I\'m having a few issues with the idle on my TII. Its a bit erratic up and down by a few hundred rpm. It doesn\'t do it all the time but it has started to do it since rs4. It also has developed a habbit of cutting out when I pull up to junctions. Same thing not all the time. Any ideas?
Mine has been doing this of late - does the problem go away once the car is fully warmed up? IIRC the issue is with the cold start assist/idle up... I think (not sure) its the thermo unit ont he side of the inlet manifold that needs changing, but I\'m not 100% on that. :wave
No it seems ok on a cold start when its on choke. Im gonna have a look at the idle control valve and give it a clean out. I have just fitted a boost gauge and this seems to have angered the problem. I\'ll disconnect it for my drive home from work and see if it is still doing it. I don\'t think its that what is causeing the problem though. Unless I messed up and plumed it in wrong.
AH - could be an air leak then! :yes
Disconnecting the boost gauge did not help. Its not cutting out anymore just idleing all over the place. I\'ll see what happens when I clean the idle control valve thingy.
Might sound simple but you sure your sparkies aren\'t in need of a change as when they clog up car can be slightly erratic ??
Apologies if already checked :Laugh
No I\'ve been lazy and haven\'t had them out yet. It\'s on my list of things to do though. They were changed in January so they arn\'t that old.
Ok. I took the BAC valve off today gave it a good clean out. I didn\'t move the idle screw though. When I put it back on the car it made the car idle at 1500rpm. Thinking it was just cause it was now clean I adjusted the idle screw only to find that it was all the way in. That doesn\'t seem right to me. Anyway I checked the solenoid was working correctly which it was and then gave up and drove home. half way home the idle speed sorted itself to 750rpm and everything seems good now. does anyone have any ideas why it would behave like this?
Quote from: adereedOk. I took the BAC valve off today gave it a good clean out. I didn\'t move the idle screw though. When I put it back on the car it made the car idle at 1500rpm. Thinking it was just cause it was now clean I adjusted the idle screw only to find that it was all the way in. That doesn\'t seem right to me. Anyway I checked the solenoid was working correctly which it was and then gave up and drove home. half way home the idle speed sorted itself to 750rpm and everything seems good now. does anyone have any ideas why it would behave like this?
That sounds like the normal wax thermo thingy doing it\'s job - it holds the revs up until the engine is warm, then they drop to the adjusted idle speed. The BAC valve only compensates for engine load from PS and lights and air con.
Thats just it, The engine was warm before I set off home cause iI had it running on and off for an hour or so. Whats this waxy thing anyway?
I took the Lambda sencer out last night to give it a clean just incase it was giving funny reading when I noticed that the wire is damaged. Could this be giving the car funny readings, ie\' the car is cold when really it isnt. Im just thinking that it may be thinking it is cold and is staying on choke. What do you think?
All the O2 sensor does is give feed back regarding the mixture - the ECU is setting the mixture dependant on this and other factors - so if its stuck in cold start then its the thermo unit thats proabbly the culprit.
its better to fix it to be honest
the car might thing its running lean/rich all the time and over compensatings
its one thing to remove from the equation if it doesnt fix it
Not sure if you\'ve seen this, but I\'ve been through this document and found answers before ....
http://www.teamfc3s.org/info/articles/idle.html (http://www.teamfc3s.org/info/articles/idle.html)
Worth a read ! :Thumbs-up
Thanks for that. Good thread. Looks like im gonna have to start at the begining though. Doh.
still having problems. It seems to be fine now unless I put the lights or wipers on. At this point the rev\'s jump up between 1200 and 2000 rpm. Is this the BAC as stated before?
QuoteThe BAC valve only compensates for engine load from PS and lights and air con.
If so what can I do to fix it if anything?
Yep it defo got something to do with the electrics. Everytime I touched the boost controller or the heater it made the idle go lumpy or raise to 2000rpm. Could it be down to a bad earth or something like that? It was really annoying not being able to play with it at the track.
You could try the resistance/continuity tests in the factory service manual to determine if the BAC valve is any good, swapping it for a spare one might be a bit quicker if you have one.
Also check the earth points (sorry the diagram with them on is on the other comp.), should still be able to find them in the FSM though.
I\'m going to be resetting and testing all my idle control devices tomorrow :P I\'ll let you know if theres anything else it could be from my findings
Ok. I swapped the BAC for a spare one I had. I set the idle and all seemed good. When I operated the electrics in the car the revs dropped slightly. I thought I should take it for a spin so got in the car shut the door and the revs jumped up to 1300 ish. Im wondering now if I have a dodgy conection on the wires that hook up to the BAC and that it keeps acting like its disconected. Im right in thinking the revs should rise when the conector is disconected arn\'t I? Or is there another way to set the idle other than the screw on the BAC?