Misfiring And Loss Of Power In The Low Rpm'su

[Vexx]

Hey guys,

First post on the forums so i'm hoping this is in the right section.

I'm a proud owner of an R34 25GT, fresh imported, full complianced. Havn't had any problems with it until now.
When imported it had approx 67,000k's clocked up so i thought i'd leave i until around 70,000 before getting a major service. Just after hitting 70,000, check enigne light starting appearing periodically, an ignition restart would remove the light so i didn't think much of it.Took it in for a major service and the mechanic shits bricks when he sees the condition of the timing belt (I saw this also, didn't look as bad as he was making out but i figured i'd get it replaced to be on the safe side). So after forking out $800 for a full service and timing kit i get my car back on the weekend and i'm less than impressed with the outcome.

Firstly, check engine light is still showing, being more persistent now than ever.
Secondly, in the low RPM range car has lost a substantial amount of power.
Thirdly, the note the exhaust is making is not what i remember at all, when driving every now and then it starts grumbling like a V8 with no exhaust.

All this is making me question the condition of the coilpacks. I took the car back to the mechanic who ran it on the computer and got an error code advising that the coilpack(s) were faulty.

I'm really beginning to question the integrity of this mechanic as he claims he cannot diagnose which coilpack is faulty so we have to replace them all and he quoted approx $320 for the parts + labour on top.
Now this sounds like absolute shit to me so i did a little research and it seems coilpacks can be tested using a multimeter? Can anyone confirm this?

Normally wouldn't care too much about the pricing but i know when i'm being shafted and i;m not keen to give this guy any more business. Can anyone either recommend a mechanic in the northern suburbs of Melbourne or is the job simple enough that i may be able to do this myself?

Cheers,
Vexx.

[RB25DETC33]

Sounds like a coilpack issue, if you definitly notice a change in power and exhaust note youve probably dropped a cylinder. If the car idles rough like its not running on all cylinders u can check which coilpack is faulty by disconnecting each coilpack. If the engine changes note again then that coilpack is fine but when u un plug one and there is no change that will be the triublemsome coilpack.

Make sure u do an ecu diagnostic to tell u which fault codes come up. If it IS a coilpack issue you will have code 21.

[RB25DETC33]

Just do a quick search on ecu fault codes. U will find all the info u need on how to bring up the fault codes.

[BuuBox]

It's difficult to test the coil packs as they may test alright on a multimeter but still fail under running conditions.

That said, it sounds more like a timing issue to me.

[Vexx]

What is making you lean towards a timing issue BuuBox?

Would timing issues be bringing up the engine light?

Also just thought i might add, she's starting to chug the petrol pretty hard lately - Another sign of a bad coilpack?

Thanks for the info there RB25DETC33, might have to give that method a try on the weekend and see how i go. =]

[RB25DETC33]

What is making you lean towards a timing issue BuuBox?

Would timing issues be bringing up the engine light?

Also just thought i might add, she's starting to chug the petrol pretty hard lately - Another sign of a bad coilpack?

Thanks for the info there RB25DETC33, might have to give that method a try on the weekend and see how i go. =]

It could well be a timing issue... Since the mechanic has done the timing belt, he may not have aligned the cams up with the timing marks, one of the cams may slightly be advanced or retarded throwing out your combustion timing.

But do an ecu check first. eliminate things that the ecu can tell you.

[Vexx]

So a little update here.

Took my car to a different mechanic for a second opinion.
This bloke said it's possible that coilpacks are shitty but he said the cam timing seems a bit off.

Went back to original mechanic who did the job and he conceded it was a little bit off, corrected it (Free of charge of course) and then ran some scans to find an error code for the CEL.
Codes came up as :

21 - P1320 IGN SIGNAL-PRIMARY

Bloke reckons i should replace all 6 coilpacks, he doesn't seem to think it would be worth trying to isolate which pack is failing.

Would it be wise to just replace all or should i attempt to isolate?

Any suggestions for which packs to go for? OEM or Splitfires?

Cheers,
Vexx.

[StevenCJR31]

if i was you i would replace all six coil packs then you wont have to worry about them for a long time. . choice of brand seems to be a personal thing on this forum so you will get a few different opinions on that

[Missileman]

Check your local Nissan dealer for a price, but you can get them for about $105 each from here....

http://www.kudosmotorsports.com/catalog/nissan-coil-pack-individual-genuine-nissan-skyline-r34-25gt-25gt4-25gtt-neo-p-1164.html

[rondofj]

I've been getting the same problem recently (R34GTT) - inconsistent misfire and farting only under WOT at 16-18psi and close to redline, a lot of the time it doesnt happen but 20-30% of the time it does. Took out and inspected my Yellow Jackets (less than 2yrs old) and copper spark plugs NGK BCP7RES gapped at 0.8mm (done only like 2000kms) - the plugs look new - no soot or signs of running rich -just the thin lower thread strip is black, coilpacks look new, no hairline cracks etc,. No visible oil/fuel in cylinders/ spark plugs.

Multimeter tests consistent resistance throughout coilpacks, and idle tests by removing coilpack connections one by one changes the engine note throughout so all coilpacks seem to be good here. But obviously under WOT it starts misfiring n farting. I didnt take out n inspect my 4th coilpack/spark plug as its under the J pipe and I couldnt be farked removing all that crap. But pretty sure its the same as others / good cond. Did take out connector under idle and it changed engine note so it seems ok.

Check engine light came on after coilpack inspection - paperclip test/clear codes and reset ecu (remove battery terminals n drain charge) didn't remove it - only threw out one error code which was the boost sensor. How do I get rid of this light?

The last couple days after removing coilpacks/plugs I get no power n torque from 1000-2000rpms but after that its normal and hammers hard under boost to redline bar the ocassional misfire/brickwall. Esp on a hill from stop to go I get inconsistent no power till 2000rpms. Is this a timing issue?? Wasnt happening before. Checked all connections of coilpacks/plugs all firm n good. Please help.

cheers

Edited September 10, 2013 by rondofj

[niZmO_Man]

Sounds a bit like AFM starting to crap out. The spark plug gap should be 1-1.1mm if you're running new/newish coil packs (for better spark/burn).

[rondofj]

I dont know about the plug gap, JEM had fitted new sparkies and set it at 0.8mm and it ran fine for 4 months till now, I'm thinking it could be the bloody afm, maybe a solder joint or something, its weird, upon first startup and driving for the initial 5-10 mins theres just NO power between 1000-2000rpms then its normal after that rpm band. Driving a bit over 10mins after its warmed up, some/not all power comes back, so could it be the thermostat or temp sensor?

[niZmO_Man]

My car does something similar, it runs rough when cold then all of a sudden after about 5 minutes it runs fine. Even weirder, when I first start it up it's fine, the issue kicks in about a minute after. I'm placing my bet on AFMs.

[rondofj]

took out Z32 afm, soldered all 4 joints and put it back together no difference - initial startup and first 5-10 mins of driving theres NO power from 1000-1800rpms for 2-3 seconds then it jerks a bit then power comes back lol. Fuel filter clogged? It doesnt happen when engines warm.

[langy0009]

Hey mate did you ever fix the check engine light problem having the exact same thing happen to me

Took it in for a service they said all was fine turned it on next morning and the same thing

Did you ever find turning off and on fixed the problem ?

[Vexx]

Hey mate,

Sorry for the lack of replies here guys.

Fixed the problem.

New set of YellowJacket coilpacks instantly fixed the engine light, stopped the exhaust note sounding like a beast WRX and gave me a noticeably quicker vehicle. =]

PS. Yes, turning off ignition and flicking it back over did remove the engine light.. for a few minutes.

[langy0009]

Yeah mate we had the same problem took it to nissan and they said it was coilpacks

Next question is it worth splashing out and getting more brand name coilpacks or getting cheap once

Have you noticed a real difference ?

Or just small ?

[niZmO_Man]

Yellow Jacket coils

BCPR6ES-11 spark plugs

[langy0009]

Don't know what plugs they are for ?

Not for R34 rb25de