Hey guys,

First time poster hoping to find some information regarding a problem I've had on and off for several years. Apologies if this is a bit wordy!

I've got a 94 V6 auto TS that developed an annoying fault about 9 years ago (!!). At the time my mechanic attempted a few fixes without much success (idle speed motor replaced, full injector service, fuel filter, flushing fuel rails etc), and then one day the fault magically repaired itself and the car ran perfectly for the next 7 years. About 2 years ago the fault returned and has remained ever since.

The fault and symptoms:

Car will idle and run fine for days and then without warning will die completely, as if the keys have been pulled from the ignition. Note it's not like the car splutters, coughs and then conks out - the engine just dies. The dash lights remain on in their "Ignition in ON" state, and I can twist the keys and the car restarts without a hitch.


The car will start first go even on cold mornings or after long periods of being unused (2 weeks or more), and finds/holds idle RPM fine (guess the ISC is probably OK?)


Problem seems more likely to occur once the engine has reached operating temperature. I'm pretty sure I've never had the stalling occur on a cold engine.


No flat spots in the RPM range, engine pulls fine across the board.


If the car is idling (eg, waiting at the lights) and the engine dies, I'll have to restart it. If I'm in motion and the RPM is up, the car will lurch as the engine goes and (I'm guessing) the inertia in the engine keeps it ticking over sufficiemtly and the engine bounces back to life. The period of the "lurch" would be less than half a second. Sometimes I'll be driving for days and experience nothing. Sometimes I'll get one lurch/stall in a trip. On bad days I might get several engine cutouts in a 300m stretch of road. On the days I get several lurches in quick succession I will sometimes hear relay clicking noises coming from the passenger side footwell where the ECU is located.


My current mechanic couldn't get his diagnostic tool to talk to my ECU to read any error codes (don't know if that means his OBD scanner is no good, it doesn't speak Magna, or indicates a fault with my ECU). However, I have checked the ON-OFF pulses with a multimeter and can confirm no error codes from the ECU (steady ON-OFF-ON... pattern), even immediately following a stall. Mechanic is thinking electrical fault rather than a fuel line fault, and given the symptoms I'm inclined to agree (no rough running, no sputtering, no poor acceleration, able to restart instantly after stall etc), but without swapping stuff out to try and isolate the problem he's not sure the best way to proceed. At the very least he has observed first hand the engine dying while he's had the car in his posession - intermittent faults are always the hardest ones to deal with!


Based on other similar faults I've seen reported here I've got a new distributor and engine ECU on their way to me now to try out, but I'm curious if anyone else might have some insight into the issue. I notice that there seem to be reports of similar faults in the TR-TS by other users here, but eventual diagnosis and correction of their version of the problem seems a bit hit and miss.

Any thoughts appreciated.

Cheers.

You've checked everything related to fuel except the fuel pump

Could also be maf sensor, bad air flow sensor can cause stalls or rough idles amongst other things

Spark plugs alright? Distributor? Can't really think of anything else that would do that

Thanks for the reply.

Haven't looked into the fuel pump. Mechanic is kinda leaning away from fuel issues given the nature of the stalling behaviour, but considering how long this has been a problem for me I'm keeping an open mind. Would a faulty fuel pump cause sudden and complete loss of the engine with the ability to restart it straight away? I would have thought fuel flow issues would manifest itself as misfiring, spluttering under power, low power, surging etc.

Distributor was what the mechanic suggested, but his comment was more along the lines of, "We can try replacing it and see what happens". I have tried wiggling the leads around the distributor with the engine idling to see if I could replicate the fault, but no dice.

Dunno about the spark plugs. Going back through the service history it looks like the last time they were done was March 2009, but the car has only done 15000 Km since then (barely gets used).

Where would I find the MAF and/or airflow sensors? Electrical fault finding and repairs I'm comfortable with. Mechanical stuff I'm not too good and rely on the help of others with more experience.

Cheers.

I don't know why but the first thing that came in my mind while reading your fault symptoms is a loose connection somewhere.....

if no fault codes

a vacuum fault - the coil exciter - coil -dissy module or cap-rotor-.-fuel pressure regulator -pump -pump relay

corrosion in a connection

does the engine light ever come on

It could be a loose connector/cracked solder, etc in the ignition switch. I had a Mazda 929 which exhibited similar symptoms and tracked it down to a cracked solder.

Thanks everyone for all the suggestions.


Mitshu473
I don't know why but the first thing that came in my mind while reading your fault symptoms is a loose connection somewhere.....

That's a posibility, but buggered if I can work out exactly where that one loose connection may be.



magna buff
if no fault codes
a vacuum fault - the coil exciter - coil -dissy module or cap-rotor-.-fuel pressure regulator -pump -pump relay
corrosion in a connection
does the engine light ever come on


No, I've never had the engine warning lamp light up. The ECU has nothing to say regarding the cutouts, which doesn't help things at all.

I had another run of the stutters earlier today. Drove the car to the hardware store and got there OK, about a 15 minute trip. Got back in the car after spending 20 mins inside, started the car, and while waiting to pull out of the car spot the engine went dead. Was idling fine for about 30 seconds prior. Restarted the old girl and pulled out to rejoin the highway. 500m up the road got two short hiccups in the space of 2 seconds, and then a third one 15 seconds later. Car ran fine after that for the next 15-20 minutes on the return journey home. No warning lights at any stage. Engine was warm from the ride into town when the first cutout happened in the carpark.



ammerty
It could be a loose connector/cracked solder, etc in the ignition switch. I had a Mazda 929 which exhibited similar symptoms and tracked it down to a cracked solder.

Good suggestion. I had considered this earlier and in the past have tried to jiggle the keys in the ignition barrel while the car has been running, but haven't been able to get it to conk out by doing this. Have also tried gently knocking the plastic covers in the nearby area with a rubber mallet with no success.

Well, the replacement ECU arrived earlier last week and I had an opportunity to swap it out and see if it made any differencce. Sadly the stalling is still a problem. Also spent time checking as many connections to various sensors and controls around the engine as I could find - no damage to anything. Each connector and cable was wiggled while the engine was idling with no induced stalling either.

Another thought I had afterwards was that the car is fitted with an aftermarket immobiliser. Before it got too dark to see what I was doing this evening I managed to remove the drivers-side footwell covers under the dash to expose the immobiliser. Ran out of time to see exactly what model it was, but I can confirm that it is a Dynamco immobiliser that would have been installed when the car was new (quality control sticker fell off the unit while I was rumaging around it - dated 05 October 1994). Anyone have any idea if a faulty immobiliser might cause the problems I'm having with this car?

I aso have a replacement dizzy here but will have to wait till I can book it in to the mechanic to try swapping it out as I don't have the right tools or experience to try it myself.

Ii would wait to swap the dissy cap rotor and module also check the ignition suggestion

(guess the ISC is probably OK) ..I think It may be faulty ..

did you say there were no magna wreckers near you ? this is a new one $95

http://www.ebay.com.au/itm/MITSUBISHI-MAGNA-TR-TS-TH-TJ-with-3-0L-6G72-Idle-air-speed-control-valve-IAC-ISC-/161414535073?pt=AU_Car_Parts_Accessories&hash=item25950e57a1&_uhb=1

imobiliser should not be the problem if its running .......1994 means its an old one
..the wires will have all the tags removed from it and you cant just cut the wires

about the Dynamco immobiliser
Designed and engineered in Perth, Western Australia
lets track down your unit so you know for next time .

.you can identify it by its siren if lucky or contact dynmaco direct

any look like the the one you may have @ listings on the web page

http://www.dynamco.com.au/products_preview.php?model=p455

interesting read about idle problems of a 1994 Magna TR V6 auto idle problem..Jan 2004 .u may have to double click the post

https://groups.google.com/forum/#!topic/aus.cars/naWW7_Pongk

The penny drops. You have a 20 year old aftermarket immobiliser system in your car?
Daughter has a Commodore, it developed a random no start condition and random cutting out while driving. RAA guy identified the immobiliser as the problem. She had the immobiliser removed by the people who installed it, all is good now.

First thing I would do is study the documentation and remove the aftermarket bit pronto.

Cheers, Magnabuff.

I'll have to wait until daylight and when I next have the time to get under the dash to track down the actual model number. Definitely too old to be any of those ones you linked to though. Very slap-dash installation from what I could see, just secured in place with cable ties.

No siren on my unit. Just controls the central locking/hazard lights and blasts the horn when triggered. Pretty sure it prevents the engine from cranking if you try starting the car without disarming it, but it's been years since I've (accidentally) tried it.

The penny drops. You have a 20 year old aftermarket immobiliser system in your car?
Daughter has a Commodore, it developed a random no start condition and random cutting out while driving. RAA guy identified the immobiliser as the problem. She had the immobiliser removed by the people who installed it, all is good now.

First thing I would do is study the documentation and remove the aftermarket bit pronto.

Thanks Madmax. Having a closer look at the immobilier is on my things-to-do list when time allows. I don't have a pressing need to get the car working (have a work vehicle) but I do want to get this thing licked as it's been driving me nuts for far too long.

(guess the ISC is probably OK) ..I think It may be faulty .. how much is one ?




Seems unlikely. As mentioned above the car finds and holds idle just fine - around 1000RPM on first start on cold mornings, gradually ramping down to 700RPM or so as the engine reaches operating temp. The fact that I'm getting cut-outs when the car is in motion surely means the ISC isn't the problem?



interesting read about idle problems of a 1994 Magna TR V6 auto idle problem...u may have to double click the post

https://groups.google.com/forum/#!topic/aus.cars/naWW7_Pongk


Thanks for the link, will have a look around and see what's there.

Think I may have finally cracked it...or at least found something that wasn't helping.

Spurred on by Madmax's suggestion I had time this evening to pull out the immobiliser module and have a closer look at it in the workshop (click for bigger):

[http://i153.photobucket.com/albums/s222/ac1176/Bloody%20Cars/th_P9080200_zpsdba28cb9.jpg (http://s153.photobucket.com/user/ac1176/media/Bloody%20Cars/P9080200_zpsdba28cb9.jpg.html)

No further meaningful part numbers to be found on it and nothing immediately obvious to see with the lid removed, but with the circuit board unscrewed from the case and flipped over something became a little more apparent:

http://i153.photobucket.com/albums/s222/ac1176/Bloody%20Cars/th_P9080197_zps82b9e38b.jpg (http://s153.photobucket.com/user/ac1176/media/Bloody%20Cars/P9080197_zps82b9e38b.jpg.html)

That pad in the centre of the pic has a hairline fracture all the way around it. The other side of the pad is a relay which goes to a pair of high-current leads and connector labelled "IM" ("ignition module" maybe?). 30 seconds with soldering iron fixed the dodgy joint. A closer pic of the relay shows what looks to be heat discolouration on the PCB track that comes off the relay:

http://i153.photobucket.com/albums/s222/ac1176/Bloody%20Cars/th_P9080198_zps7066f1c0.jpg (http://s153.photobucket.com/user/ac1176/media/Bloody%20Cars/P9080198_zps7066f1c0.jpg.html)

If this is indeed the problem it goes a fair way to explaining the faults I've been experiencing. Engine is fine when cold but randomly drops out when warm, at speed or at idle. Hairline crack on the PCB would present itself as a high-resistance joint to the ignition circuit. As the car continues to run and draw ignition current through the immobilser relay the crack heats up causing it to expand. Crack opens up slightly and ignition is momentarily lost. Crack moves again and allows the car to start. Rinse, repeat. Also may explain why the ECU gave no error codes. When a stall occurred as far as it was concerned all I'd done was pull the keys from the ignition barrel.

I'm keeping my fingers crossed at this stage, but I'm hopeful this is likely to be the problem. I won't know for sure until I can take the car out on a run, probably not till the weekend.

Cheers folks.

Hopefully that is the fix.

Just quickly following up on this.

Spent the weekend using the car as much as possible - highway driving, short trips to the shops, heavy traffic, suburban streets - and it would appear the stutters and stalls have cleared up. Early days yet, but I think I'm willing to call this one fixed.

Thanks to everyone for all the suggestions and help.

hi there people
( magna TR 3.0 V6 )

in the past four days my TR has developed the same problem. All faults & symptoms are the same as listed in OP above with the addition of the engine light turns on when the car stalls
i didn't know that these cars had an immobiliser but will look into it.

My problem was definitely the aftermarket immobiliser. Hasn't been a problem for me since I re-soldered those PCB pads.

As far as I can tell an immobiliser was not fitted to this model at the factory. Unless you have an aftermarket unit installed I'd suggest your problem is caused by something else.