Author Topic: Extremely Difficult To Start When Cold! Fine When Warmed Up (Read 3370 times)

s12midlandsuk · « **on:** 03:04:10 PM / 19-Dec-08 »

i have an 88 s12 silvia, i'm in the uk, & i've given the car a full service everything replaced, fluids/belts/plugs/leads etc etc

now the car ran fine pre-service

the problom i have now is when its cold/ loft for a few hrs or overnight its really hard to start, it takes 5 minutes of cranking then it catchs! once running its very rough & lumpy on idle then as the engie warms, maybe 15mins later it runs/starts/drive very well!

i have a hunch its the cold start/choke, where do i start to fix this promlom??????

advice needed by a new silvia owner

at present all i have done is disconnect the temp sensor (yellow 2 pin) & that has'nt helped plz help i need to sort her out as she is my daily driver & i feel the cranking may damage something else

ryan206 · « **Reply #1 on:** 07:31:40 PM / 19-Dec-08 »

Check your fuel system. If it looses pressure over time, and there is a decent leak, it'll take time to start.

200sxkitcar · « **Reply #2 on:** 07:58:30 PM / 19-Dec-08 »

This is not an uncommon problem, check the air regulator to see if its functioning correctly.

http://club-s12.org/v3/index.php?topic=18340

same item in slightly different places based on the engine, but function and diagnosis is the same.

also, check the vacuum line going to the fuel pressure regulator, pull it off and verify there is no gas in the vac line.

Lynium · « **Reply #3 on:** 10:18:46 PM / 19-Dec-08 »

just a thought, but if you were in under there tinkering with all that stuff, check over everything, vac lines, wires, connectors... make sure nothings got broke or cracked...

i had a problem on mine a while back where it ran like crud, and it turned out i had shut the hood and a piece of removed wire loom plastic stuff scrunched down on a vac line connection... it cracked the 20+ yr old dried out n hardened hose, on the underside where i couldnt see it... found it by accident realy, then broke another piece trying to fix it...

anyways, point is, id double check over everything and make sure its all hooked up n nothing partialy loose or something after tinkerin...

and on mine, i know the easiest thing to do is just let it idle, and pull the vac hose of the distrib and stick my toungue to it, (or a vac gauge if you got)

200sxkitcar · « **Reply #4 on:** 01:01:35 AM / 20-Dec-08 »

^vac lines and connections for sure as well.

Wilkie · « **Reply #5 on:** 03:38:42 AM / 20-Dec-08 »

2 words: Block Heater
Another 2 words: Get one.

s12god · « **Reply #6 on:** 04:18:48 AM / 20-Dec-08 »

I work at O'reilly's warehouse and I was looking at these the other day. You can get a few different types. They have a unit that replaces the freeze plug and a magnet type. You'll need a extension cord for both. They look like a good idea. Just tell your friends it's a E.V.

s12midlandsuk · « **Reply #7 on:** 12:47:52 PM / 20-Dec-08 »

took the car for a run today!

its rubbish to cold start still (i was hoping the fix it fairys came in the night & sorted it out lol )

once running its now btter than ever, pulls smooth & will run smooth at 34mph in 5th gear, starts to get jerky @ 30mph so 4th is needed

i was looking over the wiring & vacume hoses/pipes & took them off! blew them through with an attachment on my sompressor & they are in good order no leaks

also tightend the associated pipes around the air filter & turbo + to the afm, afm is working as is the cps asd i disconnected both & the result was

disconnected afm, rough running & rev
disconnected cps, engine stops completely

200sxkitcar · « **Reply #8 on:** 12:49:36 PM / 20-Dec-08 »

Quote from: 200sxkitcar

This is not an uncommon problem, check the air regulator to see if its functioning correctly.

http://club-s12.org/v3/index.php?topic=18340

same item in slightly different places based on the engine, but function and diagnosis is the same.

also, check the vacuum line going to the fuel pressure regulator, pull it off and verify there is no gas in the vac line.

check this

s12midlandsuk · « **Reply #9 on:** 12:55:08 PM / 20-Dec-08 »

bugger! i forgot to do the ecu diagnose thing again!!!!
should help narrow down wher the problom is
i've checked all the othe items visually & took of & on plugs to sensors, i bought some electrical contact grease today to put on the contact surfaces of the connectors

1.prevnt corrosion
2.the first reason is good enough

s12midlandsuk · « **Reply #10 on:** 04:15:17 PM / 09-Jan-09 »

well i'll be doing the ecu self diagnostic on sunday but i took the air regulator off & when its warm or cold the shutter inside has a gap f about 3mm, it move freely! but i need tocheck the resitance on the connector 70ohms i think it should be!

i have ordered a new temp sensor, fitted a silicone vac hose from the fuel pressure regulator to the intake manifold!

its running ok once warm, take me five minutes of cranking to start it!

i've cleam the afm hot wire with carb cleaner which i think has made it run a little smoother,

is it just the air regulator that is effectively the choke mechanism on the ca18et then??? i think this is my trouble?

changed my dizzy cap and rotor arm & the car is running a little smoother, just starting cold is the prob, i think i'm on the right track now! i hope! i have parts & plans & this is the only thing stopping me

if anyone has any other advice or things to check let me know!

s12midlandsuk · « **Reply #11 on:** 04:04:10 PM / 16-Jan-09 »

lads my car is really annoying me & the temps have gone to so working on the car is in short bursts, i still have this starting prob

should the be voltage or resistance on the wires going to the temp sensor???

does the fast idle contol device have anything to do with the cold start?

this weekend i have free & the weatherman says the temps are up to 8 so i'm gonna blast some work on my ca19et s12

i'm pretty pissed as i have gotmyself a bargain prted polished head & intake manifold, just need a good t25 & a my car to start in the cold & i'm a hapy chap

gibve me some advice & pointers, i'm desparate to get her going right

Michael81 · « **Reply #12 on:** 04:28:16 PM / 16-Jan-09 »

i dont know if it would help, but if u got really cheap sparkplugs u should try some more expensive ones..
When i replaced my engine i got it a full service aswell (gotta do that anyway) i "accidently" bought some cheap sparkplugs and it ran like shit! Then i bought some NGK sparkplugs and it runs way better..
Anyway, good luck with the engine sounds great with the parts u got

s12midlandsuk · « **Reply #13 on:** 04:30:25 PM / 16-Jan-09 »

yep i have ngks gapped to 0.9mm propor getting me down

Michael81 · « **Reply #14 on:** 04:34:05 PM / 16-Jan-09 »

Hmm, sounds like a really weird problem!
have u checked the fuel filter? bet its not that, but it wouldnt be of any harm..

ohh, and checked the timing?

bluke1 · « **Reply #15 on:** 07:18:59 PM / 17-Jan-09 »

do you get a strong smell of fuel under the hood while cranking? fuel doesnt vaporize well in the cold making it difficult to start, maybe check the injectors to see if they are spraying properly. its just a thought. run some injector cleaner through it and see if it helps, couldnt hurt.

s12midlandsuk · « **Reply #16 on:** 06:45:26 AM / 02-Feb-09 »

the air regulator??? is this meant to be open when cold & closed when hot/warm????

i've done the ecu self diagnose on the standard ecu & its coming up temp sensor!

i do have a feeling my air regulater is bugered though!

i have a spare iaa setup & air regulator so i've cleaned them up really well! so they are worth swapping

gettin pissed off with my car now not starting in the cold

i'm thinking of taking it to be fixed at a garage

i have also noticed the wiring for the temp sensor is a bit dodgy looking at the ecu end but its -7 here in the uk where i am so working on it is a bit of a non start

plz advise

TalkingGoats · « **Reply #17 on:** 08:46:11 AM / 02-Feb-09 »

Was it cold outside before the tune up? Add a compression check to your list. It could be tired.

mod_mastaz · « **Reply #18 on:** 01:07:28 PM / 02-Feb-09 »

If the ECU says temp sensor, then your coolant temperature sensor is dead. Check the resistance of it for different temp ranges. All the diagnostic info needed is in the FSM. If not just straight up replace it and see what happens. Make sure you don't buy the coolant temp SENDER. The SENSOR is a 2 pronged square plug.

s12midlandsuk · « **Reply #19 on:** 09:25:55 AM / 06-Feb-09 »

right chaps i've checked the temp sensor & i had a broken wire& the coldstartd problom is still there, i've checked the resistances & all seems ok, the air regulaters i have are showing 60.4 ohms & opens & closes off the car at differing temps!

is it an ecu problom, when i can get it to start it does'nt fast idle (cold start) it just sits at 500rpm & wavers up to 750rpm then back down again?

i've checked & double checked everythink i think, i've even ceaned up all my earths, the ecu has some dodgy wiring repairs so thats my next place to check but other than that i dont know what to do

i've also got two good temp sensors, & 2 air regulators, a spare FICD & i've cleaned them up, i have a feeling a wire orsome wire have possibly broken/chafed or the ecu is faulty

does the ecu come up on the self diagnose's if it has a fault????