strange idle/heavy fuel consumption...2.0l 16v "94 rado

[sambo 0]

Hi chaps, i'v got standard 9a valver apart from perf filter and kr cam. It has good power/torque 158bhp, 154lbf tqe, but i'v noticed fuel consumption is heavy, just manage 30mpg on long m-way run, calculated not going by MFA which shows 26mpg on long run. Also idles dodgy sometimes. It starts ok but even if very cold idle settles at 800rpm straight away, is this normal? Than after short journey if i restart car after few min it idles(sometimes) at 1200-1500rpm, why is this? Also when engine warm after long m-way run it idles at 500ish rpm. What could be causing this? Dont fancy booking it into garage if i could do some checks my self first. Could it be lambda probe? Thanks

[TomB 0]

It could be the ISV, as I had a similar problem with my old 2l valver. Disconnect and clean the internals out (I used Halfords brake cleaner on mine although I think I read somewhere that that might be too abrasive). Made a helluva difference.

Good luck,

Tom

[Lippy 0]

i too have had a similar problem on my valver, it was solved (not by me) by adjusting the idle timing screw (??) so that it kicked in when your foot was released from the throttle. Not sure about the economy improvements, but certainly seems to run smoother.

 

Searching will show you that we aren't the only ones with this prob..........

[sambo 0]

already cleaned out the isv, timing screw? :?:

[Lippy 0]

sorry mate cant give you a more technical desc than that :oops:

 

I will try and get some more info from my mechanic friend as I am pretty useless!

 

[CazzaVR 0]

Had a similar prob on my first valver. Check all the hoses leading to the ISV. One of mine was cracked and the idle was very inconsistent.

[sambo 0]

Wierd thing is it never wanders up or down in any one single jouney no matter how long, but if i turn engine off and than restart again after few minutes thats when it happens! Idle than goes up to 1200rpm or more and eventualy it settles to where it should be. i think is electronic related rather than vacum or similar, could it be water temp sensor or ecu it self?

[Sanj 0]

Lamda Probe??

[sambo 0]

thats what i am suspecting to be, but not sure what are the main symptoms. Will a vag-com hook up come with a fault code if it is faulty?