1300 RPM idle

hi all,

The car is a 1998 VVTI jap TT.

Having a problem with the idle, i was driving about in it all christmas and it was fine and came home yesterday and was in the house for about 20 mins and went back out to get into the car and started her up and she stalled so started her again and everything seemed fine and went a 5 min distance in the road and noticed that she was high in the idle so turned back and switched her off and started her again and she stalled again and then when she started she was high in the idle again.

So, i checked the vacuum pipes and they are all fine and i cleaned the throttlebody and still no joy. Then i took the lead off the battery to reset the ecu and started her again and same problem she is still sitting at 1300 RPM but she is driving fine and everything else seems okay.

Can anybody help me cause im o.ut of ideas.

Thanks

chek water temp sensor

IACV could be sticky or faulty.

VVti doesn't have an idle control valve, it's controlled by the main throttle opening. You need to scope the signals from all the position sensors, is it flagging a warning light? Could be a vac leak, trace that with a gas wand, or check tail pipe emissions. Sort of issue that will probably be resolved much faster by someone with the correct gear.

No warning lights. The water temperature is about 75 80 as normal if it was faulty would it not be reading low

No, the gauge and ecu are fed from totally separate and different sensors. VVTi idle issues can be a bear to diagnose and fix without a proper understanding of how it works and the necessary gear.

Just started her there fired up first go 1500 and when she get hot it just drops down to 1200

I know were the 2 sensors are but witch one is the water temperature (FOR E.F.I.)

The one with 2 wires to it, on the top hose elbow region.

hi there,

went and got the diagnostics done and the only thing that came up was error 39 which i think is the VVTI so we tested the voltage of the sensor and when it was cold it was reading 1.0v and when she got hot it went between 0.6v and 0.5v, so i was thinking it should have been going lower than this, I took a gamble and got the new sensor put it in and she is now going 100%.

good result

Hi there was out in the car there and its back at the same thing. I'm going mad.

It's probably either an air leak or a faulty throttle control motor or pedal sensor then. It needs the motor `scoping out to see if the ECU is trying to control it, but it's not responding correctly, or if it's something else. If the ecu has shut the valve right down, successfully, then it's an air leak, almost certainly. Only "try it an see" fixes now are new (and very expensive) parts. Needs diagnosing properly. VVTi Supra and its FBW can be a PITA. Give me a cable linkage any day on a road car.

wow manual chokes i remeber them

What it done was it started chugging when I was driving so I pulled in and the idle was very rough and then it died out. So, it felt like it was off a cylinder or 2 so started back up again and it seemed fine, then when I switched it off to let it sit a minute, started up again no problems but up in high revs again. So I got it back to the house checked the vacuum hoses and checked the plug on the new sensor everything seems okay.

Could it be that the new sensor has packed in?.

No, highly unlikely, needs taking to somewhere that knows how to diagnose this, with the right gear, you're now just clutching at straws.

Well there is one man I think should be able to do a proper diagnostics, but there's over a months waiting list with him. The thing I can't understand is that I put the new sesnor in her last sat which cured it and everything was good driving it everyday and it is doing the same thing a week later. What is the exact voltage reading that should be going in and coming out of that sensor? So I can make sure its not the new sensor acting up.

http://www.mkivsupra.net/vbb/showthread.php?238522-2JZ-sensor-resistance!&highlight=coolant

For this chart you need to thank Andy Blyth who did the work in checking these sensors for his ECU install.

Hi chris, i just done a quick diagnostics and im getting error code 39 and 44 do you know what they are?? can't find anything about these codes anywhere!! Thanks

Does anyone know what error code 44 and 39 is

According to my genuine factory manuals it doesn't exist, but on other Toyotas it can be the ignition amplifier (IGT) as for 39, that deosn't exits, either. Are you sure you are reading these right and they are engine codes? It may be that it's a VVTi, my manuals don't cover them. I have yet to see a genuine Toyota VVti Supra manual set, in Japanese or English. I'd like to buy them. You need to get this thing to someone good with FBW and a scope. Tell them to compare throttle pedal sensor and throttle control position sensor outputs at the ecu and check they mirror each other, ie one goes up whilst the other comes down. I tell you, you're just wasting time without doing something like that. It colud have been sorted ages ago. There must be someone in Ireland that can use a scope even if they aren't necessarily automotive specialists, it's just a feedback control circuit at the end of the day (PID control with redundancy checks).