Farkin 20v idles!

[Dell'Orto]

Right, so this AE101 I bought has always idled pretty high when cold, circa 2k rpm. Since I pulled the motor out to do the cambelt etc, its been playing up even worse.
It'll idle at about 2k still when cold, but when warm will only drop to 1500rpm, then occasionally will kick back up to 2k, stay there for a bit then drop down to 1500 again.
I've checked for vacuum leaks, and have replaced a couple of lines that were leaking with no real improvement.
ISCV was replaced with one that had been ultrasonically cleaned, and you can hear it clicking over when the revs rise and drop, with quite a noticable hissing noise - is this right?
Edit - thought I'd better add: The car throws no error codes, and I also checked the timing once warm and it was spot on 10 degrees.
Add to this the brakes turning to mush when the car is on, which I thought was a dud master but have just rekitted it and they havent changed a bit.
Giz some ideas so I dont go nato and end up parting this fcuking thing out

Brad

[deaf_rattle]

checked the timing?

[Mr Revhead]

Maybe temp sender for the EFI. Which is different to the gauge one.
used to sell heaps, they would fail and ECU thinks the car is cold all the time.

[andyztouring]

Clean the throttle body out,esp. around the butterfly,sometimes the oxygen sensor needs replacement .And what temp does the car run at on the open road,if its cold replace the thermostat.

[RS13]

The oxygen sensor and buggered thermostat won't contribute to an idle that high, I've had both before. I know you've checked it, but sounds like a vacuum leak, there are so many brittle, cracked hoses on the manifolds of those things.. other than that, have you checked the throttle cable tension? I've come across that before!

[Dell'Orto]

Yeah I actually took the line off the bottom of the plenum, and pressurised it all to 10psi, and once I'd sorted the ps lines there was no more hissing. Cable tension is fine, made quintuply sure of that Timing is spot on, and on the road temp I cant remember, but I assume it would have been normal (would recall if it was too cold/hot). Have cleaned the throttles out as they were pretty gunky, but that was pre engine removal.
Revvy - which is the temp sender? The one on the inlet side by the ISCV plug?

[Mr Revhead]

89422
http://www.toyodiy.com/parts/p_J_199106 ... _8404.html

[Lurkin]

I have a spare ISCV - but its from a BT? I'm in welly happy to post/ courier if you want to borrow it for abit? (was from a wreakers couldn't help myself)... not sure if they are the same tho?

[Dell'Orto]

Thanks dude, they are different though. Plus I'm fairly certain its not the ISCV, as it definately clicks. Just even with it adjusted to its max closed point it still idles too high

[Lurkin]

hmm. offer remains open if you change your mind.. just a thought (possibly a bad idea.. ) last time I had similar issues I got a can of start ya bars**d and sprayed small amounts about - to see if it would idle up at all? (obviously could end badly)..

[fivebob]

If you block the ISCV off what speed does it idle at?

What happens if you disconnect the wires to the ISCV?

[Dell'Orto]

If I disconnect the end at the manifold, it dies (Though was stone cold when I tried this, so not hugely surprising). Disconnecting the ISCV plug does nothing, it continues to idle high.

[fivebob]

If I disconnect the end at the manifold, it dies

but what happens if you block it off. i.e. no air coming through the ISCV.

[jondee86]

Thanks dude, they are different though. Plus I'm fairly certain its not
the ISCV, as it definately clicks. Just even with it adjusted to its max
closed point it still idles too high

Not certain about this adjustment and clicking business. AFAIK the ISCV
is a PWM solenoid with two coils. The resting position for the valve is half
open (or half closed, if you are a pessimist). The ECU modulates the
valve by applying voltage to one or other of the coils (or perhaps both,
I don't remember). The range of control should go all the way from
choking the engine off, to somewhere around 3500 to 4000 rpm.

There is a single 12V supply to the valve, and two ground wires. If you
ground one of the wires, the valve goes full open; ground the other one
and it goes full closed.

I can't think why there would be any "clicking" from the ISCV ? And the
valve is factory calibrated and sealed, so there is no user "adjustment"
available. All you will be doing is upsetting the factory calibration.

Cheers... jondee86

[Dell'Orto]

If I disconnect the end at the manifold, it dies

but what happens if you block it off. i.e. no air coming through the ISCV.

Hmm, havent tried that...the lower hose is a bitch to get at with the plenum in place.

Not certain about this adjustment and clicking business. AFAIK the ISCV
is a PWM solenoid with two coils. The resting position for the valve is half
open (or half closed, if you are a pessimist). The ECU modulates the
valve by applying voltage to one or other of the coils (or perhaps both,
I don't remember). The range of control should go all the way from
choking the engine off, to somewhere around 3500 to 4000 rpm.

There is a single 12V supply to the valve, and two ground wires. If you
ground one of the wire, the valve goes full open; ground the other one
and it goes full closed.

I can't think why there would be any "clicking" from the ISCV ? And the
valve is factory calibrated and sealed, so there is no user "adjustment"
available. All you will be doing is upsetting the factory calibration.

Cheers... jondee86

The valve itself is sealed, but on the back section there is a plate held in place by 2 screws, which you can loosen off and it changes the position of the rotating core. Turning it toward the firewall of the car made it idle higher (Which when you pull the thing apart you can see why) and toward the block, lower. They definately click, as the one I tested on the bench makes a noticable clicking noise when you ground either "earth" terminal out. I assume the clicking noise is just the core spinning and hitting a stop.

[jondee86]

The car throws no error codes, and I also checked the timing once
warm and it was spot on 10 degrees.

Gotta ask this, as it happens all the time: you checked the timing with
the diagnostic plug jumped... right ?

Cheers... jondee86

[Dell'Orto]

Ah, no actually

[jondee86]

Yes, it will click as you say, when bench tested with 12V on the coil.
But in operation, it is modulated... the valve position being varied by
the ECU applying more or less voltage to the coils. It should not be
banging against the stops, as that would mean the valve was at the
extreme end of its range.

Pulling the top hose off the end of the common vacuum rail should give
you a very high idle. And then, you should be able to regulate the idle
speed with your thumb (or some other blanking piece... 20c coin etc)
over the open end of the metal tube. If you block the tube off completely,
the engine should stall, or at least drop to a barely running condition.

Edit: If the engine continues to idle high (2000 rpm) with the tube
blocked, then you have air entering the engine from some place else.
Check that all the throttles are closing completely. It doesn't take much
of a leak to lift the idle to 2000 rpm.

Cheers... jondee86

[Mr Revhead]

Ah, no actually

I purposely didn't mention that as I thought a pro like you would know!!

[Dell'Orto]

I had the bloody thing bridged checking the codes before I did that too