Lambda & airtemp

[Louis]

How crucial are the lambda (oxygen) sensor and air temp sensor to the performance of a 1UZ? When using OEM wiring and EMU it is probably not even possible to run the engine without those, but with an aftermarket EMU there's a choice. My belief is that the engine was designed to work with those and that leaving them off would not give the best performance.
Secondly I would like to know where the 1UZ’s lambda sensor is normally situated; is it on one of the exhaust manifolds, or after the two pipes meet – the collector, if I remember correctly? In other words is it important that the gas from both banks is measured?

 

[stageajay]

From what i`ve read, on the stock ecu it`ll be in limp mode without the AIT or Lambdas, but will run. With an aftermarket ecu you might be able to get rid of both after its been tuned.

Stock lambdas, theres one in each of the manifolds, and one after each cat, so 4 in total. But the pre an post cat on each side can be wired together on each bank to remove the post cat one. Don`t know if that works on all of the ecus, but it did on mine

 

[4U2QUIK]

that's a very complicated answer. with an aftermarket system running without o2 sensors is ok, but your vehicle first has to be tuned with a wideband o2 sensor. as for running without an iat. that's ok on a standalone only if you are running a mass air flow sensor. otherwise it's required for correct fuel mapping when running speed density.

also, the stock ecu will work without either, but you will go into limp mode. and even then it's a bad idea because you lose tons of fuel and timing trim. same goes for thr iat sensor.


aaaaannnnnnd post cats are only on certain vehicles in certain countries in certain localities depending on their smog laws. (you can remove the rear ones without any efect other than it will throw a bad cat/o2 sensor code but that is all.)
most uz engines only have 2 cats.

 

[Spinnetti]

that's a very complicated answer. with an aftermarket system running without o2 sensors is ok, but your vehicle first has to be tuned with a wideband o2 sensor. as for running without an iat. that's ok on a standalone only if you are running a mass air flow sensor. otherwise it's required for correct fuel mapping when running speed density.

also, the stock ecu will work without either, but you will go into limp mode. and even then it's a bad idea because you lose tons of fuel and timing trim. same goes for thr iat sensor.


aaaaannnnnnd post cats are only on certain vehicles in certain countries in certain localities depending on their smog laws. (you can remove the rear ones without any efect other than it will throw a bad cat/o2 sensor code but that is all.)
most uz engines only have 2 cats.

ah, good. I dumped my rears but kept the front. My fuel economy is atrocious though, and its losing me races. The MAF is still working, and I'll replace the front o2s a "hail mary" to see if that helps. It runs great, but at about 7mpg which ain't enough (it is running 10hrs at a time full out though) My check engine light is DOA unfortunately. Any easy test for the IAT? I'm assuming it works as the MAF is functional, but dunno (stock USA ECU)

 

[4U2QUIK]

get the bulb working then Go jump e1 & t1 and see if you get any codes

 

[Spinnetti]

get the bulb working then Go jump e1 & t1 and see if you get any codes

not sure its a bulb... could I jumper some ecu pins with a bulb? I cut 40lb of wiring out - maybe got too zealous.

 

[4U2QUIK]

I'm talking about the check engine light.

 

[Louis]

Thanks guys. I have a locally produced aftermarket ECU and it is quite good. It was installed w/out O2 sensor and AIT and not properly set up. Fuel consumption in town was 16 mpg in town with the 3.4 V6 in my Prado 90. After the conversion that dropped to 13 mpg. Open road was 22.7 mpg at 100 km/h (62.5 mph), dropped to 21.0 mpg. Then I took it to someone to tune the tranny ECU and he had a look at the engine settings as well. Something was a bit out of adjustment which he fixed (roadtest, not dyno) and consumption improved very slightly to 14.8 mpg. This is still worse than with the V6. Performance is slightly better now than with the V6. I have bought the two sensors and plan to install them soon. After a few tank-to-tank checks on consumption, it is going for a dyno tune. That would be about as good as it will ever get and I hope it is quite bit better than now. The technical guy of the company that makes and sells the ECUs said an O2 sensor makes about 10 - 15% difference (improvement) to consumption. BTW, I have a 1UZ w/out VVTi.

 

[BlackUZZ31]

I'm currently running my cressida without AIT or O2 feedback no problems at all!

factory O2 sensors are an emission control sensor not for power or economy...

fuel economy is not something you can set on the dyno, its a road tune thing, get yourself something like the NGK wideband and then in the ECU software take note of what load and RPM bands you cruise at then lean it out to about 15.5:1

I got adverage 10.5ltr / 100km on a recent 1200km road trip

 

[gloverman]

Dont tuners in Oz know how to set cruise zones on the dyno. Maybe they need more training. A good tuner can set up cruise on the dyno.

 

[@ndy]

Thanks guys. I have a locally produced aftermarket ECU and it is quite good. It was installed w/out O2 sensor and AIT and not properly set up. Fuel consumption in town was 16 mpg in town with the 3.4 V6 in my Prado 90. After the conversion that dropped to 13 mpg. Open road was 22.7 mpg at 100 km/h (62.5 mph), dropped to 21.0 mpg. Then I took it to someone to tune the tranny ECU and he had a look at the engine settings as well. Something was a bit out of adjustment which he fixed (roadtest, not dyno) and consumption improved very slightly to 14.8 mpg. This is still worse than with the V6. Performance is slightly better now than with the V6. I have bought the two sensors and plan to install them soon. After a few tank-to-tank checks on consumption, it is going for a dyno tune. That would be about as good as it will ever get and I hope it is quite bit better than now. The technical guy of the company that makes and sells the ECUs said an O2 sensor makes about 10 - 15% difference (improvement) to consumption. BTW, I have a 1UZ w/out VVTi.

Louis I assume you have the Spitronics ECU, you will see a Mother of a huge improvement by installing Lambda and Air Temp sensors, Take it to someone to Properly tune it on a Dyno ask the Spitronics (if you have a Spit email [email protected]) to recommend a tuner, not every tuner out there tunes a car properly, don't waste your Time and Money on Road Tuning it, when the tuner is done ask them to enable Lambda sensor and closed loop and allow 10% adjustment, your Fueling will improve until the ecu has fine tuned the Map to perfection with Closed loop according to your lambda readings

 

[BlackUZZ31]

Dont tuners in Oz know how to set cruise zones on the dyno. Maybe they need more training. A good tuner can set up cruise on the dyno.

you can block a whole range out for sure, but there is no nice way of doing it on a dyno to account for aero loading, road gradients and all the other variables you don't get sitting on rollers with a fan pointed at the car

 

[BlackUZZ31]

Louis I assume you have the Spitronics ECU, you will see a Mother of a huge improvement by installing Lambda and Air Temp sensors, Take it to someone to Properly tune it on a Dyno ask the Spitronics (if you have a Spit email [email protected]) to recommend a tuner, not every tuner out there tunes a car properly, don't waste your Time and Money on Road Tuning it, when the tuner is done ask them to enable Lambda sensor and closed loop and allow 10% adjustment, your Fueling will improve until the ecu has fine tuned the Map to perfection with Closed loop according to your lambda readings

how do you suppose to get a reliable 10% fuel change with a narrow band O2 sensor?

adjusting the fuel table with a wide band sensor on the road is the best way to get fuel economy, giving a narrow band sensor the power to effect a 10% change will just turn to crap! most manufacturers give a +/- 3% window at most for long term trims in an ecu that holds learned lambda values between starts!

 

[4U2QUIK]

you can block a whole range out for sure, but there is no nice way of doing it on a dyno to account for aero loading, road gradients and all the other variables you don't get sitting on rollers with a fan pointed at the car

not true, it depends on the dynos capabilities and the capabilities of the tuner.

 

[Louis]

Yes @NDY, Spitronic. The Spitronic guys are right here in Pretoria, not more than 6 km from where I live. I did go to see them and they recommended RBTS Racing in Kemptonpark. I have not fitted the lambda and ATS yet, for I had to re-route the exhaust first. Exhaust went right under the tranny's oilpan and I am sure it heated the ATF. Also, I wanted to service the tranny and the exhaust was in the way. That has recently been fixed, and soon I shall fit the two sensors and have the dyno done. Depending on the results of that, I shall do the road tune as well. Once that is done I shall report the results here. Thanks for everybody's input so far.

[edit: the road tune I mention is for the trans]