slow starting in cold weather
 

hi guys i have an 03 saxo and recently it wont start in cold weather i have been through the usual ie battery starter motor and alternator changed them all with brand new and its still doing the same however once it has fired up its then fine until its left for 4 hours or more then back to same thing any ideas what the problem might be its doing my head in :wall:

My guess would be on a fuelling system issue.

I'd put a fuel pressure tester on it when it's cold and see what rail pressure you're getting.

Not sure what Saxo fuel rail pressure should be, but anything over 40psi should atomize fuel correctly at the injector.

If you are seeing low/no fuel pressure during prime, it could be a shitty fuel filter, fuel pump, relay, etc.

There's a bunch of good information in this article

i mean it turns over on key slow it fires up eventually but gives impression battery is flat and its not

May be daft one but if its cranking slow have you double checked wiring to starter motor?

yes mate i have all clean and tight but i just remembered it had an over heating issue that turned out to be a busted thermostat i removed it and did not replace it and its only since then i have had this problem surely it cant be that can it

first suggestion is to change all main power leads and earth leads --could be just old age bad connections seen a few main battery earth leads that look fine but internal connections are corroded enough not to pass big current --so you end up with ecu voltage dropping on cold start --put a volt meter on something like ecu main power and see what it drops to under cold start cranking
could even be a bad starter thats just drawing too much current

i put the battery on charge this morning it read half charge so charged it to full i have been out in the car only done like 10 miles and when i left my daughters it was back to usual slow cranking it fired but only after 4-5 attempts i just hooked up battery again and its back to half charge even though the battery is brand new im thinking it could be not taking a charge im going to have a check done on battery and alternator i think has to be one of them at fault i think :wall:

firstly thank you all for helping much appreciated and secondly the car is now sorted i was shocked to find what it was causing me such headaches but ......... it was down to the missing thermostat i put a new one in and its been fine since starting up like it should and no slow cranking i would never have thought a missing thermostat could do that i know the older cars used to run just fine without one but theses newer engines don't like it and play up lol

thermostat would not cause that.

saxo engine isn't new, the TU is 30 years old.

as welsh says something else if it is std ecu --even for super cold start it would not add so much fuel to wet plugs
but low voltage could cause those problems as ecu would et wrong signals

if non std ecu --then maybe cold start all wrong

well since i have put a new thermostat in it it has fired up just fine and still does no matter how cold or long i leave it without running it

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ok new problem with the car it starts fine but after just 1 mile the temp is over half way the thermostat is working fine its been tested and water system has been bled via garage any idea what could be the problem in thinking head gasket is shot

half way is fine, as long as it does not continue to rise and the fans work.

it does keep rising until it hits red then everything goes to pot heater goes cold even with hot water in the pipes it keeps dragging air into the water system no matter how many times it gets bled i scalded myself on it today

so im thinking head gasket has blown what do you guys think it has to be sucking air in somewhere and i'm thinking gasket has blown between 2 water ports could it be something else though ??

rad cap --if you open cap when it is up to temp do get a realease of pressure ?
if not cap is not holding pressure --so it will boil water in head and cause the problems + you will never stop it making air in head
atmospheric pressure water boils at 100c --with good rad cap which holds pressure it will be over 130c
new cap is £8? or less

thanks axsaxoman i will get one but will that keep allowing air into the water system aswell ?

to bleed system --get a 2litre coke bottle --cut bottom off--stuff the neck it into top of rad with a rag --then fill half way up - open bleed points till you see water--then run car with bottle still in till its water starts getting some temp in it --stop car -open bleed valves again --do not bleed with engine running--- run for a little longer --then remove bottle and fit cap --should be no air in engine now -- you cannot run it till full hot as it will just boil in head and blow water back up into bottle if no rad cap on

then run till fan comes on -if thermostat+ fan is working that should be about 10mins and fan should go on +off
If it is a h/gasket problem one of 2 things will happen --pressure will keep building up and temp will be getting hotter + fan on all the time + cap will blow off
OR water will leak into engine and little or no pressure will build up in system --squeeze hoses to feel if it is building up pressure as it warms up --eventually water may boil in head and water level will be low
check it WHEN it has cooled down --DO NOT open cap when its hot cos it will instantly boil and throw all the water out .
If your heater is blowing cold its full of air or its blocked with crap --