FOCUS ST170 mystery - mechanic recommendations please!
Discussion
Any ST170 advice massively appreciated! Bit of a mystery powertrain issue, two mechanics now haven't been able to diagnose...
My ST170 developed a rattly exhaust, then the EM light came on last year, a few months before MOT due. Plugged in at my usual mechanics (more on him later...), emissions issue and CAT breaking up so new cat needed. Fine, was still original cat on a'53 plate so over 10 yrs old. Cost a shedload but got it sorted. MOT, done. ST170 is a great car so worth looking after.
Week or so later, light back on. Plugged back in, Bank 1 sensor 1 and bank 2 sensor 2 both fail. Replaced both sensors, parts and labour pre-post MOT now £700+.
Three days after new sensors, light back on again.
Plugged in, 'catalyst system efficiency below threshold' fault again. Ran through the emissions test again and mechanic says my exhaust is failing MOT still on CO2 levels, must be a faulty CAT (but was a brand new 'replica' as Ford don't sell these anymore so fault must have been a manufacturing issue...).
2nd new CAT in a few weeks, this time on parts warranty and mechanic agrees to waive labour. (Previous service he did for me a few months before MOT he forgot to replace the oil filler cap. I proceeded to drive an 80 mile trip which came to an end with smoke pouring out the bonnet and oil all over the engine bay! fair to say it cost my mechanic a fair whack. I felt for him.)
Week or so later, EM light back on. still getting Catalyst fault but emissions are fine now after testing. Possible nackered ECU? Some days I'm getting only 10MPG, so air/fuel programme in ECU possibly? I'm not a mechanic but know a fair bit about engines. Decided to keep driving as was mostly running fine, just got thirsty sitting in traffic and runs lean on motorways to make up for it!
EM light stayed on until a month or so ago when the bulb blew.
6 months of driving with the EM light on and the engine has developed what I can only describe as an intermittent lurch or lump between 2-3K rpm that feels like it just cuts the connection for a second and looses power, then kicks back in. Only lurches under load, going up the revs, not down.
Changed mechanic for my most recent service, understandably. He also reckons might be ECU but didn't bother testing the car for the lurch like I'd asked him to and told me it would be fine and was just an old car... grrr!
Wondering, if ECU IS faulty, might in not be due to the post-service oil leaking? What IS that uncomfortable lurching at 2.5k rpm? Is my engine going to eat itself any day now? Cambelt done at about 78k, before I owned the car.
I wantto look after this car... future classic with every option available and very tidy inside and out. Less than 10k left of these on the road and numbers falling fast nowadays.
If you know any excellent mechanics in the Surrey/SW London Area with experience working on ST170's please let me know.
THANKS!
My ST170 developed a rattly exhaust, then the EM light came on last year, a few months before MOT due. Plugged in at my usual mechanics (more on him later...), emissions issue and CAT breaking up so new cat needed. Fine, was still original cat on a'53 plate so over 10 yrs old. Cost a shedload but got it sorted. MOT, done. ST170 is a great car so worth looking after.
Week or so later, light back on. Plugged back in, Bank 1 sensor 1 and bank 2 sensor 2 both fail. Replaced both sensors, parts and labour pre-post MOT now £700+.
Three days after new sensors, light back on again.
Plugged in, 'catalyst system efficiency below threshold' fault again. Ran through the emissions test again and mechanic says my exhaust is failing MOT still on CO2 levels, must be a faulty CAT (but was a brand new 'replica' as Ford don't sell these anymore so fault must have been a manufacturing issue...).
2nd new CAT in a few weeks, this time on parts warranty and mechanic agrees to waive labour. (Previous service he did for me a few months before MOT he forgot to replace the oil filler cap. I proceeded to drive an 80 mile trip which came to an end with smoke pouring out the bonnet and oil all over the engine bay! fair to say it cost my mechanic a fair whack. I felt for him.)
Week or so later, EM light back on. still getting Catalyst fault but emissions are fine now after testing. Possible nackered ECU? Some days I'm getting only 10MPG, so air/fuel programme in ECU possibly? I'm not a mechanic but know a fair bit about engines. Decided to keep driving as was mostly running fine, just got thirsty sitting in traffic and runs lean on motorways to make up for it!
EM light stayed on until a month or so ago when the bulb blew.
6 months of driving with the EM light on and the engine has developed what I can only describe as an intermittent lurch or lump between 2-3K rpm that feels like it just cuts the connection for a second and looses power, then kicks back in. Only lurches under load, going up the revs, not down.
Changed mechanic for my most recent service, understandably. He also reckons might be ECU but didn't bother testing the car for the lurch like I'd asked him to and told me it would be fine and was just an old car... grrr!
Wondering, if ECU IS faulty, might in not be due to the post-service oil leaking? What IS that uncomfortable lurching at 2.5k rpm? Is my engine going to eat itself any day now? Cambelt done at about 78k, before I owned the car.
I wantto look after this car... future classic with every option available and very tidy inside and out. Less than 10k left of these on the road and numbers falling fast nowadays.
If you know any excellent mechanics in the Surrey/SW London Area with experience working on ST170's please let me know.
THANKS!
No real help but we had one of these a few years ago, great cars.
If it really is doing 10mpg it must be over-fuelling massively, I reckon that would kill the cat again in pretty short order. Likewise, running lean will hurt the engine quickly too so I'd stop driving it until it is sorted.
I'm in the north west so no help on garages but my local place had no issues working on mine.
ETA there are places you can send your ECU for testing. I've heard good things about this lot:
http://www.bba-reman.com/uk/index.aspx
Post it off, they test/repair it, they post back.
If it really is doing 10mpg it must be over-fuelling massively, I reckon that would kill the cat again in pretty short order. Likewise, running lean will hurt the engine quickly too so I'd stop driving it until it is sorted.
I'm in the north west so no help on garages but my local place had no issues working on mine.
ETA there are places you can send your ECU for testing. I've heard good things about this lot:
http://www.bba-reman.com/uk/index.aspx
Post it off, they test/repair it, they post back.
This is the trouble with running a car close to shed territory in terms of value and taking it to a garage to fault-find and repair - it soon becomes un economical. If £700 is your current spend you've already committed to 50% of the vehicle value in repairs and still have a serious fault.
Have you got on the owners club forums and searched for similar symptoms? Forums can be invaluable in this respect.
Diagnostics won't reveal the whole issue, just indicate what sensors have been triggered. If O2 sensors have been triggered it could quite likely be because of the overfuelling / blocked catalytic converter. Is it burning oil at all? Oil kills cats quicker than overfuelling in my experience.
What are the actual fault codes? It's all very well getting a diagnostic check from a garage but if they don't tell you what codes came up you are at their mercy and can't do your own research.
A quick bit of googling reveals a possible answer to your issues - but bear in mind there is still some DIY involved (although in total this is going to cost you very little if it is the fault)
Google ST170 IMRC issue
Lambda sensors should be about £50 each from a parts shop
Have you got on the owners club forums and searched for similar symptoms? Forums can be invaluable in this respect.
Diagnostics won't reveal the whole issue, just indicate what sensors have been triggered. If O2 sensors have been triggered it could quite likely be because of the overfuelling / blocked catalytic converter. Is it burning oil at all? Oil kills cats quicker than overfuelling in my experience.
What are the actual fault codes? It's all very well getting a diagnostic check from a garage but if they don't tell you what codes came up you are at their mercy and can't do your own research.
A quick bit of googling reveals a possible answer to your issues - but bear in mind there is still some DIY involved (although in total this is going to cost you very little if it is the fault)
Google ST170 IMRC issue
Lambda sensors should be about £50 each from a parts shop
As above, I'd certainly say that an element of over fuelling appears to be occurring. It's killing your cats plus knocking out EGO sensor readings. It's very difficult to say what might be causing the issues, but I'd be surprised if there wasn't more than one culprit.
Is the car a bugger to start? If the CPS is out of commission, a car will resort to a basic cover-all bases mode and fuelling will be all over the shop. Without accurate readings from the CPS, the ECU can't accurately deliver fuel and spark. This may be the cause of your hesitation and poor fuel economy too. Check that (it'll likely be around the flywheel end of the crank), plus the EGO/HEGO sensors in case they've been damaged.
I think the ECU being to blame is unlikely unless it's had obvious damage or water ingress. Don't be pressed into buying a replacement until you're 100% sure that's it. ECUs are expensive, even more so when it doesn't solve the issue.
Is the car a bugger to start? If the CPS is out of commission, a car will resort to a basic cover-all bases mode and fuelling will be all over the shop. Without accurate readings from the CPS, the ECU can't accurately deliver fuel and spark. This may be the cause of your hesitation and poor fuel economy too. Check that (it'll likely be around the flywheel end of the crank), plus the EGO/HEGO sensors in case they've been damaged.
I think the ECU being to blame is unlikely unless it's had obvious damage or water ingress. Don't be pressed into buying a replacement until you're 100% sure that's it. ECUs are expensive, even more so when it doesn't solve the issue.
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