760T mpg and brake squeal (windows sorted)
 

Well hoorah, after the garage made matters worse not better with driver window controls, insisting that one had to fit a whole unit (4 window switches and 2 mirror controls) leaving me with working windows but incorrectly working mirrors, on the helpful advice of Steve at Trust Motor Parts who used to be Braydons, I swapped the previously working mirror controls and the now working window controls into the door housing and plugged that into the door plugs located in the green frame and bingo.

So now there are two MORE things that so far the garage has failed on.

First ghastly brake squeal. Garage said that blowing out old dust should cure that, but it has effected nothing at all. Brake operation is fine. I reckon that might be glazed pads - with 4 Volvos each one only does few miles - but if I am going in there to check and maybe deglaze with wire brush or fit new pads, I might as well check another thing. Who knows whether there should be anti-rattle (or anti-squeal) shims? and/or if there should be Copaslip between metal side of pad (and shim if any) and brake piston?

And finally for this post - 16 mpg? Seriously? Yet passing MoT on emissions. Which direction to twiddle the adjusting screw in the AFM (not AMM) to weaken mixture? Or might it be a tired AFM spring or worn track so that at low revs I get good MoT emissions but at larger throttle openings (not tested on MoT) she is rnning too rich? MIGHT it be worth at vast expense swapping the AFM? I don't think I have a spare in stock for that.

For the brakes squealing usually indicates low brake pad material, I'd be checking that first. Also remove the pads, clean the dust and rust off the inside of the caliper with a wire brush and the carrier where the brake pads sit in it. Then put copper grease or ceramic brake paste on the pads where it touches the caliper and carrier. While you have it apart you should check the piston pushes back okay.

For the low mpg, seeing as it doesn't do many miles give it a good thrashing to clear out the cobwebs and see how it goes after that.

First, when does the brake squeal occur? Is it only during braking? Is it from the front or back? Does lifting the handbrake gently alter the brake squeal, particularly if the squeal is always there?

Secondly, are you running it on Tesco fuel or any sort of normal unleaded? What are the idle CO% figures?
Don't fiddle with the AFM mixture screw without having it hooked up to some sort of gas analyser, if you set it too weak it will do even less mpg because the knock sensor will cause the ECU to retard the ignition timing.

There are other possibilities for both of these and it's possible they are linked. Another point, how many clicks brings the handbrake fully on?

Squeal
 

Squeal only at low speed/light braking effort. Bang 'em on and they are silent. Hard to gauge location from the driver's seat but I think left hand side, not sure if front or back. Handbrake makes no difference but is silent.

I would have imagined garage to check pad wear when blowing out dust which it says it has done. Visual inspection without removing pads.

I may only do few miles but there are two nearby motorway or nearly motorway stretches with no cameras, and my favourite uphill test run, so cobwebs are unlikely!

I'll have a rummage in my pile of papers but last MoT was about a year ago so may take some finding. If I find it it will have the idle settings, but my recollection is that they were spot on. I always demand the emission test figs.

I have however no idea how the garage is doing MoT tests as it says its exhaust gas anayser is broken! But mixture has got to be prime suspect in that on said favourite test hill (up) where on a cold wet night I could once see speedo 125 I now only see speedo 110 - but in the early days I had Hydras with standard tyres on and now I have Galaxies with wider tyres, so more rolling resistance.

And yes, I am naughty with petrol but I have to drive nearly 20 miles to get V-Power except at one garage that has petrol at the prices of French perfumes!

Oh - in the old days I used to set mixtures using a Gunson Colourtune and I think I still have it. Could I use that in stead of an exhaust gas analyser or is it insufficiently precise?

In that case, a piece of grit lodged in one of the pads is prime suspect for your squeal, wouldn't have been blown out due to being stuck in the pad. While you're in there, clean and regrease the slider pins, clean the calipers with a wire brush, especially where the pads make any contact, use a file to deburr the metal edges of the pads and then (before refitting the pads), wedge the file in the caliper against the edge of the brake disc and use a long lever between the wheel studs to turn the disc so it scrapes the edge of the disc against the file to remove and lip/rust build up on the edge - do this to both sides of the disc.

When refitting the pads, smear some copper grease on the backs of the pads where they make contact with the caliper pistons/caliper body and on the edges of the metal backing where they slide in the caliper.

As for the petrol, using cheap fuel is a false economy. I wouldn't bother with V-Power these days either as i'm certain (and so are several others on a different forum) that the formula has changed.

Switch to BP Ultimate Unleaded. Yes it costs a bit more than the cheap supermarket stuff but you get what you pay for.

If you're losing 1/3 of your normal economy using cheap fuel and you regain it using slightly more expensive fuel, it's a no-brainer, use the dearer stuff!

Also run some injector cleaner through the tank on the heavy duty cleaning dose (usually twice the normal dose) to help clear the gunge that builds up on injectors.

Using cheap fuel (especially less than 97/98 octane) will cause detonation aka pinking/preignition and a whole raft of other names. No matter what you call it, it triggers an output from the knock sensor (the banjo shaped animal on the left side of the block) that retards the ignition thus killing the economy and performance. Same applies to weakening the mixture.

You'd proably get away with the Colortune but if you can beg, buy, borrow or steal (only kidding on the last) a gas analyser, even a Gunsons Gastester, use that in preference to the Colortune. Remember the Colortune was developed for carburettor engines where the mixture could vary a lot more so tends to give a more average result.

Knock?
 

I am not hearing any pinking - but thank you for the thought. Now to google for BP garages - as I said the nearest home for Shell V-power has FANTASTIC prices, and the next nearest is a 30 mile round trip (ie at least a gallon!).

I suppose I'd better roll my sleeves up and get cold and dirty

That's the point of the knock sensor - it "hears" the pinking long before you would (or engine damage could occur) and retards the timing - net result, gutless and thirsty!

Before you go delving into what's wrong, you need an up to date emissions at idle figure to base your next steps on. No point tinkering without a goal in mind as the usual upshot of that is a big own goal!

If the emissions are ok, its likely the idle mixture is fine, but you do need a proper gas analyser to check it properly without O2 feedback. I have an old gunson gas tester, but am unsure if it still works properly, it was always pretty ropey anyway. You could fit a wideband O2 and gauge, or just the O2 sensor and feed it to a gauge for testing, it would need a bung welded into the exhaust.

If your mpg is so low and idle is fine, then its possible you have a bad AFM, but I'm not sure what type of system you are running.

V-Power!
 

The former BP station in Strood is now Shell and has V-Power! And I have some fuel system cleaner on the shelf so I might dump some in and put V-Power in the tank when I go shopping!

I was talking to someone with a 300+ho Focus ST and he gets all his tuning done at a place that specialise in performance "ford" 5 cylinders aka T5 engines and they say V power actually burns out valves and the best fuel they recommend is Tesco momentum 99.