Jump to content
SAU Community

Recommended Posts

Hi guys and gals!

I am currently having some misfiring problems. Yes i have change it to SPlitfires which are only 14 months old. Mechanic reckons thats the problem. Maybe a faulty one. Low boost doesnt misfires but when i am on high boost it misfires.

So i have been told it might also be the AFM but it has been changed to a new one. Spark plugs are new. We are eliminating the CAS, as the tuner says the power graph doenst show irregularities.(or something like that, power doesnt goes up and down)

What could also cause this problem??

If any of you guys ever had this problem pls let me know!! Any help would much be appreciated!!!

THANK YOU IN ADVANCE!!!! :thumbsup:

Link to comment
https://www.sau.com.au/forums/topic/263105-failing-splitfire-coilpacks/
Share on other sites

Nope... check new fuel pump + bp 98 only.

The car actually doesnt misfires that much when i had a service. Before the service it does misfires alot. Service was just a regular service(oil + oil filter).

This doesnt happen all the time. Sometimes it can work like a dream and sometimes its being a bitch!

Instead of changing the AFM/PLUGS etc and spending money on those things, the VERY first thing one should have done(i know i would have), was run a diagnostic on the stock ecu(if its still stock).

Checking simple things like timing, fuel pump pressure etc.

What gaps are you running?

I am running PowerFC. Timing was drop, tuner says nothing wrong with the CAS.

When the car is on Low Boost (10 psi) it doesnt misfires but on 16psi it just goes POP POP POP around 5k rpm....

Will check on fuel pump pressure and fuel filter(is this the one on on the fuel pump? If so it should be new.)

Car is running a gt30, fuel pump, 650cc injectors, z32 afm and all the usual upgrades. Tune looks very good. 12.1 afr which really cant be justified because every engine might have a different characteristics.

I had already brought the car back 4 times since i got the car back. Tuner still reckons its the coilpack that needs changing. Final!

during the tuning process the enigne didnt even misfire at all! On the dyno it didnt misfire hence the tuner didnt even know it was happening.

Its when i brought the car back and took it for a drive, it started to misfire and pinging (engine light keeps popping up on 3rd gear). So back to the tuner again and timing was drop and everything seems fine but its still misfiring on 16 psi.

Just added: Dyno 3 times. Didnt misfire on dyno and car made 350rwhp on first tune then timing drop it was making 320rwhp.

JUst to add some info. THe car was tune by a reputable tuner.

I have brought my car to several different place and have been told off many times. Everyone has a different story and some doesnt want to touch the car as most said "Trust in your tuner furthermore he is the best around!". This are from mechanics and tuner alike.

1st graph = when i first got the car

2nd graph = timing drop

post-40804-1238297260_thumb.png

afr2.pdf

Edited by lcy

im just having a stab in the dark here but this could be leading off your white-smoke problem in your other thread. if you've got water entering your combustion chamber then it will misfire.

fix your other problem first.

I would agree and say that it definently sounds like a coil pack problem.

Splitfires arn't infallable, infact in another 2-3 years time when some of the originals start getting older I'd put money on it we'll see more fail in exactly the same fashion the stockies fail.

Just to make sure swap it with a known good pair to see if that makes any difference, and like others have said I'd also be checking your plugs / plug gapping just to be certain.

Good luck!

Just to take a wild stab - 1 way to find out if the coils are on there way out is to measure the resistance between A-B(i think - as per factory manual).

Now i know that the readings in the manual are for stock coils. However the readings you get, write them down and compare them individually.

eg coils 1-4 have around 20k-22k resistance where as 5 and 6 are getting 29k.. that would "KINDOF" indicate that 5 and 6 possibly could be faulty, judging their resistance. This method is only going to test the primary coil tho, not the secondary coil.

Thats 1 easy way of testing it, the other is to take the coils out and take it to a professional sparky - where they can load up the coil to a few hundred V on their test bench and see if theres anything wrong. This would be better - as the coil heats up, the resitance would too, therefore this test would be more accurate.

Try checking the coil harness as sometimes they give problems especially the connectors as they are prone to get loose after some years of connecting and disconnecting and also greatly affected by the engine heat.

Even after 2-3months on a third new coil harness my engine was intermittently misfiring and my mechanic did some mods to the connectors by trimming some plastic bits in them for better contact and this cured the misfirings. Leaky valve covers gaskets will also let oil get to the plugs causing misfiring and this happened to me just this past week.

Edited by docang

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

    • Had I known the diff between R32 and R33 suspension I would have R33 suspension. That ship has sailed so I'm doing my best to replicate a drop spindle without spending $4k on a Billet one.
    • OEM suspension starts to bind as soon as the car gets away from stock height. I locked in the caster and camber before cutting off the kingpin. I then let the upright down in a natural (unbound) state before re-attaching it. Now it moves freely in bump and droop relative to the new ride height. My plan is to add GKTech arms before the car is finished so I can dial camber and caster further. It will be fine. This isn't rocket science. Caster looks good, camber is good, upper arm doesn't cause crazy gain and it is now closer to the stock angle and bump steer checks out. Send it.
    • Pay careful attention to the kinematics of that upper arm. The bloody things don't work properly even on a normal stock height R32. Nissan really screwed the pooch on that one. The fixes have included changing the hole locations on the bracket to change the angle of the inner pivot (which was fairly successful but usually makes it impossible to install or remove the arm without unbolting the bracket from the tower, which sucks) and various swivelling upper arm designs. ALL the swivelling upper arm designs that look like a capital I (with serifs) suck. All of them. Some of them are in fact terribly unsafe. Even the best one of them (the old UAS design) shat itself in short order on my car. The only upper arm that works as advertised and is pretty safe is the GKTech one. But it is high maintenance on a street car. I'm guessing that a 600HP car as (stupidly, IMO) low as you are going is not going to be a regular driver. So the maintenance issues on suspension parts are probably not going to be a problem. But you really must make sure that however your fairly drastically modded suspension ends up, that the upper arms swing through an arc that wants to keep the inner and outer bolts parallel. If the outer end travels through an arc that makes that end's bolt want to skew away from parallel with the inner bolt, you will build up enormous binding and compressing forces in the bushes, chew them out and hate life. The suspension compliance can actually be dominated by the bush binding, not the spring rate! It may be the case that even something like the GKTech arm won't work if your suspension kinematics become too weird, courtesy of all the cut and shut going on. Although you at least say there's no binding now, so maybe you're OK. Seeing as you're in the build phase, you could consider using R33/4 type upper arms (either that actual arm, OEM or aftermarket) or any similar wishbone designed to suit your available space, so alleviate the silliness of the R32 design. Then you can locate your inner pivots to provide the correct kinematics (camber gain on compression, etc).
    • The frontend wouldn't go low enough because the coilover was max low and the upper control arm would collapse into itself and potentially bottom out in the strut tower. I made a brace and cut off the kingpin and then moved the upright down 1.25" and welded. i still have to finish but this gives an idea. Now I can have a normal 3.25" of shock travel and things aren't binding. I'm also dropping the lower arm and tie rod 1.25".
    • Motor and body mockup. Wheel fitment and ride height not set. Last pic shows front ride height after modifying the front uprights to make a 1.25" drop spindle.
×
×
  • Create New...