Aircon on = high idle?

[RomanV]

as for intake....
interesting thing i have learned.
the 3sge in the altezza. a few dealers have had altezzas in with funny surges/misses which they had a mass bastard of a time finding.
on a few occasions the casue was aftermarket airfilters.
or specifically the MAF sensor not liking what the filter did to the flow.
was only found when replacing MAF with a new one and filter with genuine
owner then removed genuine filter and symptoms restarted.
unfortunatly thats about the extent of info i have on it.
apprantly measuring the outputs of the MAF was how they cottoned onto it.

The Altezza is a whole other kettle of fish again!

I've heard that it has no ISCV at all, since it has a fly by wire throttle, ie. it's controlled by a stepper motor, rather than directly by the throttle cable.
So it adjusts idle speed by adjusting the throttle plate angle.
(As far as I know, anyway... Do you have any more info on this Warwick? Do you know if it actually has a seperate ISCV?)

But yep, it's possibly looking like a symptom of a potentially different MAF signal. I've taken the car for a bit of a drive with the ISCV plug taken off, and it makes no difference.

So I can only really see it being either A: a vaccuum leak or B: thanks to the MAF signal.

have you had a look to see if the vacuum line going to the power steering is still attached? mine has come off a few times now and it does the same thing. just a thought.

SW20 has electric power steering.

[fivebob]

theres a device toyota call "valve, magnet (for idle up device)" listed for all sw20s.... showen with the aircon components
isnt that what your talking about?

should have a p/n on it of 90910-13003

Sounds like it, but as I'm 2500kms away from my SW20 I can't check. BTW wet practice for the F1's today, don't think many will venture out on the track

[fivebob]

have you had a look to see if the vacuum line going to the power steering is still attached? mine has come off a few times now and it does the same thing. just a thought.

SW20 = no power steering vacuum line

[Mr Revhead]

roman: install a motec


ill see if i can go look at an sw20 here....


practice should be on now?

[RomanV]

Okay what I was thinking about the MAF sensor.

Lets assume for a second that idle speed was controlled only by the MAF sensor reading.

Say that at normal idle, the MAF sensor reads 2.3 volts (or whatever)

If the voltage was less than this, it would open the ISCV more, if it were less, it would shut it.

Since the pipe is a slightly larger diameter, it would be reading say 2.0 volts at normal idle, so the ISCV opens till it reads 2.3 volts, which is more airflow, which means the engine is doing a much higher RPM.

However this theory gets blown out the window, seeing as how the car behaves the same when the ISCV plug is unplugged. And it doesnt make sense anyway, I mean surely it could see that the idle RPM is way too high, from crank angle or cam angle sensors.

What is also interesting, is that if I unplug the ECU, and then plug it back in, the engine idles at a good RPM, (I havent tried this since I've gotten my tacho working, will try it again over the weekend) but the engine runs like crap the rest of the time. As you drive it a little more, it starts running HEAPS better, but the idle speed progressively becomes higher.
I'm thinking that this is thanks to the ECU compensating for altered MAF signal.
As the ECU compensates for MAF signal through the majority of the range, it stuffs up the idle speed. Probably because the airspeed is much slower than expected at idle.

I suppose I should really do a quick check for error codes while I'm at it, a faulty sensor is a possibilty I suppose....

[RomanV]

BTW... the car runs absolutely fine, in fact its running bloody well at the moment.

The idle speed is the only thing right now that's amiss. It isnt a huge deal, but it would be nice to get it sorted.

[fivebob]

roman: install a motec

Good idea

practice should be on now?

Yep sure is, can't be many on the track though as I can't hear them from my apartment.

[fivebob]

What is also interesting, is that if I unplug the ECU, and then plug it back in, the engine idles at a good RPM, (I havent tried this since I've gotten my tacho working, will try it again over the weekend) but the engine runs like crap the rest of the time. As you drive it a little more, it starts running HEAPS better, but the idle speed progressively becomes higher.

Ok so now we get the full story

I would suggest resetting the ECU and unplug the ISCV when it's idling properly. Then drive and see what happens to the idle as the ECU compensates for the incorrect MAF signal.

[RomanV]

Ok so now we get the full story

Woops, forgot to mention that tiny detail.

I would suggest resetting the ECU and unplug the ISCV when it's idling properly. Then drive and see what happens to the idle as the ECU compensates for the incorrect MAF signal.

Good plan, I'll try this out this weekend.

Thanks for the help Fivebob and Warwick, I should have enough ideas to try out this weekend, and hopefully narrow it down to a few things. I'm leaning towards it being thanks to the MAF signal however.

[sergei]

A few things I learned since working in car yard.
1) 3SGE beams ecus do not like reset, or flat battery due to long term learning capabilities. (same applies to mitzis)
2) Idle on those cars is really funky, with Altezzas it is really low after reset, while on all other it is really high.
3) Sometimes the ISCVs get jammed by gunk.
What I do to fix that problem:
lets start with normal beams (no flybywire crap). Take 1 can of CRC and 1 can of Carb cleaner. Spray carb cleaner on the air flow meter (unscrew it from pipe and take it out) it will remove a lot of gunk from it. Clean out throttle body and spray some in the hole which leads to ISCV (a large hole just before throttle). Start the car, let it suck all the shit in, then while idleing (it will idle even with inlet pipe off) spray CRC (soak it) into ISCV hole. If this does not work, turn off the car and fill the ISCV with CRC, leave it there for couple of hours. After this reset ECU assemble and take it for spirited drive.
With altezzas the cause of shit idle is slightly different, they tend to collect rubish on the edge of the throttle and since throttle controls the idle it messes up with idle, so thing to do: get rid of the shit on the throttle by spraying the carb cleaner on it. It pays to clean air flow meter as well. You could coat the throttle with light coat of CRC when you finish. Don't forget to reset ECU.

I have fixed rough idle and random stalls, high idle on various cars (generally after flat battery) using these methods, I have revived a few mitzi stepper motors aswell, which were quoted stupid money to replace.

It is good practice anyway to keep throttle and airflow meter clean.