Massive Miss Fire Along With A Few Other Issues

[Cubes]

Checked CAS?

I've seen them be fine at low rpm; get the rev's up and they clag up.

[fr0st]

It runs crap at both high and low rpm. I've also checked the CAS with a oscilloscope and the megasquirt, both showed consistant pulses.

I hope its ignition... I'm running out of things to replace. If the RB30 was ready I'd just replace it with that

[nisskid]

Sounds very similar to my RB20 which is currently sitting on an island in the middle of an intersection waiting to cool down

Small pop on idle, nothing consistant to tell what cyclinder its coming from. Missfires like a hoe at 4000-5000, it boost all the way to 14psi but hits 4000 and craps out. From idle to 2000rpm is missfires and hesitates, 2000-3500rpm it runs normal.

Sofar I've replaced the O2 sensor, fuel pump, injectors, spark plugs. O2 sensor was replaced with a wideband, before it died tonight I was logging the AFR's and it was all normal, it was trimming to 14.7 on cruise and idle, 12 on boost (tuned stock ecu, nothing touched other than WOT AFR's). Changing the injectors made it run better but not well, also stopped it running very rich (>9 AFR). I also had a loose alternator belt which made the car a bitch to start from it slipping.

ECU & AFM are definately doing there job, both read in the normal (checked via consult) and the fact that the mixtures are correct suggests it not there fault either. With the better part of the fuel system replaced it leaves ignition now. Still using standard coil packs and ignitor, the ignitor I can test using my oscilloscope (will do when I get the f$%king thing home) but since its the last thing left besides swapping the entire engine out I may aswell shell out for a wasted spark setup to rule it out completely. I've got a megasquirt-II waiting to be wired in so it'll make that install a little easier when I wire in the ignition.

I had a mechanic look at it but he just gave it back to me broken and said 'get it tuned on a dyno'

Best of luck fixing your problems, I'll post up how I go with the new spark system

oh fark, thats not good news lol

[nisskid]

It can be difficult to see; you really need to look down the side of the coil and a little underneath. They don't spark on top.

ahk its just the way u said fireworks show i thought id be able to see something pretty easy. i had a close look and couldnt see anything still. i dunno, just seems weird that all the coilpacks would go at the same time, when it hits 5psi its not just one or 2 cyls that go, the whole engine breaks down.

[fr0st]

oh fark, thats not good news lol

haha yeh I'll say

Car is now sitting in the garage. Such an a-hole of a car, stalls and doesn't start not matter what... let it cool down and started it after a second or two of cranking

So now its down to either a mechanical or ignition problem that gets worse after the car is hot. I'll try and get some sort of wasted spark going tomorrow, just have to see what coils I can get from Repco or Supercheap at late night shopping. If its an internal problem then I'll have no choice but to finish my RB30 and put that it... what a shame that would be

[nisskid]

haha yep im keeping my eye out of rb25/30's just incase but i think the issue wont end up being major.

[R.3.2.G.T.R]

sorry to hijack, can someone tell me how u go about checking CAS, my car is having power issues when on boost, looking at cleaning AFM and re-gapping plugs to 0.7 this weekend..

[GTRNUR]

I just remembered one other thing that can cause these issues. I had a hole in the factory side mounted intercooler that caused an un-even idle, poor boost control, and miss firing when on boost due to over fueling. Lots of black exhaust smoke as well due to excessive fuel. Seems a stone had flicked up from the front wheel and had damaged the back of the intercooler core through the inner guard shield.

[nisskid]

can i chuck some dry ice or some bs in my intake so i can see any leaks? or could dry ice do damage for some reason?

i got a smoke machine if need be

[nisskid]

ok so turns out the stuttering and missing were different issues from the breaking down, there was a small leak in the piping which i fixed which got rid of it breaking down, but the missing is still there although i have to say its not as much of a concern than breaking down was.

so now ive gotta figure this missing out, not sure what to try next now

[r32woohoo]

seems like we have the same problem

and i think its happened after the same circumstances

mines missing at idle too

except it never missfired on boost

i just got a new set of coils and that didnt help

im stumped.

[nisskid]

yeh but im pretty sure ive had a small miss on idle the whole time, it may be normal. wouldnt worry about it if it doesnt affect acceleration etc and its only on idle.

[Cubes]

Mine idles baby smooth with a 0.9mm+ gap; as soon as I drop to 0.8mm and less it has an ever so slight pop on idle.

The old rb20det required a 1mm gap other wise it had a slight pop.

Another fix is to richen up the mixture to 14:1 on idle (well it sorts it for mine).

I've left the idle lean as the slight pop/miss doesn't bother me.

[SOOKIE]

1 mm gap? Ive been running 0.75 every time. Maybe i'll try your way.

Nisskid, do you have a BOV? they seem to be the cause of a lot of these types of issues. Otherwise, you may have to bight the bullet and whack it on the dyno. I had a similar problem in my 32 but it seemed to disappear altogether by itself

[nisskid]

no BOV, i blocked off the stock recirc. but the way my engine is now was the way it was before i had this issue, so somethings deteriorated. only thing i can think about was that wastegate issue i had, i fixed that, but even so this started well after that was changed.

[r32woohoo]

mine used to idle baby smooth too with a 0.65mm gap

but now its lumpy as

definately not just a "slight" pop

sorry to hijack the thread but maybe you guys can shed some light on my problem too

http://www.skylinesaustralia.com/forums/t1...32#entry3377332

[nisskid]

any other ideas?

[r32woohoo]

Well i seem to be getting told its a problem with the CAS

Im trying to get another and see if it fixes the idle problem

Trying a different ignitor pack today so we'll see how that goes

Then its a comp+leakdown test+dyno

[nisskid]

have u tried reducing the gap like cubes said? seriously i wouldnt worry about it heaps, if it was anything serious u would notice it under load.

[r32woohoo]

ive tried every gap with no avail.

im not so worried about it coz like you said, it doesnt cause any problems when driving

It's just annoying coz i cant figure out what it is.

I'll get to the bottom of this eventually