S2 MOT failure on emissions
Discussion
Hi, my S2 failed its MOT today on emissions, CO should be less than 3.5 at idle but mine came in at 4.2. On previous MOTs it has varied around 1.5ish. The MOT man suggested I check air filter for cleanliness, oil level, power boost valve adjustment, air flow meter operation, oil level and ECU (for fault codes).
I've checked the oil level and it is about perfect (3/4 the way up between min and max marks).
I'll clean the air filter tomorrow, but can't see this being the problem because I only changed it two years ago and I've only done 2 to 3000 miles since. I'll also pull the spark plugs and check condition and gap.
Does anyone have any suggestions for other things I should check? I'm hoping to be able to borrow a fault code reader at the weekend.
How do I clean the air flow meters? spray carb cleaner inside?
Thanks,
Ralph
I've checked the oil level and it is about perfect (3/4 the way up between min and max marks).
I'll clean the air filter tomorrow, but can't see this being the problem because I only changed it two years ago and I've only done 2 to 3000 miles since. I'll also pull the spark plugs and check condition and gap.
Does anyone have any suggestions for other things I should check? I'm hoping to be able to borrow a fault code reader at the weekend.
How do I clean the air flow meters? spray carb cleaner inside?
Thanks,
Ralph
When my engine was "set up" by Austec I recall the guy saying that if I had problems with emissions at MOT time I should "tweak" the adjusting screw on one of the AFU's, but don't remember which one, but if I had to take a guess I'd say top one top one/black plug ?
Fortunately I know a TVR friendly garage
Barkychoc said:
You could always just remove the air filter for the MOT and put it back on afterwards, it will weaken the mixture slightly.
Nope the ECU will compensate!I had an identical problem on 'Joseph' Bobhon's ex car and it turned out that the emmissions had been borderline previously because the throttle pot had been replaced and the wiring not changed to match (gold contacts TP have the two outside connectors reversed compared to the original silver model) But that wont help if the TP hasent been changed, but I would check anyway.
Dont forget phillpot has my old Star Tester, why not ask him if its available
Failing all else give Adrian Venn a ring he sorted Joseph for me
Gerald-TVR said:
Nope the ECU will compensate!
I had an identical problem on 'Joseph' Bobhon's ex car and it turned out that the emmissions had been borderline previously because the throttle pot had been replaced and the wiring not changed to match (gold contacts TP have the two outside connectors reversed compared to the original silver model) But that wont help if the TP hasent been changed, but I would check anyway.
Dont forget phillpot has my old Star Tester, why not ask him if its available
Failing all else give Adrian Venn a ring he sorted Joseph for me
Unless it's an S3C it can't compensate as the engine doesn't measure emmissions. I had an identical problem on 'Joseph' Bobhon's ex car and it turned out that the emmissions had been borderline previously because the throttle pot had been replaced and the wiring not changed to match (gold contacts TP have the two outside connectors reversed compared to the original silver model) But that wont help if the TP hasent been changed, but I would check anyway.
Dont forget phillpot has my old Star Tester, why not ask him if its available
Failing all else give Adrian Venn a ring he sorted Joseph for me
Thanks for the responses for far. I've taken the air filter off and it looks clean, the female electrical connectors on the lower AFM were a bit green so I removed metal clips from the plug and gave them a good clean with emery paper.
The AFMs looked like this inside:
Upper:
Lower:
I've cleaned them up as best I can using brake cleaner. Is the level of dirt in the lower AFM likely to have caused the issue?
Phillpot - the power boost valve is also called an adjustable rising rate fuel pressure regulator. The marketing bumpf states that unlike a normal fuel pressure regulator it allows a substantially increased amount of fuel to the injectors at like revs. It looks good under the bonnet and may add an extra couple of horses, however the man at Austec did suggest that nowadays he reccommends just fitting an adjustable fuel regulator which gives the benefits for lower cost.
Ralph
The AFMs looked like this inside:
Upper:
Lower:
I've cleaned them up as best I can using brake cleaner. Is the level of dirt in the lower AFM likely to have caused the issue?
Phillpot - the power boost valve is also called an adjustable rising rate fuel pressure regulator. The marketing bumpf states that unlike a normal fuel pressure regulator it allows a substantially increased amount of fuel to the injectors at like revs. It looks good under the bonnet and may add an extra couple of horses, however the man at Austec did suggest that nowadays he reccommends just fitting an adjustable fuel regulator which gives the benefits for lower cost.
Ralph
I'm guessing the wire sensor is an air temp sensor - unfortunately I reckon that a dirty temp sensor would probabely still function reasonably OK.. There is a little sprung door that opens to measure airflow. This seemed to be operating OK. Hopefully someone will be able to correct me on the first point...
Ralph.
Ralph.
Only one of the AFM's measured the air temperature, and its the one with 4 wires connected cant remenber which one and anyway the connectors can be just swapped over so you will need to count wires to be sure.
I dont recall seeing the black lump one other AFMs and it looks as though someone has added it to me.
The comments below are from an article in the Feb 1995 Car Mechanics magazine.
"When setting the ignition timing the management system must be put into code 60 which represents a service state and puts the ignition timing into a flat or fixed timing mode (the SPOUT signal is removed). This enables the base timing to be set at l2° BTDC and also parks the idle control valve. Achieving code 60 setting officially requires a code-reader but, Frank says there is a shortcut. Disconnecting the throttle pot switch will default the system into code60 (but will, of course, generate a faultcode as well).
With the engine running on code 60the tickover should be smooth (at about 850 rpm) and it will then be possible to set the timing with a strobe light - twisting the distributor body as required. Exiting from code 60 will re-introduce the idle control and ignition map after which the fuel•air ratio must be tackled.
Because there are twin air flow meters there can be a conflict between the two in terms their outputs to the ECU. As a rule of thumb set the air bleed screw on the rear meter (when fitted to the Granada one was behind the other. The rear meter had 3 wires connected as it did not measure the air temperature) to the fully closed position. The one on the front meter (four wires connected measuring air temperature) should be adjusted normally to produce a CO content of about 1.5%. If this cannot be achieved by adjustments on the front meter alone then open up the bleed on the rear one progressively until the correct figure is obtained. Frank’s persona method is to bleed a little off both meters to achieve the right level.
Drop me a pm if you want a copy of the full article orginally sourced from TVRgit
ETA Granada engine bay pic
I dont recall seeing the black lump one other AFMs and it looks as though someone has added it to me.
The comments below are from an article in the Feb 1995 Car Mechanics magazine.
"When setting the ignition timing the management system must be put into code 60 which represents a service state and puts the ignition timing into a flat or fixed timing mode (the SPOUT signal is removed). This enables the base timing to be set at l2° BTDC and also parks the idle control valve. Achieving code 60 setting officially requires a code-reader but, Frank says there is a shortcut. Disconnecting the throttle pot switch will default the system into code60 (but will, of course, generate a faultcode as well).
With the engine running on code 60the tickover should be smooth (at about 850 rpm) and it will then be possible to set the timing with a strobe light - twisting the distributor body as required. Exiting from code 60 will re-introduce the idle control and ignition map after which the fuel•air ratio must be tackled.
Because there are twin air flow meters there can be a conflict between the two in terms their outputs to the ECU. As a rule of thumb set the air bleed screw on the rear meter (when fitted to the Granada one was behind the other. The rear meter had 3 wires connected as it did not measure the air temperature) to the fully closed position. The one on the front meter (four wires connected measuring air temperature) should be adjusted normally to produce a CO content of about 1.5%. If this cannot be achieved by adjustments on the front meter alone then open up the bleed on the rear one progressively until the correct figure is obtained. Frank’s persona method is to bleed a little off both meters to achieve the right level.
Drop me a pm if you want a copy of the full article orginally sourced from TVRgit
ETA Granada engine bay pic
Edited by Gerald-TVR on Thursday 21st June 11:53
Gerald-TVR said:
Nope the ECU will compensate!
I had an identical problem on 'Joseph' Bobhon's ex car and it turned out that the emmissions had been borderline previously because the throttle pot had been replaced and the wiring not changed to match (gold contacts TP have the two outside connectors reversed compared to the original silver model) But that wont help if the TP hasent been changed, but I would check anyway.
Dont forget phillpot has my old Star Tester, why not ask him if its available
Failing all else give Adrian Venn a ring he sorted Joseph for me
Actually Norman thinking again I agree with you - removing the air filter alters the airflow - and what does the AFM do? I had an identical problem on 'Joseph' Bobhon's ex car and it turned out that the emmissions had been borderline previously because the throttle pot had been replaced and the wiring not changed to match (gold contacts TP have the two outside connectors reversed compared to the original silver model) But that wont help if the TP hasent been changed, but I would check anyway.
Dont forget phillpot has my old Star Tester, why not ask him if its available
Failing all else give Adrian Venn a ring he sorted Joseph for me
Barkychoc said:
Gerald-TVR said:
Nope the ECU will compensate!
I had an identical problem on 'Joseph' Bobhon's ex car and it turned out that the emmissions had been borderline previously because the throttle pot had been replaced and the wiring not changed to match (gold contacts TP have the two outside connectors reversed compared to the original silver model) But that wont help if the TP hasent been changed, but I would check anyway.
Dont forget phillpot has my old Star Tester, why not ask him if its available
Failing all else give Adrian Venn a ring he sorted Joseph for me
Actually Norman thinking again I agree with you - removing the air filter alters the airflow - and what does the AFM do? I had an identical problem on 'Joseph' Bobhon's ex car and it turned out that the emmissions had been borderline previously because the throttle pot had been replaced and the wiring not changed to match (gold contacts TP have the two outside connectors reversed compared to the original silver model) But that wont help if the TP hasent been changed, but I would check anyway.
Dont forget phillpot has my old Star Tester, why not ask him if its available
Failing all else give Adrian Venn a ring he sorted Joseph for me
Maffe said:
I´m little surprised that no one have tried the ethanol trick, or even bother to talk about it
It have saved my old cars for many years
Well then next year we'll all be fine when the E10 fuel come on line...Assuming it doesn't just melt all the fuel lines, o-rings, injectors etc first...It have saved my old cars for many years
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