Looks like the KL has an issue. Started it up just now from cold and while it was idling in park at about 1100 rpm the engine speed suddenly dropped dramatically and it nearly stalled. Did this a couple of times before settling.
I've just replaced the ignition leads and plugs because it did stall at a set of lghts a couple of weeks ago. I've also experienced hiccups while cruising after it had already warmed up.

New leads obviously havent fixed it. The only clues are that it can happen hot or cold and in neutral. Any ideas?

Hmm, I put some injector cleaner in the tank a couple of days ago and there hasnt been any stumbling since.
I wonder if its fuel related. The filter is due. All i can do is keep monitoring and see if it happens again.

Could be bad fuel. Was the issue only present during one tank of fuel?

Have you done Mal's throttle body clean?

If you have, I'd replace the fuel filter (10 min job) and then run a couple of tanks of e10 through in case it was some contaminated fuel.

Could be bad fuel. Was the issue only present during one tank of fuel?
I dont think so, pretty sure there was a fill in between the initial stall and the recent stumbling.

Have you done Mal's throttle body clean?

If you have, I'd replace the fuel filter (10 min job) and then run a couple of tanks of e10 through in case it was some contaminated fuel.
The TB was replaced a while back because I was trying to solve a rough shift/idle issue, lol. Brand new, which I believe includes the ISC and TPS. My current guess is fuel injectors clogged or fuel pump.
If this fuel addtive doesnt fix it then I'll have to get someone to fault trace it.
Fuel filter is coming up due, so maybe do that too.

If the injectors are dirty it should be a constant problem, not intermittent. Fuel system cleaner can help keep them clean, but if they're already dirty, they'd need to be removed for proper cleaning.

E10's ethanol content (which is safe for Magna) can help displace water and other contaminants. Alternatively, a fuel system stabiliser such as Morey's UCL can help if you've picked up a bad tank of fuel.

I doubt it's a blocked fuel filter or struggling fuel pump. That would manifest at high fuel flow (open throttle and high rpm) moreso than at idle. If the fuel filter is due, then do the filter anyway in case you bought some rubbish fuel.

If the injectors are dirty it should be a constant problem, not intermittent. Fuel system cleaner can help keep them clean, but if they're already dirty, they'd need to be removed for proper cleaning.

E10's ethanol content (which is safe for Magna) can help displace water and other contaminants. Alternatively, a fuel system stabiliser such as Morey's UCL can help if you've picked up a bad tank of fuel.

I doubt it's a blocked fuel filter or struggling fuel pump. That would manifest at high fuel flow (open throttle and high rpm) moreso than at idle. If the fuel filter is due, then do the filter anyway in case you bought some rubbish fuel.
I wasnt thinking dirty injectors so much, more a problem with the fuel pressure, pump or lines. Maybe the cleaner will help to sort it, i used a supposedly decent one.

Who knows? It may still be ignition related (coil) or possibly the new ISC is sticking.
It needs some testing and fault tracing, but fingers crossed, it didnt happen today.

I have something similar.

Whenever I come to a full stop (stopping at lights mostly) sometimes the car drops in revs and the car starts to shake but then it kicks back in and revs up. Its not a consistent thing either, it doesn't happen all the time which is weird. It's not my Spark Plugs or Leads because I changed them two days ago and the problem is still there.

Any idea as to what it could be?

I have something similar -
Any idea as to what it could be?
Well thats what this thread is all about, things it might be. Ignition and fuel systems, fuel quality, ECU , MAF, throttle body, vacuum leaks, ISC/TPS, where do you want to start?
I've replaced my leads and plugs as they were due and I've run some injector/carby cleaner through the system.
I'll replace the fuel pump and filter if the problem continues, (because they're also due).
Other than that all the other maintenance is up to date.
If that doesnt resolve it then it needs to go to a good mechanic who can run some tests and perform fault tracing.

If you have a multimeter it is not too hard to test the TP and ISC yourself for correct functioning and adjustment.

Whenever I come to a full stop (stopping at lights mostly) sometimes the car drops in revs and the car starts to shake but then it kicks back in and revs up. Its not a consistent thing either, it doesn't happen all the time which is weird. It's not my Spark Plugs or Leads because I changed them two days ago and the problem is still there.

Any idea as to what it could be?

Has the battery been disconnected recently?

Generally an issue like this is the ISC

I would not be using e10 in any Magna to be honest, I would not even put it in any car point blank. Have cleaned too many fuel systems with rusty tanks (although AWD has plastic tank)

The fuel system cleaner will disperse any moisture if there was any. Given the age of the car perhaps an injector service may be on the cards but your issue does not sound like this. How old is the battery in the car

Yes, don't get me wrong - I wasn't advocating permanent use of E10. Just a tank or two to remove any water that may have been in the tank from a bad batch of fuel. It is excellent for removing water contamination from fuel systems (and unfortunately bad for absorbing water from the air in a partially filled tank in cars which sit around and don't get used much).

...The fuel system cleaner will disperse any moisture if there was any. Given the age of the car perhaps an injector service may be on the cards but your issue does not sound like this.
At cold start today it immediately stumbled twice before settling. Took it for a nice drive up and down hills, plenty of gear changes at different speeds, went WOT up hill a couple of times, let it idle, never missed a beat.


How old is the battery in the car
Battery was replaced by the RACV in August 2013, 2.5 years ago.
Its the type that has a green indicator, which is showing green. (Funnily enough the last battery had one of those too and it was showing green when it died). Could a failing battery cause this issue? If possible then I will change it given its already 2.5 years old.

[edit - update] so I checked the battery with a multimeter, it was sitting at 12.7v about an hour after driving it, then after starting and while idling the engine its charging at 14v and after stopping the engine it shows 12.6v and after a few seconds climbs back go 12.7. Seems normal as far as this test goes?

Also, it didnt stumble during this test. It seems that the stumble is more likely to happen from a cold start.


Generally an issue like this is the ISC
I replaced the throttle body with new including the TPS and ISC about 50,000k's ago in Feb of 2013. Not saying it isnt the ISC, but it would be bad luck.

Worth checking the ISC and TPS anyway.

Worth checking the ISC and TPS anyway.
I'd like to have the ISC checked, the fuel pressure and ignition timing and coil.

I dont have the test procedure for the TB but I assume it means several resistance and operation tests.
Whats an ISC worth anyway? Does the system need any adjustments to swap it over? Is there any difficulty or trick involved, esoecially with the O ring fitment?

I'd like to have the ISC checked

DIY procedures: (Engine off & key out)

ISC: Remove plug with ISC on car.
Two rows of 3 pins. Measure resistance from central pin to the outer two on each row.
You should have 4 near identical readings. If not, replace ISC.

TP: 3 pins when you pull the plug off. (work out yourself which is earth, etc)

Two parts:
Idle switch resistance: Should be closed (0 ohm) at idle, but open as soon as you move the throttle plate.
Throttle opening resistance: Smooth increase in resistance as the throttle is opened slowly.

Usual disclaimer: Above may not be accurate. Mal will correct and tell me he hates me, as usual. lol

Lol well this problem is difficult for me to understand. There is now a stumble after a cold start and it seems to have happened every time I've started it in past few days, whereas the near stall at traffic light that happened couple of weeks ago hasnt come back. After its had its stumble it then seems rock solid no matter what I do.

The only new info I can add is that if i lift the RPM (via accelaerator) to about 1100 and sit there, i can hear that the rpm is going up and down slightly and regularly. Maybe a variance of less than 100 rpm which doesnt show on the tacho. Just goes up and down slightly.

Maybe fuel pressure, maybe ISC. I want to try swapping the ISC over myself until I can get this to a mechanic.
Can anyone tell me if i can just swap them over, or does it also need adjustment of anything?
And are there any tricks or traps in swapping the ISC?

At cold start today it immediately stumbled twice before settling. Took it for a nice drive up and down hills, plenty of gear changes at different speeds, went WOT up hill a couple of times, let it idle, never missed a beat.


Battery was replaced by the RACV in August 2013, 2.5 years ago.
Its the type that has a green indicator, which is showing green. (Funnily enough the last battery had one of those too and it was showing green when it died). Could a failing battery cause this issue? If possible then I will change it given its already 2.5 years old.

[edit - update] so I checked the battery with a multimeter, it was sitting at 12.7v about an hour after driving it, then after starting and while idling the engine its charging at 14v and after stopping the engine it shows 12.6v and after a few seconds climbs back go 12.7. Seems normal as far as this test goes?

Also, it didnt stumble during this test. It seems that the stumble is more likely to happen from a cold start.


I replaced the throttle body with new including the TPS and ISC about 50,000k's ago in Feb of 2013. Not saying it isnt the ISC, but it would be bad luck.

Sounding like battery is not maintaining voltage post start up after sitting for a time.

Try swapping one from the kh over, if works then i canlook after you on a hd century

Where's zilo at? It's the codes, it's just gotta be the codes. Pay mitsi to have them cleared and it will be cured for sure...


Just kidding... yea what Mal said. Try another battery. It's something easy to try and doesn't cost you to troubleshoot. Normally a visual inspection of the ISC can tell a story, whether the passage is blocked up: clean it out. Or whether the ISC motor is stuffed altogether there will be no resistance when you try turning it by hand.

...so I checked the battery with a multimeter, it was sitting at 12.7v about an hour after driving it, then after starting and while idling the engine its charging at 14v and after stopping the engine it shows 12.6v and after a few seconds climbs back go 12.7. Seems normal as far as this test goes?

A failing battery can have normal voltage on a multi-meter but can fail under load. My previous battery also had the indicator which was still a lovely, bright green colour when the battery collapsed. In my case it still provided 12 volts but lacked sufficient amps to crank the engine (or illuminate the interior light, operate the door locks, radio etc.).

Where's zilo at? It's the codes, it's just gotta be the codes. Pay mitsi to have them cleared and it will be cured for sure....
LOL ... I assume if there was a fault code then the check engine light would be on, but it isnt.


A failing battery can have normal voltage on a multi-meter but can fail under load.
Yes, I understand that. I had my battery checked at Supercheap auto today and it tested ok with %50 life left. Its was an RACV one which i'd bought when the last battery failed.


Try swapping one from the kh over, if works then i canlook after you on a hd century
Thanks Mal. Battery looked a little small and sad while I had it out of the car today and who knows how its performing once hot and loaded? I decided to swap it over on the spot. I remember the drama last time my battery failed with the speedo needle stuck over, and dont want that to happen again!

Well, its been 3 days since replacing the battery and so far no recurrence of the problem :)
Thanks again Mal for the advice on the battery; I'll keep monitoring it but hopefully this was the root cause.

The load test ideally should be cold and after sitting in the car running memory items such as radio etc. Once you start the car any tests will give you a false reading

Not sure how supercrap can state 50% life left, that is certainly interesting on its own

I can say one thing, ALL my cars have the Centrury HD with exception to my Pajero which has the Century Extreme in it. I tend to use over rated batteries, less load on them then especially in the colder months which is when a battery will be more likely to fail

The load test ideally should be cold and after sitting in the car running memory items such as radio etc. Once you start the car any tests will give you a false reading

Not sure how supercrap can state 50% life left, that is certainly interesting on its own

I can say one thing, ALL my cars have the Centrury HD with exception to my Pajero which has the Century Extreme in it. I tend to use over rated batteries, less load on them then especially in the colder months which is when a battery will be more likely to fail

This! I think the thing a lot of people overlook is that the voltage could read 12v or even 14+v when turned on but the usable amps that all the accessories have access to can be quite low in a worn out battery.

Had all sorts of small issues with the XC90 the other week. The battery was on the way out. Got it replaced with a 700cca extreme unit all issues went away that we didn't even think about (lock button on the remote started working every time now, etc).

Not sure how supercrap can state 50% life left, that is certainly interesting on its own Im glad you mentioned that cos I thought battery technology must have really moved along since my time! I have no idea what he meant by that. He just hooked some kind of meter up to it.


I can say one thing, ALL my cars have the Centrury HD with exception to my Pajero which has the Century Extreme in it. I tend to use over rated batteries, less load on them then especially in the colder months which is when a battery will be more likely to fail
I got "Super Charge Batteries" brand, gold model with 660 CCA and 40 months warranty, made in the Phillipines.
Someone tell me if they know anything about this brand/battery, and if they're any good?

The website (http://www.supercharge.com.au) states:

Gold – These are maintenance-free, fully-sealed, top-of-the-line products with superior starting power. Our gold units come with a 36-month warranty and are ideal for heavy duty vehicle use. Many consumers prefer Gold units as their four wheel drive auto battery of choice.

36 or 40 months warranty? Full or pro rata?
Should be a good battery, with warranty that long. But keep the receipt, just in case . . .

Its got 40 printed on the battery, although I notice they state 36 on the website.

Ok, here it is a week later and today the revs dropped as i went to take off, to a near stall.
Same symptoms as before, no warning, just dies.
It hasnt stumbled once at the morning cold start since the battery was replaced though.
Only thing I can add is that the air-con was on at the time.

The following has been done since this started:

Replaced leads and plugs,
Put injector cleaner through the tank, twice,
Used a couple of tanks of fuel,
Replaced the battery.


If it was a fuel pump issue wouldnt it be much more obvious at high speed?
Could it be timing, as in a bad coil? Or would there be other symptoms?
I'm beginning to wonder about the ISC, even though its only about 50 thousand k's old.
If it happens from take-off with air on, what else could it be?

Whats involved in swapping the ISC? Is it a simple unbolt/fit new O ring/bolt on?
Can I do it on the car?

Only thing I can add is that the air-con was on at the time.

I've had that before too - it seems that sometimes if you apply throttle at the same time as the A/C cuts in the car can't correct the revs fast enough, at the time (10+ years ago?) I replaced the idle up solenoid and the hose to it and the problem went away.

I'm beginning to wonder about the ISC, even though its only about 50 thousand k's old.
If it happens from take-off with air on, what else could it be?

Whats involved in swapping the ISC? Is it a simple unbolt/fit new O ring/bolt on?
Can I do it on the car?

Mal mentioned the ISC being the likely culprit earlier in this thread. Removal is basic, no need to remove TB from car. Make sure it's clean and tests correctly, test procedures here:

http://i63.tinypic.com/2qvqow9.jpg

Just the multimeter test is enough to pick up one that is a dud, one of the 4 readings will be open circuit.

Mal mentioned the ISC being the likely culprit earlier in this thread.
He sure did. The ISC was replaced with new 50,000 k's ago so I was reluctant to start there.
Decided to replace the leads and plugs - which didnt help, (they were coming up due anyway).
Then I encountered a second issue of a stumble on a cold start, which ended up being fixed with a new battery, (also Mal's advice), so its taken a while to come back to the ISC.
Max has posted instructions for testing the ISC on the vehicle previously.


Removal is basic, no need to remove TB from car. Make sure it's clean and tests correctly, test procedures here:...
The full test procedures needs the TB to be removed and then the ISC removed. I'm not sure why the TB needs removal, I assume its for ease of access to the ISC. Can u confirm theres no problem accessing and refitting the ISC and its O ring seal with the TB still on the car?

From my perspective I'd prefer to replace the ISC again rather than try testing it because I believe an intermittent fault may not be detected by simple testing. I note that the manual includes observing waveforms on a scope with a special purpose test harness plugged into a 6 volt supply, so there are a range of tests to be done with special tools before it can be passed. What about when its subject to vibration and heat in operation? How can I be certain its not faulty even after fully bench testing it?

Its possible the ISC is simply sticky with oil sludge or something, but I dont know if we can properly clean the ISC or not. I wouldnt want to soak it in solvent, could make it more unreliable!
I also believe the O ring seal is not reusable, so I need to get a new one before I remove it. Where to get a replacement O ring?

The other thing thats in the back of my mind is the recent cruise control issue. It was caused by a damaged vacuum hose, in turn caused by the idiot who stuffed up my transmission mount installation. Maybe when he dropped the motor on the transmission damaging the hose he also damaged one of the wiring harnesses...
Anyhow I will focus on the ISC next.

Just the multimeter test is enough to pick up one that is a dud, one of the 4 readings will be open circuit.
Well I will try it Max. Hopefully it will fail such a basic test, because a pass wont prove anything to my satisfaction.

Well I will try it Max. Hopefully it will fail such a basic test, because a pass wont prove anything to my satisfaction.

Test can be done while it is on the car, simply unplug the electrical connection.
It will either be ok or not. What you do after that is up to you.

The ISC controls air flow through some internal passages of the throttle body, oil sludge isn't going to be a problem. No cleaning needed. Definitely don't soak it in solvent.

Just an update, I've swapped the ISC for the original one that I'd taken off the car at about 35,000 k's, which I still have. (I'd swapped out the Throttle Body including ISC when I was chasing a rough shifting issue - AFAIK the ISC was fine.)

Seems to run perfectly, although it did die at idle when first shifting into drive after first starting ��. I think that may be associated with relearn though, as I'd also reset the ECU.
Anyway, drove it on a few trips today under different conditions without any problems and idle was very smooth, possibly better than before actually.

I was surprised when I took the air inlet hose off and discovered the throttle body looks absolutely spotless inside. I'd assumed there would be some sludge or carbon apparent after 50,000 k's but the throat and butterfly looked as clean as the day I installed it.

Cant say the same for inside the idle speed control body judging by the ISC, although its very clean to look at. The ISC had a small ring of sludge around the tip of the plunger (see photo).
Makes me wonder if the throttle body should be cleaned more often and on a regular basis? (I wonder if this is why there are often slightly rough idle problems reported with these cars, i.e.: sludge getting into the ISC and making it slightly sticky or slow?)

I did the resistance checks on the ISC and discovered it doesnt match the spec posted earlier. I get about 39 ohms on all combinations, although no shorts. Incorrect specs - wrong model?

Anyhow, I'm concerned the ISC is not the problem here. I'm having trouble understanding how the ISC would cause a stumble at speed with cruise control? (One of the symptoms). Does CC use the ISC for anything? How does ISC get used by the ECU when at speed?

OTOH could an ignition timing issue, for example, cause stalling at take off from idle (The other symptom)? Hmm...

I will continue monitoring over the next week and will also get a brand new ISC as soon as possible.

http://i1159.photobucket.com/albums/p629/Kwawd/image_zps22e1pwjv.jpeg

Resistance measurements can be uncertain, due to the ohm meter used, the type and length of the test leads, test temperature to a lesser extent. The important thing is that the readings are all the same and in the right range. The manual values of 28 to 33 ohms show a large variation 5 ohms in 30 ohms; ie 16 %. Your test leads might have 2 ohms of resistance anyway. I would say your test result of 39 ohms each is a perfectly satisfactory result.
I use both analog and digital test meters. The short leads on my digital meter shows the leads have 1.3 ohms of resistance. The analog meter cant read readings reliably less than 10 ohm.
Hope this helps.

Resistance measurements can be uncertain, due to the ohm meter used, the type and length of the test leads, test temperature to a lesser extent. The important thing is that the readings are all the same and in the right range. The manual values of 28 to 33 ohms show a large variation 5 ohms in 30 ohms; ie 16 %. Your test leads might have 2 ohms of resistance anyway. I would say your test result of 39 ohms each is a perfectly satisfactory result.
I use both analog and digital test meters. The short leads on my digital meter shows the leads have 1.3 ohms of resistance. The analog meter cant read readings reliably less than 10 ohm.
Hope this helps.
I'm using digital. I think the ambient temp could affect the measurements. The test procedure specified 20c and the room was about 26c at the time.
But as I said earler, passing this test doesnt prove much IMO.

As above, the 4 ISC readings need to be somewhere similar. You'd pick an open (infinity ohms) or shorted coil (nearing 0 ohms) straight away.

As for the ISC . . . . there is a switch in the TPS, as soon as you put your foot on the accelerator, that switch opens, and the ECU stops talking to the ISC. Putting it differently, the ECU controls the ISC stepping for a smooth idle only with your foot off the accelerator.

Of course, that is assuming the TPS is working correctly. lol

EDIT: some Magnas seem to need a fair bit of time at IDLE to get the ISC to do the right thing after a battery disconnect or ISC replacement, just driving around won't do it because the ECU to ISC link isn't active then.

A cruise control stumble won't be an ISC or ignition timing problem, more like the control mechanism for the cruise. The Magna is pretty rough on cruise control, fly by wire throttle body cars like the 380 or current Lancer are very smooth by comparison.

As above, the 4 ISC readings need to be somewhere similar. You'd pick an open (infinity ohms) or shorted coil (nearing 0 ohms) straight away.

As for the ISC . . . . there is a switch in the TPS, as soon as you put your foot on the accelerator, that switch opens, and the ECU stops talking to the ISC. Putting it differently, the ECU controls the ISC stepping for a smooth idle only with your foot off the accelerator.

Of course, that is assuming the TPS is working correctly. lol

EDIT: some Magnas seem to need a fair bit of time at IDLE to get the ISC to do the right thing after a battery disconnect or ISC replacement, just driving around won't do it because the ECU to ISC link isn't active then.
I was wondering if the ECU used the ISC to do more but if the TPS takes it out of the circuit then I dont believe the ISC can be the whole answer here.

Current symptoms are an occassional near stall when moving off from idle and an occasional sudden, quick loss of power at speed with a quick recovery (stumble).
Looks like the battery replacement has fixed the stumble on a cold start.

I think dizzy may be the next stop.

...

A cruise control stumble won't be an ISC or ignition timing problem, more like the control mechanism for the cruise. The Magna is pretty rough on cruise control, fly by wire throttle body cars like the 380 or current Lancer are very smooth by comparison.
Thats interesting Max. I had an issue recently with the CC not working. It was a torn vacuum hose. I wonder if something else is happening with the CC?

Was wondering if this fault listed in the TH & TJ might have carried through to the KW? http://martybugs.net/articles/magna-stall.cgi

Was wondering if this fault listed in the TH & TJ might have carried through to the KW? http://martybugs.net/articles/magna-stall.cgi
I've seen that before. At this stage it could be a few things including a loose connection.
If I get the same behaviour with this replacement ISC then I'll suspect ignition timing and the distibutor coil next.
The car behaved fine today...

Since swapping over the ISC a few days ago the cars driven faultlessly. Been driving to and from work in all kinds of conditions, air-con and cruise used at different times, bumper to bumper as well as coasting at 100 kmh, and today its driven a couple hundred k's as well.
Absolutely faultless.

I'll post again if the symptoms recur, but it seems the ISC was part of the problem. I dont understand how the ISC was causing a stumble at speed, so thats still a mystery to me.