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The mkiv Supra Owners Club

Afr's usual behaviour


ballsdeep
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I don't know if I should be concerned or it's the norm so I'm looking for some information on how your AFR readings perform from cold start basically how long it takes to settle @ 14.7

 

Whats making me think something's wrong is to get 14.7 will take me over 30mins?? Also the odd occasion It will be rising into the 14's but then drop back into the 13's and starts slowly trying to climb back upto 14.7? by the time I'm at work im lucky if it's 13.5

 

Idle is sometimes a bit random this morning was 1100, last night was 1000 and usually on longer journeys it settles at 900

Edited by ballsdeep (see edit history)
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:thumbs: think I will order a new one as a precaution! Are the na and TT temp sensors the same, Anyone know the part numbers?

 

The resistance readings are in the tech section, no need to randomly change it. TT and N/A are totally different I think. If you do change it be sure you are changing the ecu temp sensor, and not the gauge temp sensor! I would be looking more at the thermostat and map myslef. Temp sensors usually fail open circuit.

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What water temps is the ecu seeing? How do they correlate to the warm up map? You haven't got one of those crazy low temp thermostats fitted have you? What's the ecu? Can you log the warm up cycle?

 

Temperature sits just under half, iv had a trd thermostat fitted for a while now, piggy back is the emanage ultimate

 

The resistance readings are in the tech section, no need to randomly change it. TT and N/A are totally different I think. If you do change it be sure you are changing the ecu temp sensor, and not the gauge temp sensor! I would be looking more at the thermostat and map myslef. Temp sensors usually fail open circuit.

 

Unfortunately I don't have the software or knowledge to check the map but I'm fairly confident it's ok since lyndon mapped it and pretty sure it hasn't always been like this. Cheers chris il look into checking the resistence.

 

Do they not also influence the duty cycle of the stepper motor that controls idle Chris? or does the N/A not use one?

If the ECU is seeing a low temp the ECU will keep idle high, I guess it also depends on whether he has a stand alone or piggyback as to whether he can access a cold start map.

 

Sadly I'm using the emanage ultimate piggy back but I wouldn't know where to start anyway

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It could be as Chris says simply down to the thermostat being incorrect for the UKs winter temps, so it just taking ages to warm up, or it could be down to the ECU coolant temp sensor, if failed the ECU will run things a bit rich as default, but I thought the ECU also depends on the temp sensor to control idle as well,

once you have changed the thermostat you will better be able to see from there.

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The Temp Sender for the Gauge in the Instrument table is not the same as the one for the ecu. If you look at the Water neck you will see two sensors one with two wires(ECU Sensor) and one with a single wire(Gauge). So your gauge may be sending the right temperature while the ECU one is not working correct or there is a wiring problem. :)

If your gauge sits in the middle where it should be then the temperature will be around 70°C minimum which should get the Lambda working and the idle pretty low(almost at the stock hot idle at 650rpm). But with your description I'm almost certain it's the sensor itself or the wiring which is broken.

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  • 5 weeks later...

So just to keep this going I fitted another thermostat but it made no difference, still takes far too long! so I drove to toyota and ordered a new coolant sensor, by the time I got home AFR was 14 so I checked the o2 sensor voltage which was fluctuating between 0.72-0.81 then I left it to idle for 10mins until @ 14.7 and took another reading - 0.62-0.64 in total it must have taken at least 35mins to get to 14.7

 

Il update once the sensor is fitted!

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  • 2 weeks later...

To rub salt in the wound this morning it cut out 3 times while driving with no warning! Each time it stored error code 14, after a ecu reset it would be fine for 1-2 miles then cut out again?

 

Hopefully il get the new cts fitted this afternoon, probably not linked though?

Edited by ballsdeep (see edit history)
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The factory ignitor earths through the body so make sure the 2 screws are tight and clean. Also the frame that holds it needs to be tight and corrosion free. I've seen a few NAT's with the coil and igniter held on by one bolt and bent out of the way of the intake and filter.

 

The IGT goes through the Ultimate but the IGF doesn't. To much ignition skewing could (Although I've never seen it happen) mismatch the IGT and IGF signals causing the same effect.

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