Misfire Coming On Boost

[No Crust Racing]

I believe the ecu itself has been flashed which is why I can have the safc on zero and still not ping.

Granted I'm only using the factory sensor but im not hearing or registering any knock on the safc either. The car ha knocked before with too much boost.

Sounds like it might be worth at least checking timing and making sure it wasnt advanced when it was tuned.

I might check the manual and see if there's anything I can check with the multimeter for the fuel pump.

I'm reluctant to take I to a local place as they have a tendency to charge for hours and hours and come back with nothing.

[Rolls]

In that case find someone with a wideband gauge and at least use that yourself, better than nothing. You really shouldn't be tuning fuel without one!

Knock ears would be great as well but you aren't exactly going to go spend $1k on them for a back yard tune, maybe a visit to Melb is in order? Be cheaper than a replacement motor that is for sure!

[No Crust Racing]

Ok one more update.

I went for another drive, safc on zero, but this time I disconnected the exhaust gas sensor/O2 sensor. This is another test in the sevice manual for missing.

No missing at all with plug gaps on .8

I considered that because it is a cold night it was masking it so I sat in an industrial estate with my lights off and held 2500 rpm for period until water and oil temps were nice and warm and the bay was nice and soaked. It occasionally missed/popped during this high idle period but did not miss while driving or under load.

I'll test again during the day when it's warmer and might grab the sensor from my mates car.

[Rolls]

The missing if caused by too rich will generally be worse in cold weather as more air, but heat makes the coils spark worse also.

Really think everything will be solved with a trip to a competent SAFC tuner who has tuned skylines before.

[No Crust Racing]

See how it goes with the O2 disconnected and driven when warmer. If it's still good I I'll try another sensor.

Fingers crossed.

[Rolls]

O2 feedback is only below ~3.5k on low load, if its missing above this it can't make any difference.

Also O2 feedback generally makes it leaner, if anything it should make the problem worse unplugging it.

Edited July 31, 2011 by Rolls

[No Crust Racing]

Interesting. Just to clarify, we're talking a ca18 here not an rb. I only mention this as you referred to skylines before.

See how it goes when the temp is higher. Cold dense air might have been masking it. Previously the critical miss point was 31-3200rpm

[DVS JEZ]

02 sensors can do strange things when they play up.

Get a wideband onto it and check those afrs out

[No Crust Racing]

Update: Drove the car to work today as it's a nice sunny day, it's supposed to be 20 here today too so the drive home will be another good test. No missing at all with the Oxygen sensor disconnected.

Considering it's primarily track only I'm not in a hurry to replace the sensor. I'm going to put it on a dyno this weekend and check the AFRs after all my stuffing around and make sure it's safe before it hits the track again.

At the same time I could use the low throttle point map in the SAFC to take a bit of fuel out of at the cruising RPM with low throttle. Not as good as relying on the Oxygen sensor but better than nothing, that will only be if time permits as I'm not really concerned about highway economy. Let me know if I'm missing something else by not replacing it though.

So long as it drives well on WOT I'll be happy.

Side bar: Do the CA's have a diagnostic type port? I know they don't have a CONSULT port but do they have the standard 9 pin diag port? If so I can hook up a little diag box and check my timing easily too.

[No Crust Racing]

Dyno was a fizzle, the guy was a muppet. Went as he could fit me in this Sat, my n0rmal dyno guy was busy.

After dicking around for ages and continuing to tell me it was lean all the time, I added full correction for fuel on the SAFC (50%) the car is missing, popping flames, big plumes of black smoke from the unburnt fuel and he goes still lean. turns out his sensor is f**ked.

Not only that but he wants to run it by sitting at 60km/h in 3rd, no load no boost, then continuing to add load on the dyno and adding throttle so it just holds at 60km/h so essentially we're driving up the steepest hill in the world at 60km/h in third. The car just loves that.

He spent more time talking about his divorce, pending lawsuit with the epa, and on the phone to the guy from Mainline trying to work out how to give me the damn graph i needed to see (he could only give me real time data and nothing recorded over a run) than he did anything else.

In the end, he cracked it, I cracked it and we went our separate ways (I didn't pay anything). I'll go to my normal dyno guy next Saturday.

Good news is that other than when it had stupid fuel in it, it didn't miss on the drive over or back or on the dyno. Must have been the O2.

[_x_FiReStOrM_x_]

Sorry if this has been posted already. Whats your fuel pressure?

Not having a dig at all, but these sorts of threads pop up fairly often and there's never any basic diagnosis done. Just alot of parts thrown at the car in the hope something will fix it.

Hope you get it all fixed soon

[No Crust Racing]

An update to this.

I've since bought and fitted and AEM wideband so now I can just road tune the car myself, unsurprisingly it's a little rich down low and by a little, i mean a heap - richer than 10:1 - and

then it's a touch lean up top nipping at 13:1 so I'll bring that back to around 12.5 and dial out some fuel down low.

Should be apples

EDIT: Forgot I'd already been a good boy and updated about the O2, woops.

Edited August 25, 2011 by ActionDan