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[addy]

Had a bit of quiet time, so decided to remove the O2 sensor from the old Catalyst. I am not suprised the emissions were off. I think it is contaminated with coolant, from the Head Gasket going. Now just got to get time to take it for MOT.

[addy]

Well added new NGK O2 sensor OTA7L-3C4 which is a Titania Sensor, NGK partfinder catalogue said this is the one for my car 02/95 –>
Date of first registration October 1995 , and full exhaust from manifold to the back including new cat. Still failed on emissions again, on fast test. Idle test passed.

So did a live data today on the drive, at high revs. Can anyone see why the O2 sensor keeps going to open loop?

https://drive.google.com/open?id=1kQzSLgMtnlRkFVouTMZ5cIrI5sBrmpmM

Thanks in advance
Addy

[Doctor Gollum]

Too cold would be my guess... Temp should be at least triple what it's reporting

[addy]

Do you mean temp sender for computer?

[Doctor Gollum]

Coolant temp engine is effectively stone cold...

[addy]

Thanks for the help. The temp on gauge inside car was at 90 when I finished the data. Air temp on car display was flashing 3.0. Would any make sensor work as it is a NLS part.

Don't want to have to fight to get to the back of the engine too many times. 

[dave the builder]

your highest coolant temperature reading H is 76 degrees
the engine coolant is reading too low and the ECU will still overfuel as a cold start ,92 is running temp
also, the cat needs to be hot , a common problem , drop it off for MOT ,sits for hours till cold and then they try an emission test 
what did it fail on ? C0 high ? HC high ? lambda out of range ? need the actual numbers to know what to look for 
also , your data shows engine speed @ 1300-1400  what is going on ? does the tacho match the data ?
it suggests air leak
what are the fuel trims like ?

[addy]

MOT tester doesn't let the car get cold, as you say some do.  Natural Idle. CO .376  Fast idle CO .530 HC 81 LAMBDA 1.021

[dave the builder]

MOT tester doesn't let the car get cold, as you say some do.  Natural Idle. CO .376  Fast idle CO .530 HC 81 LAMBDA 1.021

Lambda is high side of 1 so too much fuel
C0 needs to be 0.3 or less @ 2500rpm or more for the win
from your live data 76 degrees is showing 1.48 volts
at 90+ degrees it should be down to near 1 volt ,normal running temp map
are you 100% sure you have no exhaust or manifold leaks  or intake air leaks
is the wet stat working correctly 92 degrees  ? stuck open it will goose the emissions

did the tester wait for the cooling fans to kick in  or use an ODB2 dongle plugged in to the car ,or oil temp probe to confirm oil over 80 degrees , or did he click SKIP 
check operation of the wet stat 
get the car up to temp,fans kicking in , check fuel trims, coolant temp in degrees c and voltage
air filter clean ?

[addy]

Natural idle
RPM 790 PASS
CO .376  PASS

First fast idle
RPM 2846 PASS
CO .530
HC 81 PASS
LAMBDA 1.021 PASS

Second fast idle
RPM 2864 PASS
CO .530 FAIL
HC 80 PASS
LAMBDA 1.019 PASS

As far as can tell or hear no leaks. Does a new thermostat come with the housing, or can you get the stat to fit in the housing? Did full oil, plugs, plug leads and airfilter service before mot.

Oil temp is shown on test paper as 84, it says the fans kicked in.

[dave the builder]

so ....

check operation of the wet stat 
PLUS ,get the car up to temp,fans kicking in , check fuel trims, coolant temp in degrees c and voltage

was it a cheap and nasty new cat ?

[Doctor Gollum]

Testing parameters of the 2.0 Omega...

normal idle: a) CO, b)idle speed min/max.
fast idle: c)CO, d)max HC ppm, e)lambda min/max, f)rpm min/max, g)minimum temp.

Engine Code X20SE/OHC a)0.5 b)670/1030; c)0.3 d)200 e)0.97/1.03 f)2800/3200 g)80
Engine Code X20XEV/DOHC a)0.5 b)670/1030; c)0.3 d)200 e)0.97/1.03 f)2800/3200 g)80

Taken from Annex of testers emissions.

[dave the builder]

as per the 7th post on this thread by me 

still needs 0.5 or less C0 fast idle
close but no cigar so far

[Enceladus]

The set of emission test results you posted yesterday seem to be identical to the original set from a month ago? That seems to be a bit unlikely.
It might help if you would clarify what exactly you have done in the meantime?

EG. do we correctly understand that you replaced the coolant temperature sender for the ECU?
Then you renewed the whole exhaust complete with the catalytic down-pipe from the manifold?
And then you replaced the Lambda sensor with a new NGK one?
Has the car actually had the emissions re-tested?
Or are you assuming that the high CO issue is still present as the cycling from closed to open loop is still present?

Maybe the thermostat is stuck open so the engine doesn't get to full temperature.

I imagine it would be worthwhile to check the fuel trim. When in closed loop perhaps the fuel trim reaches the limit of it's adjustment range and the system falls back to open loop until a valid reading is supplied by the sensor?

[addy]

YES it has had the emissions done, I looked at wrong emission paper.

This is the one done 9/12/19 second one

This is with new exhaust from down pipe to back box. Brand new O2 NGK sensor (Correct one for car). Waited replies about live data on the temp sensor. Got one now to fit.

Engine speed measurement was by-passed
Engine oil temp was by-passed cooling fan cut in.

FAST IDLE

RPM Not checked
CO 0.450          FAIL
HC 152             PASS
LAMBDA 1.015 PASS

NATURAL IDLE
RPM Not checked
CO 0.440 PASS

When temperature goes up on temp gauge, the fans kick in and the temp comes down to around 90, so doesn't that mean the stat is working correct?

The closed to open loop was happening both before and after doing the changes explained above.