Ford Focus MOT Emissions failure

[Tony427]

Just had the Mrs 1.6 Ford Focus Zetec fail on CO emissions on fast idle.

The Limit is 0.2% whereas the Focus was showing between 0.57 and 0.46% at fast idle, 0.25 at natural idle.

The engine check light has been on recently and my cheap hand held fault code reader tells me that their is one fault code and it is N/A 01/01 which unfortunately does not seem to be listed in the accompanying booklet listing fault coes.

I suspect a simple air leak around the cat area.

Before I start scrabbling about underneath the car stripping down joints etc would those in the know agree with my hypothesis.

Cheers,

Tony

[stevieturbo]

It is running slightly rich. First thing to check would be lambda sensor operation.

I assume the hydrocarbons were ok ? Lambda ? You only mention CO.

[Tony427]

Lambda was 1.011 on first fast idle and 1.003 on second fast idle ie pass on both, when the hydrocarbons on the second also went up 392ppm.

Cheers,

Tony

[Tony427]

Right guys this car is doing my fecking head in.

2003 Ford Focus with 106k on the clock which will not pass the high idle test because both myself and the garage cannot get the car to idle at 2500rpm without the revs dropping off, hence test has to be abandoned.

Th car will sit quite happily at a consistent, constant 2000 rpm, 3000rpm no problem, but go above 2200 rpm and the revs start to rise and then fall, and then rise again etc etc.

There are no fault codes showing nor are there any inlet air or exhaust leaks. Given the old adage that anything is fixable if you throw enough money at the problem I have so far done the following.

I have cleaned both the idle control valve and the throttle body/ butterfly valve so that they are now spotless. Cheap and I like the smell of carb cleaner.

More expensively the car now has a new Lambda sensor, a new throttle position sensor, a new MAP sensor, a new coil pack, new plugs ( gapped to 1.3mm as stipulated in the workshop manual) and new plug leads. The air filter is also new.

Why wont this thing hold a fast 2500 rpm idle?

Any guidance welcome as the Mrs, whose car it is, is losing her faith in my ability to keep our cars on the road and has started to suggest getting her a new car instead of spending money on my V8 toys.

Cheers,

Tony

[skeggysteve]

Tony427 said:

the revs start to rise and then fall, and then rise again etc etc.

I know you say no inlet air leaks but that does sound like there is an inlet air leak!

The ECU is detecting extra air so is sticking more fuel in and so the revs rise etc.

With problems like this I find it best to use common sense and go back to basics.
Hope this helps and best of luck getting it sorted.

[adam1984]

Check the rubber breather hose behind the plastic inlet manifold is not split changed a good few of these on 1.4 & 1.6 zetecs

[Tony427]

Hi Guys,

Thanks for the advice. Just to clarify the problem when I say the revs rise and fall its only because when you try to set a steady 2500rpm the revs start to drop off, so you have to push on the throttle to get the revs back up, they shoot past 3000rpm whereupon you slightly release the throttle and back down they come to sub 2000rpm.

Basically at a stationary idle you have no throttle control between 2000 and 3000 ropm. However on the road, when the engine is under even a slight load the car behaves faultlessly.

I've just checked all the hoses again , this time spraying copius quantities of butane gas all over the inlet manifold, around the throttle body and over all the likely culprit pipes and the engine didn't pick up at all...

If there was an inlet leak, even hidden, with the amount of gas I put over the engine its inconceivable that some wouldn't have found its way into the inlet tract.

Keep your ideas coming, any help welcome.

Cheers,

Tony

[Tony427]

Hi Guys,

Still having a problem with the Focus unable to hold a high idle between 2200 and 2900rpm. Revs to 3000rpm, holds it for a few seconds then drops to 2200 rpm and starts "hunting". Whilst revs are dropping no throttle inputs have any effect.

Took it for a computer diagnostics check at the weekend and there's no fault codes, but the technician said there's two possible causes, the idle control valve and the second O2 sensor after the cat.

I have therefore replaced both, with absolutely zero effect.

Suffice to say I've spunked loads of cash on relacing the following and its all been wasted.

Diagnostic check who couldn't find anything wrong.

New coil pack.
New plugs ( leads only 15,000 miles old)
New idle control valve
New Pre cat O2 sensor.
New Post cat O2 sensor
New Absolute Manifold pressure sensor.
New Throttle position sensor.

All of these things had zero effect.


The throttle body has been cleaned ( but was very clean anyway)and the air filter is only 5000 miles old.

Anyone got any ideas at all?

Cheers,

Tony

[stevieturbo]

TBH swapping parts at random, especially with new parts is sheer lunacy.

Didnt the "diagnostics" guy actually test any of the sensors or ignition system ?

And assuming all other aspects are fine, there is no exhaust leaks ( again 4/5 gas test would show this, so I'd assume any "diagnostics" person would test this ? )

Then whilst it is rare, there is a methodology that states when you have a problem with the fuel system, the first place to start is the fuel injectors.

[Tony427]

stevieturbo said:

TBH swapping parts at random, especially with new parts is sheer lunacy.

Didnt the "diagnostics" guy actually test any of the sensors or ignition system ?

And assuming all other aspects are fine, there is no exhaust leaks ( again 4/5 gas test would show this, so I'd assume any "diagnostics" person would test this ? )

Then whilst it is rare, there is a methodology that states when you have a problem with the fuel system, the first place to start is the fuel injectors.

Thanks for the info,

Yep, sheer lunacy indeed if the parts hadn't been suggested as the most likely ones being at fault, bear in mind that the car has been back on the exhaust analyser between each new part fitted. 5 times now.

The diagnostic connected up his Bosch machine went through a few programs, couldn't find anthing wrong apart from some "poor readings" on the rear O2 sensor and told me that that was the most likely culprit, either that or the ICV. I think now he was guessing much as his other mates where the MOT was done.

TBH the coil pack wasn't suggested but the Focus tends to eat coil packs ( 4 in the life of the car so far) so I put a new one on anyway as a winter precaution and kept the old one as a spare.

I see the logic in looking at fuel delivery , ( plus basically there's feck all left to change) but would the injectors create a situation whereby it would rev up to 3000rpm, then drop off down to a surging 2200 rpm even if the throttle pedal is opened.

I would presume that an injector test would be required ( hello Mr Diagnostic again) and probably a set of refurbed injectors......

Or could it be the throttle body, maybe the throttle plate/ disc isn't working correctly? How would I check this?

Cheers,

Tony

[TheEnd]

Bad cat?
That's the catalytic converters job to catalyse the CO in to CO2.

[stevieturbo]

Tony427 said:

Thanks for the info,

Yep, sheer lunacy indeed if the parts hadn't been suggested as the most likely ones being at fault, bear in mind that the car has been back on the exhaust analyser between each new part fitted. 5 times now.

The diagnostic connected up his Bosch machine went through a few programs, couldn't find anthing wrong apart from some "poor readings" on the rear O2 sensor and told me that that was the most likely culprit, either that or the ICV. I think now he was guessing much as his other mates where the MOT was done.

TBH the coil pack wasn't suggested but the Focus tends to eat coil packs ( 4 in the life of the car so far) so I put a new one on anyway as a winter precaution and kept the old one as a spare.

I see the logic in looking at fuel delivery , ( plus basically there's feck all left to change) but would the injectors create a situation whereby it would rev up to 3000rpm, then drop off down to a surging 2200 rpm even if the throttle pedal is opened.

I would presume that an injector test would be required ( hello Mr Diagnostic again) and probably a set of refurbed injectors......

Or could it be the throttle body, maybe the throttle plate/ disc isn't working correctly? How would I check this?

Cheers,

Tony

Most stuff are basic tests. You can buy a spark jumper for a few quid, or you can go for a fancy inductive current clamp and a scope to measure spark power.

Nearly all sensors are very basic either resistance or voltage. And any decent scanner will already show all of these signals anyway to see if they appear strange.
As well as injector pulse widths etc. And again, these are very easy to measure with a suitable voltmeter, or better still an oscilloscope.
Fuel pressure may be worth checking too, easy for any mechanic.

All tools which anywhere carrying out diagnostics should have.

So what are injector signals doing when the problem occurs ? are all sensor inputs/outputs stable ?
If they are, then it could point to a mechanical problem somewhere.

But it sounds like little or no proper diagnostic testing has been done if these questions cannot be answered ?

[Tony427]

Thanks for that, I'll have a look around for a trusted diagnosis bod rather than simply the guy in next door unit because he's convenient.

I had been hoping that someone somewhere has had a similar problem to mine and solved it, but it appears not.

Cheers,

Tony

[stevieturbo]

Just go through things in a sensible and logical way.

If all sensor readings remain stable with the problem occurs, then it would seem sensible that it isnt the ecu telling the engine to falter.
if injector pulse width and igniton timing remain constant when it falters....again, it's unlikely the ecu is causing it.

if however something changes dramatically, then the ecu may be telling the engine to change what it is doing, and then you need to establish why. Be it another electrical gremilin, or a mechanical issue.

But you seem to suggest the unstable rpm faulty is secondary to the non-MOT worthy emissions ? Although the two may be related as well.

Haynes used to d some books on Engine management, and Fault code reading/fault finding.
They do give fairly basic step by step how to test different sensors. There may be other similar books giving some info too.

I'm certainly not suggesting diagnosing faults is easy. Often it is far from it. But there needs to be some common sense applied to the process of going through finding any potential problems.

[Tony427]

stevieturbo said:

But you seem to suggest the unstable rpm faulty is secondary to the non-MOT worthy emissions ? Although the two may be related as well.

Thanks Stevie,

I think that the unstable and uncontrollable idle between 2200 and 3000 rpm is indeed symptomatic or even the cause of the poor emissions at the high idle part of the MOT test.

Something is indeed causing the ECU to make the CO unstable, as if its overcorrecting, but without any fault codes being logged. Prior to the MOT the engine was running sweetly ( and still does as long as you don't want to hold a fast idle without load), so a major mechanical fault does seem highly unlikely.

The MOT guy suggested I changed the TPS as he's seen a few faulty ones causing erratic idle and incorrect mixtures, and I could see the logic in his argument. When that didn't work you look at other things that affect the mixture, ie replace manifold pressure switch. Having also replaced the pre cat lambda sensor I opted to get a diagnosis from an expert, who it appears may not have been so expert as I could have suggested to replacing the second O2 sensor and the ICV thus saving me a diagnosis fee.

I was getting so fed up with the Focus I went out with the Mrs at the weekend and bought her a brand new Skoda Octavia replacement so at least we are both mobile, but this batle has now turned into a war of attrition and I will not let this Focus heap on the drive beat me.

But I will be buying shares in GSF car parts.........

Cheers,

Tony

[Simon says]

A faulty PCV valve as been the culprit of many running faults on the Zetec motor causing fluctuating RPM and throttle hesitation worth checking and cheap and may explain that high HC you mentioned earlier on

[Nigel Worc's]

Long long long shot Tony (my mate had a problem on his sons S40, not exactly as you have but sort of similar).

Have you tried a decent shot (straight into the manifold) of injector cleaner ?

[Tony427]

Simon says said:

A faulty PCV valve as been the culprit of many running faults on the Zetec motor causing fluctuating RPM and throttle hesitation worth checking and cheap and may explain that high HC you mentioned earlier on

This was next on my list following loads of research on almost every Ford Forum and indeed when last at the local car parts emporium ( Saturday) I asked them if they could supply me with a replacement PCV valve.

Unfortunately it appears to be a Ford Dealer Only part. However it is coming out tomorrow afternoon for a good clean at the very least. I will report back.

Cheers,
Tony

[Mr2Mike]

Nigel Worc's said:

Long long long shot Tony (my mate had a problem on his sons S40, not exactly as you have but sort of similar).

Have you tried a decent shot (straight into the manifold) of injector cleaner ?

What's the point of pouring injector cleaner straight into the manifold where it will get sucked straight into the engines without actually passing through the injectors?

[stevieturbo]

Tony427 said:

The MOT guy suggested I changed the TPS as he's seen a few faulty ones causing erratic idle and incorrect mixtures, and I could see the logic in his argument. When that didn't work you look at other things that affect the mixture, ie replace manifold pressure switch. Having also replaced the pre cat lambda sensor I opted to get a diagnosis from an expert, who it appears may not have been so expert as I could have suggested to replacing the second O2 sensor and the ICV thus saving me a diagnosis fee.

I'm afraid I dont see any logic in replacing parts without testing the old ones. Unless the new replacements are incredibly cheap, and very very easy to swap.

Whilst I havent read this specific book, I do have an older version. It is fairly basic, but also a good read for getting started.

http://www.haynes.co.uk/webapp/wcs/stores/servlet/...