Intermittent Stalling after hot run
Thread Starter
Track Day
Joined: Feb 2017
Posts: 17
Likes: 0
From: Brunei
I had the same issue but my car is a Kjet 928S , so no electronic injection.
I solved the issue by making the mixture more rich via the mixture screw. During acceleration, the mixture is rich enough but once it comes to an idle status, mixture becomes more lean...in my case too lean.
Perhaps MAF in your case ?
I solved the issue by making the mixture more rich via the mixture screw. During acceleration, the mixture is rich enough but once it comes to an idle status, mixture becomes more lean...in my case too lean.
Perhaps MAF in your case ?
Sticky/unresponsive (not sure really) ISV. I had this on my '94 GTS about a year ago. ISV appeared to work fine in bench testing off the car but failed when hot installed. Devil of a job to diagnose - much else was changed and tested over a period if 6 weeks in the shop...
It is logical because it is the "Idle Stabilization Valve" - but they are usually very reliable and seemed a bit illogical it would work perfectly fine - except when fully heated up (you'd almost expect the opposite)
Interesting headlights there - tell us/show us more...
Alan
It is logical because it is the "Idle Stabilization Valve" - but they are usually very reliable and seemed a bit illogical it would work perfectly fine - except when fully heated up (you'd almost expect the opposite)
Interesting headlights there - tell us/show us more...
Alan
Headlights is a small fun project for me. I'll start a thread (with lots of pictures) about it soon once I'm done completing the look.
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Joined: Jun 2005
Posts: 10,578
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From: Oman
So, you take a drive probably down the dual carriageway in the directon of BSP. The car gets fully heat soaked on a run and you have the a/c running [tropical rain forest climate- high humidity temperature low 30's centrigrade]. The throttle closed contact of the TPS [throttle position switch] is a possible failure point, not as common as the full throttle switch failure but a possibility nonetheless. The switch is a somewhat Victorian era technology and the contact strip within commonly sees the internal soldered joints fail- heat soak logically exacerbating the problem. The ISV only initiates when the brains get the signal that the throttle is closed. If this signal is failing the ISV when closed has a static gap that intends to pass sufficent air to keep a more or less stable idle when the motor is fully warm and the a/c is not running. If the a/c was running [as was likely the case] and the heat soak causes the failing switch an intermittent problem, the engine will die as the revs drop as the air flowing cannot support the engine with the a/c running.
Next time you sense this is happening switch the a/c off- if the idle stabilises then that would suggest a failing TPS idle contact problem. The trouble with intermittent failure modes is finding them as when tested they may be perfectly OK. You can try testing the TPS for make/break contact for whatever it is worth.
Next time you sense this is happening switch the a/c off- if the idle stabilises then that would suggest a failing TPS idle contact problem. The trouble with intermittent failure modes is finding them as when tested they may be perfectly OK. You can try testing the TPS for make/break contact for whatever it is worth.
Last edited by FredR; Jun 19, 2020 at 07:36 AM.
Rennlist Member
Joined: Feb 2002
Posts: 7,060
Likes: 42
From: Cambridge England
"I have a non-cat without oxygen sensors. I believe mine cannot be adjusted?" The car should have a CO adjustment pot above the fuse/relay (CE) panel, clipped
to the [late that holds the LH and EZK ECUs. As the car doesn't have cats, measure idle CO at the tail pipe and set hot idle CO to 1%.
to the [late that holds the LH and EZK ECUs. As the car doesn't have cats, measure idle CO at the tail pipe and set hot idle CO to 1%.
Thread Starter
Track Day
Joined: Feb 2017
Posts: 17
Likes: 0
From: Brunei
So, you take a drive probably down the dual carriageway in the directon of BSP. The car gets fully heat soaked on a run and you have the a/c running [tropical rain forest climate- high humidity temperature low 30's centrigrade]. The throttle closed contact of the TPS [throttle position switch] is a possible failure point, not as common as the full throttle switch failure but a possibility nonetheless. The switch is a somewhat Victorian era technology and the contact strip within commonly sees the internal soldered joints fail- heat soak logically exacerbating the problem. The ISV only initiates when the brains get the signal that the throttle is closed. If this signal is failing the ISV when closed has a static gap that intends to pass sufficent air to keep a more or less stable idle when the motor is fully warm and the a/c is not running. If the a/c was running [as was likely the case] and the heat soak causes the failing switch an intermittent problem, the engine will die as the revs drop as the air flowing cannot support the engine with the a/c running.
Next time you sense this is happening switch the a/c off- if the idle stabilises then that would suggest a failing TPS idle contact problem. The trouble with intermittent failure modes is finding them as when tested they may be perfectly OK. You can try testing the TPS for make/break contact for whatever it is worth.
Next time you sense this is happening switch the a/c off- if the idle stabilises then that would suggest a failing TPS idle contact problem. The trouble with intermittent failure modes is finding them as when tested they may be perfectly OK. You can try testing the TPS for make/break contact for whatever it is worth.
When you refer to the TPS, do you mean the idle switch click? The TPS also has been replaced and I can hear the click when adjusting the throttle cable. ISV may be suspect though since it was replaced almost 2-3 years ago.
"I have a non-cat without oxygen sensors. I believe mine cannot be adjusted?" The car should have a CO adjustment pot above the fuse/relay (CE) panel, clipped
to the [late that holds the LH and EZK ECUs. As the car doesn't have cats, measure idle CO at the tail pipe and set hot idle CO to 1%.
to the [late that holds the LH and EZK ECUs. As the car doesn't have cats, measure idle CO at the tail pipe and set hot idle CO to 1%.
Rennlist Member
Joined: Jun 2005
Posts: 10,578
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From: Oman
Worked here before? Yes I use the dual carriageway to test long distance driving.
When you refer to the TPS, do you mean the idle switch click? The TPS also has been replaced and I can hear the click when adjusting the throttle cable. ISV may be suspect though since it was replaced almost 2-3 years ago.
Hmm.. now to find a place that can measure the CO. We don't do emissions testing for vehicle road-worthiness here so might be a problem.
When you refer to the TPS, do you mean the idle switch click? The TPS also has been replaced and I can hear the click when adjusting the throttle cable. ISV may be suspect though since it was replaced almost 2-3 years ago.
Hmm.. now to find a place that can measure the CO. We don't do emissions testing for vehicle road-worthiness here so might be a problem.
I visited BSP in June 2007. On the way back to Bandar Seri Bhagawan as the car entered the capital area we went past a villa with a purple GTS in the driveway- looked gorgeous. There was a chap with a grey GTS who posted here a few years ago.
The CO pot is easy to adjust but if you do try it keep a careful record of how many turns you made so you can reset to where it was. I forget which way leans the mix and which way leans it out- I doubt that is your problem though but never discount anything until you know for sure what the problem is.
Thread Starter
Track Day
Joined: Feb 2017
Posts: 17
Likes: 0
From: Brunei
Throttle position switch is what you refer to as the idle switch. The switch may well click but that does not mean the signal is getting through to the computers. If the switch is only two years old then I doubt it will have failed but...? Good to check it is making/breaking at the computer connecting block.
I visited BSP in June 2007. On the way back to Bandar Seri Bhagawan as the car entered the capital area we went past a villa with a purple GTS in the driveway- looked gorgeous. There was a chap with a grey GTS who posted here a few years ago.
The CO pot is easy to adjust but if you do try it keep a careful record of how many turns you made so you can reset to where it was. I forget which way leans the mix and which way leans it out- I doubt that is your problem though but never discount anything until you know for sure what the problem is.
I visited BSP in June 2007. On the way back to Bandar Seri Bhagawan as the car entered the capital area we went past a villa with a purple GTS in the driveway- looked gorgeous. There was a chap with a grey GTS who posted here a few years ago.
The CO pot is easy to adjust but if you do try it keep a careful record of how many turns you made so you can reset to where it was. I forget which way leans the mix and which way leans it out- I doubt that is your problem though but never discount anything until you know for sure what the problem is.
Is there a laymans way of adjusting the CO pot? I believe its a matter of resistance? Multimeter check somewhere? Not having luck looking for a gas analyzer here.. I did try turning the pot and after a few rounds (CCW) idle did go rough. I turned it back round to its original position though just in case i messed something up.
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Pro
Joined: Oct 2006
Posts: 569
Likes: 13
From: Long Island
My recent experience - in the end, it appears to be the MAF.
https://rennlist.com/forums/928-foru...t-of-spec.html
https://rennlist.com/forums/928-foru...t-of-spec.html