1989 928 flooding
Thread Starter
Racer
Joined: Jan 2014
Posts: 485
Likes: 1
From: Winnipeg, Manitoba Canada
I had checked odd spark plugs, but not all of the spark plugs. Given the joy of removing all of the spark plugs, I have to fix that hood switch connector again, there must be good reason a person that knows 928s would ask. Although not as bad as the V10 in m,y truck.
Well it does check 8 things at once. 7 of the spark plugs were wet and unbelievably clean, the 8th, cylinder 1 was carboned up and dry. I've had that connector off for testing, so user error could be a contribution, and it was probably 30 minutes between cranking and removing that plug, it was 10 minutes from the one before it, had to glue the rubber gripper back into the wrench. But it definitely had more carbon so time and one dry test is not the only thing.
I checked all of the fuel injection connectors, all were open to ground on the power side and 62 kohms to ground through the LH, this with the LH plugged in, tomorrow I will unplug it and see if that remains, even if that is a cable leak I can't see it triggering an injector.
It is interesting how they switch ground, all of the injectors have 12v on the power as soon as I turn the power on, they also have it on the switched side as it bleeds through the all of the injectors.
All of the injectors have 14.9-15.1 ohms of resistance across the coil, none on the right, including the dry one, have any conductivity to ground, I'll check the left tomorrow, the throttle makes it more fun than it should be. I checked a couple of the factory injectors and they were just below 16, pin oxidization may be contributing.
The temperature sensor 2 housing is 0.1 ohm different than the bridge, and there is no resistance between the bridge and the frame.
Warm, humid and mosquitos here, not as fun working in the garage as it can be.
Tomorrow or Monday,
Thanks,
Lance
Lance
Well it does check 8 things at once. 7 of the spark plugs were wet and unbelievably clean, the 8th, cylinder 1 was carboned up and dry. I've had that connector off for testing, so user error could be a contribution, and it was probably 30 minutes between cranking and removing that plug, it was 10 minutes from the one before it, had to glue the rubber gripper back into the wrench. But it definitely had more carbon so time and one dry test is not the only thing.
I checked all of the fuel injection connectors, all were open to ground on the power side and 62 kohms to ground through the LH, this with the LH plugged in, tomorrow I will unplug it and see if that remains, even if that is a cable leak I can't see it triggering an injector.
It is interesting how they switch ground, all of the injectors have 12v on the power as soon as I turn the power on, they also have it on the switched side as it bleeds through the all of the injectors.
All of the injectors have 14.9-15.1 ohms of resistance across the coil, none on the right, including the dry one, have any conductivity to ground, I'll check the left tomorrow, the throttle makes it more fun than it should be. I checked a couple of the factory injectors and they were just below 16, pin oxidization may be contributing.
The temperature sensor 2 housing is 0.1 ohm different than the bridge, and there is no resistance between the bridge and the frame.
Warm, humid and mosquitos here, not as fun working in the garage as it can be.
Tomorrow or Monday,
- Check resistance of fuel injector trigger wires with LH unplugged.
- Check resistance between block and LH casing, ground may still be an issue.
- I suspect that the casing on the MAF is grounded, I'll check that. That would give me results on the wire, the connector and the MAF.
- Do another wet attempted start with the pump running and pull out the spark plug for cylinder 1 again.
- If I leave all of the injector connectors off, I should be able to get a sharper line on my percentage test
- Still have MAF wiring to check, I'll also check temperature 2 wiring.
- Try a start test with the O2 sensor disconnected.
Thanks,
Lance
Lance
Rennlist Member
Joined: Feb 2002
Posts: 7,060
Likes: 42
From: Cambridge England
The casing of the MAF is 'ground' which is gets through pins 4 (via MPIX) and pin 3 (pin 6 LH).
The case of the LH isn't grounded to chassis, only via pins to external ground points.
Have you tried disconnecting the MAF and see if it is still excessively rich at idle ? It will run somewhat rich, but certainly not as bad as you describe.
The case of the LH isn't grounded to chassis, only via pins to external ground points.
Have you tried disconnecting the MAF and see if it is still excessively rich at idle ? It will run somewhat rich, but certainly not as bad as you describe.
Rennlist Member
Joined: Jul 2010
Posts: 1,774
Likes: 406
From: Bowling Green, KY
You may apply voltage drop tests in a range of ways on the 928. Make sure you that you completely understand the circuit you want to observe before loading the ground side.
Last edited by Kiln_Red; Aug 4, 2019 at 11:58 AM.
Thread Starter
Racer
Joined: Jan 2014
Posts: 485
Likes: 1
From: Winnipeg, Manitoba Canada
Sooo I had more than a couple of hours and started from the beginning.
It started, ran like crap, rich but ran. I figured the cats are probably plugged and the LH and EZ have no adaptations set, so I'll task running of any type.
Took it for a short ride on the highway 30m just to see if I could burn off the cats a little, and maybe start some adaptations.
When I started, I had low idle and would stall at rest, no power, using lots of gas still, probably 3 times normal. Shifting was late and harsh.
As I drove, the sound got better, not yet close to good, fuel consumption dropped to twice normal, shifting got better but still crappy, and the car had a little more power, by a little power I'm talking 01 TDI with automatic transmission would still be quicker. The idle was still 400 RPM, but it didn't stall if you got down to idle slowly.
So tomorrow:
It appears that there is hope. I do recall reading that is an S4 doesn't start there is likely more than one problem.
Any other suggestions are appretiated,
Thanks,
Lance
- Not previously done, checked the LH relay, it showed some heat on one of the load terminals, this could have contributed to lower voltage, cleaned up the terminals, deoxit and new relay.
- Checked the MAF, every which way, it looked good. It did occur to me that checking the resistance from the MAF housing to the chassis is a very good annual test, it checks the integrity of the wire to the LH, the ground from the LH to the block and the ground from the block to the chassis.
- I checked the temperature sensor 2, interestingly I found that one of the terminals was loose, and would jump back and forth between 2 k ohms and 20 kohms, the other sensor was at 2 K. Took that out and replaced it with the original that I hadn't thrown out, it test 2 K on both sensors.
- I straightened out a number of the female spring terminals in the LH connector, many didn't look like they would provide good contact.
- Reconnected everything that I'd disconnect.
It started, ran like crap, rich but ran. I figured the cats are probably plugged and the LH and EZ have no adaptations set, so I'll task running of any type.
Took it for a short ride on the highway 30m just to see if I could burn off the cats a little, and maybe start some adaptations.
When I started, I had low idle and would stall at rest, no power, using lots of gas still, probably 3 times normal. Shifting was late and harsh.
As I drove, the sound got better, not yet close to good, fuel consumption dropped to twice normal, shifting got better but still crappy, and the car had a little more power, by a little power I'm talking 01 TDI with automatic transmission would still be quicker. The idle was still 400 RPM, but it didn't stall if you got down to idle slowly.
So tomorrow:
- Check vacuum lines, so many things have been disconnected so many times, I may have missed one, or there may be an actual vacuum problem.
- Check the plug on 1 it was dry, if that cylinder is lean, the O2 sensor could be richening the fuel level to try to bring it back in line.
- Check the documentation on low idle and see what might be applicable.
It appears that there is hope. I do recall reading that is an S4 doesn't start there is likely more than one problem.
Any other suggestions are appretiated,
Thanks,
Lance
Thread Starter
Racer
Joined: Jan 2014
Posts: 485
Likes: 1
From: Winnipeg, Manitoba Canada
Pulled #1 plug, it was all carboned up so I changed the injector.
Motor starts better, sounds better, but still a low idle.
Exhaust smells rich but that may be reminants of the big flood.
Vacuum lines were all intact, checked the fuel regulators and dampener, all held vacuum.
Checked the lines from the front T, there is a slow vacuum leak in the line that goes to the transmission. Disconnected and capped that line, testing from the manifold line, everything was tight.
At anything over 700 rpm, even with the transmission line connected, the vacuum is 14.5 inches, measured at the dampener with a T.
Below 600 rpm, when the idle gets erratic, vacuum bounces between 12 and 14.5.
With the littlest bit of throttle I idles well, still have to see how it drives. In addition to everything else do I have an idle valve sticking? Is the bounce in vacuum that valve trying to maintain rpms?
I'm going to put it together and go for another ride to see if there are any other changes.
Any suggestions on idle?
thanks,
Lance,
Motor starts better, sounds better, but still a low idle.
Exhaust smells rich but that may be reminants of the big flood.
Vacuum lines were all intact, checked the fuel regulators and dampener, all held vacuum.
Checked the lines from the front T, there is a slow vacuum leak in the line that goes to the transmission. Disconnected and capped that line, testing from the manifold line, everything was tight.
At anything over 700 rpm, even with the transmission line connected, the vacuum is 14.5 inches, measured at the dampener with a T.
Below 600 rpm, when the idle gets erratic, vacuum bounces between 12 and 14.5.
With the littlest bit of throttle I idles well, still have to see how it drives. In addition to everything else do I have an idle valve sticking? Is the bounce in vacuum that valve trying to maintain rpms?
I'm going to put it together and go for another ride to see if there are any other changes.
Any suggestions on idle?
thanks,
Lance,
Thread Starter
Racer
Joined: Jan 2014
Posts: 485
Likes: 1
From: Winnipeg, Manitoba Canada
So I put the air filter in, leaned out the s4 idle adjustment, and I now have a steady idle at 600 rpm. At 80 C 190 F ish, I have over 16.75 vacuum, a hair under 17. I get 17 if I disconnect and cap the transmission line.
If I turn on the ac, or the cooling fans come on the rpm drops hard to 400, not stalling but close.
Are the LH and EZ still learnings?
If I turn on the ac, or the cooling fans come on the rpm drops hard to 400, not stalling but close.
Are the LH and EZ still learnings?
Rennlist Member
Joined: Jun 2005
Posts: 10,578
Likes: 1,030
From: Oman
So I put the air filter in, leaned out the s4 idle adjustment, and I now have a steady idle at 600 rpm. At 80 C 190 F ish, I have over 16.75 vacuum, a hair under 17. I get 17 if I disconnect and cap the transmission line.
If I turn on the ac, or the cooling fans come on the rpm drops hard to 400, not stalling but close.
Are the LH and EZ still learnings?
If I turn on the ac, or the cooling fans come on the rpm drops hard to 400, not stalling but close.
Are the LH and EZ still learnings?
Ho did you lean out the idle? Is that auxiliary pot that came with Ken's chipset?
The lower the rpms the deeper the vacuum pulled.
Thread Starter
Racer
Joined: Jan 2014
Posts: 485
Likes: 1
From: Winnipeg, Manitoba Canada
I did the WD40 idle valve treatment with PB blaster, it seems to recover better to the 600 with a rapid change in throttle, appeared to still be dropping clos to 400 when extra load applied.
The aux pot for the S4 chip is, to my understanding, strictly for control of richness at idle. I noticed that if I moved the throttle, in the engine bay, just enough to get off of the idle switch, still less than 700 rpm, things settled down a lot.
As I've leaned it out the idle has come up 100 rpm. I'm going to take it for a ride now and report back shortly.
Burning out the cats may prove to be beneficial as will some LH EZ learning time.
Lance
The aux pot for the S4 chip is, to my understanding, strictly for control of richness at idle. I noticed that if I moved the throttle, in the engine bay, just enough to get off of the idle switch, still less than 700 rpm, things settled down a lot.
As I've leaned it out the idle has come up 100 rpm. I'm going to take it for a ride now and report back shortly.
Burning out the cats may prove to be beneficial as will some LH EZ learning time.
Lance
Rennlist Stories
The Best Porsche Posts for Porsche Enthusiasts
9 Features and Characteristics That Only Porsche People Understand
Verdad Gallardo
I've Written 500 Rennlist Articles: Here's How Porsche Has Changed Along the Way
Joe Kucinski
10 Most Unnecessary Porsches Ever Built (And Why We Love Them)
Verdad Gallardo
Porsche 911 GT3 S/C vs 718 Spyder RS: 10 Categories, One Winner
Joe Kucinski
This Builder Is Turning Heads With Its Slantnose 911 Creation
Verdad Gallardo
Porsche 911 GT3 Artisan Edition Pays Homage to Japanese Culture
Verdad Gallardo
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
Thread Starter
Racer
Joined: Jan 2014
Posts: 485
Likes: 1
From: Winnipeg, Manitoba Canada
So, better, but far from good.
I'm going to go out and change the MAF, I'll check the ICV wiring, the best I can while I'm in there.
The lack of torque has me thinking, that and the noise are consistent with a heavy retard, I guess rich slows the propagation of the flame until latter in the cycle.
I'll keep everyone in the loop. The good news is at least I have it in the service bay side of my garage now.
Lance
- maybe 60% more fuel at steady state.
- Louder deeper exhaust, but no crack.
- No torque
- No acceleration, lots of noise
- Shifts range from fair to rude
- Idel is worse wen driving generally around 400 rpm, it would likely stall if I didn't put it into neutral.
- Launch is painful car dropped to first gear several times.
I'm going to go out and change the MAF, I'll check the ICV wiring, the best I can while I'm in there.
The lack of torque has me thinking, that and the noise are consistent with a heavy retard, I guess rich slows the propagation of the flame until latter in the cycle.
I'll keep everyone in the loop. The good news is at least I have it in the service bay side of my garage now.
Lance
Rennlist Member
Joined: Jun 2005
Posts: 10,578
Likes: 1,030
From: Oman
I did the WD40 idle valve treatment with PB blaster, it seems to recover better to the 600 with a rapid change in throttle, appeared to still be dropping clos to 400 when extra load applied.
The aux pot for the S4 chip is, to my understanding, strictly for control of richness at idle. I noticed that if I moved the throttle, in the engine bay, just enough to get off of the idle switch, still less than 700 rpm, things settled down a lot.
As I've leaned it out the idle has come up 100 rpm. I'm going to take it for a ride now and report back shortly.
Burning out the cats may prove to be beneficial as will some LH EZ learning time.
Lance
The aux pot for the S4 chip is, to my understanding, strictly for control of richness at idle. I noticed that if I moved the throttle, in the engine bay, just enough to get off of the idle switch, still less than 700 rpm, things settled down a lot.
As I've leaned it out the idle has come up 100 rpm. I'm going to take it for a ride now and report back shortly.
Burning out the cats may prove to be beneficial as will some LH EZ learning time.
Lance
There are several reasons why the ISV may not be working viz:
1. Idle switch contact not making.
2. ISV not working
3. ISV connector not made.
4. The shuttle in the ISV is gummed up.
Squirting WD40 in there could make a difference to a sticking ISV not that I think it is a good idea- not something I would do but that is my choice given I can pull the inlet manifold and get it back on in an afternoon.. I had such a problem many years ago and after pulling the ISV found it had a dry powdery substance gumming things up- cleaned it out with cloth/swabs and it worked perfectly upon reinstatement for many more years.
Thread Starter
Racer
Joined: Jan 2014
Posts: 485
Likes: 1
From: Winnipeg, Manitoba Canada
Tried a different MAF, it was measuring less air at the low end, I had to increase the idle richness with the S4 pot.
It was different to drive better by maybe a touch. But still painful.
Returned home and pulled the plug on the O2 sensor, idle was more choppy, more torque, but again worlds away from what I'd expect.
I couldn't see anything with the ICV, the same 600 rpm unloaded 400 rpm loaded, I'll lookup the pins and see if there is a test. I can tap into the O2 sensor and see what it thinks the AFM is.
i'm half inclined to pull all of the plugs again, that was the most definitive info I've had.
I can check the valve timing, there is no reason to expect there is an issue, but that could explain, noise and lack of power.
Installing factory injectors and the factory LH chip is still on the table, I have to find the standard programming block. If I don't find evidence that the LH is trying to control the ICV, that path is a likely.
Any other ideas?
thanks,
Lance
It was different to drive better by maybe a touch. But still painful.
Returned home and pulled the plug on the O2 sensor, idle was more choppy, more torque, but again worlds away from what I'd expect.
I couldn't see anything with the ICV, the same 600 rpm unloaded 400 rpm loaded, I'll lookup the pins and see if there is a test. I can tap into the O2 sensor and see what it thinks the AFM is.
i'm half inclined to pull all of the plugs again, that was the most definitive info I've had.
I can check the valve timing, there is no reason to expect there is an issue, but that could explain, noise and lack of power.
Installing factory injectors and the factory LH chip is still on the table, I have to find the standard programming block. If I don't find evidence that the LH is trying to control the ICV, that path is a likely.
Any other ideas?
thanks,
Lance
Thread Starter
Racer
Joined: Jan 2014
Posts: 485
Likes: 1
From: Winnipeg, Manitoba Canada
Out setting up a test for the O2 sensor, I have my head under the dash and the car running. The cooling fan comes on and the car just keeps humming away.
I get up look at the tach and it's a perfect 675, but there's a problem, the dash is lit up with conserve power. I give the throttle a blip, and the warning goes out, rpms drop to 400. Clearly the voltage regulator had not cut in, and the alternator was free wheeling, but I will think about it some more.
On the O2 sensor starts at 800 when car is started, gets down to 600 and then drops to 0 and cycles between 0 and 700 plus. From what I've read it should be going to 200. I need to read some more before I say it's bad, new 3 years ago.
Lance
I get up look at the tach and it's a perfect 675, but there's a problem, the dash is lit up with conserve power. I give the throttle a blip, and the warning goes out, rpms drop to 400. Clearly the voltage regulator had not cut in, and the alternator was free wheeling, but I will think about it some more.
On the O2 sensor starts at 800 when car is started, gets down to 600 and then drops to 0 and cycles between 0 and 700 plus. From what I've read it should be going to 200. I need to read some more before I say it's bad, new 3 years ago.
Lance
Thread Starter
Racer
Joined: Jan 2014
Posts: 485
Likes: 1
From: Winnipeg, Manitoba Canada
https://rennlist.com/forums/928-foru...oblem-maf.html
So I'm checking the temp ii sensor at operating conditions,
It appears that enough rich and it will slow down idle.
Lance
So I'm checking the temp ii sensor at operating conditions,
It appears that enough rich and it will slow down idle.
Lance
Thread Starter
Racer
Joined: Jan 2014
Posts: 485
Likes: 1
From: Winnipeg, Manitoba Canada
So on Tuesday night I warmed the engine up and checked the sensor II readings. At the LH it appeared at the time to have gone to infinite. I checked the sensor and it was OK. I surmised at the time that I had a funcky wire, but I was too exhausted to check. Then the rest of the week was just work.
Just checked it again and couldn't duplicate, went over the wire connecting and disconnecting, bending and unbending, no change, deoxit on both ends back together and no change in operation. I'm reasonably confident that I made a reading error.
Pulled the plugs, 5 were sooty 3 were clean and smelled of gas.
I'm going to do the suggested voltage test across the block, failing a revelation with that I'm going to install the factory injectors and the factory LH chip. I've done a quick tune on the injectors, powered them and sprayed through them with paint gun cleaner followed by air, they all looked OK. I found the programming block so good to go. My thoughts are that given the sudden huge change it isn't something that there are multiples of. Even if 2 injectors suddenly went rogue they shouldn't make the LH go rich. The single point failures are the temperature II sensor, changed, the MAF, changed, the LH, rebuilt but original chip, and ground. I have to change the injectors to change the LH so I guess that's a bonus.
If it works I can go back and put in 8 different injectors and try the S4 chip again.
If anyone has any other ideas, let me know.
Thanks,
Lance
Just checked it again and couldn't duplicate, went over the wire connecting and disconnecting, bending and unbending, no change, deoxit on both ends back together and no change in operation. I'm reasonably confident that I made a reading error.
Pulled the plugs, 5 were sooty 3 were clean and smelled of gas.
I'm going to do the suggested voltage test across the block, failing a revelation with that I'm going to install the factory injectors and the factory LH chip. I've done a quick tune on the injectors, powered them and sprayed through them with paint gun cleaner followed by air, they all looked OK. I found the programming block so good to go. My thoughts are that given the sudden huge change it isn't something that there are multiples of. Even if 2 injectors suddenly went rogue they shouldn't make the LH go rich. The single point failures are the temperature II sensor, changed, the MAF, changed, the LH, rebuilt but original chip, and ground. I have to change the injectors to change the LH so I guess that's a bonus.
If it works I can go back and put in 8 different injectors and try the S4 chip again.
If anyone has any other ideas, let me know.
Thanks,
Lance
Thread Starter
Racer
Joined: Jan 2014
Posts: 485
Likes: 1
From: Winnipeg, Manitoba Canada
Maximum voltage drop 15 mv, and that was between the battery and the boost terminal.
No difference between the voltage across the battery and between the battery and block with the key on, or the key off. I did not do this test with the engine running, as I had the spark plugs out.
Arguably the test should be done with the engine running to see the impact of the alternator. I will do that when I have the system reverted to factory injectors and LH.
I have the factory injectors back in and also the plugs, just have to R&R the LH.
No difference between the voltage across the battery and between the battery and block with the key on, or the key off. I did not do this test with the engine running, as I had the spark plugs out.
Arguably the test should be done with the engine running to see the impact of the alternator. I will do that when I have the system reverted to factory injectors and LH.
I have the factory injectors back in and also the plugs, just have to R&R the LH.