Jump to content
SAU Community

Recommended Posts

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?

  • Replies 42
  • Created
  • Last Reply

Top Posters In This Topic

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...

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 by MBS206
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 :P

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

Thats quite interesting, thanks :bunny: 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?

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?

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.

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 :worship:

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.

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*

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

*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 :laugh:

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 :rofl:

Thanks everyone for the input given while sorting this out :P

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

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 :rofl:

Thanks everyone for the input given while sorting this out :P

PM Performance_Wise on these forums...

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

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

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 :rofl:

Thanks everyone for the input given while sorting this out :P

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 by gotRICE?
  • 4 weeks later...

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:

12012009463.jpg

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 by Lithium

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Greg speaks wisdom. These dirty old Datsuns are only value when they are cheap. When they are not cheap, there is no value. Sounds contradictory, but it's true. We are now 20 years past the hey day of modifying cheap 90s JDM cars for small amounts of money. This is a different world. If you are rich and can afford not to care about what is effectively wasting money on an old Datto shitter, then I have no reason to argue against it. But if you are wanting to experience what we all experienced back in 2005 (and I bought my car last century!) then there is no way to do it.
    • Short answer: No. Medium answer: No, because you still need to conjure the things out of thin air to bolt them to a NA to make it a NA+T. Long Answer: No - The things you need to conjure - meaning a turbo, intercooling, manifolds, exhaust, intake/manifold/piping, clutch, injectors, fuel pump, AFM (?), ECU + Wiring (woo, N/A loom fun) have to come from somewhere. You could have many scavenged these things from an OEM car that someone had upgraded from and use some of these. This will be cost prohibitive now, especially so in the USA. You'd probably pay the same for newer, upgraded components that are better than old OEM stuff from 25-30 years ago. None of these big ticket items are re-usable for the N/A car. Why not buy new and upgrade while you're there? The only real consideration is turbo and fuel sizing and determining whether you want to stay within the bounds of the OEM engine or get into rebuild territory. These limits ARE lower with a N/A motor and especially N/A gearbox at the starting point. And if you're gonna upgrade those then you may as well consider having them built to begin with. Because everyone here knows you're never far from that next engine rebuild once you start making the power you want... The cars you see on the internet and SAU etc have been built over decades. If you're really clued in... you would sell your US car to somebody for what you paid for it. You would then scour AU JDM pages or SAU and buy a car like Dose's on this forum with your powerful American Dollar. This will save you so much money in the long term. Importing it could be tricky. Or it might not because USA. I have long said the only reason 90's Japanese stuff took off was because a) Japanese people had Japanese cars so that is what they used b) Australians could import these cars to Australia with very minimal changes and use them on the road here c) Neither country had well-priced access to US or EU Sports Cars. I don't believe the JDM scene would have taken off in Australia at all if we had EU priced EU BMW M offerings, or more especially the AUS V8 Scene would never have existed if we had the multitude of US cars like Camaros, Mustangs, Corvettes at the prices you folks do. After all - Do the math. I would say put a V8 in your R34 and that's the smart way forward. It is. I did it. I know this from my own experience. But at that point there's no reason to simply not buy a C5 or C6? It would be simpler and easier and cheaper and bette-
    • Reading all this... hurts lol. I have an ENR34 5MT and I paid an inflated USA price for the car alone, had to do tons of preventative maintenance past that, and so I'm over $30K USD into the car already and haven't even touched power.  I wanted to +t it. Not even trying to make GTR numbers, I'd be happy with 250hp.  Can I get away with paying much less to make that happen?
    • Damn you’ve done well, definitely snapping necks.
    • Great weekend and event. Open fire at the caravan park, perfect weather all day and a great feed and a couple of drinks at at awesome country pub.
×
×
  • Create New...