[Mk2] [NA] High idle (1500-2000rpm) - Can't work out what is causing this.

[RobPhoboS]

My advice is dont worry about it... it works dont it

But it's killing my clutch (if I drip it to reduce revs) and going through fuel !

just a thought
is the butterfly fully closed. because i had taken the slack out of my throttle cable and when doing mataince on the car i moved the cable out of the clip its in and that had opened the butterfly , only a very small amount but it went upto 1900rpm
just incase mate

It's a completely different throttle body that is on there now.
So nothing to do with that either, plus Luke was on it so I'm sure he'd make sure that it's put on correctly

Cleaned up the ISCV properly as well, and checked that it was moving properly etc.

[RobPhoboS]

When the AC is on, the rev's actually seemed to drop !
Then when it clicked off, they rose

So could this be the potential cause now ?


So a recap as to what has been done !

1: Checked pipes - all good condition.
2: Changed the original ECU to a JMec one (same prob before and aft).
3: Different throttle body with working sensors on there.
4: New ECU Water Temp Sensor.
5: ISCV - cleaned and working correctly- gasket done correctly.

Luke at P.Works took the throttle body off and changed everything over, cleaned the gaskets etc - done completely spot on. He also checked the ISCV and cleaned it properly, tested it etc.


Note:
When the high idle occurs, the air/fuel mixture goes odd (seems like more air).

[RobPhoboS]

I got a good suggestion from Paul Woods, which I've yet to try (will do ASAP).

'An extra test for you, you can clamp the ISCV air bypass pipe with some pliers while the engine is running, if you can lower the engine rpm to idle or even stall it then you know the problem is 100% ISCV related or its control is at fault. If clamping the ISCV makes little of no difference then it suggests an airleak on the plenum somewhere/split vac pipe etc.

Another test is to check the black/yellow wire going to the ISCV has 12v IGN+ on it with the Ignition on and engine not running, Mr2s have a design flaw in the harness where this B/Y wire breaks and you lose power to various components, so definately worth checking, Luke probably already has done these tests but just in case.'

[black gts]

i done that a/c thing ages ago , didnt know it wasnt supposed to make a difference to the idle
so ill multimeter it in morning to make sure its a wiring fault or a broken valve ,thank you for that one.
cheers
Paul

[rs007]

Another test is to check the black/yellow wire going to the ISCV has 12v IGN+ on it with the Ignition on and engine not running, Mr2s have a design flaw in the harness where this B/Y wire breaks and you lose power to various components, so definately worth checking, Luke probably already has done these tests but just in case.'

I know this thread is almost 3 years old!!! But I am hoping someone experienced on here can expand on this design fault, the break, where it occurs, what is affected etc?

I've just tested that pin, and have no 12v ignition feed going to my ISCV - could explain everything about the idle issues I am experiencing, how my ISCV solenoid is in range on the ohm reading, how I can remove that and move the ISCV by hand and get full control of the idle easily - yet it seems the ECU can't control the valve...

Any experienced guys know about this, not sure if RobPhoboS is still active, I'll pm him and see...

[RobPhoboS]

Hey man,

That was a quote from Paul Woods, he's the one that'll know about it

user name: PW@Woodsport

BTW - my issue was down to the incorrect thermostat being accidentally fitted to my car when it was at Lukes place having a bunch of work done yonks ago.

[rs007]

Hey man,

That was a quote from Paul Woods, he's the one that'll know about it

user name: PW@Woodsport

BTW - my issue was down to the incorrect thermostat being accidentally fitted to my car when it was at Lukes place having a bunch of work done yonks ago.

Thanks for responding mate!!

Turns out this WAS the problem on mine, and as a bonus, looks like my tvis wasn't working either due to the fault.

I now have factory spec idle, and a little more pull low down in the rev range, when off boost, way more driveable!

Major thanks to Peter for giving me 5 minutes of his time to help me narrow this down and get a temp fix for diagnostic purposes, absolute legend buddy, thank you

[Peter Gidden]

Turns out this WAS the problem on mine, and as a bonus, looks like my tvis wasn't working either due to the fault.

I now have factory spec idle, and a little more pull low down in the rev range, when off boost, way more driveable!

Major thanks to Peter for giving me 5 minutes of his time to help me narrow this down and get a temp fix for diagnostic purposes, absolute legend buddy, thank you

No prob with 5 mins. 10 mins and you'd have had a bill.

Excellent news! Well done!

[rs007]

Turns out this WAS the problem on mine, and as a bonus, looks like my tvis wasn't working either due to the fault.

I now have factory spec idle, and a little more pull low down in the rev range, when off boost, way more driveable!

Major thanks to Peter for giving me 5 minutes of his time to help me narrow this down and get a temp fix for diagnostic purposes, absolute legend buddy, thank you

No prob with 5 mins. 10 mins and you'd have had a bill.

Excellent news! Well done!

hahaha I thought that might be the case, I was watching the call timer lol!

[dan4]

What was the "incorrect" thermostat?

[RobPhoboS]

What was the "incorrect" thermostat?

I'm not entirely sure, it just got popped in my car by mistake and took about year or so to work out what the issue was
I just binned it and put a new standard one in there.

[caldridge7]

Sorry to bring this thread back up but just wondering if someone can pin point me on my problem.

I had a idle issue with my mr2 mk2 uk modle basically it was a high idle on cold and when warm it would slowely go down, I fitted a new icv and icvs, and started the car and it went to 1500rpm and went down to 950 when warm which is great!

BUT!

I decided to take part of the intake off with the 4 butterflys valves, in the hope to free it off as they were solid...no luck but I then refitted it and now when I start the car it shots up to 2200rpm and above and just stays at around 2100 and hunts up and down from there...

Just wondering if anyone can help with whats happeneded...

Kind Regards
Charlie

[toxo]

You've got a hole somewhere. Vacuum leak causes that, a hose you haven't reconnected maybe?

[Peter Gidden]

Air leak after the throttle body.

[caldridge7]

I know that my throttle body gasket is wrecked and needs replacing but that is not the main issue.. also if i had to replace the vacumm pipes where could I get replacements?

[SonicSW20]

It's just vacuum pipe, find out the inner diameters and buy some. No reason it needs to be original Toyota. You could even get coloured ones, if that's your thing.

[alanmr2turbo]

You have checked the aircon up valve? I had problems with my car rev'ing high.

Simple way of testing it. With car running crimp the pipe coming from the inlet mainfold to the Aircon up valve. If rev's drops then replace the valve.