Hey Guys,
Got a bit of an issue with the car at the moment. Its a 1998 3.0l tf sedan and its sputtering and spurting.
Initially when it first starts, its fine, but once the engine gets a little bit of warmth (1-2mins of driving) it starts to sputter, spurt and jump around a bit with loss of power. I assume its misfiring. Then once the engine was 100% warm, it wasn't doing it as much. However, the problem seems to have gotten worse and worse, to the point where it is doing it all the time now.
It seems to be happening at about 2000 - 2300 rpm.

The car has just had the 105,000km service ($780) so the rear spark plugs were changed, and i changed the front ones myself yesterday.

What could it be?

Any help much appreciated.

Cheers,
Cam.

Fuel pump ??? Sounds like the pressure isn't there m8 as it happens around 2000rpm its starving for fuel, that'd be my guess.

Spark plug leads.
Your car is now 7 years old.
Get some decent silicone ones.
Make sure that you change the King Lead as well.. the coil to Distrubutor cap lead.

The other thing that you may find is that the Cap should be carefully checked and cleaned inside and outside. Look carefully with a magnifier all over in case it is starting to track and breakdown. A good idea is to polish it.

Last one is injectors. I had a KS with exactly the same symtoms, put your foot down between 2000 - 3000 and had a huge flat spot and misfiring. If you leave it it will become almost undriveable.
I had the set removed, ultrasonic cleaned and reflowed.
Afterwards smooth and very good throttle response.

I had a 89 TN 5 speed that used to get the stutters at about 2000-2200 rpm. When it was cold it was OK. After it warmed up it started to stutter when I put my foot down or changed back a gear to overtake. It happened after about 20 minutes after a cold start. What it ended up being was the connector in the main wiring loom. (somewhere between the phlenum chamber and the oil filler on rocker gasket) Common fault with early magnas. When I pulled it apart, it was lightly rusted from all the engine degreasing I used to do because of blown gaskets and oil seals every other week. Pulled it apart, cleaned it with emery paper (very time consuming due to lack of clearance) and re-set the gaps by squeezing the connector (to get a tighter fit).

I had the same problem.

Started when i put Octane booster and injector cleaner into a tank of Optimax.

They replaced both front and rear spark plugs, cleaned the injectors properly, replaced Dizzy & leads. was eventually narrowed down to BURNING OUT THE POINTS IN THE DIZZY!

Apparently the computer advanced the timing to the point that it was so advanced as to burn out the points..... crazy stuff. the leads were almost cactus as a result.

So yeah, Dizzy & Leads.

There is also an issue with the fuel curve in the 3.L TF Manuals... there was an 'update' to the fuelling that most have recieved. The problem was that sluggish sputtering and spurting that you mentioned. If they couldn't fix it, they were going to put in an ECU with the original 'richer' curve.

If you go to a mitsu dealer, get them to call Ross Granata Service division on (02) 6372 1766. They did mine (under extended warranty at the time) and so may be able to give your guys a push in the right direction.

your dizzy cap isnt cracked by any chance is it only has to be a pin hole as then the spark will jump through the dizzy and misfire i know it sounds odd but i have had it happen and was a real bastard to find the problem
barney

With the above, sounds ignition related, change leads (do this first) and check the dizzy.