1.7 catalytic converter replacement

[DOH]

Ok..So As I'm a mech by trade I'd get a bit techi and test the O2 sensor output voltage. Either via a scanner/code reader that's live data capable, or by a digital multi meter back probing the sensor multiplug and picking up the sensors output voltage.Your looking for a contantly altering reading between 0.2-0.8 volts with the engine idling on.... the grey wire I believe....from a distant memory?!
If your cars running rich you'll be seeing 0.8v constantly. If when you rev up the engine ,on overrun the voltage reading should go to 0.2v(or go lean).
If the O2 sensors knackered it will be unresponsive to throttle movements, or just be hanging around 0.8v.
Other causes of rich mixture include a dodgy coolant temp sensor, maybe an air mass sensor, though the later isn't common .

The above procedure for testing the Lambda is correct. I have done the voltage test in the past using a standard digital multimeter on the milli volt range and probing the back of the lamda plug using a paperclip & a small crocodile clip to hold the probe in place to it. However that test doesn't reveal whether the heating element is intact within the Lambda sensor . That is a common failure within them. The OBD diagnostic test using even a cheap ebay scanner from £13 will be useful to you both now and in the future on other cars too, however spend a bit more on it so that you can also read ABS faults and Airbag faults .

To get a reading of 5.3% CO , the plugs will be black and it's extremely likely to be the items I originally listed . There is also the possibility of leaking fuel injectors causing it to run rich ,although that is rare which could be causing the over fuelling. It needs to be scanned to diagnose correctly which is what I advised earlier.

Can you confirm that the temperature gauge on the dash sits in the middle when warmed up?

 

[chrisjenkins]

Thanks for that, all very useful. Yes, the temperature gauge sits about in the middle when warmed up.

 

[GreenEyedPuma]

Chris,
Hi, was your 2001 Puma Thunder 1.7 first registered from 1st March 2001 onwards (Y Reg.)? If so and you unfortunately do end up needing a new catalytic convertor, any cars registered from that date will need a "Type Approved" one. They are spec'd to have higher quantities of the working precious metals in them, to comply with more stringent emission control (and changes to the Vehicle Excise Duty) introduced from that date. Consequently they are more expensive than Cats that don't need to be Type Approved, for earlier registered models.

I don't want to sound like a spoilsport, but if an MOT Inspector is doing their job correctly, they should fail a car that does not have a Type Approved Cat, when it should have one, based on its 1st registration date. You'd have to rely on MOT inspectors bothering to look at the Cat to notice, but if you take it back to the original MOT station, or now have a bright shiny new Cat, they probably would look at it!

I looked into this back in 2010 for my 1.7, but luckily, my MIL warning gave an OBDII code for a failed heater circuit in the first, upstream O2 Lambda Sensor (in the exhaust manifold). I found out at the time that there are two potential connector types for the replacement sensor - a round, or a square connector! However, that is in the INTERNAL mating surfaces of the connector block, not the outside shape! The outside of the two sides of the connector (the sensor wire and the body wiring loom!) are both square-ish, but it's the INSIDE shape that is relevant, to obtain the correct replacement sensor. I seem to recall the 1.7 body wiring loom connector (and so the sensor type) changed later in the production, possibly when the 1.6 engine was introduced. All the other Fiesta, KA and Puma models and engine variants, with the introduction of the Puma 1.6, had the same body loom and connector shape, so I presume Ford changed it on the 1.7, to require just one loom variant for everything!

When I replaced mine, I found I had to gently warm the exhaust manifold by running the engine for 20 - 30 seconds, then stopping it before proceeding, for the sensor to come loose! I'd taken out the manifold heat shroud bolts before starting the engine and it only needs to be warm enough, that you can still easily touch the manifold with bare hands!

Also, in later years, I used to do an oil & filter change, check spark plug gaps & condition, maybe a new air filter, etc., then a bottle of Cataclean, together with an "Italian Tune-Up" a day or so before putting it in for an MOT. I also practised keeping my fingers crossed!

I hope this helps you, or anybody else reading this in the future!

 

[Pugmanaught]

Chris,
Hi, was your 2001 Puma Thunder 1.7 first registered from 1st March 2001 onwards (Y Reg.)? If so and you unfortunately do end up needing a new catalytic convertor, any cars registered from that date will need a "Type Approved" one. They are spec'd to have higher quantities of the working precious metals in them, to comply with more stringent emission control (and changes to the Vehicle Excise Duty) introduced from that date. Consequently they are more expensive than Cats that don't need to be Type Approved, for earlier registered models.

I don't want to sound like a spoilsport, but if an MOT Inspector is doing their job correctly, they should fail a car that does not have a Type Approved Cat, when it should have one, based on its 1st registration date. You'd have to rely on MOT inspectors bothering to look at the Cat to notice, but if you take it back to the original MOT station, or now have a bright shiny new Cat, they probably would look at it!

I looked into this back in 2010 for my 1.7, but luckily, my MIL warning gave an OBDII code for a failed heater circuit in the first, upstream O2 Lambda Sensor (in the exhaust manifold). I found out at the time that there are two potential connector types for the replacement sensor - a round, or a square connector! However, that is in the INTERNAL mating surfaces of the connector block, not the outside shape! The outside of the two sides of the connector (the sensor wire and the body wiring loom!) are both square-ish, but it's the INSIDE shape that is relevant, to obtain the correct replacement sensor. I seem to recall the 1.7 body wiring loom connector (and so the sensor type) changed later in the production, possibly when the 1.6 engine was introduced. All the other Fiesta, KA and Puma models and engine variants, with the introduction of the Puma 1.6, had the same body loom and connector shape, so I presume Ford changed it on the 1.7, to require just one loom variant for everything!

When I replaced mine, I found I had to gently warm the exhaust manifold by running the engine for 20 - 30 seconds, then stopping it before proceeding, for the sensor to come loose! I'd taken out the manifold heat shroud bolts before starting the engine and it only needs to be warm enough, that you can still easily touch the manifold with bare hands!

Also, in later years, I used to do an oil & filter change, check spark plug gaps & condition, maybe a new air filter, etc., then a bottle of Cataclean, together with an "Italian Tune-Up" a day or so before putting it in for an MOT. I also practised keeping my fingers crossed!

I hope this helps you, or anybody else reading this in the future!

I can think of a few local MOT testers that can't even spell 'Type approval' let alone enforce it!!

 

[chrisjenkins]

Chris,
Hi, was your 2001 Puma Thunder 1.7 first registered from 1st March 2001 onwards (Y Reg.)? If so and you unfortunately do end up needing a new catalytic convertor, any cars registered from that date will need a "Type Approved" one. They are spec'd to have higher quantities of the working precious metals in them, to comply with more stringent emission control (and changes to the Vehicle Excise Duty) introduced from that date. Consequently they are more expensive than Cats that don't need to be Type Approved, for earlier registered models.

I don't want to sound like a spoilsport, but if an MOT Inspector is doing their job correctly, they should fail a car that does not have a Type Approved Cat, when it should have one, based on its 1st registration date. You'd have to rely on MOT inspectors bothering to look at the Cat to notice, but if you take it back to the original MOT station, or now have a bright shiny new Cat, they probably would look at it!

I looked into this back in 2010 for my 1.7, but luckily, my MIL warning gave an OBDII code for a failed heater circuit in the first, upstream O2 Lambda Sensor (in the exhaust manifold). I found out at the time that there are two potential connector types for the replacement sensor - a round, or a square connector! However, that is in the INTERNAL mating surfaces of the connector block, not the outside shape! The outside of the two sides of the connector (the sensor wire and the body wiring loom!) are both square-ish, but it's the INSIDE shape that is relevant, to obtain the correct replacement sensor. I seem to recall the 1.7 body wiring loom connector (and so the sensor type) changed later in the production, possibly when the 1.6 engine was introduced. All the other Fiesta, KA and Puma models and engine variants, with the introduction of the Puma 1.6, had the same body loom and connector shape, so I presume Ford changed it on the 1.7, to require just one loom variant for everything!

When I replaced mine, I found I had to gently warm the exhaust manifold by running the engine for 20 - 30 seconds, then stopping it before proceeding, for the sensor to come loose! I'd taken out the manifold heat shroud bolts before starting the engine and it only needs to be warm enough, that you can still easily touch the manifold with bare hands!

Also, in later years, I used to do an oil & filter change, check spark plug gaps & condition, maybe a new air filter, etc., then a bottle of Cataclean, together with an "Italian Tune-Up" a day or so before putting it in for an MOT. I also practised keeping my fingers crossed!

I hope this helps you, or anybody else reading this in the future!

That's very insightful, thanks! I'm not up to doing any sort of mechanical work myself, but will pass this on to anyone who I can get to do it - and I'll remember the pre-MOT tips!