Running rich and still failing emissions with new Lambda + Cat

[Mr2Owner]

My car is still failing emissions after fitting a good 2nd hand Cat and a new genuine Toyota Lambda sensor.
This is a Rev3 Turbo model Jap import and in Ireland so its needs to pass emissions.

The latest failed emissions readings are as follows:
High idle Lambda 0.92 (not between 0.97 and 1.03)
CO 2.97 vol% (above 0.3 is a fail)

The car is running rich, the tester said he could get a little sniff of fuel off it before testing it and had an idea it wasn't going to pass.

This is waht has been done:
Replaced Cat with genuine 2nd hand unit
Fitted brand new genuine Lambda sensor
Serviced car with oil and new spark plugs
Cleaned aftermarket cone air filter
Checked exhaust system for leaks, seems ok.


So what can I do to fix the running rich issue and sort the emissions?

What should I check next:
Coolant temp sensor? My temp gauge works and sits in the middle. Does the gauge read off the coolant sensor or the Ecu?
Could the AFM be the problem?
The intercooler fan is on the whole time which I'm currently investigating, could this cause the engine to pump in more fuel?

Any suggestions welcome! Starting to become a bit of a saga now

[cooper514]

Are you running a standard Ecu and have you adjusted your idle control down as low as it can go not the best on rev 3s but assume it has 1

[Mr2Owner]

As far as I know its the standard Ecu. I havn't touched the idle control, the car idles fine.Would lowering the idle help lower the fuel/emissions, but surely thats not a proper "fix" or are you thinking something else?

The car has an aftermarket blow off valve fitted by a previous owner. I put a picture up, Is this venting to atmosphere? I think I'll try and put this back to the stock recirculating setup in case its having an effect on the Afm.

[cooper514]

Never seen 1 of those before but yer its venting to atmosphere and lowering the idle depending on what it's idling at now will help lower emissions as been there on my friends beast to scrap it through he's was a combination of bad lamba lowered it and lowering the idle remove the hydro carbons quite abit if

[thomp1983]

What does he car idle at when warm? You also need to use a multimeter and wiring diagram to check wiring continuity from the lambda sensor to the ecu.

Also i didn't think rev3's had afms they went to map sensors?

[Mr2Owner]

The car idles at 850rpm I think when warm, it passes the low idle emissions test ok, just fails the high idle.

[thomp1983]

Does it definitely have an afm?

[Mr2Owner]

Does it definitely have an afm?

Sorry, it doesn't have an AFM, I thought I saw 1 in there before but I was wrong. I rechecked the warm idle and it sits steady around 900rpm.

That Blow off valve yoke is a "Sard" make but theres litlte rips in the hose and the connections and plugged hoses going into the cone filter induction pipe don't look great which is why I'm trying to find standard parts to put the car back to standard.

Heres pics of the blow off valve rips and the plugs intake pipes.





Is the coolant sensor in this pic, is that it with the single wire?

[Martin F]

I have a standard rev 3 turbo dumpvalve, if you fancy taking that in part exchange plus some cash I may be interested in a swap....

[thomp1983]

From memory there's 2 temperature sensors one for the guage and another for the ecu, the single wire is the guage iirc earth it and if the guage goes to max then you know.

Id trace the o2 sensor wire back to the ecu to and use the ox pin in the diag port to check it's working correctly

[Mr2Owner]

I removed the coolant temp sensor for the Ecu today. The electrical part had corroded and separated itself from the sensor but the wires insode were still intact. Could this sensor have being giving false readings to the Ecu in this state or would it have still worked normally?

Pics below:

[mr2gooch]

How do your plugs look when you take them out?

Just a thought but you could have a duff fuel injector or seal causing it to overfuel or the cold start system not turning off properly.


A rev3 turbo should really be passing the cat test or near enough without the cat fitted provided everything is in good working order.

[Mr2Owner]

How do your plugs look when you take them out?

Just a thought but you could have a duff fuel injector or seal causing it to overfuel or the cold start system not turning off properly.


A rev3 turbo should really be passing the cat test or near enough without the cat fitted provided everything is in good working order.

Theres a picture of the plugs in the link below, I don't know how long they had been in there though, mightn't have been long. Injector seals will be the next thing I'll look at but I'm hoping that dodgey coolant sensor is the issue. Where about is the cold start setup, does a Rev3 definitely have a cold start feature, does it just pump in more fuel?
http://www.imoc.co.uk/forums/viewtopic. ... 84&start=0

[Martin F]

A few years back I had an evo that failed on emissions twice, turned out it had a bad gasket in the exhaust system and was pulling in outside air, changed gasket and it passed with ease.

So many variables , got the dump valve BTW, thanks

[mr2gooch]

Sorry just realised your car is a rev3, I don't think they have cold a cold start injector or switch so rule that out but double check I could be worng

If it was my car I would be looking at injectors next check with a multimeter etc or possibly seals just to rule them out or get it to a specialist to work out what's wrong without guessing

Good luck and don't give up on it