ST170 exhaust - mechanic recommendation needed
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!
Hello,
These have a variable inlet manifold and variable cam timing - are you still experiencing a kick or is it flat throughout the rev range? My thinking is that it could all be stuck open and it's trying to match the airflow with the right fuel and is therefore sticking a load of fuel in.
Are there any modifications on the car?
How does it idle
Are all sensors connected (Is the MAF connected - I am also thinking this could be faulty and reading backwards, lots of air flow at idle and none and full throttle)
Any other symptoms
Could be Throttle Position Sensor
If you have an Android phone, you can get a ODB11 reader from ebay for under a tenner and an App called Torque from the Play store which is free. You can then look at the live readings and see if there is an issue. You can also turn off the light when you have fixed the issue.
These have a variable inlet manifold and variable cam timing - are you still experiencing a kick or is it flat throughout the rev range? My thinking is that it could all be stuck open and it's trying to match the airflow with the right fuel and is therefore sticking a load of fuel in.
Are there any modifications on the car?
How does it idle
Are all sensors connected (Is the MAF connected - I am also thinking this could be faulty and reading backwards, lots of air flow at idle and none and full throttle)
Any other symptoms
Could be Throttle Position Sensor
If you have an Android phone, you can get a ODB11 reader from ebay for under a tenner and an App called Torque from the Play store which is free. You can then look at the live readings and see if there is an issue. You can also turn off the light when you have fixed the issue.
By kick are you referring to the lurch at 2-3rpm or the torque kicking in? The lurch happens just as you enter the torque band. So yes, it's still lumpy and getting worse now in cold weather. Idles fine and variable timing slowing down as usual from 1.5k rpm to about 1.1 on cold start-up etc. (I always try to let the engine get to its lower revs position before driving off from cold to try and protect it... except when im running late for work!)
I'm not able to work on the car myself as have very little knowledge of these things I'm afraid and i dont have a smartfone. Mechanics who have worked on it would have flagged any issue with MAF sensors etc. if they'd found any, no? Not sure what the process is for these checks though.
Ideally I need to take it to someone who knows what they're doing. Thanks for the hints on MAF and throttle position sensors. At least when I take it in to someone next I can ask them to check these so they don't think I'm another dumb blonde who doesn't have a clue!
I'm not able to work on the car myself as have very little knowledge of these things I'm afraid and i dont have a smartfone. Mechanics who have worked on it would have flagged any issue with MAF sensors etc. if they'd found any, no? Not sure what the process is for these checks though.
Ideally I need to take it to someone who knows what they're doing. Thanks for the hints on MAF and throttle position sensors. At least when I take it in to someone next I can ask them to check these so they don't think I'm another dumb blonde who doesn't have a clue!
I know the inlet manifold runner controls are a common fault on these as my dads had his st170 for 12 years and he had a code come up with this fault but I knocked the light off and it stayed off but my partners dads st170 needed a new one, the symptoms are bad fuel economy, a lack of power and poor idling. Might be worth checking.
Poynter87 said:
I know the inlet manifold runner controls are a common fault on these as my dads had his st170 for 12 years and he had a code come up with this fault but I knocked the light off and it stayed off but my partners dads st170 needed a new one, the symptoms are bad fuel economy, a lack of power and poor idling. Might be worth checking.
It will throw a code for the IMRC, OP you need to get the fault codes re-read. Hot oil spraying everywhere won't of helped the wiring and sensors in the engine bay.Are the Lambda sensors Ford OEM or aftermarket? It's common for these to get damaged during a cat replacement.
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