Weird Idle, Hard To Start When Cold

[DAN-33]

So im new here, and to Skylines in general.

Not sure if this the right section, but here goes.

Quick run down on car,

1993 S2 R33

RB25DET manual

Pod Filter

3" cat back exhaust

rest is stock.

Problem is.

its very hard to start first thing of the day, sorta like a carby car you gotta hold the throttle while cranking. once it kicks in the revs will jump to around 1200 till warm. rest of day its 1 crank start.. weird.

Once warm the idle drops to 900, all seems sweet. Till you touch the throttle slightly, the revs drop and you can actually make the car stall by doing this. press throttle slightly more and it will spring to life, sorta feels like a flat spot from 900-1000?. if you give it a slight rev to say 3-4k and back off the revs will drop to 500ish and then bounce back too 900 and hunt around the 750-950 mark. couple small revs to "clear it out" and she idles fine at 900.

Now before this the idle was hunting around the 500-900 mark, i pulled the ACC assembly out as per the DIY on here. cleaned it all, followed the idle reset guide and waaam, the idle is great at a solid 900. but then it came back

Im at a loss to what to check next? im thinking give the AFM a clean as per the guide on here,

Also curious if coil packs will cause such a issue?

Any help is appreciated, or links, guides, directions ect.

Dan

[Dose Pipe Sutututu]

are you running a catch can by any chance?

yeah give the AFM a clean, or even resolder the pins.. there's a guide somewhere on how to do that

[Hadouken]

Afm

[DAN-33]

Catch can has been bought, ive noticed a little oil in intake and pipes for cooler.

I was thinking when its sitting there idle a little oil gets in, got to hit the gas and the oil has cover plugs slightly? is that possible?

On a weird note, turning the AC on removes this issue though it only bumps idle to 1050ish. enough to pass "flat spot".. its how ive been driving ATM otherwise it feels like it will conk out, or splutter when i go to take off.

will the AFM cause the bad cold start? im assuming not

[BeastVS]

Weird problem, It might sound weird but have you checked the coil's ?

[DAN-33]

can you explain what to "look for" , i had them out when i changed plugs. it had a nasty miss when boost kicked it. new plugs gap'd correctly fixed that.

[blind_elk]

Try getting the injectors cleaned.

[DAN-33]

will do,

notice i put S2 instead of S1. 1993 S1 R33. first of the R33?

[DAN-33]

cleaned the AFM, installed catch can and a FMIC.

runs soooo much better now. still after a big rev idle will drop to 500 and bounce back to 900 and sit there.

cold starts still a hassle, time to clean the cold start valve thingy under manifold???

[Dose Pipe Sutututu]

yeah the AAC, check to see if someone has blocked it.. many mechanics do it when the valve dies to avoid stupid high idles

[DAN-33]

doesn't the ACC control the idle and what not?

i thought the valve under inlet (cold start valve) controls the initial start up and warm up period?

still new, so correct me if im wrong.

[Dose Pipe Sutututu]

AAC auxiliary air control, is the one under the plenum.. used for cold starts etc.. and has that hose connected to the crossover pipe

IAV Idle some valve is the one attached to the side of the plenum, used for idle

[DAN-33]

Still hard to start in morning,

i have to attempt to start it 4-5 times, then a little pedal work to get it to actually start. then it will hover at 500rpm for 2-3 seconds, then cold valve kicks in and bam, 1800rpm for warm up.

Idle is perfect now,

[Griffin]

I had the same problem mate with a 25. Ran a new +12v feed to coils and problem solved. Give it a try.

[DAN-33]

I had the same problem mate with a 25. Ran a new +12v feed to coils and problem solved. Give it a try.

Hey, can you PM some more details on this? might be something i can try.

[Dose Pipe Sutututu]

If your car starts fine in the cold with the pedal pressed a little, it seems like your AAC (under the plenum) is playing up. The IAV only controls idle NOT high idle for cold starts.

[simpletool]

You say stock, but you don't have an aftermarket BOV do you?

Sounds like a couple of problems.

1 - Slight leak in the vacuum lines (remove each line from the plenum during fast idle and if removing one doesn't make a difference then it's probably leaking).

2 - Get some upper engine cleaner (Nulon). Follow the directions on the can. But you don't need to bother with the squirting into the pistons, etc. Just clean the plenum and AAC/IAV.

HINT use a fast idle for both of the above ~1200rpm: Get a folded piece of paper or business card and use it as a slight spacer ~2mm on the throttle body. (Between the throttle stop and the accelerator cable). Gives you a nice fast idle ~1200rpm.

Edited November 23, 2012 by simpletool

[DAN-33]

Yeah stock BOV mate, it makes a noise why replace it? haha

Yeah i may just get some vacuum line and replace what i can anyway.

How do i go about getting the AAC off from under the plenum? not much room to work around.

[Dose Pipe Sutututu]

Yeah stock BOV mate, it makes a noise why replace it? haha

Yeah i may just get some vacuum line and replace what i can anyway.

How do i go about getting the AAC off from under the plenum? not much room to work around.

get a small 1/4" socket set and an uni-joint.. you'll manage, after some beers and loads of swearing

[DAN-33]

Ahhk Cheers Johnny,

Once its out, can it be cleaned? fixed? or is it a chuck out and replace item? Just wanna know before i pull it out.