Misfiring And Over Fueling R32 Rb25Det

[ColdFusion]

Here's the story.

So I had this really weird problem happen yesterday. Driving to work in the afternoon and just cruising along and suddenly the car starts to have a really odd cruising note. Sounds almost wrx like, but really faint. Car is fairly temperamental so don't think much of it, vary the throttle a bit and it goes away but then comes back a few seconds later. Get closer to work and now it really sounds like a boxer. Not only that, now I can see white smoke in the rear vision mirror and car is popping a fair bit. Almost at work and it bangs a couple times out the exhaust . I'm talking proper Bee-R loud here (tune is a bit rich I think as it pop and flames from time to time in usual driving). Park up and leave the car idling. I can see a little white smoke from the exhaust and it sounds rexy like, but I can't see anything wrong in the engine bay.

Ok so start the car to leave work this very early morning and car is fine. Nothing wrong at all. No smoke, No being a fake impreza. Back to normal. Drive for around 30 mins with a couple full boost pulls to make sure everything is fine, nothing seems wrong. Right after this I am about 10 mins from home and the wrx noise comes back really bad... Leaving a set of lights like a granny, hit 4th gear and loudest bang I've ever heard from the exhaust and see the brightest flame I've ever seen the car do out the corner of my eye reflecting off the night bushes. I can see more white smoke coming out the back than earlier. Stop at the last set of lights before my house to turn onto the highway and there is white smoke billowing out the exhaust, I turn the car off while I wait at the lights as it is way too much. I'm thinking oil smoke, but I can smell fuel really bad while I sit and wait for the lights. The light changes, I start the car and take off quickly. I can see a solid cloud of smoke where my car was as I leave the lights. It only smokes a little as I drive off though. Getting onto the highway I hit a bit of boost and the misfiring goes away? What?! I change gear and boost higher and, sure enough, the misfiring is gone while in high revs and boost. I get home, park up really quick and it's smoking like at the lights so I turn it off quickly. I get out to look at the muffler and there is smoke still wafting out, but it looks really weird and I can smell fuel.

I let the car cool down to see if the problem goes away again, but no go this time. I took some vid:

Idling

Video1

Reving. I felt and smelt the stuff on the ground and it is definitely fuel, not coolant or oil and it's clear.

Video2

Engine off.

Video3

This is the closest thread I can find to the same issue after searching for a while

http://www.skylinesa...-of-this-before

I think maybe an injector is stuck open, which is maybe why it stops misfiring while on high revs and boost? That one is really confusing. AFM voltage is in spec on the Power FC controller. I've never seen an issue like this before. I don't get why it smokes white? A little bit unusual as over fueling is usually black smoke? I guess there is that much fuel it's more like vapourising than burning.

Car is an R32 RB25DET stock internals, HKS GT-RS kit, FMIC, Nismo 700cc injectors, Z32 AFM, Brand new Nissan coil packs about 6 months ago, Power FC (possibly a pro version as when I hit limiter it's like a Bee-R)

Hopefully someone has some insight on this.

[DVS JEZ]

Check spark plug condition

[ColdFusion]

Yeah I will be pulling them out on Monday to have a look and see which cylinder is having the problem.

[ColdFusion]

Pulled out the plugs today and they are all black and smell like fuel (I haven't really smelt plugs before so I don't know if that's how they actually smell lol). Third cylinder plug had some fuel on it as well. If I remember rightly the last time I changed the plugs they were indicating normal combustion so I think the problem may be sensor related (CAS or AFM?) as the issue seems like it is across all cylinders not just one. More so on cylinder 3.

[ColdFusion]

Tried a spare z32 AFM that I had and no change so next options are ignitor and CAS. Coils are pretty much brand new nissan items about 5000k's ago so doubt it will be those.

Any other help appreciated.

[dinodore]

Hi there, did you end up finding the problem? I have the same problem with my Vl rb25det.

[dinodore]

Im gonna hijack since i need to know this lol

[wiix]

could be leaky fuel injector o'rings

[Cyifly]

Air flow meter or O2 sensor if you are running one.

Hard to say really

[MuTz]

Im gonna hijack since i need to know this lol

I have an R31 with RB25DET

Please Post back when you find out what your problem was.

Just last night I had the same problem, was over fueling like crazy stopped to get fuel, then would not start, let it sit for 30mins still no start could smell fuel bad, had to pop the fuel Relay out, crank it over then it would start pop the relay back in and keep rev's above 3000 or it would flood it self to death, pull up at lights and making a strange faster Idle, I'm going to try find a manual that has values I can check with a multimeter to test Air flow meter and O2 sensor and from other threads maybe temp sensor.

Started this morning but problem still there normally starts without problem this time can tell its not right killed it tried to start again, no start.

Edited November 3, 2013 by MuTz

[MuTz]

ok must be too much of the gg's cause I would have edited the above:

Still can't find an AFM on this car I bought approx. 3months ago : (Mid life crisis )

Was almost that was the problem ??

? Can a fuel injected car even run without one ?

I guess they can ?

meaning ECU replacement ?

Yep I'm at a bit of a loss here

I'm not F'n idoit maybe I am?

Need to contact the person that built the car cause its not even close to what I read in the rb25det pdf

Anyways I'll be back making more sense.

Unless anyone can tell me What How And Why I have no AFM on my RB25DET

Yea still have not takin the kick panel off yet ........sure I'll not find a standard ECU because there is no AFM I'm sure dammit I traced the Intake all the way its not there!

[Got a Pulsar]

If it's a stock ECU with no AFM then it won't rev over 2500rpm.

Likely some kind of aftermarket ECU running a MAP sensor.

[Aazzy]

They have issues with the coolant temp sensor. (The one to the ecu). When they short out they over fuel the car, some will only play up when hot, some all the time and some only when cold. I've had the rb26 do it and a few rb25's that I've been called out to as well. The wires can short out at the sensor end. or it may just be a faulty sensor. A scan tool should be able to give you an accurate temp reading, if it reads 100 odd degrees and your car is cold then you know you have issues with it.

[MuTz]

Thanks for your fast reply's and sorry about the bit of garble in my post. (Cup Day)

Yea I did read if you unplug a AFM it will not rev over 2500rpm . I'm 99.9% sure there is no AFM looked very closely.

Its over fuel at start and when at operation temp, will look into testing or replacing the coolant temp sensor and go from there.

Thanks again for your input and I'll post back when it's all sorted for future reference for others.

[Cyifly]

ok must be too much of the gg's cause I would have edited the above:

Still can't find an AFM on this car I bought approx. 3months ago : (Mid life crisis )

Was almost that was the problem ??

? Can a fuel injected car even run without one ?

I guess they can ?

meaning ECU replacement ?

Yep I'm at a bit of a loss here

I'm not F'n idoit maybe I am?

Need to contact the person that built the car cause its not even close to what I read in the rb25det pdf

Anyways I'll be back making more sense.

Unless anyone can tell me What How And Why I have no AFM on my RB25DET

Yea still have not takin the kick panel off yet ........sure I'll not find a standard ECU because there is no AFM I'm sure dammit I traced the Intake all the way its not there!

Man If there is no afm you need. Go go check the ecu and see what it is .

Secondly if its over fuelling with an aftermarket ecu you will need to get a tune

[MuTz]

Well I feel quite stupid now, went to local repco to get a CTS they had no idea of the type etc.

Found some pics on the net showing which one it is as there is like 3 thought I'd try clean it up ya never know

took the plug off and what do you know it looks like its a bit corroded, spray some electrical clearer on it ram it on and off a few times and bingo running like a dream again.

From only able to start dead cold and running like crap

to back to normal.

..and it would be nice to know what ECU is in it if I want to get a tune by someone who knows that type in and out etc.

Probably need some plugs now from the over fueling like a mofo for the 70KM home the other nite.

Thanks to all that added some input

[Got a Pulsar]

Sweet. I got a coolant temp sensor from Repco. It wasn't listed for RB25 but from the catalogue pic it was the same shape.

Put it in and it seemed to work fine. If I connect my ECUtalk cable, it says it's around 85 degrees at operating temp so I guess it works.

Hope you bled the air out after mucking round with it.

[Aazzy]

Such a commonly overlooked problem, everyone dives into ecu problems and all sorts of weird issues when a car plays up. I think I've only ever had to replace 2 or 3 ecu's in about 10 years as a mechanic.

[MuTz]

I hope I'm not breaking rules adding again into this topic.

Since found out I have a HalTech Platium Pro ECU

Ever since my Bro took my car to get tyres, dam Patrol blew up and had to take the r31 away instead

I noticed a problem sometimes when it hits Max Boost, bascially backfires and carries on, most of the time but sometimes works almost perfect.

Also noted that the MAC boost control valve is sucking air in through the part not connected to anything, reading its not supose to be connected to anything

and I'm 100% sure it never did that nor should it, also its like a fish tank air as in not clean sucking but vibration sucking, I'm assuming this maybe the cause for the boost

problems and asking if anyone has had a MAC valve starting doing this. Also where is the best place that would stock this part in Sydney's south.

From the ECU map I downloaded from the ECU it is running an open loop boost control setup, not sure if this is bad good etc .

Anyways thanks in advance if anyone knows anything about this problem

[Ben C34]

Sounds like the boost controller is plumbed wrong. The only way it could be sucking if it is connected to the inlet manifold. It should be coming off the turbo or intercooler piping as close tot he turbo as practical.

The gauge gets connected to inlet manifold, the pressure source to mac valve and waste gate as I just described.