Idle problem

[GTMatt]

Could anyone advise please, I have recently had my rev 3 turbo engine rebuilt, it is still with the garage as have reached the last hurdle of starting it up and it won't self sustain itself on idle (aka no throttle input and it stalls).

Engine has got Hks 264 cams
86.5mm cp pistons
Eagle rods
All bearings and studs replaced by the usuals (arp etc)

Currently running with standard fuelling, ecu and turbo.

Runs very smoothly when any throttle is engaged, even just holding the throttle to run it at 850-1000 rpm and it runs fine, but as soon as you let off the throttle it will stall.
Cam and ignition timing is set as it should be, injector seals have been replaced as believed it was a leak from around that area, all pipes have been checked and checked again, and no engine error codes being displayed when you perform the diagnostics trouble code procedure.

Can anyone suggest anything/ experienced something similar?

Cheers
Matt

[Peter Gidden]

Check operation of ISC.

[GTMatt]

That will be next on the check list then. Hopefully will report back with good news.
Thanks

[GTMatt]

Mechanic ensured me the isc valve was removed cleaned and is functional.

I forgot to mention in the original post it has a fidanza lightened flywheel, would the reduced inertia from a lighter flywheel be the cause of it stalling perhaps?

[bobhatton]

Mechanic ensured me the isc valve was removed cleaned and is functional.

I forgot to mention in the original post it has a fidanza lightened flywheel, would the reduced inertia from a lighter flywheel be the cause of it stalling perhaps?

No

If the isc is working ok it must be the o2 sensor if the TPS is working and set up

[dan4]

You could try adjusting the idle control valve to attempt to bring up the idle speed

[GTMatt]

Mechanic ensured me the isc valve was removed cleaned and is functional.

I forgot to mention in the original post it has a fidanza lightened flywheel, would the reduced inertia from a lighter flywheel be the cause of it stalling perhaps?

No

If the isc is working ok it must be the o2 sensor if the TPS is working and set up

I advised him to reset the TPS just to make sure. And will try to get my hands on an O2 sensor asap. To be so close yet so far is killing me!

[bobhatton]

You could try adjusting the idle control valve to attempt to bring up the idle speed

That is what the ECU does

[dan4]

You could try adjusting the idle control valve to attempt to bring up the idle speed

That is what the ECU does

To a point, there is also adjustment on the idle control valve

[Peter Gidden]

I've never had an ECU not control idle on a properly working engine.

Toyota make no mention of ISC adjustment either:

[Peter Gidden]

OP.

Has ignition timing been reset correctly?

Are cams dialled in correctly?

[dan4]

They dont specify adjustment in the workshop manual however there is an end stop adjustment and adjustment of the bimetallic spring placement. Dropped my cold idle speed to 1400 from 2000. Still specialists know best....

[ashley]

They dont specify adjustment in the workshop manual however there is an end stop adjustment and adjustment of the bimetallic spring placement. Dropped my cold idle speed to 1400 from 2000. Still specialists know best....

The problem with that is that you've potentially cured the symptom, but not the problem...why was your cold idle speed so high in the first place? That's the question I'd be trying to answer.

[rev3turbo]

Still TOYOTA know best....

yes, they designed the system to work in an intentional way, if you 'adjust' you are just masking the fault, it'll always be present.

quite simple really, just like Denso supply parts in Toyota boxes, You couldnt grasp that concept, so you've little chance with the above.

[dan4]

They dont specify adjustment in the workshop manual however there is an end stop adjustment and adjustment of the bimetallic spring placement. Dropped my cold idle speed to 1400 from 2000. Still specialists know best....

The problem with that is that you've potentially cured the symptom, but not the problem...why was your cold idle speed so high in the first place? That's the question I'd be trying to answer.

Wear on the spring, which in turn changes the scope the ecu has to open/close the valve. Slotted holes must be for something other than adjustment, silly me Its not a new thing, its been implemented in the states for a while

[ashley]

As long as you're happy dude, far be it for me to try to give you advice

[Peter Gidden]

Wear on the spring, which in turn changes the scope the ecu has to open/close the valve.

Of course! Stupid me!

OP removes engine, dismantles, rebuilds. Idle perfect before removal. Bad on refitting.

ISC spring has gone bad whislt engine out!

Toyota not so stupid after all. Shame they left it out of BGB though.

[dan4]

Op also made it appear as if the engine was built to that spec before refitting?

[ashley]

Nothing in there to suggest that he's changed his ISC spring

Actually- you know what? I bet he made the mistake of replacing it with a denso spring instead of getting a genuine toyota one, that would explain everything...damn these cheap replacement parts!

Could anyone advise please, I have recently had my rev 3 turbo engine rebuilt, it is still with the garage as have reached the last hurdle of starting it up and it won't self sustain itself on idle (aka no throttle input and it stalls).

Engine has got Hks 264 cams
86.5mm cp pistons
Eagle rods
All bearings and studs replaced by the usuals (arp etc)

Currently running with standard fuelling, ecu and turbo.

Runs very smoothly when any throttle is engaged, even just holding the throttle to run it at 850-1000 rpm and it runs fine, but as soon as you let off the throttle it will stall.
Cam and ignition timing is set as it should be, injector seals have been replaced as believed it was a leak from around that area, all pipes have been checked and checked again, and no engine error codes being displayed when you perform the diagnostics trouble code procedure.

Can anyone suggest anything/ experienced something similar?

Cheers
Matt

[Driftlimits Performance]

What a load of tosh.

Moving the throttle stop will change the idle but also willy up the tps calibration.

You've got a 0.5mm parameter on the iscv, and the spring wore this much? lol

Clearly the engine isn't getting the air it requires on idle. Just find out why. simples.