Rough idle in gear

[Freshjivin]

I've got a VS commodore exec and idles fine when 1st turned on, but once you drive it for a bit and pull up at a set of lights it coughs and splutters, chuck it in neutral and its fine. revs sit around 500ish in drive and about 1k in neutral, is this normal? Car doesn't stall or anything like that but sounds like a dog when you pull up and taking off it surges forward in a rocking motion.

Mechanics changed the spark plugs, im pretty sure they cleaned out the throttle body as well and cleaned out the air filter but still the same probs. Drove it over the weekend and it seemed fine yesterday, jumped in it this morning and had the same probs, mechanics mentioned fuel cleaner? Any ideas guys/gals.

Thanks in advance

[jakewaze]

I have a similar problem in my recently aquired vr. even worse when i run it on gas
i'll be happy to see some suggestions too

[Brett_jjj]

Maybe start by checking for any logged error codes.This only takes a minute and is easy to do, and handy to know about.Heres a link to a thread that explains how to do this test.If you scroll down near the bottom of the posts in the link,theres some excellent pictures that show you how this test is done too.---Checking error codes VR/VS (Revised)---

[Freshjivin]

Thanks heaps mate, will see what codes i can pull from it. Mechanics only idea was to put some fuel cleaner in this morning and said to drive it for this week and drop it in next monday so hopefully for some weird reason that will work. This may not be part of the reason but you never know, my heater was working on Monday when my idling problem seemed to have dissapear and the next day when the idling problem came back i noticed the heater wasnt working again, would this have anything to do with it you reckon? Sorry if it's got nothing to do with it but i work in IT and my car knowledge ranges from 0 to nothing most of the time lol

[Brett_jjj]

Im not to sure about the heater causing the engine to run crook,but seeing as it stopped working and then the car started running crook again,it might need further investigation,Id be checking the heaters fuses,relays and wiring connectors.You never know what you might find.Some people can do some stupid things to wiring when they attempt to install stereo systems etc.Ive seen some bodgy things where the person has had no idea at all,and shouldnt have even attempted it.So with problems like yours its always worthwhile checking it all out and going over the wiring.Try to buy a Gregorys workshop manual if you dont have one already.The wiring diagrams in them are a good quality, and fairly easy to follow and understand.And when attempting to find electrical problems or trace wiring etc, they are a must have.Just dont get workshop manuals like Haynes brand ones .The wiring diagrams are in them are hopeless.You can learn a lot from these manuals and save a heap of money too,well worth it.

[Freshjivin]

Thanks for the extra info, I've got a Gregorys manual so will go through that today when i get a chance, I'll have a look for some lose cables under the bonnet etc, can see it's going to be something minor giving me this grief. Car used to run perfectly too thats why it's killing me, it used to turn over a little slowly and then after a drive if you stopped it and tried to turn it back on it would take a bit or sometimes not turn over and would need to be jump started, then that was when the problem with the idle started so maybe it is electrical :S Lets hope Gregory and I can sort this baby out and get her up to scratch again

[Farax]

i had a similar problem while mine was on gas rough idle cutting out sorta sound, all it ended up being was the vacuum hose was out just push it back in and all good, it was caused by a slight backfire on gas.

[Freshjivin]

I'm not running gas but if you could link a pic of where the VAC line is that would be handy for me to check because alot of ppl seem to be pointing to that.