Rb26 Ignition Misfire

[rockvale]

So many times I read threads on SAU about additions to the OEM RB26 ignition system, yet no one has completely or conclusively understood the capabilities of the std ignition system, I have made 500kw at all 4 tyres with std ignition at 0.024". Yes I have also fitted a HKS DLI which by the way does not increase you max secondary ignition voltage, it increases the current, and the engine does run a cleaner spark plug

So the question that needs to be answered is why can some Rb26 run extreme power levels and others can not with the std ignition?

Simply because the ignition is breaking down, but where, so following test will identify your ignition problem.

1, Firstly you will need 6 x brand new plugs gapped to 0.6mm, 6 x sachets of high temp dielectric silicone greese (jaycar sells it) an aluminium sheet about 800 x 400 x thickness does matter, but say 1,0mm, you will need to drill a 9mm hole in the top left hand corner of the shortest side

2. Ensure ignition is OFF, Remove ignition coil loom from coils, remove coils from engine, eg 2 off x 3 coils in Al coil mounting brks, remove std ignitor from engine cover, remove old spark plugs, liberally apply dielectric silicone greese to the top and insulation of each new plug and install into engine

3. Remove 6 x injector connectors,

4. Remove crank angle sensor clip, ensure you witness mark around the washers of the 3 x crank angle bolts before you loosen and remove crank angle sensor from the motor, connect the crank angle sensor back onto the crank angle and rest it in a safe place loosely

5. Plug ecu & coil looms back into ignitor (which has been removed from engine cover), find 1 x small nut for ignitor bolt so that you can attach the std ecu ignitor earth onto the ignitor in std position

6. Place the Al sheet directly on top of the engine with longest edges running front to back, with the 9mm hole at the back on the drivers side

7. Place sideways down the 2 off 3 x coil packs on the Al sheet in simular position as if they were fitted to the engine

8. Find a 8mm nut and use 1 x 8mm Al coil mounting bolt to securely bolt the engine ignition coil loom earth to the Al sheet using the 9mm hole that you drilled (this earth normally attaches at the back on the head under the ignitor)

9. Now connect the ignition coil loom to all 6 x ignition coils

10, Install 6 x old spark plugs to ignition coil boots, and space up coils with steel or Al, so that all spark plug threads are touching Al sheet

11. Connect 1 x start jumper lead from neg battery terminal and connect to Al sheet

12. Turn ignition ON

13, Ensure you are well clear of the spark plugs, spin the crank angle sensor by hand to stimulate the ignition to operate (spinning crank angle sensor in the wrong direction will not operate the ignition, it must be spun in the alternate direction)

14, Testing the ignition system can occur by ensuring the Al coil mounting brkt is in contact with the Al sheet whilst you increase the distance of the spark plug thread from the Al sheet, this should be done in limited illumination to see the arc bridging, if, and where it is occuring

A good std ignition system will ionise approx 25mm air gap between spark plug thread and the Al sheet, if the gap is increased further until the coils can not fire down onto the Al sheet, the 2 off x Al coil brkts with there 3 off x coils each will only " jump" on Al sheet with no arc bridging - Ignition System Test Complete and PASS

But generally ignition misfires are caused by bridge arcing across between the top of the spark plug silicone boot connection point on coil to the ferritic iron core coil mounting plate (its on the coil with the 4 holes in it) Eg From the top of the silicon boot, across the coils body to the coils mounting frame.

Once the coils that are bridge arcing have been identified, you must remove the spark plugs and the silicon boots from these coils and retest to ensure that the coil spark initiates from the coils high tension terminal and not from a crack or pin hole in the coils housing, if this is the case it is in the bin and buy a new coil, but if it is not, what you need to do now is remove all the bridge arcing coils from there mounting positions, get a sharp stanley knife and a very good light source to closely examine the coil body silicon boot connection point for carbon tracking(some form of magnification will help with this task), and use the blade to scrap away on the coil housing until all the carbon tracking marks (ie very small thin black tracks) are removed, when done (be matriculus when you make final inspection) clean all 6 x coils with electrical spray solvent, all 6 x silicon spark plug boots are to be wash with soap and a "clean engine oil gallery brush"(suitable size one of coarse and scrub the silicon boots clean ) and finish with electrical spray solvent

Apply liberally the dielectric silicon grease to all the coil silicon boot connection points and to the top of all the silicon boots and connect the silicon boots back onto the 6 x coils and retest as above.

The final test of approval is when you can spin the shaft on the crank angle sensor and there is "NO" arc bridging when the spark plug threads are further away from the Al sheet than the spark can jump (eg >25mm approx) and all that happens is that the coils/brkts will jump a little, you also may see a very small spark coming from the coil mounting brkt to the Al sheet, this is the residual emf when you are shunting the in this test, now you can put it all back together with your new spark plugs and enjoy.

In closing

THE SECRET - CLEANLINESS AND A LIBERAL AMOUNT OF GOOD HIGH TEMP DI-ELECTRIC SILICON GREASE

All RB26 coils (even New one's) should use High Temp dielectric silicon grease on the coil/silicon boot connection point

New Nissan OEM coils are the best

Always wash, clean, liberally apply silicon grease to silicon boots when changing new spark plugs

Always apply dielectric grease to the top of the plug and insulator on new plugs

Ensure the ignition coil loom earth is in good condition and firmly connected and the 6 x ignition trigger ecu loom earth is connected to the ignitor

Ensure all 6 x ignition coil + positives are getting battery voltage (consider dedicated ignition relay direct battery feed)

Ensure main earth battery lead that goes to engine block which also connects to the car body half way along is connected and that the body earth is clean, and tight(This is a strategic point for a number of electrical problems).

ALL THE ABOVE AT YOUR OWN RISK

Edited July 27, 2013 by rockvale

[Blk33]

Hi,

An interesting article, the best one I have so far! I have just upgraded to small 2860 -7 turbos and increased the boost to about 15 - 16 psi. Occasionally around 5000 rpm I get a misfire. It feels like ignition and occurs around maximum engine load.

I like the idea of your test jig! It looks like you are creating another ground reference with the aluminium sheet and increasing the gap between the spark plug thread until a spark jumps somewhere else. Do you have any photos of the setup, this would be handy!

A quick question on the injector plugs, do you just pull them off, or remove the spring first?

Cheers

Rob

Edited August 4, 2013 by Blk33

[Guilt-Toy]

yeah.. nice... photos ???

[KiwiRS4T]

Yes very interesting test..

but regarding your miss my tuner (Soichi at ST Hitech) pointed out a miss at high revs/boost and told me to replace the copper plugs with PFR7 plugs gapped to 0.8mm so maybe that would be worth a try first.

Hi,

An interesting article, the best one I have so far! I have just upgraded to small 2860 -7 turbos and increased the boost to about 15 - 16 psi. Occasionally around 5000 rpm I get a misfire. It feels like ignition and occurs around maximum engine load.

I like the idea of your test jig! It looks like you are creating another ground reference with the aluminium sheet and increasing the gap between the spark plug thread until a spark jumps somewhere else. Do you have any photos of the setup, this would be handy!

A quick question on the injector plugs, do you just pull them off, or remove the spring first?

Cheers

Rob

[Blk33]

Hi Everyone,

I had a go this week following the information and it worked a treat for me.

I documented the process and uploaded it to YOUTUBE. Have a look and see what you think!

Thanks to rockvale for the insite.

Rob

Hi,

An interesting article, the best one I have so far! I have just upgraded to small 2860 -7 turbos and increased the boost to about 15 - 16 psi. Occasionally around 5000 rpm I get a misfire. It feels like ignition and occurs around maximum engine load.

I like the idea of your test jig! It looks like you are creating another ground reference with the aluminium sheet and increasing the gap between the spark plug thread until a spark jumps somewhere else. Do you have any photos of the setup, this would be handy!

A quick question on the injector plugs, do you just pull them off, or remove the spring first?

Cheers

Rob

[Sinista32]

Good DIY vid for a very old and well known remedy to this common issue

[portaz]

Someone sticky this link! Great job mate very clear and concise and hopefully will stop alot if missfire threads in the future.

Scott

[Ryno]

Wow, I've just cleaned my Splitfires and used dielectric grease as per the tutorial above and my misfire is gone... Great work guys!

[R.3.2.G.T.R]

awesome bit of info and followup video, will be using the di-eletric grease on my next service, even though i dont have a missfire

[SiR_RB]

that's a great write up !! definetly made things much clearer to understand...

never would have thought to put the grease on the top of the spark plug though

[Blk33]

The specifications for dielectric grease show about 20,000 volts is required to jump a 1 mm length of dielectric grease.

So by covering the top of the spark plug in dielectric grease it makes it easier for the spark to jump across the spark plug gap rather than across the outside of the spark plug.

I agree with SiR_RB on reflection, maybe leave the top of the spark plug free of grease, however as long as a good metal contact is made with the top of the spark plug, covering the top of the spark with grease will not be a problem.

[SiR_RB]

Where's the best place to buy the dielectric grease?

I saw the one at jaycar but it was called "conductive carbon grease", was not sure if this was the right one??

[R.3.2.G.T.R]

Supercheap will have it (permatex brand)

[GTSBoy]

Conductive carbon grease is exactly the opposite of what you want.

[SiR_RB]

I will try supercheap/repco

[NismoSTune]

Greasing up parts inside the combustion area is a cool idea.... And it seems to work.

I hadnt jimmied much else on my car so I bought a better ignition system and solved my misses. Good to 1000hp (though I'm far from this) and 1.4mm gaps now (running 1.2mm at this time). Bazinga

Edited October 24, 2013 by NismoSTune

[Blk33]

Where's the best place to buy the dielectric grease?

I saw the one at jaycar but it was called "conductive carbon grease", was not sure if this was the right one??

I bought dielectric grease from: http://www.parts4.com.au/

Dielectric grease is an insulator, conductive carbon grease is not what you want, it is a conductor!

[SiR_RB]

NIsmoStune-- what ignition upgrades did you do to achieve a 1.4mm - 1.2mm spark plug gaps and how much boost/power you making?

[scotty nm35]

I melted a set of iridium plugs a while back, they were 3mm gap at least and my car only just started misfiring in the top end at 30psi. VQ coils are just better designed I think, not necessarily higher voltage but less chance of the spark jumping to earth as the rocker cover is plastic, there is nowhere for the spark to earth other than the plug gap.

There is no reason a little ingenuity couldn't get RB coils jumping a similar gap...

[SiR_RB]

3mm !!!!