Diesel misfire

nivapilot · Guest

Hi all,
my KZJ70, series II landcrusier has had a replacement engine, a 3.0Td.
I bought a newer KZT-e engine in place of my KZT motor.

It was bought from a dealer and put straight into my motor, a few bits had to be changed, and fired it up, with not a lot of problems.
One of the items changed over, from the KZT engine was the oil cooler, the newer ones don't have a coolant outlet to the fuel pump.

When I first fired it up, she ran a bit ragged and so I replaced all four injectors from the KZT as they hadn't been playing up at all. It seemed to do the trick, although not 100%.
I tried changing the glowplugs and found that one of them a was broken off, and try as I may I cannot get the broken bit out, without removing the head. I left the glowplug relay disconnected and drove aroung for some time like that until the slightly colder weather got here.

Now it doesn't matter if the glowplugs are connected or not, but when I fire up the motor, I have a misfire on one cylinder, unburnt diesel pumps out the back, until it has warmed up a bit and then it runs ok?

Any ideas where to start??

jonkem · Posted: Wed Nov 02, 2011 12:00 pm Post subject:

I think you've answered it yourself. The 3.0 uses a pre heat system that continues to give heat even after starting until the engine temp is at a good enough level that it won't misfire. The heat just smooths things out a little by making it easier for combustion.

If there are some minor things wrong in the engine, low-ish compression, poor injector pattern, injection timing slightly out etc etc, the missfire will be more pronounced when the engnes is cold.

Only reasonable thing to do is get the broken glowplug out. It's not a massive job to take the head off if there's no way to remove the plug from the top.

It's worth remembering that there have been problems with some cheap glowplugs loosing the tips as well so if you can get it out from the top make sure it's all there and intact.

nivapilot · Guest

Only thing that throws me Jonkem, is it does it, wether or not, the glow plugs are connected.

So if I disconnect the glowplug relay, and start the engine from cold, it struggles to satrt, and still misfires on one cylinder?

jonkem · Posted: Wed Nov 02, 2011 4:22 pm Post subject:

I'm guessing (from a distance and from what you've described) that it is because the weather is now that much cooler, an issue in that cylinder is highlighted. As you can't preheat that cylinder you can't rule it out at the moment.

A compression check would give you an idea of the condition of the cylinders compared to each other and (still guessing) if that 1 cylinder is a bit low you need to know if the tip is still intact on the glow plug.

nivapilot · Guest

Hmmmm...looks like head off then?

jonkem · Posted: Thu Nov 03, 2011 4:03 pm Post subject:

Only if you can't get the plug out and if you can't get a comp test with it in.

I would suspect that it's possible to get the plug out, i'd certainly try before taking the head off. If it causes more issues getting the plug out the worst case is that the head has to come off so you're no worse off?

Please remember I'm guessing based on your description of the symptoms and the fact that it's been made worse by the colder weather!