Idle too high-3.5l petrol

[disco stu]

Hey all. Finally got the engine in and running in the nl-3.5 petrol.

Idle was really high. I remembered the bypass screw, so I screed that in all the way and idle has dropped down, but still too high are 1000rpm with it bottomed out and car warmed up.

What else could be causing high idle, or is there a way to drop it down?

I have cleaned out the idle control solenoid in throttle body. Could I have installed that wrong or does it need adjusting?

Would appreciate any advice you guys might be able to offer

Stu

[DibbyDibbyDJ]

Air leak from intake system?

[disco stu]

I can't find any leaks, but I'm about to look harder.

Mostly keen to know if there was anything in the throttle body I might have gotten wrong/need adjusting, as I had everything apart to clean it all up

[disco stu]

It's down to about 950, but still to high. Running through the manual for things to check, but it's hard to follow that without mut2

[motorazr]

Perhaps the cable may need backing off and moving from where it is clamped. Not allowing the flutter valve to close completely.

[disco stu]

Thanks. Did check that and there is slight amount of slack in cable, so that's not it.

Wanted to check the TPS to check idle position switch, but can't get to the connector as it points the wrong way. Might try the camry connector to plug into it

The manual mentions listening for the idle speed control sound on turning on ignition, engine cold. What the manual fails to mention is what this sound actually is like! Can anyone help me with that? I do hear a series of ticks with a very slight "grrr" or "nnnnnnn" on turning on ignition, but no idea if that is what I'm listening for

[DibbyDibbyDJ]

Try holding the motor as a friend turns key on. You should feel it moving

[disco stu]

But I have no friends

Good idea, I'll give that one a go, cheers

[Alex86]

Disconnect the battery for 5 mins. Hook it up again, turn the key to on (don’t start yet) and you’ll hear a distinct series of rapid clicks, hopefully.

[disco stu]

Thanks Alex. Yes, I have those clicks. Was just never sure where they were coming from

[stumagoo]

the idle screw is not supposed to be adjusted - if the idle is wrong there is a reason - either a vacuum leak or the Maf is reading wrong or similar - I would guess there is a vacuum leak.... they can be tough to spot

[disco stu]

Thanks Stu. Throttle body was pulled apart and cleaned (everything was on this engine) so I was thinking it would likely be out of whack. But the fact it is bottomed out was making me think vacuum also....But hoping I've missed something else that is easier to find

[erad]

There is a small steel pipe on the underside of the intake manifold. A rubber vacuum hose connects to tappings near the throttle body, and the other end goes (I think) to the fuel pressure regulator or the fuel vapour canister. It is possible that you have missed one or more of these connections. This will allow more air into the engine and the ECU will adjust the fuel dose accordingly. As the throttle opens more, this small amount of air leakage will easily be overcome and the mixtures will be adjusted again by the ECU.

[disco stu]

Thanks erad. Double checked those and both ends connected correctly, plus the other vacuum hoses. Not that there is that many on this engine.

All vacuum hoses have been replaced also

[stumagoo]

I have found the metal gasket between the upper and lower Plenum are real PITA to get to seal - I know use sealant on them - even when brand new