1uz stalls when coming to a stop after decel

[TurboRA28]

Hi all, still ironing out some bugs in the 1uz coaster.. Hoping someone might have some ideas on this one..

If you are on decel down a hill and come to a complete stop the engine stalls. Starts up again fine.

If you are just putting around and come to a stop it seems ok.. So only happening when been on decel for awhile.

Otherwise it idles and runs well.

Any ideas?

Thanks
Joel

[thechuckster]

aux-air valve OK?

[TurboRA28]

What where is that?

[thechuckster]

attached to the plenum somewhere - am not sure if the 1UZ has a dashpot on the throttle-body itself or simulates a doshpot (plus has some anti-stall features in the ECU firmware) with the aux-air valve.

[brett_celicacoupe]

yeh idle air control valve (IACV) is one possibility - clean it.

the other thing it could be is the torque converter lockup. have you wired in a brake switch to the ECU? this brake switch will unlock the TC.

i would have thought it would unlock under a certain speed anyway but i cant be sure what conditions it unlocks under other then the brake

[TurboRA28]

Thanks for suggestions.. I'll give the IACV a clean.. I haven't wired in a brake switch, interesting.. Will have to look into that.
Thanks
Joel

[RA35GT]

the iscv is the valve on the front of the plenum.

there is a separate dashpot under the tps. it should hold the throttle open a bit for a few seconds when you back off, there is a test for it somewhere but cant rerember where i put it :/

the ecu cuts lockup under any of these conditions, low speed, brake and tps idle switch.

[TurboRA28]

Still trying to fix this problem.. Doing my head in now.
Anyone know on a UCF11 1UZ what ECU pin should go to the brake switch? Seems to be something like this as it only happens once you come to a stop after you've got up over 60 or so..

[CELICASUPRA7M]

have you put it into neutral and coasted to a stop? to isolate whether its a engine issue or T/C lock up issue? just an idea lol, must be frustrating

[Cuzzo]

I had a similar problem when I converted it to manual and the speedo stopped working. The engine would stall when I come to a stop because of the vacuum drawing air ( booster etc) and I guess the ecu needs to know when to idle up at stopping ?
Do you have the speedo working? Is it wired to the ecu at all?

[The Witzl]

Would probably be the ECU not aware that you are braking.... on some other toyota engines ive wired up there is an ELS1 and ELS2 pin, one of which is connected to the brake light wire to know that you are braking.

Had a quick look at MWPs wiring diagrams for the UCF11 ecu - couldnt find anything that immediately caught my attention.
Possibly IDL1 and IDL2 pins?? Maybe these in combination with speed signals tell the ECU something??

Yeah i dunno.

[Sciflyer]

FWIW my stock UZZ31 does this occasionally, but it desperately needs a service and some attention, thats why im leaning towards it being a mechanical/vacuum issue (eg, it has a leaking PCV grommet) rather than an electrical/wiring one

[The Witzl]

i know that the ISCV on my old UZS131 was gummed up to hell, so would really struggle to open small amounts, but was fine if it needed to open a lot.
This could be contributing to your problem too, as addressed already.

[CrUZida]

IDL1 is the IDL pin on the main TPS, this should be wired in the factory harness, no need to play with it.
IDL2 is the IDL pin on the traction control TPS, this can be ignored.

UCF11 Pinout
http://lextreme.com/adaptronic.html
Plug B, pin 19, green/white

[TurboRA28]

Reckon that gets earthed or powered?