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post #1 of 21 (permalink) Old 01-02-2017, 08:57 Thread Starter
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Unhappy TF Emissions failure

Hi ! I'm new happy owner of MGTF 135 (10/2003, Royal blue/beige leather, chrome details) in Finland. Car didn't pass the emission test. On idle HC ppm is too high. Result:
On Idle
CO% 0.1 ok
CO2% 15.1 ok
HC ppm 235 NOT OK

On higher rpm
CO% 0.1 Ok
CO2% 15.3 Ok
HC ppm 77 Ok


Sparkplugs changed but check them again one is still black and littlebit wet and others are ok. I havent seen any visible coolant leaks outside the engine. No coolant smell. Temperature is normal. Car goes well. On idle only a little petrol smell from exhaust. Engine yellow warning light is on. OPD failure code P0170. Has Anyone had same kind of problem ? Fuel injector fail, coils/leads or HGF ?
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post #2 of 21 (permalink) Old 01-02-2017, 09:28
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I don't know the codes but I had a similar problem last year and my IACV was the problem. I also needed to reset the throttle.

I took the IACV off and cleaned it of the sooty deposits. I used brake cleaner with no ill effect.

The engine should idle steadily at around 800rpm. I reset my throttle. To do this, I warned the car up to operating temperature. I switched off then switched on to position 2 on the ignition (did not start the car) I pressed the accelerator 6 times in 30 seconds, waited 15 seconds and turned ignition off. The car had been idling erratically at around 1100 revs with some hunting. After the reset, the car is steady at 800 rpm or thereabouts.
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post #3 of 21 (permalink) Old 01-02-2017, 09:56
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you have probably highlighted all the things to check in your post.. but...think on this... its a clue..:

1. unburnt fuel means its not being burnt.. its reaching the cylinder, not burning completely or at all, then being pushed out into the exhaust.

2. has the engine warning light come on? if not...the ecu isnt registering a fault from sensors , neither is it having a problem setting up the air fuel mix,
so i would use an obd reader to see if it could tell me of any faults that the ecu isnt flagging. you have a fault code-p0170

i would expect that unburnt fuel in the exhaust. to mess up the oxy sensor function.. and it will naff up the catalytic convertor. so not to see an ecu fault code displayed by it turning the engine warning light on, means that the ecu is still able to keep the air fuel mix ratio in range... thats tells one the ecu cant see a fault.. yet. https://en.wikipedia.org/wiki/Exhaust_gas

3. if there are no fault codes and the car " appears" to run ok.. then something that the ecu cant see, and cant indicate --- is happening... what might that be?

the ecu is trying to set the mix, its still doing that within its operating range, the oxy sensor isnt going out of range, the injectors, cam and valve control isnt flagging fault to the ecu...

so..

4. its something after all the sensors?

spark plug not firing, even though the ecu is telling it to and cant see any prior ignition faults - that could be caused by a duff ignition circuit.. ie no high voltage generation, duff lead, shorted lead, duff plug.. all of those are after the ecu sensing..

i would check the whole ignition circuit, its connectors, supply, the coils, the leads, the plugs...

5.valve not closing properly.. not every time... but some of the time.. before the fuel has burnt... that could be difficult to investigate, because one might not see it with a static compression test, if it only happens at certain revs or at certain times..

6. valve not opening properly...not every time... but some of the time.. before the required amount of air for the fuel being delivered is the right mix.. an air intake valve problem..


7. - 5 and 6 are not common problems.. and usually are indicated by odd engine noises, and bad running, and idling.. even tapping noises on a regular basis if the timing starts to go way off... 5 and 6 are bad news, because the ecu cant see those faults.

your fault is more likely to be an electrical ignition fault, than a mechanical one.. given that you know the condition of the engine isnt far out.. just not meeting the spec..

and just one plug, being black and wet, not all four,,, is giving you a pointer which part of the ignition to look at.

8. if you are absolutely sure, that the ignition circuits are A1, but still get one black and wet plug.. it could be a cylinder problem, and you are getting oil into that cylinder, that is stopping the plug firing and contaminating the mix. i hope its not


as an aside.. a duff iacv will affect all four cylinders.. not just one. and the mix ratio wont be able to be set by the ecu, which should flag a fault... i.e it cant set the iacv.. it tries to.. but the mix stays wrong, and goes out of range..

you get a p0170 fault code because the oxy sensor is being contaminated by unburnt fuel.. and you have one wet plug not four wet plugs...... thats where the fault is. not the oxy(lambda) sensor...not the iacv... but the plug not firing.

9. if you clear the faulty plug ignition problem and are absolutely sure all four plugs burn the fuel properly, but still get a p0170 fault code.... then maybe the lambda sensor has gone awol...fried itself.. because if the air fuel mix is good, the lambda should burn of the contaminants, the exhaust should clear them out... and a good run should mean the car will pass its emission test..





.

Last edited by Incony; 01-02-2017 at 10:48.
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post #4 of 21 (permalink) Old 01-02-2017, 10:36 Thread Starter
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Thank you for the quickly answers. Yes
- only one spark plug is black
- yellow engine lamp is on
- problem seems to be only on idle speed

First I'll check the spark plug leads (if problem is in coil, 2 plugs should be black, is that correct ?)
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post #5 of 21 (permalink) Old 01-02-2017, 10:52 Thread Starter
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Thanks for the quickly answers. Yes:
- yellow engine warning light is on
- only one spark plug is black
- problem seems to be only on idle rpm

First I'll check spark plug leads. If the problem would be in coil, two spark plugs should be black, is that correct ?
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post #6 of 21 (permalink) Old 01-02-2017, 13:28
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High HC's are because of unburnt fuel. Probably as a result of a misfire. Changing the spark plugs is a good first plan. Next would be to change the HT leads. If you know which cylinder is affected (one of the spark plugs looks different to the others), then swap the components about to see if the fault moves. Then you know which component is faulty. The fault code is probably because of the misfire but could also be a leaky injector too. (those can be swapped to see if the fault moves too - or tested and fixed if they are obviously dribbling)
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post #7 of 21 (permalink) Old 15-02-2017, 17:20 Thread Starter
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Both coils, all HT leads and spark plugs changed. Fault code P0170 reset and it is not yet coming back (I bought cheap, 49; OPD reader, works fine ). But 1 plug is still getting black on idle rpm. And when engine is warm idle is not completely stable.

Next I will change one fuel injector. If it doesn't help - then I'll remove cylinder head or has anyone other suggestions ?
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post #8 of 21 (permalink) Old 15-02-2017, 18:32
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You could just swap the injectors round to see if the problem moves to another cylinder. A compression test could be a good idea before pulling the head off.
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post #9 of 21 (permalink) Old 15-02-2017, 19:46
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dont touch the head yet... you need to be sure its not an air or compression related problem. i go with what barkingdog says... if the injector isnt shutting off properly - you get excess fuel..., if its a "sticky" or a not seating properly valve... the compression will be low.. and a god forbid that its a ring or the head gasket.

it could also be residue in the cylinder that you have now cured by sorting the electrics...

i think you need to warm the engine, and take it for a spin to the redline.. then let it rest on idle for a few minutes and have another look... make the engine do some work..

it still might be that the oxy sensor isnt giving the ecu good readings because of the contamination in the down pipe... so i would want to be sure i had got rid of old carbon from unburnt fuel..




if after all that, one plug is still being contaminated.... then its water or oil getting into the cylinder...

but.. i think if that happens the ecu will see it.. via the oxy sensor... and flag a fault code still..?
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post #10 of 21 (permalink) Old 15-02-2017, 23:31
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My guess would be an oil leak, possibly a valve stem.


Everything else has been replace and you aren't showing any errors, therefore it must be a system outside of the ignition system.


Oil in the cylinder would increase HCs too.
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post #11 of 21 (permalink) Old 25-02-2017, 12:13 Thread Starter
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nr. 4 plug is still wet/black

Compression test results:
- cyl 4. 14,5 kg/cm2
- cyl 3. 14,0
- cyl 2. 13,0
- cyl 1. 14,0
I think they are ok ?

Fuel and air filter changed, oil and filter changed

- Forte valve cleaner work done (slowly measure out whole spray bottle directly to inlet manifold when 1800 - 2000 rpm).
- STP injector cleaner 2 bottles to full fuel tank

Engine light came on when motor was fully warmed. Fault code P0170 again. cyl 4. plug is wet and dark. (oil or fuel, I don't know exactly)

i didn't change the fuel injector nr. 4 because I think it needs to remove whole inlet manifold. Is that correct ?

Investigation to be continued.....
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post #12 of 21 (permalink) Old 26-02-2017, 10:18 Thread Starter
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Fuel injector nr. 4 changed

Was not so difficult. Only upper part of inlet manifold has to remove (6 bolts) before your get to the fuelrail and injectors.

But, nr. 4 spark is still getting dark and wet on idle. Now I really don't know what to do next
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post #13 of 21 (permalink) Old 26-02-2017, 10:33
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What did you do when you had the fuel rail/injectors off?

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post #14 of 21 (permalink) Old 26-02-2017, 10:57
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Quote:
Originally Posted by Dickybeau View Post
......I switched off then switched on to position 2 on the ignition (did not start the car) I pressed the accelerator 6 times in 30 seconds, waited 15 seconds and turned ignition off.....
The official method from MGR is firmly and fully FIVE times in 30 seconds, wait THIRTY seconds.
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post #15 of 21 (permalink) Old 26-02-2017, 11:07
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Swap that injector.
You could even just unplug it, the car will only run on three but you will be able to check if the spark plug still gets wet.
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post #16 of 21 (permalink) Old 26-02-2017, 11:07 Thread Starter
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Quote:
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What did you do when you had the fuel rail/injectors off?
I changed nr. 4 (first from left, first from gearbox side) fuel injector.
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post #17 of 21 (permalink) Old 26-02-2017, 11:39 Thread Starter
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Wet plug

Wet and dark plug is on the workbench now. What is the right method to be sure is that wet oil or fuel ?
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post #18 of 21 (permalink) Old 26-02-2017, 13:46
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Wet and dark plug is on the workbench now. What is the right method to be sure is that wet oil or fuel ?
Smell and texture.

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post #19 of 21 (permalink) Old 26-02-2017, 15:13
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Petrol will evaporate, oil wont.
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post #20 of 21 (permalink) Old 26-02-2017, 17:39
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I usually just put a lighter under the plug as soon as it's removed, soon tell if it's petrol or oil.
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