rorii

iTrader: (2)

Hey all,

Seems like my car is heavily missing.

It all started 2 nights ago. I decided to give it a hit and all of sudden, the car just held back, as if traction control came on. After that, i could feel it missing slightly under acceleration. It went away after 20 minutes of limping it back home. Confirmed it wasn't misfiring when i gave it WOT with no issues.

Next morning, drove to work. 1hr trip, started missing badly just 2 minutes away from my work. It was idling badly. If rev comes down to quickly, it will stall. Black smokes everywhere when i tried to accelerate but i couldn't even get past 3k rpm.

When it was time to go home, i started it up, it started rough but i was able to rev a bit more better. Then it would clear up and it was back to normal again. I was able to drive it home with no issues

This morning, i said to myself, if i started up and its having issues, i will start troubleshooting. I was hoping it was a bad batch of fuel and all i needed was to burn the crap bits off. Wishful thinking. 30 minutes into the trip, it started missing again. This time, i couldn't limp it home, won't go past 1k rpm. Had to tow it home.

TL;DR
Car started misfiring intermittently, now its here to stay.

Things i have done:

-Leaving it idling (roughly) i started to disconnect coilpacks one by one. Had no affect to the idle
-Pulled plugs, all 6 were black (this may have been the reason why unplugging the coilpacks didn't do anything)

My next course of action:

-Buying 6 new plugs, and disconnecting the coilpack so i can at least know which cylinder is missing as i have no CEL

Possible issues:

-Coilpacks
-Injectors
-Bad batch of fuel (still have half a tank left)
-Issue with injector harness

Current mods that's related to this issue:

-DW 600CC (recently replaced as i had misfiring issue 10,000km ago and a faulty injector was the cause. The misfiring i had before wasn't as bad as this one though)
-HKS V-pro 3.2 (no idea why its not showing up any codes. Do v-pro's mask OEM cels?)
-Running no MAFs, just IAT and MAP
-Exedy clutch/flywheel (recently replaced <1500km)
-Walbro 255

Im open to any other suggestions or troubleshooting advice

Cheers

Touge Z

iTrader: (3)

weird there is no code.

rorii

iTrader: (2)

Update:

Bought new plugs. Installed them and it was idling fine. Started to unplug a coilpack at a time. All 6 had an effect on the idle.

So i am unable to determine which cylinder the misfire is happening. I haven't had a chance to drive it yet but when i do, i will probably take it easy and won't hit boost until this tank of fuel has depleted

Touge Z

iTrader: (3)

could be an intermittent coilpack issue like my car did. sometimes it would run fine and sometimes it would misfire. I was able to finally get a cylinder specific code though.

Z33Garage

iTrader: (3)

Check the packs for bubbling. That's usually a sign of a bad or going bad pack.

Z33Garage

iTrader: (3)

It seems unless the missfire is 100% of the time constant the ecu won't throw a code. It took 2 weeks of random missfires to get which one was bad. By that time I had taken all the plugs out and measured the gapping, they had all gone from 1.1 to frakking 1.8-2.3!!!! I also found oil from the spark plug holes since the seals were shot

hellman_x

iTrader: (3)

Hate to say it but it might be your injectors again. I also had a bad experience with DW injectors, good luck.

rorii

iTrader: (2)

Took it for a drive, ok for 30 minutes. Then the last turn into my street, I decided to gave it 40% throttle and it started missing again but managed to come back to normal.

I seriously hope it's not the injectors. It's bad enough that you have to buy 6 at a time when you only needed one. But at least i still got 5 used good ones from my last injector ordeal that i can troubleshoot with.

Due to no help with a CEL to locate the cylinder, I will be replacing all coil packs with a new one. Decided on Splitfires. Don't seem to have the luxury of buying cheaper ones in Australia. Either I go with oEM, buy cheap ones from eBay and wait 2-3weeks for delivery, or buy the Splitfires for cheaper than OEM

From there, i will start diving deeper through the manifold and start looking at injectors and harnesses.

Should there be any else i can check? PCV valve? Don't think its a vacuum leak either as it idles fine and i've checked the plumbing.

Will update the thread as I go

Touge Z

iTrader: (3)

when I had intermittent coilpack issue, it was under load too. like I would be cruising and hit an incline, the car would misfire until I was back to cruising.

hellman_x

iTrader: (3)

The unfortunate part about injectors you have to buy all new ones or get all of them cleaned because they need the same flow rate.

djamps

iTrader: (1)

My guess is the FCON and/or it's wiring harness. Check for signs of leaks around the main grommet behind the battery.

9K RACING

How long has the car been running the piggy back?

Can you give us some feedback and info on the background of that so we can check into it.

rorii

iTrader: (2)

Update: replaced all coilpacks with splitfires. Started up fine, gave it a few WOT's and didn't hesitate or sputter. Thought the issue was fixed.

On the way to work this morning, driving it very casually, shifted it up to 2 and heard a big pop from the exhaust and car started to sputter. It sputter for probably 20 seconds before it slowly eased itself back to normal.

So the issue is still there GRRR. Will limp it back home and pray that i don't foul all my plugs by then.

I've had the F-con for a bit over 2 yrs now. Haven't had any issues until early this year with a similar misfiring issue that was solved by replacing a faulty coilpack and injectors (unsure if it was both on the same cylinder, a shop was working on it)

My next step is to pull apart the plenum and look for bad wiring to injectors. With no CEL, its just a matter of replacing parts and hoping for the best. Its turning out to be a very expensive and frustrating exercise

Resmarted

iTrader: (2)

This is pretty similar to my buddies problem on his rb26 s14.5. We changed the plugs, the igniter, fixed a vaccum leak and still crazy random missfire on idle/throughout the revs and runny crazy rich. His car has splitfires too.

Did you change your flywheel or anything else with an important sensor recently?

I really doubt it's your injector wiring. Can you pull up any data logs on the HKS? And what does your afr look like when you have a misfire....? Does the car jump from rich to lean to rich? or?

I do remember on my buddies car we had issues with the PFC just going crazy on the timing at idle (ranged from 17 to 27 deg!). We fixed that by fixing the vacuum leak, but still no cigar.

rorii

iTrader: (2)

Will have to ask my tuner regarding data log. With no wideband installed on the car, I'm afraid the info, if any, will be of use.

I can smell fuel when it sputters and my spark plugs fouls up.

I've got 5 working injectors that I will put in. The 6th one that I won't replace will be assumed the working one. If it misfire again, I will replace the 6th one with the ones I pulled out. If it still misses, then I have ruled out injectors being the issues and start looking elsewhere.

Let me know if that's how I should go about with this.

Cheers

rorii

iTrader: (2)

Yeh i did. But the car did a good 2000km before this happened. The sensor normally associated with flywheel is the crank position which normally affects cranking of the engine. Correct me if I'm wrong please

My car starts up OK

mcarther101

iTrader: (8)

Hopefully the black smoke is just from you running rich, I thought this initially... but it's sort of hard to tell smoke color I guess. I had these exact symptoms, and was misfiring badly, except was able to rev past 3k RPM. What's your oil pressure look like at idle? Does it look unusually low? Are you burning oil more than normal? If my rev's came down quickly I would stall so thought it was perhaps crankshaft pos sensor, went to change it and had oil leaking through the exhaust...

Faulty crankshaft position sensor can cause car to stall in neutral/clutch in too I believe. It's possible the engine could crank over, and run, but subsequently stall. There was a recall for this very reason on some early Z's with bad crankshaft position sensors wiring.

Resmarted

iTrader: (2)

Mc is right, a faulty CAS can cause problems too. It sounds like you did install it correctly (if you didn't the car would NOT turn on lol), but it may have a weak lead or something faulty. Usually these misfiring/stumbling issues are related to a sensor like a CAS or cam angle sensor that's just a bit off.


A trick we used to tell if the rb26 car was having ignition issues vs maf etc issues: force the ecu into limp mode. If the misfire is still persistent then it is ignition/fuel mechanically related. I'm not sure if the limp mode on the vq35 is alpha N tuning or not but if it is, it may help you narrow it down.

rorii

iTrader: (2)

Update: had a chance to work on the car and removed all injectors. Got it flow tested and found one of them had an erratic spray pattern. But flow is pretty consistent on all 6.

Is the spray pattern enough to cause the misfire?

rorii

iTrader: (2)

Apologies for the video quality:

Before the clean:


After the clean: