lumpy idle + misfire = connected???

[stevef182 0]

so having replaced the ISV and had the engine settings re done (emissions etc) my car STILL wont idle properly..its fine when cold but after a 40 min + journey the idle is all over the place! worstf all when stuck in traffic with lots of stop start...its idles up to 1700 rpm then drops to 200 rpm then back up and down until after about 20 mins of doing this it seems as if it just gives up and idles at about 500-700rpm but this is a very uncomfortable idle as it makes the whole car rattle like hell..which brings me on to my next point..even when it idles properly there is a slight misfire, but only on idle..is it likely that the two are interconnected and what should i be looking to replace/clean/do to fix it..im at my wits end!!! any help MASSIVLEY appreciated!

[stevef182 0]

oh and i forgot to mention that the dodgy idle seems to get worse when anything electrical is used, for example even just indicating or switching headlights to full beam or opening/closing the windows seems to cause the idle to play up..im so confused!

[easypops 8]

my dodgy idle was sorted when i found a broken wire on the plug for the throttle potentiometer.....it was broken inside the plastic coating.....i tried lots of things and found this by accident......that was months and months ago and idle steady since

worth checking around there

[CazzaVR 0]

Steve, also check all the air hoses/pipework for splits/holes. Had an identical prob on my first 16v, which turned out to be a small split in one of the ISV hoses.

[stevef182 0]

Steve, also check all the air hoses/pipework for splits/holes. Had an identical prob on my first 16v, which turned out to be a small split in one of the ISV hoses.

 

yeah i was told it might be an air leak..but surely an air leak would cause it to be dodgy the whole time..this is quite intermitent and only when warm?? and would using indicators and windows etc cause a dodgy idle if were an air leak?

have had a quick look but will investigate further

[stevef182 0]

my dodgy idle was sorted when i found a broken wire on the plug for the throttle potentiometer.....it was broken inside the plastic coating.....i tried lots of things and found this by accident......that was months and months ago and idle steady since

worth checking around there

 

again worth a shot..but i dont know where/what i should be looking for/at?

[easypops 8]

my dodgy idle was sorted when i found a broken wire on the plug for the throttle potentiometer.....it was broken inside the plastic coating.....i tried lots of things and found this by accident......that was months and months ago and idle steady since

worth checking around there

 

again worth a shot..but i dont know where/what i should be looking for/at?

 

not sure exactly about the 1.8 but the throttle potentiometer (throttle position switch) will be on the throttle body.....it is on the 2.0

good luck

[CazzaVR 0]

Steve, my air leak only caused the idle to fluctuate when warm too. Dunno why though!

[mattkh 0]

Hi

Apparently there is an idle control ecu in the passsenger footwell

[Toad 0]

Hi

Apparently there is an idle control ecu in the passsenger footwell

 

That's the abs.

 

The idle is controlled by the ecu, isv and the idle speed screw on valvers.

[Chris VR6nos 0]

funny reading, sounded like the blind leading the blind lol :lol:

I have a similar problem on my VR, not taken a look at it yet but i know there's a jubilee clip missing on one of the pipes around the ISV so i'll start there, other than that and i'll have to go a hunting and it's a process of elimination but the ABS isn't working either so there's a few things to contend with.

 

 

 

Chris

[BigD 0]

i had the same on my vr, was realy crap idle after warming up cutting out every so often so i checked my plugs at the weekend an the were all black as hell, looked like they were the same from new :lol: ive put some new ones in and its fine now.

 

so id give them a check aswell.

[Yandards 0]

my dodgy idle was sorted when i found a broken wire on the plug for the throttle potentiometer.....it was broken inside the plastic coating.....i tried lots of things and found this by accident......that was months and months ago and idle steady since

worth checking around there

 

again worth a shot..but i dont know where/what i should be looking for/at?

 

You wont have one ;)

 

What you will have is an idle microswitch and a WOT microswitch on the TB, make sure the idle microswtich is contacting when the throttle is closed by pulling the throttle cable by hand and listening for it clicking.

 

I suspect the reason that you only get the problem when warm and only at idle is that it is at idle that the engine is at its near stall point. When the engine has heated up the hoses etc will expand slightly making the leak.

[stevef182 0]

What you will have is an idle microswitch and a WOT microswitch on the TB, make sure the idle microswtich is contacting when the throttle is closed by pulling the throttle cable by hand and listening for it clicking.

 

I suspect the reason that you only get the problem when warm and only at idle is that it is at idle that the engine is at its near stall point. When the engine has heated up the hoses etc will expand slightly making the leak.

 

wise words..havent has time to look properly yet for the air leak but i will do soon..as for the microswitch i checked that a while back and it makes contact most of the time but not ALL the time so im thinking i should try a new throttle cable too as mine is not in great shape!

[stevef182 0]

have had a look for an air leak but not having much luck! my water temperature gauge is broken and have also noticed my oil temp on the MFA reads 56 degrees the whole time, so im guessing i have a few broken sensors, guessing maybe this may be contributing to the problem as i guess the ecu doesnt know if the engine is hot or cold or is technology not quite as advanced on the early valvers?