304 VR issues when cold

[mat-355]

G'day guys,

I've got a stock as a rock 150 odd thousand km VR ss manual.

When the car is warmed up and at temperature there's no dramas. When it is started cold it can be hessitant in the low rpm range. For example instead of rolling away from a near stop in 2nd i'll have to use first gear or it shakes and shudders a bit. The best way i can describe it is by saying it feels like a carby car when cold, but once warm no problems.

It's not throwing any codes on the computer.

any ideas ?

cheers
matt

[Pub247]

Possibly your IAC vaklve on throttle body might need cleanign or replacing. When its cold its not letting enough air to bypass the TB or its blocked and not letting enough air through.

Also on a whim i'd check your timing is right too.

[Darren_L]

check ignition leads
could also be a faulty coolant temp sensor. If you have the gear you can check it's reading. If it's reading too high at low engine temps, it won't necessarily throw a code, but will cause engine issues when cold.

[Mirkz]

I've noticed my 304 VT doing something similar only for the first few seconds though.

When cold the car sounds like it's a hot rod or carby or something, chugs and splutters a bit until it gets revs up to idle then it's fine.
It'll also shake/shudder slightly when starting to move, but usually only a couple times and then it's fine, if I idle for a while it usually doesn't do the shake/shudder.
I've recently done all the plugs, leads and dizzy cap, starter motor, battery and alternator. Have also replaced IAC and TPS with brand new ones.

Once the car's warmed up, I can turn it off, and start it up half hour or an hour etc later and it'll start perfectly normal and fine.

Edit: mine could be coolant temp sensor as mine throws a code (without showing the engine light), showing something about the voltage to it.

[Bilbs]

my vr ute does same thing mate, just feels lie a hesitation as you go to take off, mainly when ya wanna get movin quickly, id be leaning towards checking the coolant temp as well, but mine doesnt do it when on gas, so maybe check fuel filter as well

[mat-355]

Thanks for the ideas guys. It's only a weekend cruiser, not a daily driver so there's no urgency to fix it but i will try all of the above mentioned ideas.

Darren, just wonr=dering why you suggested ignition leads, what changes with these whan they get warm as apposed to being cold? As for the coolant temp sensor, is there a resistance that it should be at cold or are you talking about measuring a voltage at it when cold?

Bilbs- fuel filter was changed 5,000km ago, and i am picky about where i get fuel, but i suppose it only takes one bad batch for things to go wrong and its not too hard to replace it.

[Darren_L]

Mat, when an engine is cold a strong spark is particularly important to aid good combustion. I often used to find (when working on Holdens at a dealer) that ignition lead or coil missfires were particularly worse when the engine was cold. Just do a check with an ohmmeter/multimeter. Usually if a lead is stuffed, it will show up as 'OL' or infinity resistance. Otherwise, shouldn't really get more than 14K ohms for the longest leads, less for the shorter leads.

You can do a resistance check on the coolant temp sensor, I've got the VN factory manual here (should be the same as VR) which from memory specifies coolant temp resistance vs temperature. But the easiest way is if you can get someone with either a tech 1 tool or a laptop with software that can read the coolant sensor temp at the ECM.

But let me know if you need the resistance values. I can have a look for my VN book and check it out for you.

[Warranty Void]

Yeah it could be spark, most likely though is dirty injectors. Run a brand name injector cleaner through you next tank of petrol if you're broke or better, get an injector clean done on the car for about $150, look up injector cleaning system on utube to see what you should get done then phone around and ask which system gets used at garages nearby.
Proper systems have cleaner reservoir connected to fuel injection port, fuel pump fuse pulled, cleaner reservoir pressurised, car runs on cleaner fluid for 20 minutes or so, done! You can see the stuff going in, at least you know they did something, heh.

[50LTRv8]

Yeah it could be spark, most likely though is dirty injectors. Run a brand name injector cleaner through you next tank of petrol if you're broke or better, get an injector clean done on the car for about $150, look up injector cleaning system on utube to see what you should get done then phone around and ask which system gets used at garages nearby.
Proper systems have cleaner reservoir connected to fuel injection port, fuel pump fuse pulled, cleaner reservoir pressurised, car runs on cleaner fluid for 20 minutes or so, done! You can see the stuff going in, at least you know they did something, heh.

My vt has been doing the same, if it was injectors i would have thaught that it would do it when it was warm too. I am yet to change plugs and leads but will do them soon as they are due. Will keep an eye on this thread for ideas, thanks.

[mat-355]

I finally got around to chucking a new set of spark plugs and leads into it and it seems to have fixed the problem.

Thanks for the help.