Steve W Posted September 1, 2002 Share Posted September 1, 2002 I know someone mentioned in a thread a while ago about the IAC (Idle AIr Control) / ISC (Idle Speed Control) Valve. [Alex ? ?] I STILL think my idle is a little high AND my cold idle is very high:- ~800 when fully warmed-up, ~1600 1st thing / ~1200 after about 30secs/1min. WOULD the IAC/ISC do this ? Is it worth giving it a 'WD' out ? and, most importantly WHERE IS IT ? ? I've looked on the spec sheets on mkIV.com and YES they show a diagram of the IAC - on an N/A - but not on a TT ! It just says it's basically the same, but, the diagram looks nothing like my intake manifold set-up:- PIC 1 = main throttle + sensor, and, sub-throttle + sensor. PIC 2 = a.n.other sensor/valve ? ? any offers ? ? ps. already tried resetting ECU - seems to work THAT once, then, next start back to too high ? ! ? Fat S. Quote Link to comment Share on other sites More sharing options...
GavinL Posted September 1, 2002 Share Posted September 1, 2002 Hi... I believe that I have a sticky IAC however it does not seem to behave the same way as yours. Reading between the lines I suspect that your problem is consistent whereas my car will vary it's idle as the mood takes it e.g 600, 800 1000 1200 and occasionally 2000 rpm. Blipping the throttle to 4000 rpm settles the idle to 800-1000 rpm. Has the car been checked for error codes? There are no error codes on my car with the sticky IAC a failed sensor would probably show up though. Gav Originally posted by Steve W I know someone mentioned in a thread a while ago about the IAC (Idle AIr Control) / ISC (Idle Speed Control) Valve. [Alex ? ?] I STILL think my idle is a little high AND my cold idle is very high:- ~800 when fully warmed-up, ~1600 1st thing / ~1200 after about 30secs/1min. WOULD the IAC/ISC do this ? Is it worth giving it a 'WD' out ? and, most importantly WHERE IS IT ? ? I've looked on the spec sheets on mkIV.com and YES they show a diagram of the IAC - on an N/A - but not on a TT ! It just says it's basically the same, but, the diagram looks nothing like my intake manifold set-up:- PIC 1 = main throttle + sensor, and, sub-throttle + sensor. PIC 2 = a.n.other sensor/valve ? ? any offers ? ? ps. already tried resetting ECU - seems to work THAT once, then, next start back to too high ? ! ? Fat S. Quote Link to comment Share on other sites More sharing options...
Alex Posted September 1, 2002 Share Posted September 1, 2002 Steve, 'twas me that mentioned it. On your first pic right under the U of sub throttle is the thing I sprayed. If you open the throttle (when the engine is switched off!!) and then realease it you'll see it connects to that little actuator under the U (unless your car is different from mine) You'll also note that the actuator is moveable and has a rubber collar. I sprayed this and inside the rubber collar with WD-40 and my idle has been much more consistant since. It was a shot in the dark when i did it but it worked som I'm happy. BTW, you know that with these engines they hunt the idle point every time you come off the throttle..which means if your engine was cold and idling at 1100 rpm when you set off...when you next stop the car even 20miles down the road it will go to 1100 rpm and then take a minute to work it out after that...so if you stop, for, say, traffic lights then you may not get to stay stationary for long enough to find the warm idle point in which case the engine will try again from whatever rpm level it got down to at the last stop...if you see what I mean. Quote Link to comment Share on other sites More sharing options...
banaman69 Posted September 2, 2002 Share Posted September 2, 2002 i also had idling trouble with my car,but then spayed copiuos amounts of wd40 over both side of throttle and i must admit the idle seems fine now. Quote Link to comment Share on other sites More sharing options...
Steve W Posted September 4, 2002 Author Share Posted September 4, 2002 Gav: NO, no error codes - that would be TOO easy ! ! (ggrrrr) Mr. Banana (is that Euro-Straight, or, UK Bent-Proper ?): AS USUAL, I will probably end up using your technically advanced method of "Spray-it-till-problem-goes", but, was hoping to employ a slightly superior technique of "WOT THE HELL IS IT" first. Alex: Those 4 items are (I think ! ) definitely the throttles and sensors - but I'm not sure wether the little screw/actuator is to adjust the sensor/idle or what ? the screw is 'painted' so it IS adjustable but is 'supposed' to be left ? ! ? I think I'll do the WD40 method on/in/under everything in sight and, when all the solvent has been combusted nicely, maybe the idle will settle. Stiil would like to know where the IAC is (any clues what the 5th thingy is ? It's the right 'shape' for an IAC but would it do it's job that far down the inlet ? ? Fat S. (off to buy a CASE of WD40 ) Quote Link to comment Share on other sites More sharing options...
Terminator Posted September 4, 2002 Share Posted September 4, 2002 If it has paint on it don't touch it, unless the paint already shows signs of movement in the adjuster. Quote Link to comment Share on other sites More sharing options...
Steve W Posted September 6, 2002 Author Share Posted September 6, 2002 quote from Phil If it has paint on it don't touch it, YEAH, MY SENTIMENTS EXACTLY........ .....whenever I'm asked to repaint any walls...woodwork....etc ! ! No, I know what you mean Phil - " If it's painted, it's because you shouldn't adjust it - I will try everything else first, but, I have a suspicion that the screw in question either alters the sensors' reading of the throttle/ or / actually adjusts the amount of throttle 'controlled' ? ? I'll try spraying externally and also take the large intake pipe off and use carb/injector cleaner (SPARINGLY!) on the butterflys' and sensors from inside.... If that doesn't do it....... ? ? Over the past couple of colder mornings the starting idle is up to ~1,800 now ! ! I'm not too happy with that ! I don't like any engine revving away with no oil around it ! ? Something needs doing............. Fat S. Quote Link to comment Share on other sites More sharing options...
Terminator Posted September 8, 2002 Share Posted September 8, 2002 If it is a variable idle speed problem, I would guess it is eletrical rather than mechanical. The painted adjuster would hold a preset level and would require analysis equipment to set up properly. I dont have a solution, but have you tried just unplugging and reconnecting the eletrical connector to the main throttle sensor/sender. Also check all the small hoses around the area to see if they are firmly in place. Quote Link to comment Share on other sites More sharing options...
Steve W Posted September 8, 2002 Author Share Posted September 8, 2002 NO Phil, it's not a variable idle speed, the idle is VERY steady (and, it even follows Alex's 'learning'/settling routine) - I would say it's perfect, if it wasn't for the fact that it just seems to be about 200 rpm too high (when cold, and when warmed !) I wonder if perhaps it's the rev' counter needle that might be wrong (ie. 2/3mm too far clockwise ? ?) I'll get a 'true' rev reading from a meter. Can you use the 'rev'-meters on the 'HT' leads when they're NOT actually HT leads (coils direct on plugs !) does the pick-up work on LT leads ? ? BTW - sprayed the Main throttle and sensor (and the little actuator) with plenty of WD40 today - will see what it's like cold tomorrow. (didn't attempt to remove big inlet hose from manifold - it is stuck onto manifold quite solid - will try that another day - COWARD !) Fat S. Quote Link to comment Share on other sites More sharing options...
Terminator Posted September 8, 2002 Share Posted September 8, 2002 Underneath the main sensor on your pic is a small damper that slows the throttle closee when you let your foot off. Check that this is free to move, if it is sticky it may not return to its minimum position this would give a mm of so of extra throttle at rest, may be the cause. Just open the throttle right up and push the little plunger up and down a dozen or so times that should free it if it is sticking. You can pic up a rpm from the IG pin of the check connector in the engine bay near the dip stick. Quote Link to comment Share on other sites More sharing options...
mazman Posted September 9, 2002 Share Posted September 9, 2002 Steve, the second picture that you have with the Question mark(?) is you IAC...controls your idle. 1.maybe clean the throttle body 2.check your TPS adjustment 3.Air leaks Quote Link to comment Share on other sites More sharing options...
Steve W Posted September 9, 2002 Author Share Posted September 9, 2002 WELL, the spraying (externally) hasn't made any difference today:- 1,700 RPM at start-up... 'starting' to drop after ~20secs... but taking ~1min to even lower to ~1,100 ? ? Am I worrying about nothing, or, are these revs just a little above the 'norm' ? ? PHIL - will 'pull-my-plunger-up-and-down' in the morning before leaving for work ! ! I did spray it outside but, perhaps it needs the Phil-Pull, or, some spray inside ? ? Mr.Maz - Your the 1st person to mention they think THAT is the IAC.....I'm suprised no-one else has confirmed or said otherwise ! ! If it IS I'll whip it off and 'lube' it a bit ! ! {TPS adjustment ? How's that/where's that ? T-hrottle P-osition S-ensor ? } REGARDLESS - cheers for the input Gentlemen [ ps. it's not stopping the driving pleasure - just annoying ] Fat S. Quote Link to comment Share on other sites More sharing options...
cg084 Posted February 5, 2004 Share Posted February 5, 2004 Just wanted on this bulleting. I believe my prob is similar. Only thing is does you problems cause the revs to become lower or even cut out at rest? Cheers Craig. Quote Link to comment Share on other sites More sharing options...
cg084 Posted February 9, 2004 Share Posted February 9, 2004 All, I have tried spraying with WD but nothing so far has worked to clear the problem. Quite the opposite it seemed to just cut out as soon as my foot went on the clutch to change gears. The remainder of the gear change being used to bump start the car again and coninue. It did this about 8-9 times on saturday morning until i limped to the garage. Where the engine was off for about 5 minutes then started and run fine. Until i used the car to go out on saturday afternoon. Was going to try and remove the IACV on sunday to see what that was like but realised i would more than likely need to remove the throttle body to get to the damn awkward bottom screw on the sensor. Checked all air intake pipes up to the throttle body. Checked the oil and water levels all ok apart from the murky brown/reddy rad fluid. May look at flushing the rad but i will have to wait to do that. I have got the car booked in to the local garage on wednesday so will see what they say. The car with a bit of luck will play up when they pick it up so they know what to look for. If anyone else has any ideas. Quote Link to comment Share on other sites More sharing options...
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