Won't Idle Now....

[PhilKenSebben]

Okay, I've been reading for 4 days now, and can't find an answer, so I'm going to have to ask. I don't like to ask because

A) Someone says "do a search moron"

B) This is going to take some typing, and I can't drink while typing, only read. sigh.

Anyway, my R33 series 1 gtst has been getting re-sprayed, and only just got back together, after around 2 months of not moving. The battery was dead, so I removed it and charged it, checking first that this would not affect my PFC tune. All knowledgable parties assured me "No".

When I started it up again, it ran fine at the higher idle speed of around 1200 rpm, but when it tried to drop back to its usual ~850 rpm, it stumbled and died. Ok, I thought, needs a bit of a run. Took it for a blast, pulled up at the lights in the middle of the main road, where it promptly died and would not re-start. Called my mate to come get me out of everyone's way, and figured fueling issue, as it simply would not start again. But after 5-10 mins of checking my first point of call, the fuse box (they were all fine) I tried starting it again and PRESTO! Drove it back to my mates place, keeping the revs above 1500rpm, and it died in his garage as soon as I let the revs drop again.

Simple things first, the fuel in it (given that I very rarely drive it) would be at least 4 months old by now. It was tuned for 98, so maybe the fuel quality was just poor. I filled it with fresh 98 and some fuel system cleaner, just to see if it would make ANY difference. The answer, of course, was NO.

The PFC hand controller showed readings of 250mv from the AFM, raising to around 2200mv with maybe 5000 rpm. I have no idea what these should be, so I hit the AFM with some co-contact cleaner. No change.

I have cleaned my AAC before, but decided it was worth a try. Shiny and clean now. No change.

Took out my spark plugs. Look the way they should, and all correctly gapped. Bought a new set anyway, they were old enough to warrant replacement, and $30 ain't exactly going to break the bank for that piece of mind. No change.

I'm thinking of doing the coilpacks next, and maybe the igniter, this is the box on top of the valley cover, yes? Maybe even the wiring loom. My logic is that these things are now 18 years old, so while it may not fix the problem, it can't hurt to cross another item off the list of things to check and things on my car that are really bloody old, and I ain't living in destitute, so why not. However, the splitfires going for $415 on nengun won't exactly be on my doorstep tomorrow. While I have no qualm in waiting for them, my mate's wife may have a problem with her car staying out in the weather while mine takes up her garage.

The engine has a slight "wobble" to it intermittently when running, around the 1500 rpm onwards mark, that I never noticed before, which is why I'm thinking a cylinder is not firing properly. That to me says electrical problem, but I suppose the injectors could be to blame too. Keep in mind I have had this car for roughly 6 years, and it has NEVER had a problem before I had it painted. I know, I broke a cardinal rule. I fu@#ed with something that wasn't broken, and now Murphy's Law is being imposed upon me.

I took off the FMIC to spray it too, but given that the problem occurs off boost I doubt this has anything to do with it. I've checked all hoses and plugs, but ultimately the ONLY thing that was changed was that the battery was unplugged. Unless the paint is conducting bad joo-joo.

Before you ask, NO, I have a standard plumb-back BOV. Mods are full exhaust, done years ago, FMIC, done years ago, PFC, done 6 months ago with no issues, boost tee running 12 psi, and a fair few braking and suspension mods.

The handling department is at a stage where I'm happy to take the power to the next level, meaning that turbo, injectors, fuel pump and z32 AFM are the next upgrades. Hence, if you believe any of these may sort out the running issues (yeah, I'm sure a bigger turbo will make it all better) then I'm not afraid to replace them anyway, making this exercise slightly less daunting. Otherwise, give me your suggestions so I can at least get this out of my poor mates house.

Sorry for the long post, I'll be surprised if many people read it anyway, which is why I didn't really bother posting sooner. Please feel free to make the first few replies somewhere in the order of:

Cool story bro

Brool story Co.

Do a search

Clean your AAC

Reset your ECU

Then please give me some actual help.

Thanks guys.

[89CAL]

Hmmm sounds like an AAC valve issue but if you've cleaned it and it's plugged in properly then it shouldn't be that. I think it has two plugs, make sure the wiring and plugs are fine (although i see no reason why they would be all of a sudden not fine)

I think one goes to the AAC valve itself and the other to the cold start valve?

However you've said it wouldn't start once cold start cycle wad over, does this mean even if you gave it some throttle while cranking?

If youcan get your hands on a CAS just to try (borrow one?) then that might be worth a try.

Your afm voltages from memory are similar to what I get but as I never really check that I won't confirm they are normal

Replacing the whole loom seems a bit drastic

[PhilKenSebben]

Ha! You forgot "cool story bro" before telling me the AAC was the most likely!

It has the Mitsubishi CAS which I've learnt, from 4 days of reading, is possible to service. I also forgot to add other mods include adjustable exhaust cam gear, but I see it as less like that the CAS would suddenly be wrong.

Then again, I only assume ignition because I've had motorbikes over the years which have had CDIs just not work after sitting for a while while I work on something else. I'm thinking connection/disconnection of the battery has killed something.

I may have to actually join SAU Qld and meet up with some other owners here to borrow some bits. Like I said though, this stuff is all getting old. Brand new is not a bad idea unless you're really strapped for cash.

cheers though, will do some more reading on CAS faults

[PhilKenSebben]

And yes, I've ONLY had trouble starting it once, when in the middle of a 3 lane highway. But that's more to do with Murphy's Law than anything else I suspect. EVERY other time I've tried, it's started no problem. Hot, cold, whatever. It just can't sit below 1000 rpm without sputtering out.

[Moodles2]

Sounds like stale fuel, use something with alcohol (wd40, brake cleaner etc) around the intake manifold and the intake piping (joins etc).. if theres a intake leak the revs will respond. The intake manifold gaskets are paper for example and can crack due to age.

[PhilKenSebben]

I just remembered I also have a new O2 sensor ready to go but need the socket for removing it. Anyone know where to get one? Up in Cairns we only have Autobarn, AutoOne, Repco and Coventry so a part number from any of those stores would be great

[PhilKenSebben]

Sounds like stale fuel, use something with alcohol (wd40, brake cleaner etc) around the intake manifold and the intake piping (joins etc).. if theres a intake leak the revs will respond. The intake manifold gaskets are paper for example and can crack due to age.

Cheers Moodles another easy check I can try tomorrow. I'll also clean the pod filter and all intake hoses thoroughly to eliminate another area. I just figured fresh fuel and system cleaner would show SOME change if the fuel was the issue.

[BH_SLO32]

It sounds like someone has disconnected the fuel pump dropping resistor. My guess is during the respray the guys may have accessed the back left panel(where the jack sits) to remove the aerial. There is a silver rectangular device (dropping resistor) with a single 2pin plug. If it has been disconnected it will give you the dramas you are experiencing. Seems to be a common problem.

Let us know how you go.

Cheers

Ben

[PhilKenSebben]

yes! I wondered what the hell that box was! We removed the aerial completely and filled the hole and I thought that was part of the aerial system.

I don't recall actually unplugging it, unless simply unbolting it has stopped it from grounding or something.

Thanks mate. I'll try that after work. If I get my car back for the weekend I'll owe you one

[PhilKenSebben]

yes! I wondered what the hell that box was! We removed the aerial completely and filled the hole and I thought that was part of the aerial system.

I don't recall actually unplugging it, unless simply unbolting it has stopped it from grounding or something.

Thanks mate. I'll try that after work. If I get my car back for the weekend I'll owe you one

[BH_SLO32]

yes! I wondered what the hell that box was! We removed the aerial completely and filled the hole and I thought that was part of the aerial system.

I don't recall actually unplugging it, unless simply unbolting it has stopped it from grounding or something.

Thanks mate. I'll try that after work. If I get my car back for the weekend I'll owe you one

Yep that will be your problem. The factory fuel pump control uses 2 grouding circuits, one is through the FPCM and the other via the dropping resistor. The FPCM is controlled via the ECU so when it is not activated and the dropping resistor is not connected, the fuel pump simply stops working. Took me a little while to diagnose the same problem on my sisters R33. Such a simple thing can lead to many hrs of head scratching! Let us know how you go.

Cheers

Ben

Edited January 14, 2011 by BH_SLO32

[PhilKenSebben]

Well Ben, you have officially been bumped to the top of my list of people who are legends.

Thanks mate. Problem solved.

[BH_SLO32]

Well Ben, you have officially been bumped to the top of my list of people who are legends.

Thanks mate. Problem solved.

Cheers David, only too happy to have been able to help.