VS not too healthy

[bnsvsute]

Hi there,

I have a '97 vs ute, auto and its stared to develop an ignition or fuel problem lately. What happens is that when the motor is hot it starts to miss fire, bog down and occasionally backfire. a few times it has fully stalled. this happens when cruising at 100 and when im doing 50. what i have done so far is put a new fuel filter on, new spark plugs and leads, a new throttle position sensor (because i got an error code saying that it was undervolting). I have checked the coils for resistance and it all seemed to be as normal, i had a chat to the local holden dealer and he said it could be that when the coils are hot theyre shorting out. The problem seems very intermittent.
Any help would be greatly appriciated,
thanks guys!

[Dum*P*ster]

When car is running at normal operating temp.. Put you're hand over the coilpacks themselvs.. And see how hot they get.. They should just get warm, but not to warm where it would burn you're hand... Overheating pack(s) can cause this issue.. as the Holden person wouldve said..

As for intermittent, it could be in general of the temp outside and how often you are stopped.. (Maybe) ...But I'd personally have someone check you're coil packs

[nathanVY]

When was the fuel filter last changed?

Check your vac hoses, especially,

- back of the plenum to fuel reg
- bottom of the throttlebody to the manifold. (if it's never been changed its almost definitely cracked)

won't cost more than a few bucks and 5-10 minutes to change. while you're looking at vac hoses, check the brake booster vac hose for cracks as well and behind the plenum more towards the drivers side theres 2 vac hoses sitting there they shouldn't be cracked but can sometimes fall off.

good luck

[bnsvsute]

The fuel filter looked as though it was the one that came standard from the factory many years ago. Since its not a normal service item i doubt that it wouldve been changed, a good reason to do your servicing at home!

[hako]

I'd check for error codes again. Also I'd consider replacing the coilpack - testing will not show up a coil that misfires only when hot...the only real test is substitution. There are coilpacks on Ebay right now for about $50 delivered which will be less than what Holden will charge to 'check' the coils.

[PRAVX II S]

First thing you wanna do is get the car playing up again.
Once its playing up check for spark. if there is no spark its the IGN side of things.
If you have good spark check fuel pressure. these test will let you no what is going on.
then go from there. Dont go guessing you dont diagnose cars like that.

[mrv8]

Check the crank angle sensor. when it stalls, does it restart right away? If it doesn't pour some cold water over the front pulley, and if it starts, this is your fault. They tend to play up more so when they are hot.

[bnsvsute]

the thing is it plays up at random, so i cant really check spark and it never lasts long enough to pull over and check for spark. how would i go about checking fuel pressure?
i did a check of the coils getting hot, none of them got hot, just warm. would it be worth me replacing them anyway?

also, when it stalls it generally starts within 2 or 3 tries, so id say it starts pretty much straight away.