R33 Missing After Highway Driving....

[arrydjay]

So I thought I had all my misfiring problems sorted but nope its back again!!!

Now it is missing after I drive it for a long time on the highway. Usually driving to work and back i give it a bit through the gears and i dont notice it missing, but when I just cruise it on the highway for a while and then try and give it a hit it just misses like crazy. After I drop it down a few gears and take it to redline a few times it gets better.

My theory is that it is running rich and fouling up the plugs, there is a fair bit of exhaust build up on the back of the car and I have seen unburnt fuel spitting out the exhaust.

Any ideas what I should be looking at/changing?

[GTSBoy]

Plugs, coils, air filter, cat converter, ECU......

[abr33]

If your sure its fueling id be looking at 02 sensor as well as new plugs and clean afm?? Sounds odd

[arrydjay]

plugs done 2000k's, already got yellowjacket coils, running a covered pod, replaced 02 sensor with a falcon one a couple months ago..

someone has told me to change all the hose clamps on the cooler pipes to those beefy bolt down ones incase it is leaking boost.

My battery is a bit sus as well, could low voltage cause a misfire?

[arrydjay]

This problem is really doing my head in now.... Can anyone recommend a workshop somewhere in Sydney where I can take this thing to get sorted....

[DVS JEZ]

How do the spark plugs look. I can put it on the dyno and test it out for u if u want. Im on the central coast though

[pipster11]

cas could be getting heat soak and then playing up

or leaking injector fouling the plugs

pull the plugs and check the colour

[51NNA]

Have you tried unplugging a coil at a time too see what cyl is miss firing? i have brand new yellow jackets that lasted 2 weeks before one died lol. Also the beefy bolt down ones is just a wank factor, unless your running 50psi+ I wouldnt bother, you'd split your hoses before the clamp let go..

Edited April 25, 2012 by 51NNA

[MBS206]

Beefy hose clamps would be good if you were on boost, but you're in vacuum on the highway.

What plugs are you using? You may have the wrong ones.

[arrydjay]

it doesn't miss until I jump on it but...

I've got standard NGK plugs with a 0.8 gap

I've only got the stock boost gauge atm and it was sitting about halfway between the 3.5 and 7 mark...

Turned it down so that it sits just on the 3.5 mark.... it has helped a bit, but I can still hear it missing occasionally.

I have found that once it starts to miss if I turn it off and let it cool down a bit the problem goes away for a while until it gets warm again...

[AngryRB]

How important is the 02 sensor? could it cause misfire?

[DVS JEZ]

Try disconnecting the 02 sensor

[AngryRB]

its permanently disconnected at moment cause the dump pipe that i got made has no hole for it, and the car idles like a subaru and hesitates just over idle and thru the revs a bit too, just wondering if its only important for crusing?

[rob82]

its permanently disconnected at moment cause the dump pipe that i got made has no hole for it, and the car idles like a subaru and hesitates just over idle and thru the revs a bit too, just wondering if its only important for crusing?

That's probably your cause - when you disconnect the 02 sensor you are most likely adding 25% extra fueling throughout the entire rev range even onto load.

Edited April 25, 2012 by rob82

[AngryRB]

ah ok, that explains it then, cause when its cold its especially lumpy, after a long drive its calmed down a bit, but still sounding like very lumpy cam , which i have no complaints with, cheers for the reply been scratching head about this for weeks.

[Hadouken]

That's probably your cause - when you disconnect the 02 sensor you are most likely adding 25% extra fueling throughout the entire rev range even onto load.

Who would have thunk it?

facepalm.jpg

[arrydjay]

ah ok, that explains it then, cause when its cold its especially lumpy, after a long drive its calmed down a bit, but still sounding like very lumpy cam , which i have no complaints with, cheers for the reply been scratching head about this for weeks.

Haha dude, thanks for taxing my thread! lol

Ive just bought a new turbo from hypergear...SS1PU, so ill try putting that on with new injectors and Z32 AFM and tuning it and see if that solves anything.

[AngryRB]

sorry mate, was just after a quick answer ,

[rob82]

Who would have thunk it?

facepalm.jpg

Not always the case though. I know there were some derivations of r32 ECM that wouldn't add fuel when the o2 sensor was disconnected - maybe the same for r33 ecm's.

[DVS JEZ]

Lumpy idle sounds like an airleak to me