Recurring Low Idle - Low Power - Pistol is loaded
10-02-2011, 09:57 PM
#16
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10-06-2011, 09:27 PM
#17
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Once I got it through my thick skull which pins were which(upside down and reverse for EZH and just upside down for LH). Follow the picture and open pin designations and all is good...
Completed Temp II and Idle/WOT Switch resistance checks on LH and EZK. Idle/WOT test was out until I released tension on the Cruise Control cable. It was not allowing throttle to get to Idle position by just a CH. Both measurements toggled between 0L(infinite) and 0.2ish as accelerator was pressed which is according to spec.
Temp II sensor resistance at ambient was 2.4kOhms for both LH and EZK. At 170F Op temperature LH was 60kOhms and EZK was 350Ohms. The spec calls for both readings to be in the 250k-290k range.
Looks like I need a new Temp II Sensor so far. Tomorrow I continue tests on Idle Stabilizer, Resonance Flap and Tank Vent. Thanks to David Chamberland for his PPI document on 928OC site.
Completed Temp II and Idle/WOT Switch resistance checks on LH and EZK. Idle/WOT test was out until I released tension on the Cruise Control cable. It was not allowing throttle to get to Idle position by just a CH. Both measurements toggled between 0L(infinite) and 0.2ish as accelerator was pressed which is according to spec.
Temp II sensor resistance at ambient was 2.4kOhms for both LH and EZK. At 170F Op temperature LH was 60kOhms and EZK was 350Ohms. The spec calls for both readings to be in the 250k-290k range.
Looks like I need a new Temp II Sensor so far. Tomorrow I continue tests on Idle Stabilizer, Resonance Flap and Tank Vent. Thanks to David Chamberland for his PPI document on 928OC site.
10-06-2011, 09:37 PM
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Temp II sensor resistance at ambient was 2.4kOhms for both LH and EZK. At 170F Op temperature LH was 60kOhms and EZK was 350Ohms. The spec calls for both readings to be in the 250k-290k range.
Looks like I need a new Temp II Sensor so far.
Looks like I need a new Temp II Sensor so far.
Thanks to David Chamberland for his PPI document on 928OC site.
You're welcome. But, thank Rennlist for hosting, not the 928OC.
Last edited by worf928; 10-06-2011 at 09:55 PM.
10-07-2011, 10:23 PM
#19
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Completed checks on Idle Stabilizer, Resonance Flap and Tank Vent and all checked out. So ECU(LH & EZK) tests all tested OK except for Temp II Sensor.
No corrosion on Temp II wiring/contacts so I’ll be replacing Temp II sensor as this was the only component with a measurement out of spec.
She’s still on jacks for some vacuum tests on transmission that will be completed tomorrow but I suspect the Low Idle at Op Temp was more influenced by the PO setting of Cruise Control being too tensioned. The search for the smoking gun on Idle weirdness even if the de-tensioning of Cruise Control cable and Temp II are fixed may not be definitive until next summer because ambient temp is -25F when problem occurred.
It’s always something, I love this car.
No corrosion on Temp II wiring/contacts so I’ll be replacing Temp II sensor as this was the only component with a measurement out of spec.
She’s still on jacks for some vacuum tests on transmission that will be completed tomorrow but I suspect the Low Idle at Op Temp was more influenced by the PO setting of Cruise Control being too tensioned. The search for the smoking gun on Idle weirdness even if the de-tensioning of Cruise Control cable and Temp II are fixed may not be definitive until next summer because ambient temp is -25F when problem occurred.
It’s always something, I love this car.
08-23-2012, 04:46 AM
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I hate it when there is no follow up. Either it got resolved or it never did...
One thing never mentioned is checking the flex plate tension on this car. A thrust bearing failure exhibits these symptoms. I fought an 86.5 for a week before discovering the lovely TBF... I'm really surprised no one asked if he had checked crank fore/aft play...
One thing never mentioned is checking the flex plate tension on this car. A thrust bearing failure exhibits these symptoms. I fought an 86.5 for a week before discovering the lovely TBF... I'm really surprised no one asked if he had checked crank fore/aft play...
08-23-2012, 03:05 PM
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I am sorry to hear about your TBF Mike. I've been there too. I had just rechecked my flexplate and torqued both the front at rear TT pinch bolts to 66 ftlbs (everything was within spec). Prior to the flex plate check, I did an engine swap with a known good engine (no TBF). The issue I've got has got to be electrical (I think). When cold, she runs perfect, a little high on idle at at first start (near 1000 rpms) but levels out to around 700-800 within a minute (rich fuel-open loop). Whenever the cooling fans kick in, the engine immediately goes idle hunting and levels out after a while. If I hit the throttle (not literally, of course), she revs fine but then has a difficult time staying above 400 rpm. Put it in gear, she stalls. Throttle it, she stalls.
Here is another piece of the puzzle, my alternator gauge is at 13 volts at cold start and drops below 12 when warm, then the car stalls. It is hard to turn her over, as if the battery were dead. Wait 15-20minutes, it will start up with some throttle assistance. Idle is low again and the issue recycles itself over again.
Come back to it a few hours later, she'll start right up...
Track with me on this:
If my temp II sensor is bad (my spare) or the wiring to it have a short to ground, then it could be misreading the temp and kicking in the cooling fans on too late, after the fuel in the rails have already begun to boil and evaporate? That could be causing excess compression, bad fuel/air mix and higher fuel pressure. That could be the reason why my idle is too low and why she is hard to turn over immediately after stalling. A couple of hours is plenty of time for the fuel to cool, compression to settle down, and/or wiring to cool/contract and short or ground to go away.
What I can't seem to understand is when she is cold started and has been running for a few minutes, the highest battery voltage reading I receive at the charging post, the starter, and the battery is 13.68 volts. Shouldn't I be getting over 14v when the alternator has kicked in?
I am starting to think that I may have two distinctly separate problems. What do you guys think?
Here is another piece of the puzzle, my alternator gauge is at 13 volts at cold start and drops below 12 when warm, then the car stalls. It is hard to turn her over, as if the battery were dead. Wait 15-20minutes, it will start up with some throttle assistance. Idle is low again and the issue recycles itself over again.
Come back to it a few hours later, she'll start right up...
Track with me on this:
If my temp II sensor is bad (my spare) or the wiring to it have a short to ground, then it could be misreading the temp and kicking in the cooling fans on too late, after the fuel in the rails have already begun to boil and evaporate? That could be causing excess compression, bad fuel/air mix and higher fuel pressure. That could be the reason why my idle is too low and why she is hard to turn over immediately after stalling. A couple of hours is plenty of time for the fuel to cool, compression to settle down, and/or wiring to cool/contract and short or ground to go away.
What I can't seem to understand is when she is cold started and has been running for a few minutes, the highest battery voltage reading I receive at the charging post, the starter, and the battery is 13.68 volts. Shouldn't I be getting over 14v when the alternator has kicked in?
I am starting to think that I may have two distinctly separate problems. What do you guys think?
08-23-2012, 03:46 PM
#26
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Voltage is going to fluctuate with RPMs and my setup would hit a low RPM drop and then Voltage would DROP in the 10-11s and whenever the front louvers would cycle open and close voltage, the reading would take a further hit. Idle hunting would then start but sometimes it would just conk out.
My alternator may also be on the cusp of failing because at idle with both AC blowers running Voltage readings go low.
Additionally, I suspect my low idle problem was not just a single fix. I went through and ohmed out all recommendations I could find in RL, cleaned all ground points, chanted, drank more beer, etc. There seemed to be slight improvements along the journey but it may have just been hopeful thinking. A new Temp II seemed to be the final repair that made the difference.
My alternator may also be on the cusp of failing because at idle with both AC blowers running Voltage readings go low.
Additionally, I suspect my low idle problem was not just a single fix. I went through and ohmed out all recommendations I could find in RL, cleaned all ground points, chanted, drank more beer, etc. There seemed to be slight improvements along the journey but it may have just been hopeful thinking. A new Temp II seemed to be the final repair that made the difference.
08-23-2012, 06:55 PM
#27
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I hate it when there is no follow up. Either it got resolved or it never did...
One thing never mentioned is checking the flex plate tension on this car. A thrust bearing failure exhibits these symptoms. I fought an 86.5 for a week before discovering the lovely TBF... I'm really surprised no one asked if he had checked crank fore/aft play...
One thing never mentioned is checking the flex plate tension on this car. A thrust bearing failure exhibits these symptoms. I fought an 86.5 for a week before discovering the lovely TBF... I'm really surprised no one asked if he had checked crank fore/aft play...
08-23-2012, 07:52 PM
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Another possible cause of low idle (although it should not affect power) is an idle stabilizer that is stuck closed. Encountered a car with that issue today.
08-23-2012, 09:32 PM
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Voltage is going to fluctuate with RPMs and my setup would hit a low RPM drop and then Voltage would DROP in the 10-11s and whenever the front louvers would cycle open and close voltage, the reading would take a further hit. Idle hunting would then start but sometimes it would just conk out.
My alternator may also be on the cusp of failing because at idle with both AC blowers running Voltage readings go low.
Additionally, I suspect my low idle problem was not just a single fix. I went through and ohmed out all recommendations I could find in RL, cleaned all ground points, chanted, drank more beer, etc. There seemed to be slight improvements along the journey but it may have just been hopeful thinking. A new Temp II seemed to be the final repair that made the difference.
My alternator may also be on the cusp of failing because at idle with both AC blowers running Voltage readings go low.
Additionally, I suspect my low idle problem was not just a single fix. I went through and ohmed out all recommendations I could find in RL, cleaned all ground points, chanted, drank more beer, etc. There seemed to be slight improvements along the journey but it may have just been hopeful thinking. A new Temp II seemed to be the final repair that made the difference.
08-23-2012, 09:39 PM
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Hey Bill,
I realized I had shot the cleaning fluid down the wrong hose yesterday and realized I had done so after I traced the hose back. Luckily, I didn't screw anything up...What is the best way to clean the ISV without pulling the intake apart?
By the way, what did you find out about your TT?
Felix
I realized I had shot the cleaning fluid down the wrong hose yesterday and realized I had done so after I traced the hose back. Luckily, I didn't screw anything up...What is the best way to clean the ISV without pulling the intake apart?
By the way, what did you find out about your TT?
Felix