Mk1.5 Focus Will Not Rev When Warm

[Blackie_No1]

No split in hose, just collapsed under idle but opens under throttle. The mechanic and I took it out a good run (has to do a minimum 6 mile test cycle on his diagnostic machine)

And no further codes found. We then came back and did a key test (key in, engine not running) and still no codes.

I'm currently on a run with a 18mile round trip, and so far so good.

Yea it can be tough to diagnose over the web, but suggestions where what I was after as I was baffled going on my own knowledge of cars and what my little scanner was telling me.

Thanks to all your input guys.

[wase16ll]

hope its sorted, but a strange set of symptoms for a bad sensor...

[Blackie_No1]

As do I wase, thanks again for your help

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[jeebowhite]

What was the total bill then?

[Blackie_No1]

Mates rates!! £60 sorted it, including fixing a radiator hose that decided to blow in his yard! Lol

He had to cut about 1.5 inches of the end of the hose as it was dozed/rotten.

[jeebowhite]

Not bad at all!

[Blackie_No1]

If its cured, yes lol

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[Blackie_No1]

Ok, not cured. I put £30 of fuel in the car after it was worked on which took it to just below half full. I've driven 96.6 miles and it has gone just below a 1/4 full again and it's started all over again, though this time I didn't switch the car off, just let it idle for a few mins.

Bit of a scattery vid here but hopefully you get the point. At the start before I put the hazards on the accelerator is flat to the floor!

It then gets to the point where it nearly dies, so I stop the car and get out and try to get a clip of the exhaust note.

[Blackie_No1]

I'm going down wase16ll's route and going to dismantle the exhaust system today.

The cat I've been told is hollowed out, but I'll find out for sure later, though I'm not so sure based on the evidence of a blowout between the manifold and the cat.

[Blackie_No1]

First off, the cat, well not so much off as in dropped from manifold, defo not it, it has indeed been hollowed out due to it collapsing in the past:

Had to stop as I'm working outside and the rain has got just to much :(

[wase16ll]

as i understand it...you had 02 sensor changed, drove 90 miles before problem reoccured

was that in a single journey?

also, this time, you didnt switch off, let it idle for few minutes, then found the power returned?

blockage is still a possibility, so still worth carrying out checks for it...but if you can get hold of a tester, may be worth carrying out a fuel pressure test, you might have a problem with the pump

[Blackie_No1]

No it was from Wednesday to yesterday, to and from work mainly, 13+ miles each way.

Yea, I just let it tick over for a while before driving on.

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[wase16ll]

exhaust blockage or fuel pressure problems, including a blocking filter, could give you these symptoms without flagging any codes/faults

could also be a problem with maf sensor, but would be unusual for that to happen and not flag anything.

may also be worth testing throttle position sensor, reasonably easy test if you have a voltmeter

[Blackie_No1]

Nope but can get my hands on one easy enough, what shouldmi be doing with it?

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[Blackie_No1]

Got the front pipe separated from the middle exhaust section. I was able to see up the first (essentially straight through silencer) to the bend and no sign of blockage, not sure of the second silencer yet, but I have a feeking it isnt blocked.

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[wase16ll]

problem with the silencers is you wont see through them anyway...ideally to test for blockages is what i wrote a few posts back or find someone with a back pressure tester.

if you can get hold of a fuel pressure tester, you connect it to the schraeder valve on the fuel rail and read the pressure at idle with pressure regulator vacuum disconnected..should read approx 4 bar, with vacuum connected and assuming the vacuum is good (approx 5psi) pressure should read approx 3.5 bar

the TPS should be a 3 pin sensor...disconnect and connect an ohm meter to the outer pins (1 and 3) of the sensor, approx just under 4k ohms

connect ohm meter to pins 2 and 3

with butterfly closed..approx 4.2k ohms, butterfly fully open, approx 1,2k ohms...but its vitall that the resistence reading is a smooth curve from closed to open and back, so operate the butterfly slowly and watch for any sudden jumps/drops in readings as that will indicate a faulty sensor.

may pay to renew the fuel filter anyway, but at least diconnect the filter and drain it to see if the fuel is coming out clean

[Blackie_No1]

Yea, gonna replace the filter just to see as you say

[Blackie_No1]

Someone has suggested a coil pack, what's your thoughts wase16ll?

[wase16ll]

going by the fact you believe there is no misfire when power drops, its unlikely.

if there is a misfire thats bad enough to virtually bring the engine to a halt, will almost certainly have set a code and flagged a light

[Blackie_No1]

Yea that's sort of what I was thinking. No miss firing or hesitations at all, just a sudden loss of power and will not accelerate/rev.

I can't get anyone here in N.ireland who can pressure test the exhaust, but I stuck an airline down it and there felt like a good flow, so I don't think it's it.

[wase16ll]

not a foolproof way of doing it but going by your last description of allowing it to idle, it then seemed to clear itself has lessened the chance it being an exhaust blockage...though doesnt eliminate it.

im tending to think it might be more fuel pressure related, either a filter blocking or pump failing maybe...worth testing for

[Blackie_No1]

I got a filter today but I ended up locking it in my car with the keys!

Spent the rest of the day googling how to get back into it without a locksmith/breaking a window lol

Oh, I should add that when tinkering with the engine earlier I disconnected a fuel line at the injector rail and whilst the pump operated, I dont think the fuel was coming out with much pressure, more than a trickle but not a spray like I would imagine!

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[wase16ll]

that fuel should pump out at a fair rate, so you might be onto something...

ive just had one of those days myself :)

should add that free flowing fuel will trigger the cut off fairly quickly, so make sure that switch hasnt been triggered

[Blackie_No1]

No hasnt been triggered, once I eventually got into the car I started it and ran it for ten minutes at idle, gave it the odd rev, but that was to boost the battery as it's a tad low

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[Blackie_No1]

Defo thinking its fuel related based on the colour/condition of the fuel coming out of the fuel filter(admittedly from the wrong directional flow of the filter)

Now going through the extensive receipts I got with the car, it would appear the filter has not been changed since 2007, though I am dubious about that, maybe someone can confirm if £14.10 sounds like a genuine ford fuel filter price?

I havent taken it for a drive yet due to the fact that I've been left with two of our four kids :(