4G63 question

[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

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!

[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!