Why 98 + needed for a mitsi GDI?

For real. Well to tell the truth I dont have a scan tool for three dimonds lol but the data list for d4 shows large amounts of egr at idle and light throttle angles. And as far as I was informed by mitsubishi the d4 and gdi systems work very close to the same. must have been missinformed. Bloody three dimonds lol.

Ok then with the D4 engine missing while in ECO mode (green light on), this is due to a build up of carbon in the throttle body, plenium chamber or both!
Therefore removing these parts and giving them a good clean out, eg with carby cleaner, then running car on 98 and use good quality oil will slow down the return of the bloody annoying miss!

I would be very surprised to see an engine inject EGR gasses at idle, for one combustion temperatures are rarely at levels to increase NOX emissions so there simply isn??

Yes, running on 98 will likely help out the D4 too as its my understanding that like most direct injection engines it is designed for high octane.

As well as that, don't forget what Gadgit said about using a high quality oil. I have been doing some thinking on that and I suspect what the quality oil may be doing is producing less or cleaner crankcase fumes.

Remember the EGR system dosn't just suck in exhaust gases it also recirculates the crankcase fumes via the PCV valve. I think its safe to assume these fumes would also contribute to the carbon build up fairly significantly.

I would say those crankcase fumes would be affected by using low octane fuel too as unburnt fuel from incomplete combustion would find its way down the bores, where it would mix and evaporate out the PCV system.

These gases could also be directly contributing to your miss if it is occurring during periods of high EGR. I think someone may have mentioned this a few posts back as well (sorry its late and I can't be bothered checking)

Now all of that said. when it comes to the D4 I have next to no direct experience, my experience is with VW and Alfa Direct injection.

gammelvind, lengthy blurb above aside, my advice would be to firstly change to 98 and a high quality synthetic oil of exactly the right type for the engine. Personally I would throw a set of fresh plugs in at this point as well.

Then see how its running before you carry on removing parts, although giving everything a clean out is always a good idea if you don't mind doing it.

Check in with the Toyota experts too as a slight miss under high EGR conditions may even be normal with NZ fuel if its an import and was designed to run on Japanese 105 Octane or whatever it is they use.

Yea thats how I was taught it to. but when we started seeing these D4 engines in the workshop back in the early 2000's I ran a few case studies and mapped data. And my findings were reduced EGR opening angles at wider throttle angles. go figger lol

Just spitballing here so this might be a long shot. Remember a key reason of going to all the trouble of direct injection is economy. Theoretically EGR reduces pumping losses at fairly closed throttle angles.

Say they find a way to get around the catalyst temp issue or they find they can get away with at least some EGR before its an issue.

That would make a valid case IMO for running EGR like you have observed even though it fly's against savanna's conventional EGR theory. (Because savanna's understanding is based around using EGR primarily for emissions and temp control not economy.)

Now, here's some Toyota ignorance for you to laugh at. does it have a throttle plate! Technically a direct injection engine doesn't need one and if the D4 doesn't have one that would to some degree throw my theory out the window as if that's the case pumping losses would be low anyway.

BTW, the idea of EGR to reduce pumping losses might not be as crazy as it sounds, over the years I have heard of ecomodders playing around with it for this reason. In particular I remember an article in an Australian online magazine where they tested it (OZSPEED or something like that, great articles in that BTW). I can't remember what the outcome was but the theory was there.

Yea they do run a throttle plate. The only Toyota petrol engine with out a throttle plate is the ones set up with valvematic.

Good to know. Well, that certainly goes along with my theory of why they might do it.

BTW. valvematic. sounds like a 3 in one radiogram with automatic turntable. I always said Toyota were living in the past. (Sorry couldn't resist a stir!)

Lol yea it dose.
Great system tho Jazz have a look it it on Wiki.

Will do. but don't tell savana, learning without getting your hands dirty is forbidden remember!