weird idle

[Stott69]

Hey guys. picked up the car today and after a short drive it decided to go a bit funny. Had the car stopped for a few minutes while my WOF guy checked things off and did the paper work. once done about 10 minutes later the car would crank but not fire. turned it off, left it a few seconds and tried again, this time starting like normal. Drove it down the road and parked at a mates place where once in park it wanted to change idle up and down, a change of about 1krpm. I've now tried pulling codes but it wont show them, engine light doesn't flash or anything. Did a ecu reset and car returned to normal. Then turned the car off waited a minute and tried again, and the problem is back.

So, where do I start looking for this problem since the ECU doesn't want to tell me?

[Mr Ree]

Had the battery been disconnected while at the workshop before you picked it up? If so, its possible its just in self learning mode and hasnt sorted out its fuel trims properly yet.

Just take it for a nice drive, going through all variance of throttle positions/loads and see if it settles down a bit.

Alternately, have you considered your IACV might be dirty? TPS not to spec?

[Dell'Orto]

Air leak in the new pipework somewhere possibly? Made sure you had a good contact between E1 and TE1? The grease in there often makes it tricky to get a good connection

[Stott69]

Had the battery been disconnected while at the workshop before you picked it up? If so, its possible its just in self learning mode and hasnt sorted out its fuel trims properly yet.

Just take it for a nice drive, going through all variance of throttle positions/loads and see if it settles down a bit.

Alternately, have you considered your IACV might be dirty? TPS not to spec?

I have had the battery off for the last 6 months and taken the car out for 3 round the blocks before taking it in with nothing of the sort so relearning is low down on my possibility's. Will look in to the IACV as that has only got a small filter straight on it and may have been subject to dust at the panel shop. Will also check TPS as I've splices into this just before the ecu.

Can't hear a air leak, just noisey valve train. checked for codes straight after reset and it blinked away happily, l also tried the plug under the dash with the same results

[Stott69]

Are these water lines going to the bottom of it? if so would these airlock and cause problems?

[Stott69]

What ever is causing this must be heat related. Start from cold, no problem. Turn off once its idled up to temperature and then restart, wont show codes and high idle pulsing returns. Will let it cool then see if if runs smooth again.

Edit: Its cooled and now starts and idles fine again. How does the ICV get its temp signal? would something be causing it to not read hot? dash temp goes up fine

[Dell'Orto]

Maybe ECU temp sensor is b0rked? Usually they read low but it might have dropped resistance? Failing that, they don't run an idle up like 16v 4AGEs do they?

[Stott69]

Yea just did a google search and temp came up, had a look n the plugs got 20yo-itis. The wiring is all cracked and showing wire. Test from to most break to plug and intermittent failure.

So, where can I get a 2jzgte suitable plug on a Saturday?

[Dell'Orto]

Pick a part, probably be the same as all manner of Toyota plugs

[Crucible]

Is the coolant level ok. Sounds like air lock in IAC, Honda accords and a few others incl 4ages will give the same symptoms if low on coolant when warm pulsing etc..

You may need to disconnect coolant lines at IAC and run while keeping topped up to bleed air out, they tend to get airlocks because they are normally the highest point, ie higher than radiator etc.

Normally any rise in rpm at idle etc is air bypassing the throttle plate by one way or another. To check.. pull duct off throttle body and block IAC port with youre finger rpm should drop to normal.

[Stott69]

Yea, posted this on the jzs147 forums too, guy on there saying the water lines on it are just for below 0 temps so it doesn't freeze. Will try bleed it any way and change the sensor plug

[Stott69]

Ok, so fixed that wiring issue to no resolve. Started the car this morning and took the filter of the ICV. Putting my finger over it lowers the idle but doesn't kill it. Tried this once it was warm and showing fault and it wanted to idle around 2.5-3k, finger over and it drops down. Ive checked the resistances on it and they all seem fine. So is it new ICV or is something else causing this?

[jaypines]

probably the icv needs cleaning and loosening up... the valves/flaps inside it are seized. remove the icv and soak it in crc.

[Stott69]

Thats the thing, I have. Possibly not enough tho?

[Crucible]

My understanding is any coolant operated Idle control allows air around throttle when cold and gradually closes off once warm, Im not familiar with 2j ones though.

I would check power and earths before replacing it. No doubt you have come across this pdf in your search but maybe of some help?

www.97supraturbo.com/.../IACValve.pdf

[JZCrazy]

Have you tried bypassing the fuel pump ecu?

When engine is at operating temp. switch off engine and try to restart. If it wont restart, short Fp and B+ at diagnostic port and try restarting.
If engine starts and runs your fuel ecu is faulty.

[Stott69]

Well, pluged the ICV and it idled normaly. So went for a drive around the block and it started surging when it came on boost. Got it back home, opened the ICV and started it again only to find it would turn over but not fire. Tried a few times over a couple of hours and same. Just tried the above it fired and warmed up. But once warm shut it down and restarted and its Idle pulsing but even higher, more like 2.5krpm.

Just a thourght, panel shop would of done welding. If they failed to disconnect the battery would they have fried something (ecu) to cause this?

Starting to get real frustrated. Ment to be driving to Auckland next weekend.

[Crucible]

Hmm,

About now is where scan tool live data is really helpful as you can literally spend hours testing and going through a process of elimanation. Not being able to retrieve codes is a slight concern (ecu not communicating?). I know a very good mobile sparky based where you are who maybe able to put you on the right track.

If your stuck hit me up.

[Anth_555]

are you sure you dont have vacuum leak. if you block off the ICV and the car is still running then its getting air from some where else

[Stott69]

Just had auto sparky around. Current diagnosis is fried-ECUitois. He ended up pulling the ecu out to a fishy smell, opened it up to leaking caps. May be fixable.