Veero 1 Posted September 24, 2007 After months of searching for a new TB mine seems to be idling at 1000 now all by itself. Anyway it's does sound like it's misfiring on idle so it chugs and the whole car shakes at the lights and sometimes when engine braking it's burbling and popping so for some reason it's not igniting the fuel all the time in one or more cylinders. Now if you give it beans it's fine and sounds perfect, let it idle, and it starts chugging, sometimes dropping the revs to 950 as the whole car lurches around on the spot. I'm sure it was ok after the rebuild last April and it's only really started to annoy me now. 15,000 miles ago it had new rotor, cap, arm, plugs, HT leads and ignition amp. Worth cleaning up the gearbox earth and getting some new HT leads for it? If not what could be the main causes for this misfire? Veero Share this post Link to post Share on other sites
rapidmi 4 Posted September 24, 2007 (edited) run it 5 mins on idle. then take ur plugs off and see if there all gettin fuel, clean them up with a wire brush check there all sparking, take ur fuel rail and injectors off and give them a good clean up with brake cleaner or something similar and se how it goes from there, used to be a gr8 cure for my old mi Edited September 24, 2007 by rapidmi Share this post Link to post Share on other sites
jackherer 543 Posted September 24, 2007 It sounds like the idle mixture is out. It might be that it was adjusted to compensate for a knackered TB and now your TB is sorted it needs winding back, or it oculd be your TB is now more broken and that is why your mixture is out. Try pressing gently on the secondary butterfly linkage when its chugging, mine smooths right out when you do that and I have temporarily made a shim to press the linkage at idle. If you do tweak the idle mixture screw count the number of turns you give it in case it is actually correct and just due to TB issues. Share this post Link to post Share on other sites
Veero 1 Posted September 24, 2007 Ah ok, Ill give the mixture screw a try first, it does smell like it's overfuelling on idle. Ill check the plugs as well. Cheers Veero Share this post Link to post Share on other sites
gti_al 1 Posted September 25, 2007 Where is the mixture screw on an mi? Is that the one on the afm? Share this post Link to post Share on other sites
jackherer 543 Posted September 25, 2007 Where is the mixture screw on an mi? Is that the one on the afm? yes, thats the one. Share this post Link to post Share on other sites
Veero 1 Posted September 25, 2007 yes, thats the one. Idle mixture screw made no difference. Will check condition of the plugs, leads and rotor tonight, clean them up if necessary and re run it to see what colour the plugs go. There doesn't seem to be any excessive play in the second butterfly linkage. Share this post Link to post Share on other sites
jackherer 543 Posted September 25, 2007 how many turns did you give the mixture screw? it might need a fair few turns before you get to the right spot and see a difference. you should see a difference at some point even if this isnt the cause of the problem you have. it should at least get worse Share this post Link to post Share on other sites
Veero 1 Posted September 25, 2007 how many turns did you give the mixture screw? it might need a fair few turns before you get to the right spot and see a difference. you should see a difference at some point even if this isnt the cause of the problem you have. it should at least get worse Oh right, I didn't want to go mad so only went maybe 3 turns each way and back and couldnt perceive a discernable difference. Ill go mad tonight Share this post Link to post Share on other sites
Miles 331 1 Cars Posted September 25, 2007 The AFM's quite often do this now, as most of them are worn out, You might be able to re-track it like the 8v ones but I;ve never tried Share this post Link to post Share on other sites
taylorspug 7 Posted September 25, 2007 Ive tried to retrack a couple and it didnt really make any difference. The screws for the carbon track are bastard tight and like rounding off. They are certainly not as easy to retrack as an 8v one. Share this post Link to post Share on other sites
Veero 1 Posted September 25, 2007 The AFM should be ok, it was a refurbished unit I got from Rob T on here when I did the conversion, he said it had only done 3k miles since the refurb. I do have another spare one at my folks though, unlikely both would be knackered to the same degree so will try the spare one at the weekend. Veero Share this post Link to post Share on other sites
