# The most elusive RB misfire issue ever



## Lith (Oct 5, 2006)

Hi all,

I am fully running out of ideas for a very annoying ongoing issue I have with my Skyline. The symptoms are that it has a serious misfire/hesitation which only rears its head when the car has been warmed up and driven for a while, and is mainly in effect between 2500-3500rpm at any load level - straight cruise or at full load. The car will cruise fine at 2000rpm, or at 4000rpm+ (even wide open throttle above 4krpm is perfectly fine) - but in between gets very iffy. 

Does anyone have any ideas on what it could be?

Information on the setup:

R33 GTS25t with the original RB25DET, compression test a couple months or so ago gave +/- 5psi across all 6
Runs a upgraded (Garrett GT3076R) turbo on 1bar of boost
Running a GTS Link plugin ECU (MAP sensor, no AFM)
Has stock inlet and exhaust manifolds
Has been dyno tuned, and on the road aside from when the miss happens mixtures seem sensible - though the uncombusted air I assume would be responsible for the lean spike on the LM2 when it happens
Runs a wasted spark ignition system using GM/Holden Commodore VN V6 coils and a Link 3channel ignition amplifier with NGK "BCP" heat range 6 plugs gapped to .8mm

Things we have tried to diagnose this issue so far:

- Changed Spark plugs
- Changed coil packs
- Changed ignition leads
- Changed exhaust manifold 
- Done a road test with wideband to check mixtures

All of the above things resulted in no change whatsoever. 

Thats all I can think of that might paint a picture of whats going on, any input would be greatly appreciated - feel free to ask any further questions... I am at a wits end with this now, its unlike anything I've seen before and making the car very hard to enjoy. 

Cheers,
Dan.


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## GT-R Glenn (Nov 9, 2002)

I blame the link and the wasted spark ...
Has it ever run right ?


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## Lith (Oct 5, 2006)

Yeah it has, though I have been plagued by various ignition issues - one of which was on the stock system which is why I went to wasted spark in the first place. The car was tuned running a Mitsi 3-channel ignitor and the VN coil packs and ran a few months without issue.

I started getting a different kind of issue, where it would drop 1/2 cylinders after it warmed up - which was eventually resolved by putting a NEW Mitsi ignitor in (first one was used) and the car was smooth again, for a little while. The exact same issue then resurfaced, and got worse - until eventually it would only run on 4/5 cylinders.

This is where the heavy duty Link ignition module was called apon, we installed that and also found the coil loom was looking less than happy so made up a new one and again the car became happy and cruised/thrashed around without hitch up until reasonably recently.


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## Lith (Oct 5, 2006)

Oh yeah, every other time I have had the ignition issue (including the stock system) it has started with a typical Skyline misfire - the one at heavy load between 4500 and 5500rpm, the issue I now have actually is not a problem at all in that rev range! I can pull from 4500rpm and up with no problem whatsoever.


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## frostmotorsport (Aug 10, 2007)

what are you using for CAS? factory Nissan CAS or some aftermarket Hall effect sensor? I heard that MOTEC had issues years ago with their sensors going nuts at random times and causing issues - I just wonder if it's something obtuse like this... are there any other symptoms when the misfire occurs? i.e. tach goes crazy etc? Also, what version Link and is it repeatable enough to do a data log during the misfire to check all sensors and outputs on the Link....


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## Lith (Oct 5, 2006)

Its using the original CAS, and I'm running a GTSLink which I bought in 2006 - whichever version thats likely to be, I can't remember. It was before the G3 etc, those plugin versions were given a different name if I remember rightly.

The issue is fully repeatable, every time its warmed up it does it - we did a drive with LM2 etc to check the tune etc, while we didn't log it I had a mate watching the sensors and at a glance the MAP, RPM and TPS all seem sensible... my rev counter looks completely sane as well, hence me knowing which rev range it plays up


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## Jez200 (Oct 6, 2002)

Had missfiring issue with a wasted spark set-up on my RB25DET. Have gone back to coilpacks (Splitfire) and all is well now


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## stonehac (Sep 3, 2008)

I had somewhat of the same issue. when it happens use a choke tool on the igniter. cool it down and see if it goes away if it does you igniter is going bad. I relocated the igniter away from the engine and my ignition issue is gone.


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## Lith (Oct 5, 2006)

Damn I hope its not, I had considered the option of that but its a fandangled new one and its moved to a relatively cool part of the engine - on the plenum side. I went to this igniter because the old Mitsi one i had started playing up, though it was different - it would drop cylinders at full load then deteriorate until it would finally drop a cylinder even at idle. With this problem its above idle and below the normal 4500rpm-5000rpm problem area.

Did yours misfire at full load/revs? Idle?


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## stonehac (Sep 3, 2008)

Mine would start under load then as it got more heat soaked it would get worse. i would have to let the car cool down before i would get all 6 again. I added about 20 inches to the harness and hung it from the firewall on the intake side never had another problem. once a get a new one i plan on mounting inside the car under the dash.


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## Lith (Oct 5, 2006)

Hmm mine is already in a similarly protected place to yours then, so that won't help


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## Asim R32GTR (Sep 24, 2003)

What size / type injector do you have?


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## tweenierob (Aug 5, 2003)

What is your dwell settings?

R.


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## [email protected] M/S (Feb 16, 2002)

Snap......was going to say the same thing as Twennie.

But why would it only do it once it has warmed up, have you tried richening the fuelling up when it is warm to see if it goes, ss it is okay when it is cold?


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## Lith (Oct 5, 2006)

Asim R32GTR said:


> What size / type injector do you have?


Nismo 555cc injectors, the car has been running for about 2 years with this general setup so its something which has developed recently as opposed to a gremlin trying to get it running. I have had a couple of "traditional" Skyline ignition misfire issues along the line hence now being with wasted spark but ended for having it running for a while completely smoothly, then with no change this issue arose.



tweenierob said:


> What is your dwell settings?


Pretty sure dwell time is not configurable with the GTSLink ECU.



Abbey M/S said:


> But why would it only do it once it has warmed up, have you tried richening the fuelling up when it is warm to see if it goes, ss it is okay when it is cold?


Yeah we had a play with it on the road when we went out with the wideband and it had absolutely no effect. It was running sensible AFRs to start with aside from when it missed and the miss happened, we figured the lean spike read by the O2 was caused by that but added some fuel just to be sure. The ignition timing everywhere is consistent/sensible all the way through for the entire affected load zones etc. We were hoping something would make itself obvious when we put the probe on it 

Cheers for the input guys, appreciate it heaps  keep it coming!


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## fletch.rb30 (Jun 12, 2008)

Have you got one of those noise suppressors on the power to the ignitor?

Try putting one between the power and bolt the cap body to the head with a good, and also run an earth from the head to the ignitor, back to the ecu and also to the coil bracket earth.
I had a few problems like that and earthing was a big part of it.
I believe it was interference, as it was also causing the fuel pump relay to flicker a little bit and fuel pressures became slightly unstable.
That was on a linkplus v14 wire in.

I went to 6x mitsi/hanshin coils off u12 bluebird sr20/ca20 and the skyline ignitor. You could try that, only cost ya $100 all up from wreckers, or bolt all the coils together and say its a 'coil pack' and pay $50. Then just pair up the inputs to the ignitor to run waste spark, only with one coil per plug.


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## Lith (Oct 5, 2006)

Thanks man a couple of good ideas there - yeah I have been thinking that there is a good chance that its interference, though still haven't been too sure how its temperature related. We're sorting out some better earthing and going to test a few things out this weekend. 

No, don't have a noise suppressor to the power to the ignitor.... might have to look into that too  Thanks mate!


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## tyndago (Oct 24, 2002)

Bypass the fuel pump control module.... do the GTS have them ? I have had a weird one on a GT-R be that. In exactly the same rev range.


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## Lith (Oct 5, 2006)

Oh really? Thats interesting. I'm not sure - where is it, and how did you do it? I assume you just arrange a constant voltage feed to the fuel pump?


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## tyndago (Oct 24, 2002)

R32 GT-R. 









Picasa Web Albums - Sean - GT-R pics RB ...


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## beaumackenzie (Jan 21, 2008)

1 of 2 reasons it does it once it is warmed up, (1) because the circut or item affecting(causing) the missfire is connected with or relys on the thermostatic circut for a reading to operate. 

(2) an electrical component's insulation has become brittle with age and has hairline cracks appearing, mine was the 18 year old ignitor pack that up untill this year i replaced with a brand new triton(australia) unit, after the wasted spark conversion to dispose of the coils of the same era the car has run like a dream since.


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## Lith (Oct 5, 2006)

Ok well we have ruled a fair bit out - today I swapped out the wasted spark setup for a stock COP setup from a mates 100,000km+ S2 R33 and went out for a general cruise. It didn't skip a beat. We're going to try a pretty much unused Link 3-channel ignitor in the wasted spark setup and see what happens there, if it still plays up I have a good mint to just get a set of Splitfire coils and be done with it.

The thing is, the set I have been using is less than a year old - we had tried 2 sets of coils and the Link ignitor I was using is <5,000kms old!

I think we should be fully on top of it shortly, thanks everyone for the input


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## tyndago (Oct 24, 2002)

The last time Mr Tamura was here, I asked him about coils and he said he swaps coils about every 6 months. He works for Nissan, so its a little easier for him. 

The coil harness gets crispy for sure. That has caused me problems in the past. You can't really tell from this crappy cell phone picture, but there is extensive corrosion at the crimped on terminals. http://picasaweb.google.com/tyndago/GTRPicsRBMotoring#5075184144747649234

The Link. I have not heard too many good things about that box. I ran a real old one on a car about 10 years ago. I really didn't like it then. Since then Power FC for most cars for me. Works well.


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## GT-R Glenn (Nov 9, 2002)

Lith ,you dont need splitfires.
The HKS drag car ran standard coils.
Theres red splitfire copies on t/m sometimes.
Yoda runs standard coils too actually.
Sean th G3's are a really good ecu


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## Lith (Oct 5, 2006)

GT-R Glenn said:


> Lith ,you dont need splitfires.
> The HKS drag car ran standard coils.
> Theres red splitfire copies on t/m sometimes.
> Yoda runs standard coils too actually.
> Sean th G3's are a really good ecu


Which do you reckon would be cheaper, splitfires or stock Nissan ones?? Thats one of the main reasons I'd go splitfires - I'm under the impression the stockers are harder to get and aren't competitively priced. The reason I went to wasted spark is because the stock ones weren't up to it, as soon as I went for >11psi they cried, hard. The GTSLink having 3 ignition drivers/firing in wasted spark doesn't help things for the stockers. I bet the HKS GTR didn't rev >14,000rpm haha.


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## tyndago (Oct 24, 2002)

AEM runs waste spark. We do more than 600 whp with stock coils. Good stock coils, good plugs. I hate the Splitfires, I think they are garbage.


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## Lith (Oct 5, 2006)

My stock coils are no good, so I have to find other healthy ones somewhere... seems to be a bit tricky


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## Phil69 (Sep 13, 2006)

Without reading the entire thread, I had very similar symptoms this time last year with my GTR which has a Tomei Reytec ECU which also uses a map sensor and not the AFM's.

Turned out to be the map sensor itself was faulty. Changed it...no problems since.


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## GT-R Glenn (Nov 9, 2002)

I ran stock coils up to when I changed ecu
I never had any issues with them.
Car was making about 480hp at the wheels @ 1.3 bar.
PFR6A 11's gapped to .8mm
Only issues I ever had were afm related, hence the d-jetro.
Hard to believe 11psi would stress out a standard coil.
Anyway ....
Wait for those red coils to reappear on t/m , I paid about $600 for my splitfires from Nengun.


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## Lith (Oct 5, 2006)

GT-R Glenn said:


> I ran stock coils up to when I changed ecu
> I never had any issues with them.
> Car was making about 480hp at the wheels @ 1.3 bar.
> PFR6A 11's gapped to .8mm.Only issues I ever had were afm related, hence the d-jetro.


Did you ever run a Link ECU, or any other which fires the standard coils in wasted spark? 



GT-R Glenn said:


> Hard to believe 11psi would stress out a standard coil.


I'm quite surprised, you've been around the Skyline crowds for ages - how can you have missed the myriad of people asking about alternatives to Skyline coils after having the same issues? There are people who have had misfires on less boost than that when the coils give up.



> Wait for those red coils to reappear on t/m , I paid about $600 for my splitfires from Nengun.


Not sure if the red ones are done for S2 (no factory ignitor) setups are available, and I'm still keeping an eye out to see how they last. I'm quietly hoping I'll find the exact cause of my problem, maybe an earth loop or something - but if not I still feel like my safest bet would be to get a set of Splitfires and be done with it.


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## GT-R Glenn (Nov 9, 2002)

No, I was "instructed" never to use a link on a GTR, (that was years ago) (G3 or better is acceptable)
I dont like wasted spark and unlikley I would ever consider it.
Yoda runs 1.8 bar and standard coils ....
For every person you no who says they had coil issues , I know 2 who dont.
11psi is nothing ....
Anyway ....
In my experience people are too quick to rubbish the standard coils and race out and buy an alternative, when they dont really need it.
I have some standard gtr coils you can have if you want them ....


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## Lith (Oct 5, 2006)

I don't think anything is wrong with the design of Nissan coils - the reason I replaced them wasn't that some random on the net said I need to... it was to fix a problem I was having, with a full load misfire which we went through a process of elimination which lead to the stock coils. I couldn't replace the ignitor to rule that out as Series 2 R33s don't run a 6 channel ignitor, they are integrated with the coils though I am pretty confident it wasn't it. Coils fail with age, people with every kind of car run the risk of their coils breaking down and our cars are getting on.

There was no way I was going to pay good money for used coils which could be well on the way to developing the same issue and if I went for OEM Nissan coils I'd pay the same price for 3 of them as I could for a coil loom and 6 coilpacks from Splitfire, my full wasted spark for the price of one Splitfire.

Alas wasted spark is my only option one way or another, GTS and G3Links only run up to 4 ignition drives too so even if you have a standard coil per cylinder setup on an RB - each one will get fired on both the ignition and exhaust strokes hence the reason I went wasted spark, as theoretically it shouldn't have made any difference though it seems like we've gone wrong somewhere. 

Cheers for the offer on the GTR coils, problem is I would need a coil loom for a GTR and an ignitor - as in all their wisdom Nissan decided to change the ignition setup for S2 R33s to have no remote ignitor.


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## beaumackenzie (Jan 21, 2008)

stock nissan ones(new) are just as expensive 145+gst NZ each "i think" the last time i checked. dont qoute me on that, that was through nissan new market in auckland. 

the wasted spark system employing the coil pack from the vt-vz holden commodore range is cheaper at 178 NZ from repco for the block of 6. 

you also need to remember that when wiring for wasted spark the ecu uses the pulse from the number one coil(lead) to set the electronic timing for the system, 

so when applying wasted spark it will be getting two pulses (1 and 6), these pulses are far enough apart to have the same effect as a engine with a conventional distributor running off the trailing edge rather than the leading. 

where 1/6 come from the ignitor pack to meet at the coil you should have three wires. you need to join ignitor 1 wire and the pulse signal wire, diode then the number 6 ignitor wire to stop the signal wire from receiving a pulse from the number six wire but still allow it to travel to the coil. 

it took about 10 minutes of explaining from the local auto sparky before it dawned on me why it was still running like sh*t.


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## Lith (Oct 5, 2006)

beaumackenzie said:


> stock nissan ones(new) are just as expensive 145+gst NZ each "i think" the last time i checked. dont qoute me on that, that was through nissan new market in auckland.


Yeah thats why I have been saying I'd go to Splitfire if I can't find a good set of coils and loom as I can get the wires and loom new from Splitfire for less than the equivalent Nissan parts. My factory loom was butchered to make the wasted spark seetup.



> the wasted spark system employing the coil pack from the vt-vz holden commodore range is cheaper at 178 NZ from repco for the block of 6.


Already have that.... my first post outlines this



> you also need to remember that when wiring for wasted spark the ecu uses the pulse from the number one coil(lead) to set the electronic timing for the system


I have a Link ECU, so this doesn't apply.


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## fletch.rb30 (Jun 12, 2008)

Lith said:


> Cheers for the offer on the GTR coils, problem is I would need a coil loom for a GTR and an ignitor - as in all their wisdom Nissan decided to change the ignition setup for S2 R33s to have no remote ignitor.


You can hook up an igniter from an earlier model. 
Chop the plug off where it plugs into your coil loom and solder on an older ignitor plug. then you can run a standard ignitor and coil loom.
Earlier r32/r31 rb20de/det had a square plug thats a b tch to get off, try and get the later oval edge one.

If you fancy a drive to waverley i have a set of good coils and possibly a good coil loom. Box of beers or something


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## Lith (Oct 5, 2006)

Wow, clearly you aren't actually in N.E London then  Could possibly be keen, so the ignitor plug to go for is the one to suit the R33 S1 RB25DET? I may possibly know someone who has one. I will PM you when I am definite on what I'm going to do  

Cheers!


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## fletch.rb30 (Jun 12, 2008)

Yea im still in london, but my car and spares are in my old mans shed.
I have no idea what ignitor i have, i think its late r32 rb20det, they all work the same. the later you go, the smaller the heatsink, i believe thats because the electronics were better and they produced less heat.
The one i have doesnt get hot and im running heaps of dwell and some resonably large coils.


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## beaumackenzie (Jan 21, 2008)

theres your problem right there. link.


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## Lith (Oct 5, 2006)

beaumackenzie said:


> theres your problem right there. link.


Aside from the fact the problem fixed itself when I tried a healthy factory ignition system? :lamer:


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## Lith (Oct 5, 2006)

Hello again everyone - I thought you guys might be interested in the resolution of this, the fix I settled on has so far (touch wood) worked real well. It is not intended to be a permanent fix, but I intend on rolling with it for a while to see if or how long it lasts as it works - and works better than any of my previous experiments on the "trying to fix the RB misfire" mission.

The first plan of attack - try and make it a more familiar issue. This was easy, I put a stock RB25DET S2 coil loom and coils back in. The weird 2500-3500rpm misfire/dropping cylinders issue went away and I developed a 4500-5500rpm full load misfire, much like the one I had which forced me to start looking at things like wasted spark.

Sweet! Next thing to do, try hair brained ideas to fix this issue for as little money as possible... so off to Repco to buy a tube of silicone, and cover the bottom of the coils in goo in the hope that maybe what was happening is the coil's charge decided it was easier to jump out to the cylinder head than to go and blow up the air fuel mixture the end of the spark plug was dowsed in.

Picture of the aweful black gooey mess:









Result?? The car drives better than ever before - no misfire whatsoever. Not one for the pretty fix fans amongst us, but perfect for those cheap bastards who think spending $1000 to fix something they suspect is caused by something simple.


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## andy42uk (Sep 17, 2005)

The coils leak around the 'seams' and arc to the mounting frame, I have fired a set up on my test-bench.
A good fix would be a frame made of a high-temp insulator, bakalite anyone?


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