New Shark Owner needs help
09-12-2010, 06:32 PM
#16
Rennlist Member
Yes, when I mentioned the idle switch, I was referring to one half of the inappropriately named 'TPS'. The 'Throttle position switch' is really just a set of contacts that have three states (for the purpose of this discussion).
1: idle
2: cruise
3: WOT
The LH determines which fuel map to use based on this. If the idle is dropping down really low but the idle switch isn't reset, it's going to try to fix it with the cruise map rather than the idle fuel map and the cruise map doesn't expect it to come down below 750 or so, so it's going to bounce.
Good luck with it.
1: idle
2: cruise
3: WOT
The LH determines which fuel map to use based on this. If the idle is dropping down really low but the idle switch isn't reset, it's going to try to fix it with the cruise map rather than the idle fuel map and the cruise map doesn't expect it to come down below 750 or so, so it's going to bounce.
Good luck with it.
But..the tonneau cover...nah...no way.
09-12-2010, 10:10 PM
#17
Intermediate
Thread Starter
I was able to fit a gauge to the intake which is how I found the leaky FI. Soap and water is what I used to find the FI leak. Unfortunately, I still can't build any pressure and I can't hear the leak. I'll probably try again but I'm thinking I'll focus on ruling out electrical and TPS for now.
09-12-2010, 10:16 PM
#18
Intermediate
Thread Starter
This is off topic, but if anyone is looking for an 86.5. I was tempted to go after this one on CL....
http://denver.craigslist.org/cto/1945602815.html
I love the color but when I found a 5 Spd local, my choice was made easier. I never called on this one so it could be gone for all I know. I found that most folks are having trouble finding buyers for their 928 so it might still be available if it was legit to begin with. I have no affiliation to this whatsoever.
http://denver.craigslist.org/cto/1945602815.html
I love the color but when I found a 5 Spd local, my choice was made easier. I never called on this one so it could be gone for all I know. I found that most folks are having trouble finding buyers for their 928 so it might still be available if it was legit to begin with. I have no affiliation to this whatsoever.
09-13-2010, 07:23 AM
#19
Intermediate
Thread Starter
Update
So I tried to go through the procedure for troubleshooting the LH-Jetronic from the WSM (24-108). I quickly realized that all of my diagrams were for S4 models and their 36 pin connectors. I was able to find a 25 pin connector diagram on the forum and did a few tests. I believe it was Ken who posted that - thank you. I did all of these tests with the ignition in the "on" position FWIW. Here are the results...
1. Testing voltage between pins 9 and 5 on the LH: no voltage. I'm thinking his can't be right b/c the car does run. I wanted to test voltage from the plug but the WSM tells me to test the X plug and I don't have an X plug. I figure it's the W plug but mine has 10 pins and not 8 so I'm not sure which one to test. Does anyone with an 85/86 know which terminal I should be testing on the W plug for voltage?
2. Testing voltage between pins 18 (ignition on) and 5: battery voltage. I did this just to verify that I could get a reading and that I was using the multimeter properly. When I turn the ignition "off", the voltage between 18 and 5 goes to zero.
3. Testing resistance between pins 2 (temp 2 sensor) and 5: 2.4 kOhms which was within spec considering the car was cold. While doing this, I was wondering how one would go about testing across the temperature range. Maybe the car will run w/o the LH?
4. Testing resistance between pins 3 (idle) and 5: inf. ohms with the throttle open or closed. Based on this result, it seems the idle switch has a break.
5. Testing resistance between pins 12 (WOT) and 5: inf. ohms until I put the pedal to the floor, then 8.1 ohms. Interestingly, I have to floor it to measure any resistance. 2/3 pedal doesn't do it. I'm not surprised as I've thought the pedal needed adjusting from day one. It occurred to me that the idle switch may not be reading a "closed" position simply b/c the throttle needs adjustment. Is that possible?
I've never used a multimeter to test anything other than AA/AAA batteries, so it's safe to say that I'm no expert. The multimeter does seem to be working properly (measures 0 resistance when I touch the leads together). For any 85/86 owners out there, I could use some help in verifying that my LH is getting power or troubleshooting it if it isn't. Specifically, which pins do I use to verify voltage?
Thanks in advance.
1. Testing voltage between pins 9 and 5 on the LH: no voltage. I'm thinking his can't be right b/c the car does run. I wanted to test voltage from the plug but the WSM tells me to test the X plug and I don't have an X plug. I figure it's the W plug but mine has 10 pins and not 8 so I'm not sure which one to test. Does anyone with an 85/86 know which terminal I should be testing on the W plug for voltage?
2. Testing voltage between pins 18 (ignition on) and 5: battery voltage. I did this just to verify that I could get a reading and that I was using the multimeter properly. When I turn the ignition "off", the voltage between 18 and 5 goes to zero.
3. Testing resistance between pins 2 (temp 2 sensor) and 5: 2.4 kOhms which was within spec considering the car was cold. While doing this, I was wondering how one would go about testing across the temperature range. Maybe the car will run w/o the LH?
4. Testing resistance between pins 3 (idle) and 5: inf. ohms with the throttle open or closed. Based on this result, it seems the idle switch has a break.
5. Testing resistance between pins 12 (WOT) and 5: inf. ohms until I put the pedal to the floor, then 8.1 ohms. Interestingly, I have to floor it to measure any resistance. 2/3 pedal doesn't do it. I'm not surprised as I've thought the pedal needed adjusting from day one. It occurred to me that the idle switch may not be reading a "closed" position simply b/c the throttle needs adjustment. Is that possible?
I've never used a multimeter to test anything other than AA/AAA batteries, so it's safe to say that I'm no expert. The multimeter does seem to be working properly (measures 0 resistance when I touch the leads together). For any 85/86 owners out there, I could use some help in verifying that my LH is getting power or troubleshooting it if it isn't. Specifically, which pins do I use to verify voltage?
Thanks in advance.
09-13-2010, 08:00 AM
#21
Craic Head
Lifetime Rennlist
Member
Lifetime Rennlist
Member
JP,
If your LH wasn't getting power your car wouldn't be running so I don't think you have to worry about that. FWIW, unless you're REALLY good with a VOM (Volt-Ohm Meter) you should only be testing things with the key off (and probably with the battery disconnected).
You can unplug the LH and EZK plugs without causing a problem with the key off (even with battery in) but I wouldn't turn the key on to do any testing unless you're really confident. If you short anything out in there with the leads of the meter you could toast something.
The tests for idle and WOT switch operation are not voltage tests, they are continuity tests across terminals on the harness so you can do them without power.
Idle test (on LH harness, which is the one without the vacuum line)
Engine ground is pin 25, idle switch is pin 3 (edited, previously said 5 sir)
WOT test
Engine ground is pin 25, WOT switch is pin 12
From Porken's site:
What I do is put my meter pins in the right place and hold it there and have someone step on the gas pedal or just reach over with a broom handle or something and push the gas pedal down.
You're probably right about your gas pedal adjustment. There are lots of things that could go wrong with that linkage from one end to the other.
Here are a few I've found in my car (or someone else's)
1: Throttle rod adjustment- If it's too tight, the spring from the throttle console will not let the idle switch (part of the TPS) reset.
2: Throttle cable loose- This can give sloppy performance and move the WOT all the way to the floor (because the slack causes it to engage late).
3: Throttle cable too tight- (Might not reset idle switch for same reason as #1).
4: TPS adjustment out of whack/full of oil- There's much written on this but suffice it to say that if you haven't done a top end refresh you may want to address this. The TPS can get oil in it from the throttle body and it affects the contacts in the TPS. It can also be out of alignment and require adjustment.
5: TPS wiring/harness- Roger at 928sRus has a new harness that goes from the TPS switch to the back of the test port on the front of the engine (shown in Ken's pic above). Yours may look OK but if it's original it's probably very brittle and the pins at both ends just push on so if there's any corrosion you may have issues with resistance. It's hard to replace unless you're doing a top-end refresh, but it can be done if you're careful and patient.
6: Gas pedal issues: Check that the carpet isn't interfering with it, check for free operation of the pedal throughout the range of it's operation. Check that the bushings at the pivot point are clean and lubed. In fact it's good practice to just remove the whole assembly and clean it up to get everything moving smoothly, then adjust the throttle cable in the engine compartment. You may notice (like I did) that it wasn't anywhere near as smooth as it could be.
I agree that job 1 needs to be to make sure the TPS contacts and especially the idle switch input is reaching the LH before moving on. If you have any vacuum leaks they're not bad enough to cause a rough idle or surging so they may wait for another day.
If your LH wasn't getting power your car wouldn't be running so I don't think you have to worry about that. FWIW, unless you're REALLY good with a VOM (Volt-Ohm Meter) you should only be testing things with the key off (and probably with the battery disconnected).
You can unplug the LH and EZK plugs without causing a problem with the key off (even with battery in) but I wouldn't turn the key on to do any testing unless you're really confident. If you short anything out in there with the leads of the meter you could toast something.
The tests for idle and WOT switch operation are not voltage tests, they are continuity tests across terminals on the harness so you can do them without power.
Idle test (on LH harness, which is the one without the vacuum line)
Engine ground is pin 25, idle switch is pin 3 (edited, previously said 5 sir)
WOT test
Engine ground is pin 25, WOT switch is pin 12
From Porken's site:
What I do is put my meter pins in the right place and hold it there and have someone step on the gas pedal or just reach over with a broom handle or something and push the gas pedal down.
You're probably right about your gas pedal adjustment. There are lots of things that could go wrong with that linkage from one end to the other.
Here are a few I've found in my car (or someone else's)
1: Throttle rod adjustment- If it's too tight, the spring from the throttle console will not let the idle switch (part of the TPS) reset.
2: Throttle cable loose- This can give sloppy performance and move the WOT all the way to the floor (because the slack causes it to engage late).
3: Throttle cable too tight- (Might not reset idle switch for same reason as #1).
4: TPS adjustment out of whack/full of oil- There's much written on this but suffice it to say that if you haven't done a top end refresh you may want to address this. The TPS can get oil in it from the throttle body and it affects the contacts in the TPS. It can also be out of alignment and require adjustment.
5: TPS wiring/harness- Roger at 928sRus has a new harness that goes from the TPS switch to the back of the test port on the front of the engine (shown in Ken's pic above). Yours may look OK but if it's original it's probably very brittle and the pins at both ends just push on so if there's any corrosion you may have issues with resistance. It's hard to replace unless you're doing a top-end refresh, but it can be done if you're careful and patient.
6: Gas pedal issues: Check that the carpet isn't interfering with it, check for free operation of the pedal throughout the range of it's operation. Check that the bushings at the pivot point are clean and lubed. In fact it's good practice to just remove the whole assembly and clean it up to get everything moving smoothly, then adjust the throttle cable in the engine compartment. You may notice (like I did) that it wasn't anywhere near as smooth as it could be.
I agree that job 1 needs to be to make sure the TPS contacts and especially the idle switch input is reaching the LH before moving on. If you have any vacuum leaks they're not bad enough to cause a rough idle or surging so they may wait for another day.
09-13-2010, 07:27 PM
#22
Intermediate
Thread Starter
Thanks Mike. I wasn't sure if the switches would work w/o power. By the way, you say the that idle switch is pin 5, but the diagram says pin 5 is ground and pin 3 is idle. Is the diagram wrong? That's the same one I was using and I don't want to do any more damage than I may have already done. If the diagram is right, what is the difference between the ground on pin 5 and pin 25?
09-13-2010, 07:31 PM
#23
Intermediate
Thread Starter
Thanks Dan. Bill actually helped the PO with a TB replace some time back. I can use all the help I can get and may have to bribe Bill with beer and pizza. The car is due for a new TB (about 5 yrs).
09-14-2010, 06:06 AM
#24
Intermediate
Thread Starter
another update with some pics
JP,
If your LH wasn't getting power your car wouldn't be running so I don't think you have to worry about that. FWIW, unless you're REALLY good with a VOM (Volt-Ohm Meter) you should only be testing things with the key off (and probably with the battery disconnected).
You can unplug the LH and EZK plugs without causing a problem with the key off (even with battery in) but I wouldn't turn the key on to do any testing unless you're really confident. If you short anything out in there with the leads of the meter you could toast something.
The tests for idle and WOT switch operation are not voltage tests, they are continuity tests across terminals on the harness so you can do them without power.
Idle test (on LH harness, which is the one without the vacuum line)
Engine ground is pin 25, idle switch is pin 5
WOT test
Engine ground is pin 25, WOT switch is pin 12
From Porken's site:
What I do is put my meter pins in the right place and hold it there and have someone step on the gas pedal or just reach over with a broom handle or something and push the gas pedal down.
You're probably right about your gas pedal adjustment. There are lots of things that could go wrong with that linkage from one end to the other.
Here are a few I've found in my car (or someone else's)
1: Throttle rod adjustment- If it's too tight, the spring from the throttle console will not let the idle switch (part of the TPS) reset.
2: Throttle cable loose- This can give sloppy performance and move the WOT all the way to the floor (because the slack causes it to engage late).
3: Throttle cable too tight- (Might not reset idle switch for same reason as #1).
4: TPS adjustment out of whack/full of oil- There's much written on this but suffice it to say that if you haven't done a top end refresh you may want to address this. The TPS can get oil in it from the throttle body and it affects the contacts in the TPS. It can also be out of alignment and require adjustment.
5: TPS wiring/harness- Roger at 928sRus has a new harness that goes from the TPS switch to the back of the test port on the front of the engine (shown in Ken's pic above). Yours may look OK but if it's original it's probably very brittle and the pins at both ends just push on so if there's any corrosion you may have issues with resistance. It's hard to replace unless you're doing a top-end refresh, but it can be done if you're careful and patient.
6: Gas pedal issues: Check that the carpet isn't interfering with it, check for free operation of the pedal throughout the range of it's operation. Check that the bushings at the pivot point are clean and lubed. In fact it's good practice to just remove the whole assembly and clean it up to get everything moving smoothly, then adjust the throttle cable in the engine compartment. You may notice (like I did) that it wasn't anywhere near as smooth as it could be.
I agree that job 1 needs to be to make sure the TPS contacts and especially the idle switch input is reaching the LH before moving on. If you have any vacuum leaks they're not bad enough to cause a rough idle or surging so they may wait for another day.
If your LH wasn't getting power your car wouldn't be running so I don't think you have to worry about that. FWIW, unless you're REALLY good with a VOM (Volt-Ohm Meter) you should only be testing things with the key off (and probably with the battery disconnected).
You can unplug the LH and EZK plugs without causing a problem with the key off (even with battery in) but I wouldn't turn the key on to do any testing unless you're really confident. If you short anything out in there with the leads of the meter you could toast something.
The tests for idle and WOT switch operation are not voltage tests, they are continuity tests across terminals on the harness so you can do them without power.
Idle test (on LH harness, which is the one without the vacuum line)
Engine ground is pin 25, idle switch is pin 5
WOT test
Engine ground is pin 25, WOT switch is pin 12
From Porken's site:
What I do is put my meter pins in the right place and hold it there and have someone step on the gas pedal or just reach over with a broom handle or something and push the gas pedal down.
You're probably right about your gas pedal adjustment. There are lots of things that could go wrong with that linkage from one end to the other.
Here are a few I've found in my car (or someone else's)
1: Throttle rod adjustment- If it's too tight, the spring from the throttle console will not let the idle switch (part of the TPS) reset.
2: Throttle cable loose- This can give sloppy performance and move the WOT all the way to the floor (because the slack causes it to engage late).
3: Throttle cable too tight- (Might not reset idle switch for same reason as #1).
4: TPS adjustment out of whack/full of oil- There's much written on this but suffice it to say that if you haven't done a top end refresh you may want to address this. The TPS can get oil in it from the throttle body and it affects the contacts in the TPS. It can also be out of alignment and require adjustment.
5: TPS wiring/harness- Roger at 928sRus has a new harness that goes from the TPS switch to the back of the test port on the front of the engine (shown in Ken's pic above). Yours may look OK but if it's original it's probably very brittle and the pins at both ends just push on so if there's any corrosion you may have issues with resistance. It's hard to replace unless you're doing a top-end refresh, but it can be done if you're careful and patient.
6: Gas pedal issues: Check that the carpet isn't interfering with it, check for free operation of the pedal throughout the range of it's operation. Check that the bushings at the pivot point are clean and lubed. In fact it's good practice to just remove the whole assembly and clean it up to get everything moving smoothly, then adjust the throttle cable in the engine compartment. You may notice (like I did) that it wasn't anywhere near as smooth as it could be.
I agree that job 1 needs to be to make sure the TPS contacts and especially the idle switch input is reaching the LH before moving on. If you have any vacuum leaks they're not bad enough to cause a rough idle or surging so they may wait for another day.
I also tried again to verify voltage to the LH. I'm still getting no voltage between pins 9 and 25. Perhaps I shouldn't be concerned but the test is straight out of the WSM. I just can't figure it out. I took a picture so you could see what I'm seeing. Does this look right?..
I also noticed two wires coming out of both the LH plug and EZK plug which were not connected to anything. They look like they were intended to be connected to each other but were simply taped to the harness. Any idea what the green/blue wires below are for? This is the EZK plug but the LH plus also has two brown wires just like these hanging loose...
I have to admit I'm not looking forward to a top end refresh. The PO refreshed the intake and it looks great but he didn't address the harnesses. If I could find a way fix the idle switch and solve my jerky acceleration at 2700 RPM, I might just drive the car until winter. My real concern is that I'll refresh the intake but still have the jerky acceleration issue since I have no idea what's causing it. It didn't happen before I went through the grounds so I must have done something. I guess I'm probably right where many others were at one point or another
09-14-2010, 07:37 AM
#25
Craic Head
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Thanks Mike. I wasn't sure if the switches would work w/o power. By the way, you say the that idle switch is pin 5, but the diagram says pin 5 is ground and pin 3 is idle. Is the diagram wrong? That's the same one I was using and I don't want to do any more damage than I may have already done. If the diagram is right, what is the difference between the ground on pin 5 and pin 25?
I wouldn't worry about the LH voltage, if you didn't have any voltage for that, your car wouldn't be running at all.
For the plugs on the EZK and the LH harness:
The one on the EZK is the 'low octane plug'. I forget what the one on the LH is for, but they're both supposed to be unplugged in normal operation. If you plug in the 'low octane plug' I think it retards the ignition a bit, so it will make your car lose power. Maybe someone else can chime in on the LH plug in stock configuration.
If your idle switch isn't resetting at all then I think that would explain the problem with the idle dropping really low at a light and then surging back up and finally finding a sweet spot.
I'm hoping someone else will have some ideas about the surge at 2700 as well. Does it coincide with the WOT switch engagement by any chance?
09-14-2010, 09:07 AM
#26
Rennlist Member
At 2700 rpm is a harmonic with a drop of torque in the dynograph.
I think you have a vacuum or fuelproblem.After my complete intakerefresh I miss the powerhole at 3000 rpm.
The oil in your enginevalley comes from a broken hose or gasket .
The dyno is crank hp.
I think you have a vacuum or fuelproblem.After my complete intakerefresh I miss the powerhole at 3000 rpm.
The oil in your enginevalley comes from a broken hose or gasket .
The dyno is crank hp.
09-14-2010, 05:21 PM
#27
Intermediate
Thread Starter
I'm resigned to taking off the intake and cleaning up this mess but would really like identify the cause of this surging issue so I can be sure to fix it. Any chance my surging could be caused by a faulty impulse sensor connection? One of the things I noticed while cleaning the ground points under the airbox was that the impulse sensor harness was out of the retaining bracket and had been taped up heavily. It had obviously fallen apart and I'm thinking a slight bump could have been all that was needed to create a break. Is there any way to test if the impulse sensor is working properly? Any other tests I can run outside of those in WSM 24?
09-17-2010, 02:25 AM
#28
Intermediate
Thread Starter
So I solved the jerky acceleration issue. Because this all started after I cleaned the ground points and checked all the fuses, I knew I must have gone wrong somewhere. Because the interior lights had been on for some time while I was checking fuses, the battery was weak and the car almost didn't start a couple of days ago. So I bought a battery maintainer and charged it back up. The car seemed a bit better but the problem was still there. I'd already rechecked all ground points in the front of the car. The only thing left was to go to the battery box and check the battery connections. I reinstalled the battery cables and tightened them up including the connection that goes directly to what I think is the fuel pump. Then I went for a drive and, low and behold, the problem was gone. It's a bit embarrassing that the solution was so simple and that I spent so much time chasing other things. But it was a great learning and troubleshooting experience. In the process, I found out that my TPS needs replacing and my gas pedal/linkage could use some adjusting. I'm also much more familiar with the car. Now if I could only replace my TPS w/o removing the intake.
Thanks to everyone (esp Mike Frye) who helped with advice and moral support. As a newbie, knowing you're not alone in this is invaluable. I'll post some pics once the car is cleaned up.
Thanks to everyone (esp Mike Frye) who helped with advice and moral support. As a newbie, knowing you're not alone in this is invaluable. I'll post some pics once the car is cleaned up.
