Jump to content
SAU Community

Recommended Posts

well i've had a intermintint missfire in my car for quite awhile now and nearly coming to the point of not knowing what to check next, its also become quite hard to determine which cylinder it is. Diagnosing had become rather a big pain and am asking for help!!

so far i've, not all realating to fixing miss but could help....

changed engine loom wiring

changed CPU (currently got auto one, and manual car)

changed CAS

had injectors professionally cleaned and tested

changed AFM

replaced O2 sensor

cleaned ACC valve

checked cooler piping for leaks

done compression test with 10psi difference at the most

replaced coolant temp sensor

re wired coolant temp sensor

next thing i'm probally going to replace is the coil packs with some spitfire ones, but is there anything else that ive missed out on checking??????

Link to comment
https://www.sau.com.au/forums/topic/47634-missfiring-problems/
Share on other sites

You did not say you changed the plugs but I guess that was a given? :Oops:

I know when I last had fitted iridium plugs and got MD to dyno my car he had to change back to platinums to get rid of misfiring. Even gave me back my $30 each investment :rofl:

My 33 started misfiring after i changed from coppers to platinums (still a 0.8 gap) and ran more boost and timing with the powerfc. I dont think the standard coil packs have much kick left in mine so im replacing them with spitfire's next week hopefully. I'll let you know how it goes. Oh, and as a temporary fix im using coppers gapped to 0.7, seems to have eliminated the misfire.

-rb25

yeah forgot to mention, i have replaced the spark plugs a few times now. i've tried platinums, iridiums, and now currently using coppers, gapped to 0.7 i think.

i'll probally try swaping the ignitor soon with a mate. coil packs are gonna be changed no matter what as they have those little cracks on nearly all of them at the top, as mentioned in another thread that i've read awhile ago.

Try this thread: http://www.skylinesaustralia.com/forums/sh...ead.php?t=32356

It has been the solution for many including myself.

If you talking about an RB25DET, then they are notorious for isfiring above 4500 RPM on higher than standard boost.

- a SAFC or PFC with mixtures leaned out to 12:1 will GREATLY help.

- copper plugs gapped at 0.8 (BCPR6E)

- and coils taped up like describd in the post above...

A SAFC fixed my problem, but the misfire came back recently...

I just finished taping up my coils, now the mis has completely gone...

Give it a go... it will only cost you 1-2 hours and a couple of $$ in tape...

thanks for the reply zahos, unfortunatlly, taping them up is really only a temporary fix. i have already done that, it helped slightly at high revs but its still got the intermintint miss at idle.

yeah you could possibly be right about the SAFC, it is running a bit rich, so maybe thats the issue. i'm gonna try get hold of a ignitor module today to swap if i can.......

it couldn't be running that rich to cause a miss surely?!?

its basically all stock cept for boost running at 10psi and the fuel pump, and 3" cat back-- that wouldn't cause that many issues would it with the fueling. thou i am getting only like 350km outa a tank but with a bit or hard driving that is...........

Mine was missing like crazy at around 4500-5500 rpm before I intalled and tuned my SAFC. With the SAFC tuned it was as smooth as a baby's arse!

I developed a miss again lately, but that b/c of the coil pack cracking.

Now with the coils taped up.... it's like a baby's arse again

thanks for the help so far guys.

Trust me, thats what it is, what year is your car?

When you boost it, it dumps more fuel in and floods the cylinders.

its a 89/90 R32 with a rb20det

the miss is mostly noticable at idle with it been a constant intermintant one. (like every 3-5 secs) thou is also noticable with the revs held up higher.

When you boost it, it dumps more fuel in and floods the cylinders.
I've replaced my iridiums (which looked fine) with brand new coppers, taped all my coils but then replaced #1 + #4 which I believe are the fault 1's with 2nd coils and my problem has gone from 'missing' to now feeling like a few 'flat spots' under load on only 7psi so obviously I still have a coil issue but do you think my car is running rich enough to cause the missfires too ?

cam-afr.jpg

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

    • I came here to note that is a zener diode too base on the info there. Based on that, I'd also be suspicious that replacing it, and it's likely to do the same. A lot of use cases will see it used as either voltage protection, or to create a cheap but relatively stable fixed voltage supply. That would mean it has seen more voltage than it should, and has gone into voltage melt down. If there is something else in the circuit dumping out higher than it should voltages, that needs to be found too. It's quite likely they're trying to use the Zener to limit the voltage that is hitting through to the transistor beside it, so what ever goes to the zener is likely a signal, and they're using the transistor in that circuit to amplify it. Especially as it seems they've also got a capacitor across the zener. Looks like there is meant to be something "noisy" to that zener, and what ever it was, had a melt down. Looking at that picture, it also looks like there's some solder joints that really need redoing, and it might be worth having the whole board properly inspected.  Unfortunately, without being able to stick a multimeter on it, and start tracing it all out, I'm pretty much at a loss now to help. I don't even believe I have a climate control board from an R33 around here to pull apart and see if any of the circuit appears similar to give some ideas.
    • Nah - but you won't find anything on dismantling the seats in any such thing anyway.
    • Could be. Could also be that they sit around broken more. To be fair, you almost never see one driving around. I see more R chassis GTRs than the Renault ones.
    • Yeah. Nah. This is why I said My bold for my double emphasis. We're not talking about cars tuned to the edge of det here. We're talking about normal cars. Flame propagation speed and the amount of energy required to ignite the fuel are not significant factors when running at 1500-4000 rpm, and medium to light loads, like nearly every car on the road (except twin cab utes which are driven at 6k and 100% load all the time). There is no shortage of ignition energy available in any petrol engine. If there was, we'd all be in deep shit. The calorific value, on a volume basis, is significantly different, between 98 and 91, and that turns up immediately in consumption numbers. You can see the signal easily if you control for the other variables well enough, and/or collect enough stats. As to not seeing any benefit - we had a couple of EF and EL Falcons in the company fleet back in the late 90s and early 2000s. The EEC IV ECU in those things was particularly good at adding in timing as soon as knock headroom improved, which typically came from putting in some 95 or 98. The responsiveness and power improved noticeably, and the fuel consumption dropped considerably, just from going to 95. Less delta from there to 98 - almost not noticeable, compared to the big differences seen between 91 and 95. Way back in the day, when supermarkets first started selling fuel from their own stations, I did thousands of km in FNQ in a small Toyota. I can't remember if it was a Starlet or an early Yaris. Anyway - the supermarket servos were bringing in cheap fuel from Indonesia, and the other servos were still using locally refined gear. The fuel consumption was typically at least 5%, often as much as 8% worse on the Indo shit, presumably because they had a lot more oxygenated component in the brew, and were probably barely meeting the octane spec. Around the same time or maybe a bit later (like 25 years ago), I could tell the difference between Shell 98 and BP 98, and typically preferred to only use Shell then because the Skyline ran so much better on it. Years later I found the realtionship between them had swapped, as a consequence of yet more refinery closures. So I've only used BP 98 since. Although, I must say that I could not fault the odd tank of United 98 that I've run. It's probably the same stuff. It is also very important to remember that these findings are often dependent on region. With most of the refineries in Oz now dead, there's less variability in local stuff, and he majority of our fuels are not even refined here any more anyway. It probably depends more on which SE Asian refinery is currently cheapest to operate.
    • You don't have an R34 service manual for the body do you? Have found plenty for the engine and drivetrain but nothing else
×
×
  • Create New...