Nifty Posted April 23, 2002 Share Posted April 23, 2002 I am experiencing a problem with my throttle sticking open, that at first I thought might just be a dirty cable. However, I have cleaned the throttle cable, which didn't appear to be malfunctioning off the car anyway, but the problem persists. I have checked out all the linkage up to the throttle body and it appears to be fine. Manually moving the throttle quadrant does not appear to give the same symptoms. When driving along the road the engine doesn't necessarily settle down to idle correctly at junctions, preferring to stick around 1200 -1500 rpm. This is just irritating, however the other is quite frightening - when I give the engine a decent about of boot beyond 4,500rpm and overtake a couple of cars, when I pull in behind the third car the engine is not throttling back and wants to plough into the car in front. Sharp dipping of clutch and braking whilst engine screams is a somewhat unnerving not to mention a little embarrassing!! Engine will die back but very slowly. This does not appear to happen when using 2-3000 rpm pootling mode, just erratic idle speed problem (which I assume is connected). Since buying the car in December I have done nothing to the engine apart from check the oil level until this problem first appeared as a one off a month ago. It is now doing it consistently when I execute the manoeuveres detailed above. Please help a frightened carrot cruncher see through another dark night!! Nifty. Link to comment Share on other sites More sharing options...
F355GTS Posted April 23, 2002 Share Posted April 23, 2002 Nifty I'll take a look at mine tomorrow evening, but sounds like the return spring has become detatched or broken (this may be a coil like spring around the throttle actuater,Quadrant as you described it), either way as a temporary fix you could fit a large spring in the pedal box to ensure the pedal is returning, if the problem still persists it would suggest a cable problem or maybe it's possible that something is fouling the plenum inside the throttle body, It's possible to check this if you remove the air filter and actuate the throttle, you can see the plenum moving inside. Another thing to check is the pedal is free to move on it's spindle and not fouling on something in the pedal box Mark Link to comment Share on other sites More sharing options...
Nifty Posted April 23, 2002 Author Share Posted April 23, 2002 Mark, Thanks for the reply but I have checked the pedal freedom, cable and quadrant return springs - all seem in good order. Nifty. Link to comment Share on other sites More sharing options...
Blatman Posted April 23, 2002 Share Posted April 23, 2002 I'm no K expert, but I'd also check the throttle pot is secure, and that the wires attached to it are in good condition, assuming a plenum equipped K has a throttle pot........ Mark's suggestion of checking the butterfly in the plenum is a good, especially as the plastic plenum can distort if incorrectly tightened/disturbed (I think)............ A frayed cable can be difficult to spot, especially if the frayed part is deep within the outer. The only way to know for sure is to remove the inner completely, which probably isn't possible. Then of course, it could be the outer that is causing the problem......... Link to comment Share on other sites More sharing options...
tony isherwood Posted April 24, 2002 Share Posted April 24, 2002 Could be the potentiomenter on the plenum activatred by the throttle. It can go creakly (like a duff volume control on a radio). try manually openning and closing the throttle by hand several tens of times (engine OFF !) it might clear the corrosion on the slider. Otherwise it might be a new bit ! Link to comment Share on other sites More sharing options...
Allen Payne Posted April 24, 2002 Share Posted April 24, 2002 My 1400 often will idle at 1200-1800 when the car comes to rest and then slowly falls back to normal. As resetting the ECU seems to help I don't think anything sticking so it must just be a function of the ECU or idle control valve. Your problem seem more severe then this. Regards Allen Link to comment Share on other sites More sharing options...
F355GTS Posted April 24, 2002 Share Posted April 24, 2002 Nifty Where in the country are you? I've got a new spare cable you can try to see if it cures it Mark Link to comment Share on other sites More sharing options...
Peter Carmichael Posted April 24, 2002 Share Posted April 24, 2002 Do you have the plastic plenum and throttle body or the aluminium one. The plastic ones deform if you do up the filter too tightly. Link to comment Share on other sites More sharing options...
CHRIS CLARK Posted April 24, 2002 Share Posted April 24, 2002 Good point PC. Also Allen P, the throttle pots are not indestructible and will also give this 'hanging-on-to-the-revs symptom if faulty. Link to comment Share on other sites More sharing options...
Tony Martyr Posted April 24, 2002 Share Posted April 24, 2002 I sounds like the Idle air valve is playing up. The symptoms are classic. I suggest you wait until a time when the engine is warm and the idle is correct then pull the plug out of the IAIV and leave it disconnected. Inside the valve there is a small stepper mptor driving a spindle and they simply stick in random places with any dirt or out of plain cussedness. I simply abandoned mine and got on with reliable motoring Link to comment Share on other sites More sharing options...
Nifty Posted April 24, 2002 Author Share Posted April 24, 2002 Thanks for the advice. Won't have time to look until the weekend. I have not touched the air filter so overtightening couldn't be the problem or it would have done this from the word go. Embarrassed to say I don't know whether the thottle pot is plastic or ali..will know shortly though. Nifty. P.S. Mark - Norfolk - Thanks for the offer but I have a replacement cable and it is no different from the old one. Link to comment Share on other sites More sharing options...
Mark Piper Posted April 24, 2002 Share Posted April 24, 2002 Nifty, also try the following. Switch off and pumup the throttle slowly six times. I've had the same problem ever since I bought my car on a (thankfully) infrequent basis. This resets the IACV thingummaydoody. I spent yonks checking out the route for the cable and so on and this simple act did indeed sort it out...bet it reoccurs, though Link to comment Share on other sites More sharing options...
CHRIS CLARK Posted April 24, 2002 Share Posted April 24, 2002 Nifty. The plenum (air chamber. Aluminium with a Caterham logo cast- black in colour) is the large object on the right side going to the inlet side of the engine. The throttle body itself is the section at the front that has the airfilter attached to it with a jubilee clip and also has connectors going to it. One of these connectors goes to the throttle pot(entiometer) This is also black with normally two screws holding a small aluminium rectangle plate (with no.'s on it). Hope this helps with the recognition! Link to comment Share on other sites More sharing options...
Mick Day Posted April 25, 2002 Share Posted April 25, 2002 Check the throttle pedal bush inside the pedal box. This can seize causing the problems you describe. Mick Link to comment Share on other sites More sharing options...
Nifty Posted April 25, 2002 Author Share Posted April 25, 2002 Cheers Chris, Appreciate your concern with my education. What I actually meant was that I have not looked at the throttle pot closely enough to notice if it is plastic or ali (I've never had the nosecone off in the 4 months I've had it - water level looks fine so no need to remove). I shall make a point of looking at all these things on Saturday (work permitting and get back to you all. Cheers, Nifty. P.S. No problem with pedal, cable seizing. This has already been checked. Link to comment Share on other sites More sharing options...
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