Timing Fluctuations In Rb26/30

[KiwiRS4T]

Hi guys, a mate (not on this forum) has an issue with their Skyline running an R34 sourced RB25DET - the car is running a G4 Link and can get sporadic detonation at points from around 5000rpm up running no more than 12degrees timing on 1bar of boost with high 11:1 AFRs, this thread makes me wonder if this issue could be occurring and causing the intended timing to become much much more than intended timing?

SDU president Tony (R33_400R) makes a crank trigger set up and Shred in Wellington have a solution too.

[Lithium]

I am aware of that, I wasn't asking about what to buy - but if it sounded like a familiar symptom. It's not my car so I don't have the freedom of going and messing with it whenever I want, I was just asking people who may have experienced it if it sounded like the kind of thing they see... buying a trigger setup like that would be pointless if there is no triggering issue at all and it turned out to be cam timing/something else related.

The owner of the car doesn't have heaps of money to throw around to fix it, otherwise he'd probably just drop it off to Speedtech and get them to make it good.

[kitto]

I am aware of that, I wasn't asking about what to buy - but if it sounded like a familiar symptom. It's not my car so I don't have the freedom of going and messing with it whenever I want, I was just asking people who may have experienced it if it sounded like the kind of thing they see... buying a trigger setup like that would be pointless if there is no triggering issue at all and it turned out to be cam timing/something else related.

The owner of the car doesn't have heaps of money to throw around to fix it, otherwise he'd probably just drop it off to Speedtech and get them to make it good.

What timing belt does it have on it?

[PSI086]

Impressive in that it only requires 3 slots to function correctly

Works out to 1 tooth per cylinder as 2 crank revolutions equal 1 cam revolution

[20SIX]

interesting read.

we have just been running in my built rb26.

and we were aware of the scatter issues then happen with some of the engines, espically with bigger cams.

We decided to see how it goes before looking at crank triggering, as i dont have much rom down the front, so probably not an option.

So after awhile the scatter has appeared, but its generally only down low-mid on lighter throttle, havent seen in up high rpm yet.

we are running 272's with up around the 11mm lift (dont have spec sheet with me atm for accuarte lift specs)

we replaced the cas with a rb25 one just to test it, it helped alittle bit, still does it but not quite as often or as bad.

My tuner came up with the idea of laser cutting new counter disc for the cas , which he had done for a car years ago to make it work on a setup.

We founnd out that AEM make a 24 counter disc, so we are going to install that and see if it fixes the issue.

I read on here about the gates belt being a possibly contributer also.

We are running the blue gates belt and also i stabilizer bar on the tensioners to eliminate any flex at rpm.

I will keep you guys updated with feedback on how we go.

the CAS is still the original one, considered possibly buying a new one too.

[GTR_JOEY]

I'm running the ross crank trigger same as Piggaz and a few other boys kicking around, as you will see here from a thread Paul posted a while back it makes a big difference to timing.

http://www.skylinesaustralia.com/forums/topic/384932-new-rb-parts-with-results/

It was stated that there seems to be a lot of these issues coming out of Unigroup

What it looks like to me is that Yavuz actually points out to people when there is timing scatter where as other tuners just FOB it off, do the tune and get the cash instead of trying to make the result the best it can be.

At the end of the day engine timing is spot on and the overall results and drivability speak for themselves

It's a lot of cash but I'm very happy with the engine and how it drives

[20SIX]

im running an ATI balancer, but also my engine is in a silvia not a skyline, so theres about 10mm or so clearance from the front of some of the pulleys and the radiator.

so i dont really have alot of room down there.

[mitchum]

i have about a 300 rpm fluctuation in the higher RPMS on my RB25/26 but im not going to worry about it much as fuel curve stays steady and timing is within a half a degree or so around those columns, my only fear would be it over revving

[discopotato03]

My RB25 never quite sounded the same since its belt and tensioner change , I wish I'd known about this because I would have insisted on a genuine timing belt . I have a link I'll post from GTROK where someone mounted a crank trigger wheel reasonably cheaply on an RB crank pulley .

A .

[discopotato03]

GTROK link .

http://www.gtr.co.uk...ger-shells.html

I don't see anything like 3 grand in fitting this and a Hall sensor on an RB20/25/26/30 .

If you can get the existing CAS to output a single sync pulse before no 1 TDC this is as difficult as it has to be .

It would be brilliant if some enterprising business could organise a group buy kit that included a new factory crank pulley with the trigger gear mounted and balanced and the sensor plus mounting hardware . Throw in a laser cut CAS disc or instructions to modify the OE one and what would it owe us , would people pay a grand or so to basically achieve what Ross does for three times that ? Reckon I would .

Cheers A .

Edited December 31, 2012 by discopotato03

[32rrr]

Bit of an update we have found that the gates belts (especially the blue ones) are in certain cases causing issues with timing oscillation, the audible humming seems to also induce more belt oscillation at high rpm than the std Nissan belt. After swapping back to genuine belts the issues were fixed (3 cases now). No matter which way we adjusted the belt tension we could not get rid of the problem... fitted std belt with factory tension... issue fixed.

If anyone has some new ones handy it would be good to get some secondary measurements on the tooth profiles, I have had a customer make comment (after measuring them up) that the blue belts have a slightly different profile and are not as snug in the cam sprockets as the genuine belts.

I dont have any new ones handy to compare but it may be worth looking at if anyone gets bored. It wont be the case in every timing issue but one that is worth looking at if you run one of theses belts.

Oh man.. the more and more i search about RB trigger issues as i am having major problems at the moment trying to solve me problem, reading that it could infact be the stupid f**king blue belt just makes me furious haha

Also for those of you with R34 CAS's Autronic make a 6+1 trigger disk for them. as the r34's have a D shape locator unlike the R32/33's which have the 3 locating holes.

Oh.. and mine starts to happen around 3200rpm and wont actually let me rev past about 4 due to the trigger miss's

I have been through everything from Possible interference from the M&W CDI setup to running new wires and trying multiple cas's including changing out the exhaust cam to see if the earlier model CAS would make a difference.

I'm waiting for my autronic trigger disk to show up and if that doesnt fix it I'll be making my own crank setup off the balancer as i cant justify 1800-2000 for the ross kit.. it is sexy and i would reccomend it to anyone who doesnt already have a expensive balancer thats building a big hp motor

[black bnr32]

Just wanted to bump this thread to give another example of what the fluctuations look like. this setup jumps around about 500 rpm above 7 or 8k rpm. this setup includes a 2.6L, pfc + datalogit, original CAS, new oem belt and pulleys, no a/c, ATI damper, 280/10.8 cams, and HKS cam gears.

not sure what i'll do about it.

[Gts-t]

Its a long shot but there is obviously a bearing in the cas unit. When any bearing wears out it will produce noise which could be causing the interferance

Slowly getting all the bits for a for a decent rebuild and i bought one of those blue timing belts god dam it

[simpletool]

Sorry if anyone has already mentioned this but Jim Wolf has another solution which is replacing the CAS pin drive. Obviously this is potentially only a VG30 issue, but might be realted. http://www.jimwolftechnology.com/wolfpdf/VG30DETT_CAS_COUPLING_MISALIGNMENT.pdf

I've also thought if I come across the problem and it is a worn pin drive then a cheap trick worth a try would be to coat the CAS pin with Loctite 243. (Obviously disassembly might be a bit tricky)

Edited August 6, 2013 by simpletool

[tk80]

any update on the belt? anyone else switch from gates to standard belt and have the problem resolved?

[XKLABA]

thought this would the best place for this

I brought the full Ross trigger wheel set, nearly $1900, and as part of the kit I got a convertor box to change the signal to standard nissan so the stock Ecu or PFC can read it, I've since gone a full stand alone ECU and don't need the convertor box any more so if anyone is interested in buying it and saving some coin PM me, it's still new in box never opened

anyone tried different belt tensions to see if it makes a difference

[tk80]

Does modifying the standard cas wheel from 360 holes to 6 holes fix most of the problem for a very small outlay?

http://forums.hybridz.org/topic/56681-cas-trigger-wheel-fix-for-aem-ems-released/

[tk80]

By the way, ATI don't do a bolt on trigger wheel for the 33 damper (part 917753).
Copy and paste of email they wrote to me....
No we don't and if we make a custom shell it will move the belts to
accommodate the ring. A custom ring would be around 450.00 for that damper
do to the belt ribs and a ring.

Edited August 20, 2013 by tk80

[Simon-S14]

your much better off modifying the balancer to run a trigger and then using that CAS trigger mod to tell the ecu the home position

Does modifying the standard cas wheel from 360 holes to 6 holes fix most of the problem for a very small outlay?
http://forums.hybridz.org/topic/56681-cas-trigger-wheel-fix-for-aem-ems-released/

[tk80]

agreed. just trying to find a way to fix 90% of the problem with a few hundred dollar fix, rather than spending $2k. i'm turning into a tigh a$$ in my old age.