with the noid light will help diagnose that potential issue.
The throttle plate cable is close-enough to the right-side engine ground that careless maintenance can result in the cable slicing into the ground lead. I've seen that more than once. Also, which engine block ground hosts the injector ground seems to vary. It might be the one under the cable.
But in either case, a single strand of copper wire on either side of the injector or a poor ground connection will give a 'good' voltage or continuity reading but can't pass any real current. My single-injector-connected test with the noid light will help diagnose that potential issue.
The throttle plate cable is close-enough to the right-side engine ground that careless maintenance can result in the cable slicing into the ground lead. I've seen that more than once. Also, which engine block ground hosts the injector ground seems to vary. It might be the one under the cable.
11-26-2015, 02:29 PM
#39
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We would love to have you here
You have obviously been looking over your maps. Centennial used to be a town of 100 people. It now is almost 300 as people learn about this place. It's an old gold mining town. Now, we just mine a lot of snow.
I've been skiing for about 75 years, taught my wife how to ski 55 years ago and we started teaching about twenty years ago. We took instructor training at Steamboat and eventually became the Ski School Managers at Snowy Range. At eighty years old, we just ski for pleasure now.
We used to ski a lot at Steamboat but settled in on Winter Park/Mary Jane. If you haven't been there, give it a shot. Mary Jane has some of the gnarliest double diamond trails around; at 80 we now stick to dark blue and some occasional black although the Snowy Range "black" would not qualify for that at Mary Jane. The pictures on my thread are of Medicine Bow Peak at 11,000 feet.
By all means, let us know your plans as they materialize. We have a couple of empty bedrooms if you are looking for a place to settle for a day or two. Big log home on top of a hill.
Barney
I've been skiing for about 75 years, taught my wife how to ski 55 years ago and we started teaching about twenty years ago. We took instructor training at Steamboat and eventually became the Ski School Managers at Snowy Range. At eighty years old, we just ski for pleasure now.
We used to ski a lot at Steamboat but settled in on Winter Park/Mary Jane. If you haven't been there, give it a shot. Mary Jane has some of the gnarliest double diamond trails around; at 80 we now stick to dark blue and some occasional black although the Snowy Range "black" would not qualify for that at Mary Jane. The pictures on my thread are of Medicine Bow Peak at 11,000 feet.
By all means, let us know your plans as they materialize. We have a couple of empty bedrooms if you are looking for a place to settle for a day or two. Big log home on top of a hill.
Barney
11-26-2015, 02:35 PM
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Forgot to mention
I gather you would be coming out on I-80. If you got off in Laramie it is only a half hour to Centennial on Wyoming 130. Wyoming 230 is a direct shot down to either Steamboat or Winter Park.
07-27-2016, 07:50 AM
#43
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{QUOTE=BaEdwte;13480994}I know its hard to separate truth from fiction when M people are saying something not based upon knowledge of the system and N people are describing something based on knowing what the system is designed to do and you don't know who belongs in M and who belongs in N.
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Absolutely. It is a copy of the first sentence of one of my posts.
I've screwed with the format coding so that everyone can see what's behind the shiny facade and to memorialize the bot post before it's deleted.
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Absolutely. It is a copy of the first sentence of one of my posts.
I've screwed with the format coding so that everyone can see what's behind the shiny facade and to memorialize the bot post before it's deleted.
07-27-2016, 07:53 AM
#44
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What is interesting is that the links in the post are being filtered-out (for me at least.)