revs at idle problem

[millepeed]

hi all you surfers out ther. i have a 2nd gen 3.0td and i have a small problem more of a niggle the truck starts fine when cold dose exactly what it should do but when its hotsomtimes the revs are at about 650 at idle and sometime at 900 at idle after a short time at standstill the revs will drop to 650-700 can anyone explane why this is happening otherwise its perfect cheers vince ohh and merry xmas

[stormforce]

At idle the revs should be about 650 to 750rpm.The revs will be higher till the engine warms up a bit then they should drop back to the 650-750

[G1xer]

Dont forget if your aircon is on it will cause the revs to fall too!

[Paul1566]

my 3.0l is a pain it changes its mind daily.....
If i up the idle when hot in the morning, come home time even when its warmed up its gone way to high, so drop it off a bit and next morning its gone back way too low .....
If i wind it to 750 when hot can guarantee next time i fire her up it will run at 1100...
Got fed up and found a happy medium now ticks over about 600.

[Wez ssr-x]

Been having the same problem with my 3.0 since the cold weather started.Some times it will be 500 going up to 900 next minute it will be a steady 750 adjusting it made the problem worse so set it all back.I did check all the vacum hoses and found a couple to have gone hard and spilt,mainly off the valve's at back of rocker cover so chaged them so silicone ones.

[Albannach]

I'm intrigued. How are you adjusting the engine speed?

[millepeed]

I'm intrigued. How are you adjusting the engine speed?

im not adjusting anything, at cold its fine when it warms up and gets hot most of the time its fine revs dropping down to 650ish but sometimes it stays at about 900 rpm at standstill for a duration of 10-30seconds then dies down to 650ish its more of a niggle just have to apply slightly more pressure to brake when at the lights or junction, cheers for all your replys though glad its just not me
cheers

[Albannach]

Sorry Milleped, I wasn't asking you. I had many beers in me when I posted, I should have quoted the 2 guys immediately above my post.

[Paul1566]

I slacken the lock nut and adjust the throttle stop on the butterfly 1/2 turn till revs increase a tad. Probly just sooo much slop in the system that after a cool down and run again it never sits right where it was earlier.

[Albannach]

I always thought the idle speed was set by the ECU? The actual position of the butterfly etc. is irrelevant (as far as idle speed is concerned).

[Paul1566]

Could be why the results fluctuate after cooling/heating etc, ecu sees adjustment and counteracts thus resulting in revs all over the ###### place.
Must do some research and find the answer now.
Bugger............

[Paul1566]

Well found some info but when they started mentioning feeler gauges and TPS adjustment, worn valve thingy and wot not i stopped reading.........
Need to get me toyota manual out and read that rather than stitch together info from various sites....... ho hum

[Oplayneo]

Can i join this club?

I have just picked my surf up from the garage after a service and the idle is low causing a little vibration when idling in park and very annoying vibrations when in drive with my foot on the brake. I spoke to garage to see what they could have done to cause this as it is a bit more than a coincidence that it was fine this morning. They cant think of anything that could of effected the idle other than tightening the belt which you can easily see at the front of the engine just behind the rad fan (sorry dont know tech name). I have checked it with aircon on/off, lights on/off, high rev button on off, if i rev it on the peddle up to 750/800 all is fine and normal, but it is sitting around 650.

Does anyone know if tightening the belt may be causing it?

Is it easy just to set it to idle a little faster?

[IanB2]

Dont forget if your aircon is on it will cause the revs to fall too!

I'm very new to diesels, but on a gas engine, fuel injected car the ecu actually RAISES the idle speed when the AC is on. Are diesels different?

[Paul1566]

oK SO THE ECU CONTROLS IDLE VIA A COMBINATION OF INPUTS FROM VARIOUS SENSORS (damn caps lock key) and determines the optimum flow to achieve 750 rpms, so if any one of the many inputs is not happy the ecu will not set the idle correctly.
If you want to spend time checking sensor input voltages etc to find the worn sensor nock yourselves out guys, i think i will leave them alone and put up with it.
By the way going home last night she sat at 750 every time i stopped till i got on the drive then dropped to 600.....biatch