4G63 question

[Subaru ETA]

My Airtrek has the 4G63 turbo engine from the evo 7 GT-A. First question does anyone know these engines well?

The problem is it has what can be described as a miss fire. Usually happens when giving it light to half throttle. Usually when coming off a round about or entering a motorway. It is intermittent - it will do it once a day for a week, then go away for a month! It has also intermittently developed a slight "miss" on start up.

The plugs looked a bit shot so i replaced them. I thought I had it fixed but it has come back. I have tested the coil packs (runs wasted spark system) and they seem fine. There are no codes and no engine light.

I have taken it to the dealer who had it for a day, double checked everything I had done, did some data logging and they are at a loss! Doesn't help that it would do it while they had it!

I'm now thinking EGR or oxygen sensor? Anyone got any ideas?

[elnevio]

Have you checked the leads? Could be the start of one breaking down.

We had this on the RVR when we first got it. It eventually became quite obvious when you removed the lead, as it was shorting through the shrouding to the head!

[Subaru ETA]

yes i have, and the dealer has as well apparantly. But now you say that, when i did the plugs it went away (first i regapped them which stopped it, but then i repleaced them). maybe having them on and off so many times has caused one to start to beak down...

ill take a look when it has cooled down abit

[Subaru ETA]

have just pulled the EGR valve out and given it a good clean. put it all back together and it is still the same.

the leads tested ok but later tonight when it is darker ill run it with the covers iff and jiggle the leads and see if they arc

[Subaru ETA]

hmmm - the long lead test at 5.71ohm and the short 2.7ohm so i am happy with that.

When it is idling however, if i move the long lead , the idle drops, then comes back.

[BEG4ME]

I had a bit of a similar problem but worse and only when engine was warm. turned out to be the spark tracking down the coil-spark plug boot. Also i've seen the boots fail and completely arcing through the rubber to the head as Nev has said. Would be a good idea to check for tracking either on the old spark plugs or inside the boots and leads. You're looking for a greyish lightning kinda pattern.

[Subaru ETA]

Yeah there is no tracking (I'm a mechanic by trade :p ). Should have brought a Mazda being an ex Mazda tech!

I'm thinking that the long lead may be the culprit. However, when I move it around with the ohm meter connected it doesn't change the reading by much. Im prob going to chuck a set of leads at it and see what happens

[BEG4ME]

Mazda, good one. Haha. Although, a bit off topic here, but the 2.3 turbo 323 thing sounding quite a fun little drive.

[Subaru ETA]

Mazda 3 mps - awesome little car! I would own one if I had the coin

[Ryan]

Would rather have the Mazda 6 MPS... been in one as passenger and it was most enjoyable. I'd definitely buy one of those cars based on looks, spec level and performance /yes

[Subaru ETA]

Would rather have the Mazda 6 MPS... been in one as passenger and it was most enjoyable. I'd definitely buy one of those cars based on looks, spec level and performance /yes

Pity they don't make the 6 mps anymore

[BEG4ME]

http://www.trademe.co.nz/motors/used-cars/mazda/auction-384812753.htm
That but turbo and manual would be my choice. Rare though. Not available stock in 4WD manual turbo, as far as i'm aware.

[Subaru ETA]

They never did a turbo wagon but you can get a HKS turbo kit which is very straight forward to fit. Wouldn't fit a turbo kit to a 2002 though - they had a smaller sump

[BEG4ME]

Anyway, back on topic. could you not just make up a temp. spark lead to test? You would probably have all that gear in the workshop, yea? Even using an old lead off a different vehicle (obviously not a faulty one) or borrow one.

[Subaru ETA]

That's the problem - I have a desk job now so no workshop!

I'm going to go see my Nate who is a auto sparky, see what he has laying about

[Ryan]

That's the problem - I have a desk job now so no workshop!

I'm going to go see my Nate who is a auto sparky, see what he has laying about

Is it this Nate by any chance?http://www.thecitrusreport.com/wp-content/uploads/2011/03/Nate-Dogg-RIP.jpg

[Ryan]

Double post.

[BEG4ME]

Mechanic with a desk job? Almost unheard of. Haha. Yea sparky *M*ate should definitely have something to try.

[Subaru ETA]

Stupid cars! I checked it last night and it was fine. This arvo I put it all back together, started it up and it running like a complete sack of ****! Idle is quite rough and has a miss just off idle.

I was talking to a different MATE today and he said he may actually have a near new set of leads off a late model Evo in his tool box so he will have a look on Monday. ( he was the Subaru mechanic at everyones favorite car dealer fast 4s!)

[Ryan]

Heh, hope it all works out Dave. Sounds like this one is particularly frustrating. :(

[Subaru ETA]

I hate cars. I have replaced the leads and it is still doing it! It must be the coil packs.... They gave been tested by 3 different people (myself, an auto sparky and Andrew Simms mitsubishi newmarket) and they test fine.

Think I'm going to take it into Andrew Simms Henderson tomorrow and get them to look at it as I don't have the time to do it! I'm suppose to be preparing training material and presentations on the mitsi electric car for our roadside mechanics! Don't have time for this archaic internal combustion stuff :p

[Subaru ETA]

Car has been at Andrew Simms Henderson since Monday. They thought they had it fixed, but when he started it this morning it was running on 3 again.

This morning he got it to surge on the motorway - it feels like fuel cut, but happens at light throttle. The guy working on it is the foreman and is really good. He is at a training course tomorrow so if going to run it past the head technical guy who knows everything Mitsi and see what they come up with.

When he rang this morning i was worried about what the bill was going to look like! but they aent charging me for the diagnostics which is awesome!

I would rank the service at Henderson better then at Newmarket. Yes Newmarket has the big flash dealership, but it has big dealeship mentality - get as much work in and out as possiable. I know what this is like working for a big franchise dealer like i used to

[miller]

Maybe the MAF is on its last legs? My old Evo which I replaced the MAF in had intermittent faults when it was hot?

If the EGR or o2 sensor was on its way out they would throw a CEL.

[Subaru ETA]

This has issues when hot and cold. They have checked the maf and reckon it's all good but its a possibility.

EGR system is all good and O2 sensor is fine. O2 sensor want always throw a code (well in the cars I worked on - ford and Mazda it didn't!)

[BEG4ME]

Maybe those dudes out there with the AECS Scope machines? (something like that) would be able to find the problem. We get Radiator magazine every month at work, and some of the faults they come up with are wicked aye, but always solved.

[exevoowner]

there are a few issues with these engines that can cause missfires one being valve seats that can allow passing wrong coded plugs or heat range also try cam and crank senors or even the disc on the crank for the crank senors long shot but worth a try have you run the exhaust gases test could be rich ?

[Subaru ETA]

The plugs are defiantly the right ones. Cam and crank sensor would give a code surely?

[Subaru ETA]

got the car back. they found a split vaccum hose at the back of the engine, which they replaced. they were unable to get it to fault again so it is a case of wait and see.

i was thinking, if this hasnt fixed it, would a dodgy BOV give the same issue? it is running the factory one which is the same as the vr4

[Subaru ETA]

****en thing! It won't idle now :(

[exevoowner]

you could try cleaning the throttle body as they foul up

[Subaru ETA]

You could eat off the inside of the throttle body it is so clean! I cleaned it and so did mitsi, along with the stepper motor.

Wife drove it yesterday and it did it when it was warm. I drove roughly 20km parked it for three hours and then another 20km home and it was fine. This morning I drove it to work, stopped at intersections etc and it was fine. Stopped to swipe into the carpark and it stalled. Now it's idling at just under 500rpm. Took it out 1.5 hours later to get a pie and it was doing the same....

Still think it could poss be the BOV as it does seem to be getting louder

[scott.mohekey]

Have you tried resetting the ECU? It may need to relearn its idle after having fixed the vacuum leak.

[Subaru ETA]

I did think of doing that when I get home. However I would have thought it would be doing it all the time

[scott.mohekey]

It sounds like its doing it once it's heated up, and I'm pretty sure the idle calculations are different once the coolant has reached operating temperature.

[Subaru ETA]

Good point. I'll give it a go at my lunch break

[Subaru ETA]

An update - idle problem fixed. Dead cell in battery. It was loosing power under load and dropping it low enough for it to loose it's idle setting.

I have driven roughly 4000km in the last 7 days (touring the south island). It has been fine the whole time until the drive from Invercargill to Dunedin today. It's surging alot and had it's "miss" a couple of times going up hills. I shut it down in belclutha and started it straight back up and it purred like a kitten until I got off the motorway at Mosgiel, it surged and miss quite bad. Got it to one of our roadside mechanics we use at work and he ran a scan over it. It was hunting a little at idle but everything was looking ok on the data log. Once again no codes.

I'm starting to think it has a ECU issue

[scott.mohekey]

That is VERY weird. Loose connection somewhere maybe?

[Subaru ETA]

Myself and 2 Mitsubishi dealers have gone through every bloody connection and cleaned then and made sure they are secure.

When we get back to Auckland it will go back to the dealer one more time. If they can't fix it I'll be trading it for an outlander. I love the style of the car and the seating position and height of the car are really good for my stuffed back and knee. The wife has spoken and wants a outlander so who am I to argue lol

[Subaru ETA]

well its back at the dealer again. they cant work it out. they have opened the ecu and cant see anything obvious wrong with it. They are now thinking injectors. Only thing is is that they dont really want to remove them and get them flow tested etc as they dont know if that is the problem! Doesnt help when it is running perfectly fine at the moment.

I have told them they can have it for the week....

[taylor]

Does it have a 3 or four plug ecu?

I Have coil plugs / Leads / AFM you can try if you like, although the mitsi dealer probably does aswell

Few other things I can think of:

Resistor pack having a dry join inside it: has been known to have similar traits on the evos

Fuel resistor / relay

Theres a relay that kicks down the pump through a resistor, if the resistors not connected/ faulty itl run like a bag of ****

If you can get it to sit there running crap, pull the afm plug and force it into limp and see if idles

[Subaru ETA]

i cant remember how many plugs the ECU has.

It has brand new leads on it so it aint those. Its quite a pain in the arse to disconnect the AFM while it is running - it sits under the airbox and you cant get to the plug! i did try to do that but i had to remove a heap of **** to get to the plug - so it wont run anyway! when i get it back i will try position it in a way that i can get to it.

Im pretty sure that last time they had it the road tested it with different coil packs on it and it played up, but if you do have some spare coil packs it could be worth a try?

[Subaru ETA]

Picked it up from mitsi yesterday - they have admitted defeat! They have been driving it all week and used nearly a tank of gas - hasn't faulted once! Obviously they cant fix it if it ain't doing it!

But, you guessed it, it played up for me last night.....

[scott.mohekey]

Different fuel?

[Subaru ETA]

I always fill it at 2 different gas stations - doesn't matter which one I fill it at it still does it. I filled at all sorts of different stations on our trip. Didnt make any difference

[Rossco Type-S]

Did you ever resolve this issue?

I was having the same issue after a reflash a few weeks ago. The missfire was always at 3000 rpm exactly under lightish load. It would go fine one day and then the next would run like crap.

When it got really bad I would reset the ECU and it would run fine for 20km then it would come back.

As it was always exactly 3000 rpm I knew it was ECU related, so I did some research and the best I could determine it relates to the gearbox fuzzy-logic. At the shift point there is a brief fuel cut to lower torque, but this was occuring at the wrong throttle positions. The only possible solution I have seen to this is TPS scaling. Alternatively, trying reflashing a new ROM into the ECU.

I reset the ECU and then drove the recommended 50km (without WOT) to get the ECU to relearn the gearbox settings and it hasn't come back. That being said, I also repositioned the TPS so that its voltage at throttle closed was closer to the recomended 0.5V

[Subaru ETA]

It was running sweet for a few months, but came back. It didn't surge but had a really rough idle and miss on start up. It went away for a week, then came back for a few days, and now it's fine!

I have checked the TPS and was pretty much .5 volts. However I was actually thinking it could be an intermittent TPS fault the other day so I'll look into that next time it plays up

[Rossco Type-S]

It was running sweet for a few months, but came back. It didn't surge but had a really rough idle and miss on start up. It went away for a week, then came back for a few days, and now it's fine!

I have checked the TPS and was pretty much .5 volts. However I was actually thinking it could be an intermittent TPS fault the other day so I'll look into that next time it plays up

It has the same TPS as a Evo and they are a known weak part that is subject to wear.

My issue seems to have gone away as well, if it does come back I will try and log it on EvoScan.

I also had a rough idle on start up, that seems to have dissappeared when I reflashed a new ROM onto it and reset the ECU. The previous ROM went corrupt or something and retarded the timing badly... to the point where I was getting 20L/100km fuel economy. FPR was also on its last legs (and finally died while it was on the dyno).

When the miss was happening I was getting a small surge while cold at low load. It went away when the engine came up to temperature.

[Subaru ETA]

Well an update. Wife was driving it today and it nearly stopped as she was coming onto the motorway. Check engine light came on (first time it has done this) but went out when she was nearly home. I have tried to pull the codes - none stored.

It currently has known good coils and ecu in it so it cant be those.

Still idles like a sack of ****.

I havent got rid of it because i dont want it to defeat me!!!

[wintertidenz]

Did you ever get the injectors checked out?

How about logging data on EvoScan when it's running badly? I'm happy to lend you my cable, but you need a laptop to plug it in to :P

Also, what about the battery and charging system? Is it possible that a bad battery or alternator can cause the issues?

[Subaru ETA]

No I never got the injectors checked but that may be the next step.

I have datalogged it with a MUT-II in the past but it didnt show anything up. I may take you up on the off of the cable tho.

Battery is brand new and charging system is fine

[wintertidenz]

How's the fuel filter? And is it always the same cylinder that has issues, or does it vary? Wondering if there is something floating round inside the fuel rail that moves once the pressure is relieved, and every so often it blocks off an injector?

[lancerevo3]

i picked up another evo last week with a bad idle and missing under load.
things i found
1.injector plugs loose no retaining clips fitted
2. spring in one coil pack was to far back to make contact
3.plugs were not gapped correctly
4.throttle cable was too tight.
5.vac pipe to bov split

now runs and gos like a hot snot.

sorry if you have covered the above as i didnt read all the way through

[Subaru ETA]

Ok so an update...... ITS FIXED!!!!!

So the whole time it's been doing it it has never had a fault code in it. Different parts were fitted and it still played up.

Warrick (squatting dog) gave me some coils and an ECU to try, to no avail. It had airflow meters, o2 sensors etc but no good.

Turns out the aftermarket cambelt tensioner had a crack in it through the casting mark on it. The cambelt was then of corse loose and the ECU was retarding the timing.

So new tensioner and re time the engine. As soon as engine was started after this, it still ran like a bag of ****, however not quite as bad. This time however it put the engine light on. Codes checked - airflow meter!

Airflow meter fitted - purrs like a kitten!
The reason it had no codes before? The timing was getting so retarded it was disguising the airflow meter fault! As soon as the timing issue was fixed, it picked up the airflow meter.

I'm pretty annoyed that I didn't find the fault myself, but hey, I dropped it into Andrew Simms Newmarket in March and got it back last week, so it took them a long time trying to find the fault working on it full time! I was only able to look at it when not at work and obviously it wasn't playing up all the time.

Another thing, I don't know if many people know this but mitsi New Zealand have a dismantling yard in porirua and you can buy parts via the dealers from them. Kempys wanted $800+ GST for the airflow meter. I got mine through mitsi for $350 plus $10 shipping!

So all up for the diagnoses, tensioner, airflow meter, oil and filter change and transfer case and diff oil (figured they might as well do it while it was on the hoist) $1250! Bit of a trade discount but not bad for 3 months work at a main dealer!

[lancerevo3]

often wondered about this .good news

[elnevio]

A very interesting fault - not something anyone would really think of, I guess! Also as evidenced by the length of time required to suss it out!

Glad to see it sorted! /yes :)

[Subaru ETA]

So flew back in from oz yesterday and went to drive home - bloody thing won't idle. Stepper motor is jamming up on its hot idle setting. I can pull it apart and free it up and she runs fine, until it warms up. Turn AC on and it stalls. Pulled the stepper motor out and it actually looks like it is coming out slightly too far and jamming.

Problem now is finding one! It's looks different to a vr4 so don't think that will work.

I can't find a dismantler with one. Mitsi want $560!

[elnevio]

If you find anything in the UK (e.g. eBay, etc.) then I can help out with getting it bought/shipped over to you if they say UK only.

Is it a standard 4G63T part, or is it specific to your application? I.e. is it on the Evos?!

[Subaru ETA]

Wife is doing work on the laptop so can't get onto CAPS to find out!

That's for the offer - I will let you know :)

[Subaru ETA]

Got it sorted. Got a second hand one from mitsi for $300. Thing it tho, they sent me the whole throttle body with TPS etc, but only charged for the stepper motor. Thinking I might bore this spare throttle body....

[elnevio]

Every cloud, and all that! :thumbsup: