VP 5Ltr running rough

[heny154]

Hey guys, so i have a VP clubsport that has been sitting around for a while now, i start it weekly and let it idle for a while, ive got it timed perfectly , new leads and plugs only a couple hundred kms ago, it runs perfect
However last week i started it and it runs like a pig, bit of a missfire and it wont sit at idle, its constantly surging between 750 - 1100 RPM.
When i put it in diagnostic mode with the paper clip in the plug it actually begins to run smoother, ive done alot of the standard checks, cleaned sensors etc
Any ideas??

 

[gtrboyy]

Any fault codes come up?

Could be cat convertor,coolant temp sensor,iac needs cleanout...letting them idle for a bit is ok but proper drive around the block to get everything lubricated & heated up is better for car

 

[MikeC]

Fuel good, 12 on the diagnostic and IAC valve OK, then I'd be looking for a manifold leak.

 

[heny154]

Yeah so the only code that it throws up is 12, which means everything is ok ?
But when i start it up , at idle the check engine light will come on, once i take off the light goes off, as soon as i stop again, engine light comes back on
I didnt check the IAC valve i honestly didnt know it was there so ill have a look at that today
The reason im leaning away from poor fuel is the car sounded terrific literally a couple days earlier and now ****.
Thanks for the advice boys ill try some of these ideas

 

[MikeC]

Make sure the IAC valve is retracted enough to clear it's housing when you install it and you will need to go through a few rev cycles to reset it. The procedure's somewhere in this forum.

 

[heny154]

is it better to replace it? or giving it a good clean it just as goood??

 

[gtrboyy]

Check engine light or oil pressure light?

CEL comes on there will be a code for a fault except maybe o2 sensor that is dying code won't come up untill it's completely dead.

Throttle body cleaner or can give seafoam/subie upper cylinder cleaner...make sure it's outside in open lol

It's usually something simple just got to plod away at it one thing at a time.

 

[heny154]

its the check engine light mate, when i put it in diagnostic mode though the only code i get is 12
is there anything to look out for in regards to the IAC valve, ive got it out atm, cleaning, but ive seen something about the length of it? can that have any factor on it??

 

[BlackVXGTS]

The next time you get the problem, don't turn off the engine. Just put it into diagnostic mode and see if any errors come up. BTW, code 12 doesn't mean that everything is OK, it just means that the engine is off. Likewise, if no other errors come up, it doesn't mean that everything is OK, it just means that no errors have been logged. There are many engine/trans problems that don't result in an error being logged.

 

[MikeC]

12 means no fault codes logged, but the whole system is pretty primitive. If you haven't got this here's an explanation of how it works: