absurdly high idle!
03-25-12, 01:29 PM
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absurdly high idle!
So I just purchased a 92 Lexus sc400 this week I did not pay much for it. The only mechanical problem it has is that the idle is anywhere between 2k and 3k when I put it into park or neutral and I can let off the gas when I'm in d and it will (slowly) speed up to 25-30mph on its own and even shift gears even up hill.
Did some searching but have not found anyone with the problem to this extent. I've read that cleaning the IAC can help because maybe its not shutting properly but some people have reported that this has made it worse. Thinking sense the car is accelerating it's self it would be the throttle position sensor. Taking it to the dealership later this week but was wondering what I can do to myself to look at this or if anyone has had similar issue.
EDIT: so far ive taken it three places and they are stumped now the transmission wont go into reverse or neutral and it slips so much in reverse. the idle air was fine. the throttle body had some guck on it but it is still idleing super high not sure if what they have done to the engine has fixed the surging issue because the trans slips so much now. there was one vaccume leak but fixing it diddint change anything
basicly as far as we have gotten is that when you unplug the MAF sensor it idles back down to where it is suposed to be but the idle is SUPER rough and when you rev it it sound pretty bad. does this mean i need to replace the MAF sensor or is this a sign of the ECU being bad or what? like i said three places arent sure what to do next the logical thing is to put a different sensor on there and see if it fixes the problem but i dont want to spend over 100 on a used part that i can't return. what do i do now?
Did some searching but have not found anyone with the problem to this extent. I've read that cleaning the IAC can help because maybe its not shutting properly but some people have reported that this has made it worse. Thinking sense the car is accelerating it's self it would be the throttle position sensor. Taking it to the dealership later this week but was wondering what I can do to myself to look at this or if anyone has had similar issue.
EDIT: so far ive taken it three places and they are stumped now the transmission wont go into reverse or neutral and it slips so much in reverse. the idle air was fine. the throttle body had some guck on it but it is still idleing super high not sure if what they have done to the engine has fixed the surging issue because the trans slips so much now. there was one vaccume leak but fixing it diddint change anything
basicly as far as we have gotten is that when you unplug the MAF sensor it idles back down to where it is suposed to be but the idle is SUPER rough and when you rev it it sound pretty bad. does this mean i need to replace the MAF sensor or is this a sign of the ECU being bad or what? like i said three places arent sure what to do next the logical thing is to put a different sensor on there and see if it fixes the problem but i dont want to spend over 100 on a used part that i can't return. what do i do now?
Last edited by Bassrocker; 05-01-12 at 11:54 PM. Reason: update
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03-26-12, 09:26 PM
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okay so have an off day wendsday going to clean the throttle body and if that does not work play with the throttle skrew. hopefully my daizen steering column bushing will be in by then too and can get that done as well and if i still dont get anywhere have the shop look at it. my hunch is it has to be the throttle body sticking because it did not do this when i first got it but after driving it for a week now its stuck so obviously this car has not been driven in a long time going to change the oil too
03-28-12, 06:38 PM
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so i had a mechanic look at it and said the throttle position sensor was bad .. never saw him test the power on it or anything tho so still not sure on that one. he said that is why the car is taking off in park. as for the idle the mechanic also said the Mass air sensor is bad because when he unplugged it it idled down to 1k but 1k is still a bit high he said after i replaced the throttle sensor it should go all the way down to where it is supposed to be.
so where is the best place to get these parts? ALSO i had ANOTHER mechanic look at it later today and he said that next to the throttle position sensor im missing a vaccume hose and he said that is why it is acting up. totally lost at this point about to take it to the dealership and just have them tell me what i need because aparently evryone is telling me different things. that or take it back to where i got it from and tell them to fix it or i want my money back because it was not doing this when i picked the car up and the mass air sensor is made by "fuji" so its obviously been replaced before already. maybe fuji has a warrenty idk
anyways heres a pic of my throttle position sensor the plug for the vaccum hose that im supposedly missing is smack dab in the middle of the picture to the left of the throttle position sensor. what is that hose called? is this normal?
so where is the best place to get these parts? ALSO i had ANOTHER mechanic look at it later today and he said that next to the throttle position sensor im missing a vaccume hose and he said that is why it is acting up. totally lost at this point about to take it to the dealership and just have them tell me what i need because aparently evryone is telling me different things. that or take it back to where i got it from and tell them to fix it or i want my money back because it was not doing this when i picked the car up and the mass air sensor is made by "fuji" so its obviously been replaced before already. maybe fuji has a warrenty idk
anyways heres a pic of my throttle position sensor the plug for the vaccum hose that im supposedly missing is smack dab in the middle of the picture to the left of the throttle position sensor. what is that hose called? is this normal?