Thread: Rough Idle

when you say that the tacho was all over the place was that just at idle or was it working as normal while driving? i have seen tachos on these things fail where they start to charge in a/c instead of d/c and they wont idle. there are a few things that will cause it to idle low/rough like incorrect throttle blade gap, loose or off hoses or control valve - stepper motor, etc even electrical plugs not connected properly. is the engine diagnostic plug connected to its other half? is the purge valve operating at idle? like i said a few things that will upset it

Thanks for the reply.
The tacho is all over the place at idle. The Disco operates normal while driving. Just went out to start the Disco and it was fine!!! Smooth idle. So it seems the rough idle is happening when hot.


control valve - stepper motor, etc even electrical plugs not connected properly. is the engine diagnostic plug connected to its other half? is the purge valve operating at idle?

cant see any disconnected hoses, apart from the plugs, not sure about the other bits you've mentioned.

Cheers,
Jackdad

Buddy this sounds similar to mine, if you have a multi meter you can do a few checks, ill find the pdf for you to follow, try the MAF (Mass Air Flow) meter check first as it is a bit easier to access and change, then try the TPs (Throttle Position sensor)
The Maf is inbetween your airbox and your intake/plenum chamber and should be easy to identify, and the TPS is on the front side of the plenum chamber/intake and is a little circle device with 2 screw either side of it, i havent tested that yet as my wires dont match the colours in the tutorial so need to work out the differences, so give me a sec and ill post the link

http://www.aulro.com/afvb/1092934-post12.html
So try this PDF it should be easy to follow
I forgot to ask if its a v8 or tdi, not that i know how much different they are but someone else maybe able to shed light on one or the other, mine is a v8, 3.9 96 d1, cant offer you much more help but the maf tune was easy and my MAf was set to 2,1 volts when 1.3 is the desired setting. Im going away but will check back on your progress when i return if you have any q's ill try answer before i leave tomorrow

Thanks for your help.
I'll give it a go tomorrow. Also, because it seems only to be running rough at idle after 30 or so minutes, could this have something to do with the auto choke remaining on?

Cheers,
Jackdad

Originally Posted by Jackdad

could this have something to do with the auto choke remaining on?

You don't have a carby on your motor .... So no auto choke

If you have a V8 .... then follow the tutorial
If you have a Diesel .... then the tutorial is no good to you


Mike

Of course there's no choke.....sorry bout that. Just frustrated that it only idles rough occasionally. Drove for hours today....smooth as.....go figure.

Thanks all again and hope 2010 is a beauty.

Jackdad