UKC

This one stumped the AA man but I know there's a wealth of mechanical knowledge simmering under the surface on ukc so any help is much appreciated...it's quite a long list of symptoms.

Ford focus 1.8 petrol 2001 estate

During the first 30 mins of driving the car sometimes half dies while it's going along, the speedo dies, the milometer displays just dashes, the engine feels sluggish, acceleration is weak like you're in too low a gear, whatever it is that makes rough gear changes smooth (if that makes sense) stops working (being a newish car you can usually change gear like a retard and you'll not notice/it'll compensate the revs for you but while it's in half dead mode you notice if you don't change gear properly), if you pull up to a junction and stop while it's running poorly then the engine will either vibrate and rumble or just cut out. When it jumps back into life all those symptoms reverse, if you're holding the accelerator steady then when the car comes back to life it'll speed up like someone's hit the turbo boosters.

Sometimes it lasts for a few seconds, sometimes a few minutes.

After 30 mins it's fine, on a long journey it's fine, it's really hard to pin down the conditions under which it happens but I think it probably does it more in town and it probably does it more when the revs are low. I've got a suspicion it sometimes happens when you hit a bump but I'm not 100% sure on that and I haven't been able to replicate it, and it definitely happens when the car is travelling on a smooth road too.

Today I was driving along at about 30mph, the engine was as described above but even though I was in gear and trying to accelerate it started rumbling and the accelerator did nothing, eventually it just rolled to a stop and cut out. Turning the key did nothing, as in literally nothing, not turning over, not clicking but the dash lights were up. There was no engine warning light. The battery's well charged and there are no fault codes.

About 5 minutes after phoning the AA I gave it another shot and it started as normal. We repeated this when the AA guy was there and then it cut out again while idling, but it started ok this time.

The problem is getting worse, it's been losing power as described in the 1st paragraph for about a year but it's getting more frequent and it didn't ever cut out till recently. I took it to the garage a while back and (without phoning me like I asked) they changed the spark plugs which cost a ridiculous amount of money and (predictably imo) didn't fix the problem. It's got 171k on the clock and with the MOT coming up for renewal soon if I can't fix it myself then it'll probably be going to the car park in the sky, so any suggestions to keep her running are greatly appreciated.

The ridiculously cool diagnostics suggestion thing on the AA guys PC suggested very similar symptoms for a throttle sensor cable that was worn through, but the cable was fine. The other thing I'd thought myself was the exhaust, which has been leaking for a while and the back of it came off a couple of weeks ago...but the AA man said this might make it sluggish if it had two O2 sensors but wouldn't make it cut out. I'm loathe to spend money on a new exhaust unless there's at least a theoretical chance that it could be the problem.

If you've read all that then thankyou, if you have any suggestions I'd be grateful as it's really bugging me.

In reply to Sharp:

A common zetec fault is corroded cylinder head core plugs. There are two core plugs situated between the spark plugs, in the "well" between the cam boxes. These corrode and leak coolant into the "well" creating a damp atmosphere/moisture, causing the plug leads to short hence a misfire. As the engine warms, this dries up and normal running returns.

When the engine is cold, pull the plug leads off and have a look down between the spark plugs with a torch. If it looks brown and rusty, or there is a lot of moisture you need to investigate.

Core plugs are about £1.50 a pair from ford, and take about an hour to fit. You may need to replace the plug leads as well.

Cheers Adam

In reply to Sharp:

Probably entirely electrical. My guess, considering the age of the car, would be an earth fault somewhere as they can cause really odd errors that don't seem to match up. Not sure where the earth points are on the 1.8 but on my 1.6 they are to the right of the battery directly under the filler for the washer fluid so pretty much every time you top up the washers you get some corrosive washer fluid on the earths. The battery is in the same spot on the 1.8 so these are likely in the same spot. The other one is to the left of the engine close to the air con compressor (probably not there on the 1.8). When the focus was relatively new there was an issue with corrosion on the main circuit board behind the dials, the solution was to take it out and clean it with WD40, nice and easy to do so could be worth a go.

In reply to butteredfrog:

I have a 57 plate Focus, on which the plug wells used to fill up with water. I thought it was the core plugs, but it turned out to be rainwater coming through the screen washer jets on the bonnet - apparently a common fault, solved by 2p of sealant.

In reply to Sharp:

I had the same symptoms on my 2002 focus and it was the alternator intermittently failing to charge as the belts where slipping. might be worth making sure the alternator is charging consistently, and tightening or swapping the belts if need be. (the battery showed well charged most of the time. the slipping only happened after periods at low speed)

throttle sensor cable was going to be the next thing i swapped.

In reply to John Ww:

You are right John, forgot to add that's what causes the core plug corrosion in the first place!

In reply to Sharp:

Given the dashboard misbehavior and the misfire it's probably electrical, loose or corroded connectors possibly or a bad earth connection somewhere around the engine or ECU. Could also be a poor connection from the battery causing system-wide brownouts under vibration conditions or high electrical load. If it started when the exhaust fell off I'd look for any wiring it could have damaged/shorted even if seemingly unrelated to the ECU.

From what you say about behavior during gear changes I suspect it may be struggling under any real load which could indicate duff data from one of several sensors on the engine getting to the ECU causing mistimed sparks or incorrect fueling.

jk

In reply to Sharp:

I had something rather similar sounding on a Ford Focus Diesel. Four Ford garages in three countries, numerous AA call outs and about £2000 later, I cut my losses and sold it for scrap. The consensus eventually seemed to be that it was an electronic engine computer thing, but no one could get to the bottom of it.

In reply to butteredfrog:

That's lots to be going on so I'll have a good play on Thursday when I'm off. It's always the same names that pop up for car trouble and it's always appreciated.

Thanks all

In reply to Sharp:


Good luck with this, it could be something caused by a trivial thing (like the core plugs) or something no computer/code reader could ever pin point. Any half decent spanner monkey can inteript fault codes (which is much harder than it sounds) and replace parts but you need someone with a full understanding of electronics to get to the bottom of a problem like this and even then it could be hit an miss. An example is to look at a common fault on Nissan Primerias - when the temp drops to near freezing the dash display screen goes off. This is a problem as the sat nav, radio, heater controls etc are all run using this screen. Nissan never did find the cause of the problem nor did any independant, The fault was found by pure chance by someone with a donor car to swap parts in and out of. Logically the first thing to try was the actual screen, everyone else had already tried (and charged the customers for) a new screen but no joy - the problem returned when the temp dropped. The problem turned out to be in the actual radio unit itself. The power supply board that dropped 12v to 5v in the radio was made by a 3rd party electronics comp in tiwan and it turned out they had used inferior manufacturing methods. A white glue was used to cover the electronics on the board and to reduce the buzzing noise coming from a coil, age affected this glue and when very cold it shinks and pulls a transistor off the board. Temp increases again the glue expands and presses the transistors poorly soldered legs back on the board. Thats all the problem ever was, it was chance it was found after a home mechanic found the fault to be in the actual radio and then others took it further. I had a brisk trade in reconned radio units myself once the nature of the problem was found. Nissan offered no recall or replacement program and denied all responsibility saying if out of warranty then hard luck. Interestingly though, Nissan has started to replace the radio units now when this fault appears rather than the screens/ECU as they did before. Nothing to do with your problem focus I know but its a tale that shows how some faults can be extremely hard to find and paying an auto electrician £50 an hour to find the fault can quickly lead to it being unecconomical to pursue.
If I had time and the money to sort this I'd buy exactly the same car as you have now and over time, swap over every part of the ignition/electronic system until the problem is resolved. It may be a fault in the actual wiring loom or earthing point so even parts swapping won't cure the fault.
I hope its something simple but TBH, a 13 year old 170k focus is IMO reaching the end of its ecconomical life.

In reply to Sharp:

Could be the tdc sensor, also known as crankshaft position sensor. Very common fault on Renaults that produces similar symptoms but usually accompanied by toxic fume warning light once it's this severe. Tenner to replace probably......... one other possibility is an air leak around the inlet manifold. If the gasket is knackered and air is getting in or out where it shouldn't you'll get similar symptoms. Then once the engine has warmed up enough to seal the gap, hey presto car runs fine! Again only five squids for a tube of gasket maker. Tbh I'd do both just to eliminate them as it's probably the cheapest fix of all the possibilities. Then plug leads after checking for signs of water damage, as another poster mentioned, known issue on some Fords. I've done inlet manifold gaskets and tdc sensors on two of my cars that had similar symptoms and it sorted the issue and on my sister's focus with similar problems it did turn out to be badly corroded leads. Hope this helps and good luck.

In reply to Sharp:

Symptoms sound similar to what happened with my motorbike. The rectifier/regulator was failing intermittently so the battery would drain whilst riding. The lights would dim, the engine tried to stall at junctions and would be sluggish. I don't know how well cars do these days if the battery is removed/drained (while running). If it does it more when revs are low that can point to not enough charge being produced. While it doing it's issue try and measure voltage on the battery to see if the charging circuit it working ok.

In reply to wilkie14c:

It's a shame but I guess this is the way of cars now, they're so complicated that home repairs get harder to do and mechanics are so expensive that cars have just become another victim of our throw away culture but you're right yeah, the car is on it's way to the scrappy but I was hoping to eek out the last few months of the MOT on it. I'm not sure what the answer is, maybe look for something older next time...but then you lose in fuel costs.

In reply to richyfenn:

Thanks, though the intake manifold looks like a bit of a pig to get to.

In reply to Sharp:

I've just rebuilt a clio engine (snapped belt) and to be honest, they are easy to work on with lots of room and everything about it has been easy. If you need to keep the big car then you'll not go wrong with a mondeo diesel. The duel mass clutch isn't a problem like its made out to be as long as you can drop your hands on 500 quid if it goes.