Warm Start Problem

[Tangents]

Ok so recently the car has started to develop a problem. If I drive it park it and do something for 5 - 20 mins then come back and try and start it it either wont start or needs to be cranked for a bit with a bit of peddle to get it to turn over. but if you leave it for 20 mins plus it will crank over first hit every time. Cold starting the car is fine first hit every time every morning or after extended periods of time being parked.

changed the battery about 2 - 3 months ago to a smaller drycell that i had which is going to be the first thing i test when i find a multi meter. could it be a starter or alternator issue tho?

Edited March 12, 2010 by Tangents

[Rusty_185]

i have a very similar problem mate.. i have an R32 gtst and its just had an engine rebuild.

it starts fine when its cold and when its hot, but leave it for 20mins and its a cop to get going again.. gotta crank it a few times and give it some gas before it will limp to life.. but after that it runs normal again..

i run a nistune computer so i reverted back to the stock tune to see if that would fix it but it made no difference so i can only assume its a mechanical fault.. but it just has me stumped as to why it would only occur when warm??

anyone who have any ideas on this? would be much appriciated!

[Stinky Rooster]

aACV - Aux air control valve would be my guess. Try giving it a clean and see what happens.

http://www.skylinesaustralia.com/forums/Di...nd-t110431.html

and while you are at it you might as well give the IACV a clean as well. Its the one above it (as mentioned in the above tutorial)

[Tangents]

Ok so I have cleaned the AACV/IACV unit, has made idling a bit better but still having the warm start up problems. Checked the battery with a multimeter and get 12.something DC.

There is no leaks etc I have checked everything twice, even though I wouldnt think a leak would effect a cars ability to start whilst warm? When it starts cold first time every time.

I have tried the error code thing but the write up was for an m35 (wasnt sure if it would work on my c34) and nothing happened. Does anyone have a consult cable they can throw on my car to retrieve my fault codes (if any)?

Or does anyone have any other idea as to what it might be? AFM? Alternator? Starter?

HELP

[mike40sydney]

Ok so I have cleaned the AACV/IACV unit, has made idling a bit better but still having the warm start up problems. Checked the battery with a multimeter and get 12.something DC.

There is no leaks etc I have checked everything twice, even though I wouldnt think a leak would effect a cars ability to start whilst warm? When it starts cold first time every time.

I have tried the error code thing but the write up was for an m35 (wasnt sure if it would work on my c34) and nothing happened. Does anyone have a consult cable they can throw on my car to retrieve my fault codes (if any)?

Or does anyone have any other idea as to what it might be? AFM? Alternator? Starter?

HELP

ive got the consult cable etc here ive never tried it yet .if ya wanna come over tom arvo id be happy to help out.im flat out today im afraid bud .

[Tangents]

Cheers mate that would be awesome! I'm at work today anyways, I have ordered a consult cable but if we could atleast clear them (if any) until I get mine to try and figure this out.

[chef_stagea]

fuel delivery maybe? have u tryed starting it cold... run for like min or so... then let it sit then go again? or does it actualy have to get to full temp then sit for the prob?

[Tangents]

If I drive it for say 10 - 15 min or so, then it is guaranteed to not start unless it is let cool down

[chef_stagea]

so it HAS to come up to temp for it to happen... not start then off and go again... was your aac valve cloged up bad? changed plugs recently?

[Tangents]

The aacv seemed fairly clean to me, some mild carbon build up. Same plugs from when I bought the car. It has just ticked over 70k kms, might change them and give the coil packs a clean anyway.

Chef, it has to come upto temp and then it won't start again for minimum 15 mins.

[pipster11]

run it up to temp then remove the ecu (2 wire) coolant temp sensor plug

give it a go then and if it starts (pretty sure it goes to cold maps with it d/c) then you problem lies with that

if those sensors fail, they fail at operating temp but normally work cold

could also be the cas as its heat related

[Tangents]

I will give that a go... with the cas you can just poor water on it when after the car gets to operating temp to cool it down right?

[QWK32]

it does sound like a lack of fuel, when was the last time you changed the fuel filter? it could be blocked up and restricting fuel flow. if you unplug the coolant temp sensor the ecu just uses a 40 degC temp. at that temp there is about a 3% increase in cold start correction. so you may not notice a difference.

try it, if it helps then you know its a lack of fuel either from a fuel supply issue, or an air leak adding more air. the lower temp enrichment could be helping by adding in more fuel. how does the engine run/idle once up to operating temp?

also do not poor water on the CAS.

[NewKleer]

check AAC value with consult when the car is warmed up and idling. should be <25

[pipster11]

check AAC value with consult when the car is warmed up and idling. should be <25

25? with the ecutalk display mine sits at 50-80 :S

i'll check all my idle gear again but i cleaned it a few months ago

[NewKleer]

yeah <25. turn your idle screw down, the AAC at the moment is helping keep idle at idle speed, means it has less 'room to move' to catch falling revs or to less room to open to start car when warm etc.

its fairly easy to do, just have car fully warm, then watch AAC as you turn idle screw...once it gets down around 20's, at some point any further changes in idle screw wont have any more impact - so you just stop then.

mine was up at 50 and i would stall on warm start (unless open throttle, i think it was, a while ago now). adjust idle screw and all good.

of course it could be gunk building it, but cant be bothered cleaning

[DaveB]

Thanks for that excellent info' Peter

[wolverine]

yeah <25. turn your idle screw down, the AAC at the moment is helping keep idle at idle speed, means it has less 'room to move' to catch falling revs or to less room to open to start car when warm etc.

its fairly easy to do, just have car fully warm, then watch AAC as you turn idle screw...once it gets down around 20's, at some point any further changes in idle screw wont have any more impact - so you just stop then.

mine was up at 50 and i would stall on warm start (unless open throttle, i think it was, a while ago now). adjust idle screw and all good.

of course it could be gunk building it, but cant be bothered cleaning

Although I have a PowerFC in the stagea this advice has just sorted out a small but longstanding issue with warm start. It always takes a little longer cranking than the instant start when cold.

The idle screw has been butchered but I managed to get some WD40 in there and then left it overnight. I used a long handled flat spanner and managed to get some bite on the idle screw and managed to get it to shift. I disconnected the 2 pin plug to the idle stepper (located at the back of the cam covers) and then started the car (prior to adjustment it was idling roughly around 550rpm when the plug was disconnected) and adjusted the idle to around 800rpm.

Once the plug is reconnected the idle settles nicely (and quickly) to around the 800rpm (per PFC idle setting).

The warm start seems spot on already and there was a subtle tendency to hunt for idle previously which will no doubt be gone.

Thanks NewKleer your post motivated me to check.