The Most Elusive Rb Misfire Issue Ever

[MBS206]

When you check the car again.

Pull the CAS off, and have a look down inside it at the little "teeth" that mesh it to the cam. See if they're worn, and allowing swap.

Compression tested it?

[Lithium]

When you check the car again.

Pull the CAS off, and have a look down inside it at the little "teeth" that mesh it to the cam. See if they're worn, and allowing swap.

Cheers, will look into that though I would have thought if the CAS was playing up it would be in the entire rev range?

Compression tested it?

Was listed in the initial post that it did +/- 5 across all six...

[MBS206]

Cheers, will look into that though I would have thought if the CAS was playing up it would be in the entire rev range?

Was listed in the initial post that it did +/- 5 across all six...

Sorry, forgot that I'd read that already re comp test.

As with the cas, generally the teeth being worn rears its head as a miss fire when ever you're cruising at a constant speed, or backed off...

Wondering, it does it at the same revs in EVERY gear?

Can you try disconnecting your knock sensors as well? I'm wondering if they're picking up noise from valve train at those revs... (This will only affect if your ECU actually does something if it detects knock)

Edited December 17, 2008 by MBS206

[Lithium]

As with the cas, generally the teeth being worn rears its head as a miss fire when ever you're cruising at a constant speed, or backed off...

Wondering, it does it at the same revs in EVERY gear?

Can you try disconnecting your knock sensors as well? I'm wondering if they're picking up noise from valve train at those revs... (This will only affect if your ECU actually does something if it detects knock)

Yeah its the same revs in every gear. The ECU doesn't do anything if knock occurs, its not that clever unfortunately

[Fastrotor]

a GTS LINK plug in still has knock retard , if its enabled. and it will pull timing out. And this resets once turned off, timing goes back to where it was. But i doubt this is your problem.

Try reloading a new map in full, then modify to your specs , abit of a pain i know, however i recently had an old link giving me grief, and it turned out to be a corrupt map file. and even though i kept messing with it etc , the fault was still present..... a reload with another map solved problem (TPS was working in reverse !) So once i proved this i just adjusted maps to suit and parameters and it was all good....

Weird i know but i proved it by reloading original map and TPS was suddenly reversed again..... so worth a shot if you have hit a brick wall with other avenues.

Gary

[Lithium]

Thats quite interesting, thanks I would have thought that kind of thing would show up when we downloaded the MAP and also datalogged using the PCLink software?

Its been brought to my attention that Link recommend using a 2uF noise suppressor between the coil pack's positive feed and earth with a wasted spark setup, which I do not have. I'm not sure if that could possibly explain some of the issue, or if it would be just to eliminate general noise from the system?

[Adriano]

It could definately explain it, as could a corrupted file.

[Lithium]

It could definately explain it, as could a corrupted file.

Gah I do actually have a suppressor in there, oh well back to the drawing board

[MBS206]

Gah I do actually have a suppressor in there, oh well back to the drawing board

I'd be putting a brand new map in the car like suggested above and retune it...

[Lithium]

I'd be putting a brand new map in the car like suggested above and retune it...

Can you guys confirm that you downloaded the map from the ECU and found that everything looked completely normal, not to mention everything adding up on the wideband when road testing it when it was playing up?? I would have thought that if the data pulled off the ECU is correct, then the data IN the ECU should be?

[Lithium]

To help with the investigation, I swapped out the wasted spark setup for a stock COP setup from a 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.

[STATUS]

To help with the investigation, I swapped out the wasted spark setup for a stock COP setup from a 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.

slap a set of AU coils on there

http://wiki.r31skylineclub.com/index.php?t...ersion_For_RB20

[Lithium]

slap a set of AU coils on there

http://wiki.r31skylineclub.com/index.php?t...ersion_For_RB20

I'm going to try a different ignitor first, I have tried other sets of VN coils and it made no difference to the problem so not sure that its the actual coils.

[gotRICE?]

To help with the investigation, I swapped out the wasted spark setup for a stock COP setup from a 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.

*cough* 57,000km S2 R33 *cough*

[paulr33]

theres probably not a lot of things that could make a car loose 50rwkw

so i guess just run through the list and youll find it- but sounds like you may have found it anyhoo

but for those who aren't sure

fuel pump - unlikely, either works or doesnt, if it was to struggle car would make more power, and show up on AFR

turbo - unlikely, either works or doesnt, when its shaggged, typical result is no boost

compression - very likely, check this (i know you have) - but for others

inlet system (afm, ducting, intercooler) - unlikely you would see it and if its leaking would be obvious (car would be laggy as and make no power at all)

ecu / tune - very likely, less timing everywhere would cause what you are seeing

cas - likely, it may be slipping or loose, result in offset timing, less power everywhere

injectors - unlikely, either work or dont, if they dont, would show up on AFR or engine would go bang or stall and not run

spark / coils - very likely, either loosing spark or brekaing down, could be shagged plugs, wrong gap, dead coils, typical observation is misifire or sluggish

clutch - likely, when clutch dies engine free revs (revs climb without hesitation) and car makes bugger all power, wonky torque graph (i know its not clutch in your case)

so just some ideas for others debugging problems

[Lithium]

*cough* 57,000km S2 R33 *cough*

IS THAT ALL ITS GOT? My bad, I must have confused it... man its coils aren't a virgin anymore

Thanks again for that, man - quite a weight off my mind though still have to find out exactly what part is causing it if I'm to not spend $1k on splitfires or whatever they are

Thanks everyone for the input given while sorting this out

Edited December 21, 2008 by Lithium

[MBS206]

IS THAT ALL ITS GOT? My bad, I must have confused it... man its coils aren't a virgin anymore

Thanks again for that, man - quite a weight off my mind though still have to find out exactly what part is causing it if I'm to not spend $1k on splitfires or whatever they are

Thanks everyone for the input given while sorting this out

PM Performance_Wise on these forums...

He needs someone to do some testing of coil packs and it might help you out largely...

[gotRICE?]

IS THAT ALL ITS GOT? My bad, I must have confused it... man its coils aren't a virgin anymore

Thanks again for that, man - quite a weight off my mind though still have to find out exactly what part is causing it if I'm to not spend $1k on splitfires or whatever they are

Thanks everyone for the input given while sorting this out

ahaha yeah man. You seriously gave them there virgin rheeming! LOL.

PM Performance_Wise on these forums...

He needs someone to do some testing of coil packs and it might help you out largely...

What an idea! I never thought about that one.

Dan that could be a dam good investment. Much cheaper MUCH cheaper than Splitfires, and if they dont work, then you dont loose anything.

Edited December 21, 2008 by gotRICE?

[Lithium]

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.

Edited January 12, 2009 by Lithium

[Jet 20]

Good job, If it keeps working

How often do you look at the bottom of the coils anyway...