Small Starting Up Proplem When Cold

[RamR33]

hey guys,

have a small problem when starting my car up when cold.

Just recently started that when i start the car when cold it feels like its blocking up like revs are real low and runs rough like 200/300 rpm for like 10/15 seconds and then clears up and idles normal.

As soon as car warms up it wont do it again but when it does warm up and idling normal it go back to running idling rough like its blocked or something, it be like for 30 seconds idling rough and then with a bit of revs it goes back to normal again.

Any ideas cause was thinking maybe fuel filter but not sure because mechanic said the fuel filter is new.

[mr031]

might need to clean your AFM

[RamR33]

cleaned my afm but still does it wen cold and starting it up in the mornings.

[Moodles2]

Clean out the AAC valve if you can

[RamR33]

Had cleaned my aac valve a couple of month ago so dont think its got dirty again..maybe my afm has shit itself.

[pipster11]

i too am pondering this problem too

start up when cold (tassie, under ~10°c) - 98% iac valve, rough for 5-10 secs then all good (iac decreased in %, read off an ecutalk display)

start up cold in qld - starts, sits on 1200 rpm and 98% iac for a few secs then off we go

i have taped my coilpacks with self amalgamating tape (rubbaweld) and new o2 sensor

[BOOZTJUNKEY]

Maybe a dodgy c.a.s ? Swap it with a know working one

Could be a fuel pump/pressure issue also check what the pressure is doing on cold starts .

[RamR33]

was thinking the fuelpump or c.a.s has its hesitation and roughness wen cold but wen its warmed up to normal operating temp seems to be almost running perfect besides abit of the idle dropping 100/200 rpm lower then normal but back up after a bit of reving,sounds like fuelpump or pressure...

[SargeRX8]

Ive got the very similar, if not the same problem with my car. Ive got a Series 2 R33 Rb25Det. Fairly modded, with all the bolt ons and this shit started recently.

Only happens on first cold start, car will start and bog to very low rpm then either die or fire up if I give it some throttle. If it switches off, it starts just fine second time. I had a 2nd hand GTR pump in there, so I pulled that out and put a brand new 040. No luck. I cleaned my AAC, no luck. Ive tried resetting my power fc, no luck.

I haven't tried a different AFM. I haven't tried a different CAS. I haven't tried a different water temp sensor, and it is actually very common for the water temp sensor to be causing this problem. It is also common that it could be a vacuum leak, but I have sealed up my whole intake with no change. I also get the drop in RPM when backing off, might drop a couple hundred rpm then rise up, sometimes it might stall. Ive got the stock BOV too.

I would NOT think it is the fuel pump. The fuel pump will be at most strain under full load where it wont be able to provide fuel to the engine, cause leaning and probably knock its arse off. My car runs perfect under boost. If it wasn't for this dodgy cold start, I wouldn't have any issues. Someone suggested leaky injectors but mine are brand new Nismos.

I am really leaning towards the water temp sensor. Google search Skyline or R33 won't start first time and similar search terms. You will get alot of responses with different solutions.

I am going to reset my tune again and start all over. The drop in RPM between gear changes could be too much fueling and not enough air so pulling fuel out can fix that issue.

Are you using the standard ECU?

[RamR33]

no mate i got the greddy emange on it but like u said i got this aswell when the add ons and bolt on mods...im leaning towards the water temp sensor aswell.

what you said on yours is almost same as mine as in cold start if no accelerate it just idles around 200/300rpm and just switches off and might occasionally pick up after 5 seconds to its normal cold start revs.cant really drive it till its warmed up.

Strange when if i just drive it say after 30 secs, its ok to drive but then as the temp goes up a lil say to the first line between the rev range of 2500/3500 rpm just hold back and and can hear the from the exhaust cutting out like brrrrrrrr like trying to clear up but then after a 10 min drive and warmed up no problem wat so ever beside that idle drop a lil and sounds like the cold start again but very rough and then clears up after abit of reving....still thinking afm but could be wrong but cant be more then 3 or 4 things.....

Edited November 16, 2011 by RamR33

[BOOZTJUNKEY]

Try the water temp sensor also that's one I forgot to mention

[RamR33]

Is that with the 2 pins near the radiator hose that comes off to go to the radiator....

or there another one?

[drunkn snail]

ive got a similar problem, car will run rough for about 0-5sec when turned after being left over night, but after that it runs fine with no problems. doesnt really bother me, doesnt seem to bother the car either besides those few seconds

[RamR33]

i have noticed on my water temp sensor when its plugged in i rev the car a lil and it clicks everytime i go over 1200rpm,is that normal?

[DVS JEZ]

Thats the vtc solenoid clicking

[central coast person]

i changed my coolant temp sensor to see if i could stop this but it did nothing.

I work at nissan so i got BRAND NEW genuine fuel pump, TPS, AAC valve , cold start regulator (one under intake manifold), O2 sensor, injectors and have also done a engine rebuild (bottom and top end and a complete genuine engine gasket set with all new genuine breather hoses). nothing fixed it, it was the only problem left.

I have had the same problems on cars that are not skylines and its always pump or injectrs or coolant temp sensor so i gave up on this ages ago when i replaced them, its the only thing wrong with my car now.

[RamR33]

Same with me,only problem left but i just give a lil accelerator in the morning like a tap on it and all good but im getting the hesitating between 3000/4000 rpm until it hits normal operating temp then fine.....dont no if its the same problem as the cold start but seems to be happening alot wen cold and really just giving up now and just letting it fully warm up and all good.....

[bubba]

What plugs are you using?

[RamR33]

NGK Bcpr6es 0.8 I gapped em to 1.1 n that didn't help on that problem but ran better cause I got new coils so dnt see the point of gapping...should I try diff plugs cause alot on here use them. but had read on here saying the bcpr are for rb20?maybe oil is to thick cause I'm running 15/50 cause I'm up 2500km on this oil,,,maybe the oil taking ages to warm up?

[DVS JEZ]

Have u tried more or less enrichment post start?