sambo 0 Posted March 13, 2005 :mad: Stupid idle is driving me mad now! Every time i start my car it idles at different speed. Sometimes 800rpm, other times 500rpm but mostly it goes up to 1800rpm! Just now car was fully warmed up and it idled at 1500rpm, if i pinch a vacum hose to isv, it drops to normal which tells me isv is fully open. Checked voltage to it and it had full 12.5v. Surely it shouldnt be getting voltage this high ones engine is fully warmed up? Does ecu control it or is there a sensor that controls the voltage directly? Please help as the mot is due and its also driving me bonkers! :mad: Quote Share this post Link to post Share on other sites
kongo127 0 Posted March 13, 2005 What car are you talking about? Anyway, i´m quite sure it´s not ECU involved. Maybe it´s only your ISV leaky or even the idle bolt on the back of the throttle body (if it´s like my G60). If the batery voltage drops below 12.5v the ECU will enter in safe mode (fueling up your engine by 25%) just to be sure it won´t run lean. Quote Share this post Link to post Share on other sites
sambo 0 Posted March 13, 2005 Sorry, 2.0l 16v Quote Share this post Link to post Share on other sites
sambo 0 Posted March 13, 2005 are motronics ecu-s "inteligent" like digi on your g60? I thought they are not as clever as that, could be wrong tho? Quote Share this post Link to post Share on other sites
dr_mat 0 Posted March 14, 2005 Sounds like the ECU is confused. Or faulty.. Probably some sensor is telling the ECU to put more air in at idle, so it's opening the ISV further. May be the lambda? Dunno, but worth looking at the lambda wiring. Quote Share this post Link to post Share on other sites
aide 0 Posted March 14, 2005 Do 2 litres have ISV micro switch, this controls signal to ISV on a 1800... it's tiny switch on trottle body, with throttle open try depressing the switch - a slight alter in engine pitch will tell you it's operating (should vibrate too) First of all i'd try cleaning the ISV with carb cleaner or similar tho, dirt plays havoc with them Worth noting revs do alter a bit on valvers to help when they're warming up... Quote Share this post Link to post Share on other sites
sambo 0 Posted March 14, 2005 isv - cleaned micro switch checked,ok lambda is the only other thing beside isv that could be faulty, i think i will try and borrow one of my mate and try it, see how it affects the idle. Any other possibilities? I just run the car for 25 miles with isv disconnected and idle remained at 1000rpm for most of the time but then itwent up to 1500rpm for a while! I am confused now, how can it change with isv disconnected? Quote Share this post Link to post Share on other sites
aide 0 Posted March 14, 2005 your idling of the bypass valve which is why idle is steady... if idle continues to falter with ISV disconnected then it is likely to be a fuelling issue - howsoever caused?!?! Quote Share this post Link to post Share on other sites
sambo 0 Posted March 14, 2005 Fuelling ey? ok than, i think i'l disconnest 5th injector first so i can rule it out but than where do i go from there? It is heavy on fuel 25mpg at most! Quote Share this post Link to post Share on other sites
aide 0 Posted March 14, 2005 by 5th injector do you mean cold start? if so either pull off the blue connector to actual injector, or the brown connector to the thermotime switch on side of block - both should stop it providing fuel. i don't know how the metering head works in a 2 liter am afraid... Quote Share this post Link to post Share on other sites
sambo 0 Posted March 14, 2005 They havnt got a thermotime switch but a proper water temp sensor that varies resistance as it warms up, might disconnect that and all and check how it goes, cheers for all replies lads Quote Share this post Link to post Share on other sites
sambo 0 Posted March 14, 2005 I'v just had another look at all things relevant and as i was fiddling with a microswitch wire, idle went to normal! Yey, i think its a bad connection or a broken wire, result anyway, will post back ones i remove the throttle body for further inspection Quote Share this post Link to post Share on other sites
sambo 0 Posted March 14, 2005 Ok, i'v just removed the throttle body and i'v discovered microswitch is a bit more complex than i thought, it is in fact also a throttle pot sensor. didnt know they used em on ke-jet with motronic ecu. No wonder my idle was all over the place. Gona try fixing the broken wire first and if it doesnt work out will have to buy a new one. Anyone knows how much it costs? Quote Share this post Link to post Share on other sites
aide 0 Posted March 15, 2005 oh right didn't know they had potentiometer jobby, good job ID'ing it tho Quote Share this post Link to post Share on other sites
sambo 0 Posted March 15, 2005 Well today i'v priced up new microswitch assembly, £58 +vat! So i decided to get it open and check what could be wrong. Its a sealed unit so hacksaw came in handy. Got it open and all thats inside is two microswitches! One for fully open th body and one for closed th body. Nothing to go wrong really, tested ok with a multi meter all the way to the plug so i think only thing it could of been wrong with it is the actual connection. Will clean it out, reassemble and try it on the car. Will update. p.s. what a rip off ey? Over £60 for 2 switches! Quote Share this post Link to post Share on other sites
aide 0 Posted March 15, 2005 sorry if this is a little obvious, but you have checked the arm on your throttle is activating the throttle switch when throttle is closed?! Quote Share this post Link to post Share on other sites
sambo 0 Posted March 15, 2005 yes i did and you could hear switch clicking, anyway i'v just put throttle body together and cleaned out connections on the plug and put whole back in the car. Started the car and warmed it up took it for a spin and all its well! :D :D Reset my mfa and it was showing 27mpg after few miles round town, which is much better than i managed on m-way last week! Well happy cheers for all input you all Quote Share this post Link to post Share on other sites
