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R34 Gt-T Bad Fuel Economy, Misfiring And Rough Idle. Help!

green180sx
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green180sx Enthusiast

green180sx

Posted
Posted

Hey guys just swapped my 09 Lancer for a R34 GT-T and I'm loving it!

Recent problems that I have had in last 2 days,

Rough Idle.

Rough idle is on start up, when cold and when the A/C is first turned on.

It will stall every now and then from these things but its not chugging it just lowers the revs right down and just stops and then starts up just fine again..

Misfiring?

The car only does this down the low (1500rpm-2000rpm) and high (4500rpms-7000rpm) revs of the car, its just one or two misfires down low but when you hit full boost at 4000rpm the misfiring goes crazy at about 5500rpm and does not stop till the revs go back down..

Fuel Economy!

So I'm driving not too fast doing the speed limits not excessively boosting or anything have it in 5th gear at 60kmp/h and I'm just reaching 300kms from a full tank! The guy I bought it off said he gets 450-500kms from a tank. When changing down gears the amount of fuel that you can hear being burnt is ridiculous! I love the sound but I rather drive the car for longer!!

So mods that the car has:

GT30/40 Turbo

Adaptronic ECU (tuned)

3" Turbo Back Exhaust

Air Intake

Intercooler

12Psi

240rwkw

Stock Injectors tho

etc..

I've done some searching and there was one really good post on here but the links no longer work because it is too old, so if anyone could either direct me to a link or give me some info that would be great!!

I have a feeling it's spark plugs or tune? Hope it's something small and not expensive $$$

Thanks everyone!

RBMunkie Rising Star

RBMunkie

Posted
Posted

Check your intake piping, could be gunked up, rough idle could involve your Air Flow Meter.

Can't tell you for sure without looking myself though.
But that's what was wrong with my '32 when it was idling like a twot.

green180sx Enthusiast

green180sx

Posted
  • Author
Posted (edited)

So today I cleaned the AFM (Z32) and changed the spark plugs to iridium's. The old spark plugs we're platinum's and we're showing signs of the car running too rich. Since I've done this the car will not hold Idle, it sounds like misfiring and there are sparks flying out of the exhaust when you drive it with your foot down so obviously it's running super rich?

What do I do?

Is the AFM responsible for this? The car sorta runs fine under 2000rpm but once past that or putting the pedal past 1/4 it just sputters

Edited by green180sx
Got a Pulsar Grand Master

Got a Pulsar

Posted
Posted

What gap are the spark plugs? 0.8mm would be best. Sure they are the correct model of plug?

$30 worth of NGK Coppers gapped at 0.8mm is all you need plug wise. Not sure about R34 but for R33 - NGK BKR6EYA is perfect.

a set of these stopped my idle misfire I had with Freshish Costly Plugs. :yes:

green180sx Enthusiast

green180sx

Posted
  • Author
Posted

What gap are the spark plugs? 0.8mm would be best. Sure they are the correct model of plug?

$30 worth of NGK Coppers gapped at 0.8mm is all you need plug wise. Not sure about R34 but for R33 - NGK BKR6EYA is perfect.

a set of these stopped my idle misfire I had with Freshish Costly Plugs. :yes:

Thanks for the answer! The problem was one of many..

I'm still get getting too much fuel above 6000rpm now but it's totally clear of misfires in first gear.

Problem number 1:

Spark Plugs were not the correct ones, the guy from Burson's argued with me that I needed these different spark plugs.. I put the old ones back in and solved my total car break down. My current spark plugs that work well are 1.1mm gap

Problem 2:

o2 Sensor was filled with carbon! couldn't buy a new one so for the time being just sprayed some carby cleaner and it fixed the fuel economy problem, the rough idle and the misfiring

Problem 3:

The coil packs were not in the correct order which also was causing misfiring and most likely bad idle

Problem 4:

ECU needs a second tune, it's running too rich still but the main problems have been fixed for now.

Hopefully this helps anyone with similar symptoms with their R34 RB25DET NEO

msports180 Mentor

msports180

Posted
Posted

Id be thinking coil packs to, our's went through them when we first got, lucky to get 300k's a tank, put in spitfires got 450-500.

Is the Adaptronic ECU a plug and play using a AFM? I thought they where map sensor based?

I dont see how the coil packs being out of order could cause problems? if they where plugged in wrong as in the firing order your lucky it even ran!

I would definitly use copper plugs to, a complete pain in the ass to change on a NEO, but IMO better, as as soon as u foul some platinum's or irridiums their junk.

blind_elk Grand Master

blind_elk

Posted
Posted

Waste of time driving around at 60k in 5th gear. The engine works best near peak torque. 60 in 5th is not within a bull's roar of peak. If you need to accelerate even slightly, you labour the engine. My 32 (with RB25DET) doesn't even get into 5th at 80, and I still get 400+ in city driving.


And "not excessively boosting" means little. Boosting chews fuel.

green180sx Enthusiast

green180sx

Posted
  • Author
Posted

Thanks for the tips guys, still learning on this whole power thing and how to best drive the 34.

The adaptronic ecu is a plug and play I guess it's really similar to the power fc but without the hand controller.

I'll look into getting some split fires, copper plugs and I think it needs another tune because the place that tuned it ive heard nothing but bad things

mad082 Grand Master

mad082

Posted
Posted

how many litres are you calling a full tank? without knowing that the economy issue is useless. you might as well say that you are getting 1 hour of driving to 3 Bernards of fuel. it means nothing. and low rpm doesn't always mean better economy. you would probably get better economy using 4th gear at 60kmh.

green180sx Enthusiast

green180sx

Posted
  • Author
Posted

how many litres are you calling a full tank? without knowing that the economy issue is useless. you might as well say that you are getting 1 hour of driving to 3 Bernards of fuel. it means nothing. and low rpm doesn't always mean better economy. you would probably get better economy using 4th gear at 60kmh.

When I say I'm not getting a full tank I mean I am getting less than 250km to an entire full tank of fuel.. Since cleaning my oxygen sensor I have almost gotten to 500kms and the tank has 1/8th left. (which is roughly 1 hour of driving to 9 bernards of fuel :wacko:)

And yes I understand that lower rpm isn't always better but when you live next to a flat and fairly straight road its easy to cruise on 1650rpm at 60kmp/h for say 4-5kms

The coil packs were not in the correct order which also was causing misfiring and most likely bad idle

what is the correct order? i dont get this statement :(

As in the wiring goes shortest to longest for the coilpacks so coilpack 6 was connected to coilpack 5 wiring etc

mad082 Grand Master

mad082

Posted
Posted

Unless you actually take note of hire many litres of fuel you put in you can't say whether or not you are actually getting bad economy or not. everyone's gauge will read slightly suddenly, and everyone will class "a tank" as a slightly different point on the gauge. Plus a faulty gauge can mean that that the gauge shows empty with there actually 1/3 of a tank. i can drive 60kms to work once the fuel light comes on in my car, trip computer will show 0kms to empty by the time i get there, yet when i filled up it turned out i still had 10l left in the tank. but now my light comes on about 60kms earlier, yet my economy is unchanged (i use an app on my phone to keep track of my fuel usage and it calculates my economy). So if i purely went off my gauge, if think my economy was getting worse, but it isn't.

Moral of the story, calculate your economy in L/100kms and then you will get more accurate answers as to whether your economy is poor or not.

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