Ford Focus 1.6 ti vct - Help with emissions fault for mot

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Mon 27 Jun 2016 17:16
Ford Focus 1.6 ti vct - Help with emissions fault for mot - Veed79
Hi, I'm after some help with emissions on my Mrs Ford Focus its the 1.6 to vct engine, management light came on little while ago and came up with p0036 o2 sensor.

knowing it was due an mot soon I got a friend to do an emissions test first to see if it would pass but it didn't he said it was just over.
So bought new sensor couple weeks later took it to mot garage and asked them to fit before they they mot it, they put there scanner on and it to check which one was faulty and it came up with an additional fault p0056 as well so seems like they've both registered a fault, according to the codes these are both number 2 sensors after the cat bank 1 and bank 2. Garage replaced them both reset codes and light went out ok but car refused to pass emissions test still.

So need help with next step,mechanic said both sensors were pretty coked up and asked when plugs where last changed, told him we'd only had the car 7 months so not to sure service history showed it had been regularly serviced but didn't show plugs and air filter changes. So I'm going to replace plugs and air filter anyway is it worth trying some cat cleaner? Or is it likely that if both them sensors have failed the cat is already had it?
Cheers guys
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Mon 27 Jun 2016 21:16
Ford Focus 1.6 ti vct - Help with emissions fault for mot - elekie&a/c doctor

So ,did the diagnostic tester actually say replace the o2 sensors.or was that a guess??Fault codes are only a rough guide.I would think more investigation is needed.

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Mon 27 Jun 2016 22:17
Ford Focus 1.6 ti vct - Help with emissions fault for mot - Veed79
Well I reset fault codes and sensors fault would come back instantly and I searched a bit on google and seemed like it could be the sensors failing so it was more me being swayed by what I read, but now they've been changed the fault codes have not returned so can only think that they was faulty or surely the light would have come back on?
But yes definitely needs more investigating as although it has cured the management light being on I still need to sort emissions.
Where would be the first place to start investigating? Changed air filter going to do the plugs next and maybe car cleaner? Quite happy to do a bit myself if I can.
Just wondering if the cat was damaged possibly by the high emissions would the management light not come back on? As I thought that's what the number 2 sensors did, monitored the cat efficiency?

Forgot to mention earlier that mpg is at 27 at moment I'm guessing that's low for this engine dunno if that's relevant.
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Tue 28 Jun 2016 00:24
Ford Focus 1.6 ti vct - Help with emissions fault for mot - bathtub tom
Forgot to mention earlier that mpg is at 27 at moment I'm guessing that's low for this engine dunno if that's relevant.

That's disgusting, unless it's only doing short journeys.

What does the temperature gauge show? It may not be reaching optimum working temperature and running rich. Do you have any service history? Have you owned it for long? May be worth changing the thermostat if the temperature gauge is showing cool after a decent run.

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Tue 28 Jun 2016 08:46
Ford Focus 1.6 ti vct - Help with emissions fault for mot - elekie&a/c doctor

Can you post up the emissions test results?

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Tue 28 Jun 2016 13:34
Ford Focus 1.6 ti vct - Help with emissions fault for mot - slkfanboy

If the air filter is coked up and the plug old then it's lightly to be running rich.

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Tue 28 Jun 2016 18:28
Ford Focus 1.6 ti vct - Help with emissions fault for mot - Veed79
Air filter wasn't too bad but not checked plugs yet gonna hopefully change tomorrow night, guy also mentioned to check for any air leaks if I can so will have a look as much as I can.
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Tue 28 Jun 2016 18:25
Ford Focus 1.6 ti vct - Help with emissions fault for mot - Veed79
I haven't got them as I picked the car up when they'd all gone home he mentioned on the phone what they was but I can't remember but do remember him saying they was only just out, if it's still out after the plug change when I take it back il make a note of them and post up
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Tue 28 Jun 2016 18:24
Ford Focus 1.6 ti vct - Help with emissions fault for mot - Veed79
I was wondering if it had anything to do with thermostat as when we bought it 7 months ago I noticed temp gauge hardly moving at all mentioned it to dealer and he said he will sort it out, Mrs picked the car up and when she got home noticed it wasn't working still. Took it back and said think the thermostats playing up so dealer had it changed and now it's fine sits on half way once warmed up.

Guess if it's been running cold for a while then that's not gonna help running rich and could have damaged plugs and cats? but should still be better than 27 mpg now thermostats changed Mrs does do short journeys but her last car was focus 1.8 Zetec and doing same journeys it was averaging more than that.
It's got service history but it's just been stamped with mileage and date they've not actually ticked the little box to state what they've changed. I've done air filter gonna change plugs hopefully tomorrow and take it on a run and garage said bring it back in and test emissions again.
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Tue 28 Jun 2016 20:21
Ford Focus 1.6 ti vct - Help with emissions fault for mot - John F
Forgot to mention earlier that mpg is at 27 at moment I'm guessing that's low for this engine dunno if that's relevant.

If so, there must be something seriously wrong. Our old 1.6 Focus with twin non-variable camshaft sprockets does between 35-40mpg. Might be worth giving it a good thrashing when warmed up; max revs in low gears; blow out any cobwebs? How many miles has it done?

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Wed 29 Jun 2016 00:52
Ford Focus 1.6 ti vct - Help with emissions fault for mot - Veed79
It's just done 90,000 was gonna give it a run on motorway after the plug change is that cat cleaner a good idea or is it a waste of £15?
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Wed 29 Jun 2016 17:02
Ford Focus 1.6 ti vct - Help with emissions fault for mot - hardway

I have used "Cat a clean" and have to say it does work.

But it does not fix what caused the cat to become blocked in the first place.

You need to be checking it right,

What are the STFT and LTFT doing,

And rather than replacing the o2 sensors read what is their output readings.

Just renewing parts is going to end up costing way more than getting someone who knows what they're doing to scan it.

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Wed 29 Jun 2016 23:32
Ford Focus 1.6 ti vct - Help with emissions fault for mot - Veed79
Yeah I understand the codes don't always tell what's at fault more point you in a direction, seems like he did take a bit of a chance just changing o2 sensors, although he didn't say if he tested voltages, but in saying that seems like they was causing management light to come on and register fault codes as since they've been changed light has stayed off were as before the light would come back on right after cancelling it.
Though I agree it seems it has not cured the emission fault.

Do the number 2 sensors have any control over adjusting the fuel mixture or are they just there to monitor the cat?

Also it could be really obvious but what does STFT and LTFT stand for?
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Wed 29 Jun 2016 23:36
Ford Focus 1.6 ti vct - Help with emissions fault for mot - Veed79
Changed plugs and apart from the fact they was super tight they didn't look that bad, (although I'm no expert) they wasn't black more of a white colour than I was expecting.
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Thu 30 Jun 2016 10:22
Ford Focus 1.6 ti vct - Help with emissions fault for mot - hardway

STFT and LTFT are both monitors of fuel control.

Short term fuel trim is how much fuel is being added/subtracted in running conditions.

Long term is as stated how much fuel has been added over time.

So looking at the trims would tell me if the car has/is running rich or lean.

As for the o2 sensors scanning them when running in conjuction with the STFT would tell me if there is a fueling problem,a vacuum leak or a number of other possibles.

You trims really ought to be around + 5 -5.

Any more then say +5 on the STFT means it's over fuelin,-5 means under fueling but your MPG isn't too good so unlikely.

That a basic understanding but there's a lot more to diagnostics than reading a scanner.

Understanding what a scanner is telling you is the skilled part.

And it would appear that your garage is lacking in the skill part.

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Thu 30 Jun 2016 14:13
Ford Focus 1.6 ti vct - Help with emissions fault for mot - Railroad.
Totally agree with the above. The system is known as 'Closed Loop' meaning the O2 sensor reports to the ECM, which then in turn responds to that information. STFT is the O2 sensor telling the ECM the overall state of the air/fuel mixture. A positive % means the engine is running rich by that amount, and a negative % means it's running lean.

LTFT is the ECM's corrective response to STFT. A positive % means the ECM is adding fuel in response to a lean condition. A negative % means the ECM is reducing fuel in response to a rich condition.

As Hardway says, if your garage don't know or understand this then go elsewhere to someone who does.
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Thu 30 Jun 2016 21:02
Ford Focus 1.6 ti vct - Help with emissions fault for mot - Veed79
Righto I get the idea now but yeah seems there's a lot more to it than I'm going to be able to do and that's the next step to find out what exactly it's doing and how it's running.
Not sure where everyone who's posted on this thread is from but don't suppose anyone knows of a garage in or near the Epsom area that they have experience with or can recommend?
If I can be recommended one its a lot easier than trying to find one I can trust. The only garage I used to use and trusted sold up and moved away.
Thanks for all the help guys
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