Emissions failing - The latest test readings - Nightmare car

[Mr2Owner]

I have an on-going saga regards the emissions on my Rev3 turbo Mr2 and I cannot get it to pass the annual Nct test. I'm in Ireland so its Nct instead of an Mot.

Here's whats being done to the car:
Toyota spark plugs
Toyota Coolant sensor
Toyotal Lambda sensor
Toyota Cat (Yes, a brand new genuine cat )
Serviced oil, and refitted standard air filter system)
Refitted standard blow off valve
My mechanic said he cleaned the throttle body, tried adjusting the throttle or idle to see if it helped, it didn't) The car idles fine by the way.

Brought it to the test centre today and it failed on the High idle only and the lambda was just within spec.

Results:
High Idle - Lambda 0.97 (between 0.97 + 1.03 is a pass)
2830rpm - CO 1.1 vol% (above 0.30% is a fail)
HC 73ppm (below 200 is a pass)

The low idle passed fine 950rpm - CO 0.20 vol% (above 0.50% is a fail)

Does anyone have some advice, suggestions, or diagnosis based on the high idle readings above. What can possibly be wrong, the car drives fine.

[Mullen]

Find a 'friendlier' tester?

My latest readings were:

CO level, 0.60 % vol
HC level, 145 ppm
CO2 level, 13.67 % vol
O2 level, 1.39 % vol
Lambda, 1.044

It is a rev1 turbo and the rules are different for later revs but our readings aren't that different.

[markstevieandmads]

Was it hot when tested?
Its failed by a very small margin so give it a good thrash before having it tested. Especially if it has a new cat, will need to get it nice and hot for it to be effective.

[androo007]

Emissions tests are not required for pre 95 turbos here as the dvla hold no details on them. Therefore decats are perfectly legal. I'd be surprised if Ireland had any details to actually benchmark it on....

[mr2gooch]

Could be worth checking your injectors. Remove and have them flow tested and cleaned by a specialist. I had similar problems on a mr2 and used cp fuel injection. One of my injectors was way out and actually had to be replaced although my car seemed to idle fine.

When they were refitted it also idled smoother and drove better which was a bonus too.

[cosmos]

What about fuel injector cleaner every 5,000mls STP etc not a fan of Redex myself. Personally i never use supermarket fuels that allegedly have less cleaners!
Fill up with Shell Optimax etc and add STP cleaner or similar and hope the crap gets dislodged and blows out the exhaust.

[Mr2Owner]

Emissions tests are not required for pre 95 turbos here as the dvla hold no details on them. Therefore decats are perfectly legal. I'd be surprised if Ireland had any details to actually benchmark it on....

Does the Mot do any sort of emissions test fro a pre 95 turbo model, does it do a smoke test even? If a 1994 turbo model turns at an Mot centre and theres black smoke coming out of it, what happens, what does the Mot tester do? Just ignore it, or is there a smoke test like for diesel cars?

[thomp1983]

Non cat cars in England do what is known as a basic emissions test (bet) it's an emissions test but just for hydrocarbons and Co2 and the figures are alot higher something like 1200ppm and 3.5%

[Mr2Owner]

Non cat cars in England do what is known as a basic emissions test (bet) it's an emissions test but just for hydrocarbons and Co2 and the figures are alot higher something like 1200ppm and 3.5%

Ok, but this car has a cat so will it still fall into that category? Are ye saying it falls into that category because its year of manufacture is 1994 and before 1995 so therefore whether it has a cat or not makes no difference because the DVLA don't have any details on it so automatically put it into the Bet ye speak of?

I might have to get a friend in Northern Ireland to Mot it and then sell it into Northern Ireland because I'm just fed up trying to get it to pass our stupid NCT emission tests and its starting to cost too much trying. Its a shame but what can I do.

[thomp1983]

Yes it will still fall into that category the cat is irrelevant, the mot emissions test requires the tester to put the reg in then choose the vehicle type and as no Mr2 turbo is listed they select Mr2 and exact match not found or similar then enter the engine specs and it automatically picks the bet test

[rev3gtturbo]

Brought it to the test centre today and it failed on the High idle only and the lambda was just within spec.

Results:
High Idle - Lambda 0.97 (between 0.97 + 1.03 is a pass)
2830rpm - CO 1.1 vol% (above 0.30% is a fail)
HC 73ppm (below 200 is a pass)

The low idle passed fine 950rpm - CO 0.20 vol% (above 0.50% is a fail)

Does anyone have some advice, suggestions, or diagnosis based on the high idle readings above. What can possibly be wrong, the car drives fine.

I have a 1994 rev3 turbo so here are some test figures for comparison.
2015 Basic Emission Test results (Pass):
High Idle Lambda 1.004, CO 0.197 %vol, HC 11 ppm
Natural Idle CO 0.260 %vol

2016 Non-Cat Test results (Pass):
CO 0.429
HC 74


Usually use supermarket super-unleaded fuel rather than the more expensive branded stuff.
I think the only things that are not originals on this car that would affect the test results are the plugs, ht leads, dizzy cap, rotor arm, thermostat, throttle position sensor

[SonicSW20]

I have a 1994 rev3 turbo so here are some test figures for comparison.
2015 Basic Emission Test results (Pass):
High Idle Lambda 1.004, CO 0.197 %vol, HC 11 ppm
Natural Idle CO 0.260 %vol

2016 Non-Cat Test results (Pass):
CO 0.429
HC 74

Are those figures with or without a cat fitted?

[Mr2Owner]

Brought it to the test centre today and it failed on the High idle only and the lambda was just within spec.

Results:
High Idle - Lambda 0.97 (between 0.97 + 1.03 is a pass)
2830rpm - CO 1.1 vol% (above 0.30% is a fail)
HC 73ppm (below 200 is a pass)

The low idle passed fine 950rpm - CO 0.20 vol% (above 0.50% is a fail)

Does anyone have some advice, suggestions, or diagnosis based on the high idle readings above. What can possibly be wrong, the car drives fine.

I have a 1994 rev3 turbo so here are some test figures for comparison.
2015 Basic Emission Test results (Pass):
High Idle Lambda 1.004, CO 0.197 %vol, HC 11 ppm
Natural Idle CO 0.260 %vol

2016 Non-Cat Test results (Pass):
CO 0.429
HC 74


Usually use supermarket super-unleaded fuel rather than the more expensive branded stuff.
I think the only things that are not originals on this car that would affect the test results are the plugs, ht leads, dizzy cap, rotor arm, thermostat, throttle position sensor

They're good Co figures, at lease I know it is possible to achieve them Cheers for taking the time to post them.

[rev3gtturbo]

Original exhaust with whatever is left of the cat internals after 22 years and approx 210,000 km / 130,000 miles.

[Mr2Owner]

If the flexi part of the exhaust was leaking slightly, what effect would this have on the car regards emissions? As its after the lambda sensor and the cat would it have any effect?

If it will affect, would it be a rich or lean effect?

[Martin F]

If the flexi part of the exhaust was leaking slightly, what effect would this have on the car regards emissions? As its after the lambda sensor and the cat would it have any effect?

If it will affect, would it be a rich or lean effect?

I had an evo 6 that failed on emissions, turned out a gasket on the exhaust had corroded and that was enough to throw off emissions so the answer to your question is 'Yes'.
I mentioned this before, can't remember if it was yourself previously or someone else

[SonicSW20]

If the flexi part of the exhaust was leaking slightly, what effect would this have on the car regards emissions? As its after the lambda sensor and the cat would it have any effect?

If it will affect, would it be a rich or lean effect?

Yes, it will affect MOT emissions because the MOT emissions lambda value is a calculated value based one the gasses present at the probe they stick up the exhaust pipe. If there is a leak after the cars lambda sensor then the MOT probe will get a false reading because of the leak.

[Mr2Owner]

I got the leak at the backbox flange fixed, retested the car on the emissions test machine and the Co figures are still way off as in 4, 5, 6, etc... and the lambda reading way down.

Could the throttle body be faulty and not metering the fuel properly?

[SonicSW20]

Have you tested your O2 sensor? What is your fuel trim voltage at?

[Mr2Owner]

Have you tested your O2 sensor? What is your fuel trim voltage at?

I put a new genuine toyota lambda sensor in it.

Two people have tested this new sensor, 1 used a digital multimeter and he said the sensor is ok. He said the multimeter indicated it was behaving as expected when ideling but not reading as expected when revving it. He said the wiring and sensor is ok and its a running rich condition.

Another lad tested it with an oscilloscope and he found the sensor to be oscillating at low idle but at high idle when revved its just a straight flat line, he too said it's running rich the whole time.

SO, no one has tested it with an annalogue needle tester, I tried and the needle didn't oscilate but maybe thats not the meters fault, maybe its just doing what it seems to be doing on both the digital meter and the oscilloscope.

Is the oscilloscope a good tool to test this sensor, can I take its findings as a good test of the sensor or can it "only" be done with the analogue meter? If the oscilloscope readings can be taken into account, what would cause the sensor to flat line and not oscollate at high idle?