Anyone with A 3rd Gen Manual have idle probs?
Mine is very slow to come down to idle & sometimes sits around 1800 to 2100 revs before a sudden drop to 800 revs.
It also idles around 1000 to 1200 revs sometimes.
It makes it a pain in the bum when changing gears as the revs don't come back down & even go up at times.
Mitsi told me they have no idea except Idle Speed Control Unit which is now done with no change at all, they also suggested a new computer at $3000:shock: :cry: .
Any ideas please.

Anyone with A 3rd Gen Manual have idle probs?
Mine is very slow to come down to idle & sometimes sits around 1800 to 2100 revs before a sudden drop to 800 revs.
It also idles around 1000 to 1200 revs sometimes.
It makes it a pain in the bum when changing gears as the revs don't come back down & even go up at times.
Mitsi told me they have no idea except Idle Speed Control Unit which is now done with no change at all, they also suggested a new computer at $3000:shock: :cry: .
Any ideas please.
3G for a new standard computer? they couldn't of been serious. A quality stand alone is around half that price

Thats what they say!
They also said $322 for the ISCU but I sourced a new one for $125.
I will do a better price for the computer if needed but im not convinced yet that it does.
Im looking for other ideas so threw it out here to see other peoples experiences.

Okai, lets look at this problem in a proper problem solving way.

What is the problem, the car is reving higher then what it should.
Now what causes a car to rev? extra air and fuel. What else could cause this? a lean mixture?

So now we have two cases that your car could be having.

How can your car get extra air and fuel then what its suppose to? Maybe your TB isnt closing properly, so your foot is off the pedal but the TB is open a bit letting in air and fuel causing the rise in revs.

What about a lean mixture? could your injectors be dirty so there not injecting right amount of fuel?
Could you have a leak in a gasket somewhere like between the runners and the TB? causing air to be sucked in that the sensors dont know about causing it to run lean?

Get it on a diagnostic computer and see if its running lean and take it from there.

All done at Mitsi twice with no outcome.
I asked all the same questions as i have worked on many cars over the years & trucks, they have no answers for it except the computer & im not replacing that in a hurray.
Im looking for a shortcut here but failing that I will have to go through all the elimination myself.

How do they know its the computer? because they have tried other things and cant come up with a good answer isnt an excuse for changing the computer.
What extension should the IAC be at when your car is idling? (according to a workshop manual)
What extension is YOUR one at? if its at a different extension then why is it recieving a dodgy signal? Is it a dodgy signal caused by your computer or is your computer recieving dodgy info from other sensors like maybe your TPS?

There should be a fairy straight forward answer why your car is idling high, eg too much air getting in or its running lean. Once your find out this answer the hard bit is finding out why this is happening.
If the mechanic cant figure out the first answer, then dont expect them to figure out your problem expect by changing things and getting lucky, dont see that mechanic anymore, simple.

Maybe your coolant temp sensor is dodgy so your car thinks its running cold so it raises the idle? Best thing to do is get a manual for your car so you can test all your sensors and go from there.

"Maybe your coolant temp sensor is dodgy so your car thinks its running cold so it raises the idle? Best thing to do is get a manual for your car so you can test all your sensors and go from there."

If you've got over 100Ks on her that's very likely. Also - if the Throttle Body has ever been removed, check that there's a gasket protruding on the top face, at the front side. As per Pic. This gasket can be installed in the wrong place and it causes idle problems and peculiarities - I know because I made this mistake once. If the diagram is a bit hard to decipher, let me know and I'll get a PIC happening.

"Maybe your coolant temp sensor is dodgy so your car thinks its running cold so it raises the idle? Best thing to do is get a manual for your car so you can test all your sensors and go from there."

If you've got over 100Ks on her that's very likely. Also - if the Throttle Body has ever been removed, check that there's a gasket protruding on the top face, at the front side. As per Pic. This gasket can be installed in the wrong place and it causes idle problems and peculiarities - I know because I made this mistake once. If the diagram is a bit hard to decipher, let me know and I'll get a PIC happening.I will check this gasket 2moro in the daylight Larry.
It is not always bad sometimes it is good for a while, I am pretty good with mechanicals but not much chop with electricals so see how we go.

If you do think you need to get the ECU or other stuff checked out I recall that these guys can test it thoroughly and also have a remanufacture/repair service.They used to credit the test fee against any repair work.
Good luck.
http://www.petroject.com.au/index.html

can you explain the original problem a bit more?

When it occurs, do the revs drop and rise constantly?
does it happen fast or slow?

Or does it just idle at a higher rev then normal when the problem happens?

Clean out the PVC valve on the drivers side tappet cover on the front bank. You'd be amazed the number of problems that this fixes.

I'd also try and eliminate the ISC system as source of excess air.

It can be closed off by removing the ISC motor from TB, dismantle it and wind rotor to fully extend (close) the valve. Reassemble, put back on TB but leave it disconnected. It's now out of the idle equation.

ECU has no knowledge of where the ISC motor is at, no feedback other than other engine parameters. It gets set to initial position in period between ign off and fuel relay shut off.
ECU assumes that it follows every command sent to it....unfortunately not the case as things fail :cry:

See what the idle is like now, base idle air screw might need a tweak if it's too low.
There is also the fast idle air valve on the TB, a wax thermo thing. Never heard of faults with those though.

I've had the misfortune to have trodden this path already :shock:

can you explain the original problem a bit more?

When it occurs, do the revs drop and rise constantly?
does it happen fast or slow?

Or does it just idle at a higher rev then normal when the problem happens?It will want to sit around 1800 to 2100 revs when you pull up to idle or push the clutch in to change gear & if you do stop it will stay up for 1or2 seconds then slowly come down sometimes to idle & other times to 1000 to 1200 revs sit there then come back to 700 to 800 revs.
That is pretty much it but at times It is perfect comes nicelly down to 750 revs.
It's been that way for a few months & im just getting sick of it so put it at the top of my do list.
Lander Mitsi say everything is within tolerances when tested 2 times but I don't trust them to much, by the way It's done 118,000kms.

It will want to sit around 1800 to 2100 revs when you pull up to idle or push the clutch in to change gear & if you do stop it will stay up for 1or2 seconds then slowly come down sometimes to idle & other times to 1000 to 1200 revs sit there then come back to 700 to 800 revs.
That is pretty much it but at times It is perfect comes nicelly down to 750 revs.
It's been that way for a few months & im just getting sick of it so put it at the top of my do list.
Lander Mitsi say everything is within tolerances when tested 2 times but I don't trust them to much, by the way It's done 118,000kms.

I suppose its worth suggesting on the principle of simplest things first - could the throttle cable be sticking? That should be replaceable without too much cost.