Hi everyone,

Totally new here and thrilled that this Australian forum dedicated to all things Magna exists.
Of course I found this site whilst Googling for trouble shooting guidance to fix my Magna.

Mitsubishi's "run" in our family and I have 3 of them viz; a 1981 Sigma owned from new, a 1990 Magna TP and a 1995 Verada.
The Magna TP is the only one on the road at the moment but misbehaving badly (the Verada won't start and the Sigma is ?).

The Magna TP is an automatic station wagon with a 2.6 litre EFI astron engine. It always had some quirky behaviours but these are now compounded with others that I can't ignore.

Long term quirky behaviours:
1) At slow driving speeds, occasionally the speed will suddenly drop and quickly pick up and then hunt like this until I accelerate a bit. - happens only when engine is hot.
2) Similar thing when taking off except I accelerates through the hickup - also intermittent and only when the engine is hot.

More Recently:
*** SOLVED *** 3) The engine feels like it momentarily stalls, mostly whilst idling and sometimes whilst driving - engine hot or cold.

Most Concerning:
4) Braking gives a "thud" just before the car stops. But if I gently brake and roll on everything is fine. The "thud" might be a rough gear down shift or some other gearbox action.

The throttle position stop has an effect on issues 1) 2) and 4).

Issue 3) is probably a fuel delivery issue and so first port of call will be to change the fuel filter this weekend (was a spark plug problem).

Could really do with some expert thoughts as to what might be going on. I do have the Haynes Repair Manual for the car but it isn't always that clear or complete and the terminology throws me a bit (just a hobby car mechanic!).

Help Please.

Aquar

180413) I changed the fuel filter but nothing has changed except that the car drives a little bit more responsive. I dryed out the old fuel filter and found a lot of resistance when blowing through it. So it was good I replaced it but the problems are elsewhere.

190413) Checked the dizzi contacts (had cleaned them before as the contact were corroded and car wouldn't start). Checked HT circuits (no problems) and replaced spark plugs (badly worn). Seems the worn sparkplugs were resposible for the the momentary stalls / misfiring (issue 3). Hot electrodes were worn down with gaps up to 1.1 mm (probably not sparking to cold electrode).

270413) Tried Trotty's engine mount check, did not noticed any movement in engine mounts and no "thuds" during this rocking.

070513) Checked resistance of the pulse generators, both spot on specification (242 and 244 ohms).

1,2,and 3 will be all caused by the same problem by the sounds of it....sounds like fuel pump

4) check engine mounts for the thud when stopping, put the bonnet up, start car. In drive with brakes applied give the motor a bit of a rev and check for engine movement. then do it in reverse as this simulates compression braking/gear changedown

do the basics and go from there... give the plugs a clean. clean throttlebody.

I'm going to say it's the TPS given it's an auto efi.
the fact it's doing it when hot is the indicator for me.

The thud I'd say is from the top of the front suspensions towers, had that problem a decade ago.

Meanwhile, as Trotty says, give the car a good service with plugs and that will also benefit the car.

Thanks very much guys, it's fantastic to be getting input like this.
I'll maintain a bit of a log in reply #2 of this thread, in case others have an interest in this.

The thud feels/sounds a bit like going over a bump in the road but its hard to convey in words.
The gearbox changes gears very smoothly so suspension or engine mounts are a much better bet for the "thud" (thanks for that).

How is the TPS coupled to the throttle axel?

Hi Aqua,
hope you get your problems solved.
Try this web address for a manual.
http://depositfiles.com/files/cen9su9k9 (Thanks to Coldamus for this)
Even tho its for gen 2, I use this manual A LOT because my gen1 TP has ongoing carby problems. I find this Mitubishi Manual is REALLY comprehensive and mostly applies to the TP. In the manual reference is made to test equipment; to diagnose faults you will HAVE TO HAVE an ANALOGUE VOLTMETER. The problem with a digital voltmeter is that it only changes its reading about 3 times per second. You can use a digital but when testing the TPS, make sure you turn it SLOWLY so the digital voltmeter can track the voltage changes being measured. I have both types; prefer the analogue; you can get a digital from say Jaycar for 10 - 15 bucks and is quite OK.
good luck.

Hi rumpfy,

Thanks for the link, I'm DLing the manual straight away as I also have a gen 2 (verada that refuses to start!).
Taken the TP of the road so I can work on it in peace. Back in my trusty sigma (it first needed a relay to better feed the starter motor solenoid).

I have both digital and analogue mutimeters for diagnosing faults and adjusting the TPS is next on the TP todo list.
Only new thing I tried on the TP has been to adjust the throttle stop screw. The moment it touches the throttle stop tab the ISCM starts to hunt (engine hot).
This is probably the reason for issues 1) and 2). I am hoping this is due to a TPS sensor mis-adjustment.

I have both digital and analogue mutimeters for diagnosing faults and adjusting the TPS is next on the TP todo list.
Only new thing I tried on the TP has been to adjust the throttle stop screw. The moment it touches the throttle stop tab the ISCM starts to hunt (engine hot).
This is probably the reason for issues 1) and 2). I am hoping this is due to a TPS sensor mis-adjustment.

I think you might be on the right track there. There is a good description in that 2nd gen manual of the operation of the TPS (page 13.2.6) and the ISC (starting from page 13.2.9). Adjustment procedures for both are later in the same chapter (13).

Incidentally, I can't take credit for the manual. I only posted a link to it. I'm not sure who originally scanned it but it was karj who uploaded it to depositfiles. However I recently acquired a TP series factory service manual in as new condition. As soon as I can figure out how to do so without destroying it, I will scan it and make it available.

AQUAR i have some tp throttle bodies here if you need one.

@ coldamus
I am thankfull to everyone for providing words of wisdom and sundries, it helps a lot in trying to do the work myself.
Hopefully you can find a way to scan the factory service manual into a pdf file, it would give members here the detail often
missing from third party service manuals.


@ magnaman89
That's great, I'll call on you if the TPS turns out to be stuffed.

I tried Trotty's method to check if the engine mounts are loose but it seems fine and there were no thud sounds during the process.
Might of course still be lose engine mounts or the front suspension as per Astron Boy.
However I did notice the thud was less severe with no contact between throttle stop screw and throttle stop tab (whatever its called).
This makes me think it might be an inappropriate gear change that is caused by a bad TPS / TPS adjustment.

If the thud is due to rough transmission down-changes when slowing down, check the kickdown servo switch and the wiring from it. Also check the two pulse generators on the transmission and the wiring and connectors for them.

If I understand correctly, the TCU (transmission control unit) uses information from the kickdown servo switch and the two pulse generators on the transmission to co-ordinate gear changes, both up and down.

The kickdown servo switch is on a big round plate about 10 cm diameter on the side of the transmission and accessible from the engine bay. The plate itself is called the kickdown servo cover and is made of bakelite or brown plastic. It is held in place with a large snap ring (circlip). You can test the switch without having to take if off.

To quote from the manual: "A faulty switch can result in excessive shift shock, flaring between shifts or no shift to 2nd gear". Testing is as follows: "(1) With the ignition switched OFF, check continuity between the switch terminal and earth. Continuity should exist. If not, replace the switch". "(2) With the engine idling in D (with handbrake applied), check continuity between the switch terminal and earth. If continuity exists, replace the switch."

The switch is only the part in the middle of the plate (kickdown servo cover). If it is faulty, you'd normally replace the plate and switch as one piece. I think Pick n Pay Less charged me $5 or $10 for one. A pair of right-angled circlip pliers (compression, not expansion) will be required. There is a rubber O ring or seal behind the plate and a small amount of transmission oil may drip out when it is removed. However you don't need to drain the transmission oil and won't lose any significant quantity so long as you don't run or drive it with the plate off.

The pulse generators can also be checked while in place. Resistance should be 245 ohms + or - 30 ohms. Refer to page 23.2.16 of the 2nd gen service manual.

@ coldamus
Thanks, you raise an interesting possibility to check out. And this also triggered my memory, in that I felt the TP wasn't that great in kicking down to 2nd gear when pushing the pedal to the metal (very rarely do this so I forgot).

The Haynes manual mostly ignores anything to do with the auto transmission but does have a little section on the kickdown servo unit.
It shows a metal kickdown server cover with a bolted on switch. I had a quick look at the TP and see that the kick down cover it is more like you describe, except the switch seems to be integrated into the kick down cover.
There is a single wire poking out from an extrusion on the kickdown server cover (same shape as the bolted on switch in the Haynes manual) that seems to lead into a multiwire connector under the air filter pan.
I am not sure it actually terminated into this connector as it was just a quick look and see, but if so I presume back probing this connector is the only way to check this switch in situ.

Re the pulse generators shown in the 2nd gen service manual, are the references to connector layout (resistance across terminals) the same for the TP as 2nd gen?

Yes, the connector pin layout and resistances are the same for the TP. It is the same F4A23 transaxle in the TP and the 2nd gen. carby 2.6 litre.

The single wire from the kickdown servo switch goes via a circuitous route to a connector mounted on a bracket in the gap between the brake fluid reservoir and the top of the strut tower. There are two or three connectors on the bracket. I think it is the front one. You only need to measure continuity (or lack of it) between that wire and earth. If it is too hard to get at the connector, you could just stick a pin in the wire anywhere convenient.

It is the same F4A23 transaxle in the TP and the 2.6 litre 2nd gen.

Most TP have the KM177-6 Automatic transmission unless the later F4A23 has maybe retrofitted to it. Vee

KM177-6 is only an alternative designation for F4A23. They are the same box. http://mitsipedia.info/index.php?title=KM177-6 The factory service manuals refer to them as F4A23.

In relation to 2nd gens, I should have been more specific. The F4A23 was only used in the carburetted 2.6 litre 2nd gens. I've edited my above post to correct that point. The 2nd gen V6 and efi 2.6 used variants of the F4A33. http://mitsipedia.info/index.php?title=F4A33

Had a better look today. The kickdown servo switch wire indeed continued on underneath this connector below the air filter and ending up in a connector near the brake fluid reservoir as described by coldamus.
I looked for other wires coming from the automatic transmission to find the pulse generators. There were two identical "gadgets" on top of the transmission box with 2 green wires coming from them. From the cross sectional diagram in the gen2 service manual, the gadget nearest the kickdown server seems to be a pulse generator, the other one looks like it must be underneath the transmission (its hard to orient from this diagram).

With a bit of luck I'll check their condition this weekend and update the trouble shooting log in post #2.

The picture in the mitsipedia link (thanks!) for KM177-6 matches what is in my TP and on this picture you can just see the pulse generator on top with two green wires coming out.

I looked for other wires coming from the automatic transmission to find the pulse generators. There were two identical "gadgets" on top of the transmission box with 2 green wires coming from them. From the cross sectional diagram in the gen2 service manual, the gadget nearest the kickdown server seems to be a pulse generator, the other one looks like it must be underneath the transmission (its hard to orient from this diagram).
I think both pulse generators are on the top although it doesn't look that way in the diagrams. The wires from both of them go to a single four-pin connector. If you trace the wires from the one you've found up to the connector and then follow the other two wires back from the connector, you should end up at the other pulse generator. I guess it doesn't matter which is A and which is B for checking purposes as both have the same resistance specs. Let me know if you can't find them and I'll try to get a photo of mine (I have an efi wagon and a carby sedan, both autos).

@ coldamus

Thanks for your generous feedback (my magna TP is a wagon as well!).
I am pretty sure I spotted both the pulse generators but the diagram cast a bit of doubt in my mind.
Knowing they are both on top and going to the same connector will make it easy to find.

Dr google provided an interesting link to a service manual for this auto transmission (in PDF format).
http://www.caixautomatica.xpg.com.br/manuaiservicos/Mitsubishi/MANUAL%20DE%20SERVI%C3%87O_MITSUBISHI_KM-177.pdf

Finally had a moment to check the resistance of pulse generators on the Magna TP. One has a value of 242 ohms and the other has a value of 244 ohms (spot on spec).
On the bracket with the 3 connectors, it is the one closest to air filter box (front of car).

Hi everyone, I am back in the Magna TP now after using the Sigma SE in the winter months.
The plan was to try and resolve the issues whilst the car was not being used.
But other things put that plan on the back burner, and now I am driving with these issues again.
Help would be most appreciated.

I keep reading that the transmission needs the mitsubishi transmission fluid to properly work, and others saying that this just isn't true.
Now I did change part of the transmission fluid with proper after market fluid after replacing the rubber boot in the CV joint.
Might this be a good reason for the rough downshift?

Anything's possible but I think that's unlikely. While you've been away, I've retired my carby TP sedan and bought another TP, this time an efi sedan. With the carby sedan, I used to get very occasional bouts of rough shifting, both up and down. It mostly happened after I'd parked the car while shopping and restarted while the engine was still hot. The cause was a tiny leak from the coolant hoses that go to the carburettor. Despite my best efforts, I could never completely stop the leak because of the corroded state of the pipes where the hoses attached.

A few drops of coolant would drip onto the transmission and presumably this sometimes interfered with the operation of the pulse generators or kickdown servo switch or the TCU's reading of information from those devices. It might be worth your while to check that you don't have a similar problem. Since yours is efi, the heater hoses and the water pump to manifold hoses are possible suspects.

Its nice to come back and find people still talking about these old cars.
Interesting you replaced one TP with another, but these old beasts do sort of feel like part of the family (even my old sigma!).

Now my TP has many bouts with water leaks from water pumps to hoses and radiator.
I fixed all but the radiator one. It has an on again off again micro leak in the top corner under the metal bracket.
I can't see the leak and it took weeks to find the spot where it gets wet.
Fixing it is a whole other thing, but its not losing a lot of water and a piece of paper is keeping things clean.

Another problem has appeared. This time the mcpherson struts sound like squeezing a soapy sponge when going over a decent road bump.
When I looked at them I also found the rubber cylindrical sleeve that protects the strut is broken at the top.

rubber cylindrical sleeve that protects the strut is broken at the top.
Just remove it they donot last long and alot of cars have nothing. Hard to find replacements i have on occasion put motorcycle gaiters in them instead.
Oil type struts do make some noises in operation. Vee

@ veeone,

Thanks.
Who knows how long the rubber sleeve has been broken like this.
The front suspension bounces ok on both sides, but both squeal nicely with a good work out.
When going over a speed bump it just makes this annoying sound.

If anyone knows any tricks to make them sound a little less than a pig about to be slaughtered, please let me know.
Pity there arent any other members here in Canberra, as I would love borrow and try another throttle position sensor.

Just a quick update on the thud issue.

I've been driving the Magna for the last 6 month (now back in my Sigma for 6 month!).
During this time, it has only exhibited a light thud on a few sporadic occasions.
The change from nasty thud to light thud was induced by completely winding out the throttle stop screw.

I think this action, makes the throttle position sensor move past some unstable threshold point.
And so the down shift is more gentle (behaved) in the gear box.

It seems this may well be another indicator of having a faulty throttle position sensor.
If I ever get the time I'll have to get and try out another sensor.

you may want to chase a wrecker first

this is the only new price I can find this week

http://www.myshopping.com.au/PT--171_Auto_Parts?Find=magna%20throttle%20position%20 sensors

Pity about the hefty price tag of these little units.
Hopefully the local wreckers will be a little less demanding for a secondhand one.

If it fixes this issue, and some of the other ones I mentioned in this thread, it will be worth it.

Mate,if you get desperate for a throttle sensor I'm pretty sure the transmission guy I go to would have one. I think I remember him saying he had some carby sensors there.. He's in Bankstown, a company called Dantrans. They are good guys

Mate,if you get desperate for a throttle sensor I'm pretty sure the transmission guy I go to would have one. I think I remember him saying he had some carby sensors there.. He's in Bankstown, a company called Dantrans. They are good guys

Not too many wreckers here so I may well get desperate.
Maybe a good clean will fix it? (not that lucky!)
I have 6 months to look, buy and try before I register the magna again.

do you still need a TPS for the EFI ?

Hi magna buff,

Haven't done anyhing as yet with the magna TP (due to other jobs!).
Hopefully I will get a spare moment next couple of weeks to remove and clean the TPS.
If that doesn't work out I'll be hunting for a replacement.

Thanks for asking.
Did you locate a good soure for the TPS, or do you have one?

Dont buy one
..
till we ask around .. will send you a pm
Do you know how to do the diagnostic on this system ..diagnostic plug is above the glovebox door

diagnostic tells you if its the TPS switch or the accelerator pedal switch adjustment ( page 46) -- symptoms you have could be either

you can use a volt meter but better if you have an LED test light .. all you need to do is count the flashes

you have the TPS info .from page 20 ....just the diagrams are wrong LHD second gen diagnostc plug shown

http://www.caixautomatica.xpg.com.br/manuaiservicos/Mitsubishi/MANUAL%20DE%20SERVI%C3%87O_MITSUBISHI_KM-177.pdf

Not used the diagnostics system on this car before, but have no problems with electrical circuits.
I must have wanted to do that before as I actually DL'd that pdf more than a year ago (file already existed in my download folder!).

here is the plug pins then you dont have to remove the glovebox just pull down the plug

if you need to diagnose the efi engine system its on the round plug near the passenger mudguard near dissy

http://i253.photobucket.com/albums/hh59/magnabuff/diag_plug_128.jpg (http://s253.photobucket.com/user/magnabuff/media/diag_plug_128.jpg.html)