About CCO and stock egt sensor in JDM cars

**jerryjt** · 06-01-2008, 01:12 AM

hi

I have question about CCO connector in ECU purpose.
that is for some kind as stock egt probe that is in stock cat converter.
Urban legend say it is only for showing that cat is overheating...
BUT
1. it is in place where NOT-JDM cars have 2-nd oxy sensor...
2. we try simulate its resistance (as in service manual) but it seems do not work (looks as ecu looking not only for right voltage but it changes too).
3. without it car seems run rich and ignition seems to be not where to be
4. idle seems be too low (550 RPMs to low : should be 750)

so anybody know something about that sensor
I have soarer 1jzgte but ecu and all sensor looks very similar in mr2
thanks
Jerry

below is cco-egt sensor

http://img155.imageshack.us/my.php?i...tsensorrn8.jpg

**CrUZida** · 06-01-2008, 02:56 PM

I can see one flaw in your theory.

I can confidently say that 99.99% of people who have done a conversion with a 1UZ, or any other Toyota motor that runs the CCO sensor, has NOT installed the sensor or any form of trickery during the conversion.
And 99% of these people have not had the problems you've mentioned.
And if they have, it has been for other reasons.

I personally believe that it is just there to sense when the catalytic converters overheat.
They are placed AFTER the cats, where as the o2 sensors are BEFORE the cats.

ECU measured the EGT through these sensors, and if it gets too hot (ie, your cat is now a red glowing mass), the ECU turns the cat overheat light on.

I think back in the early 80's the sensor was directly connected to the dash light, and was just a switch, not a sensor as such.

Anyway, my 2c.

**thechuckster** · 06-01-2008, 03:20 PM

that sensor is a K-type thermocouple temp sensor - as cruzida says, as it comes after the CAT it would only tell you if the cat core has turned into a molten lump.

A clever ECU might use it work out whether the CAT is up to operating temps and possibly play around with ignition timing until that point is reached.

the TSM for Mk3 Supra has a 2nd O2 sensor for california-only and it's a 4-wire heated job. It comes into action when cruising at low rpms and load (under 80 kmh in 4/5th gear) where the exhaust gasses are not hot enough for the standard un-heated sensor to work correctly. It's for regions that have cars spending a lot of time cruising at fairly low speeds (e.g. a place full off over-crowded freeways like LA).

**jerryjt** · 06-01-2008, 11:13 PM

it is not truth about position oxy sensors.
look for example on 1uz-fe lexus ls or sc 400. FIRST oxy sensors are at exhaust manifolds but SECOND sensors are AFTER cats. and they read how cats performs.

it is strange if cco input in ecu was only for check light. more it is same important as SECOND oxy sensors in US and EURO version. it is simple egt but when it in not in right range ecu play with ignition and injection.

my friend have 1jzgte soarer as me. As me when he do not have that sensor in cat it car run low idle (500 -550 rpms), and run as rich as you can easily smell gas in air.... after he put that sensor car idle 750 rpms as say japan service manual and burn a lot less fuel.

that must be something close co related with ignition timing, say you run idle and you touch only timing: when you advance your idle will be higher. that is exactly what is doing with idle with and without that sensor: with sensor idle 750 rmps and without it idle 550 rpms.

something is in that sensor what is important in ecu program for right ignition.

we try simulate right voltage for cco pin (service manual say it should be about 2.5 volts) but ecu will not perform right. seems it is clever enough and looking not only for right voltage but for changes too.

**The Witzl** · 07-01-2008, 07:56 AM

i can also confirm that the EGT/CCO signal is 100% not necessary when doing an engine conversion with a Toyota motor and stock computer.

You problem lies elsewhere.

**CrUZida** · 07-01-2008, 08:36 AM

Are you sure you are playing with JDM ecu's, and not EUDM ecu's ?

**jerryjt** · 07-01-2008, 08:54 AM

yup
soarer 1jzgte was only jdm.

**Mos** · 07-01-2008, 02:20 PM

Every engine I have wired up has had the CCO/EGW pins removed, mainly due to the fact that the sensor will never be installed in a conversion situation, and many times it is not present in the half cut or engine package. Chances are that *NO* toyota conversions in Australia ever have this sensor fitted... I don't know anyone that runs it.

The absence of this sensor has never shown any sort of problems. Jerry, it might seem in your case and your friend's case that the sensor affects the engine management, but the general concensus in Australia is that is has no effect and no one, to my knowledge, has needed to install the sensor to correct any sort of problems....

When you say "sensor removed" does it mean the sensor is disconnected electrically? or removed from cat but still connected to the loom?

The second oxy sensor (fitted to some toyota and lexus models in Australia also) is mainly there to tell if the cat is working or not.

Mos.

**CrUZida** · 07-01-2008, 02:32 PM

Just a thought Jerry, have you opened up the ECU and replaced the capacitors?

They are common to fail on the 1JZ and give symptoms similar to what you are having.

**jerryjt** · 07-01-2008, 09:15 PM

thanks

I think that problem is with ignition something related

so I try rewire my knock sensors as mentioned there:
http://www.supras.com/06/techcenter/display.php?QID=69

it can be issue because I live in Europe and I swapped that engine into my Lexus sc400 car and it is left hand steering. so my JDM engine/ecu loom is extremely stretched to reach passenger footage.

will look throughly to ecu cause I opened it earlier but do not see any damage inside.

**cambelt** · 07-01-2008, 09:17 PM

Well i installed the cat temp probe in my X83 , even to the ECU and back to the factory cat temp globe on the MX83 dash . ive never seen it come on , car idles fine when its unplugged also . I just installed it on my conversion cause im German.
Dave