Jump to content
SAU Community

Recommended Posts

  • Replies 54
  • Created
  • Last Reply

Top Posters In This Topic

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 :)

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

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.

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 :(

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.

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 :)

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.

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.

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 :down:

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.

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

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

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

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

    • For once a good news  It needed to be adjusted by that one nut and it is ok  At least something was easy But thank you very much for help. But a small issue is now(gearbox) that when the car is stationary you can hear "clinking" from gearbox so some of the bearing is 100% not that happy... It goes away once you push clutch so it is 100% gearbox. Just if you know...what that bearing could be? It sounding like "spun bearing" but it is louder.
    • Yeah, that's fine**. But the numbers you came up with are just wrong. Try it for yourself. Put in any voltage from the possible range and see what result you get. You get nonsense. ** When I say "fine", I mean, it's still shit. The very simple linear formula (slope & intercept) is shit for a sensor with a non-linear response. This is the curve, from your data above. Look at the CURVE! It's only really linear between about 30 and 90 °C. And if you used only that range to define a curve, it would be great. But you would go more and more wrong as you went to higher temps. And that is why the slope & intercept found when you use 50 and 150 as the end points is so bad halfway between those points. The real curve is a long way below the linear curve which just zips straight between the end points, like this one. You could probably use the same slope and a lower intercept, to move that straight line down, and spread the error out. But you would 5-10°C off in a lot of places. You'd need to say what temperature range you really wanted to be most right - say, 100 to 130, and plop the line closest to teh real curve in that region, which would make it quite wrong down at the lower temperatures. Let me just say that HPTuners are not being realistic in only allowing for a simple linear curve. 
    • I feel I should re-iterate. The above picture is the only option available in the software and the blurb from HP Tuners I quoted earlier is the only way to add data to it and that's the description they offer as to how to figure it out. The only fields available is the blank box after (Input/ ) and the box right before = Output. Those are the only numbers that can be entered.
    • No, your formula is arse backwards. Mine is totally different to yours, and is the one I said was bang on at 50 and 150. I'll put your data into Excel (actually it already is, chart it and fit a linear fit to it, aiming to make it evenly wrong across the whole span. But not now. Other things to do first.
    • God damnit. The only option I actually have in the software is the one that is screenshotted. I am glad that I at least got it right... for those two points. Would it actually change anything if I chose/used 80C and 120C as the two points instead? My brain wants to imagine the formula put into HPtuners would be the same equation, otherwise none of this makes sense to me, unless: 1) The formula you put into VCM Scanner/HPTuners is always linear 2) The two points/input pairs are only arbitrary to choose (as the documentation implies) IF the actual scaling of the sensor is linear. then 3) If the scaling is not linear, the two points you choose matter a great deal, because the formula will draw a line between those two points only.
×
×
  • Create New...