Removing Lambda Sensor

[jmracing66]

Hi All...

Is there a trick to removing the lambda sensor in the CAT ? I have tried everything I can think of and its still stuck fast.

Its not on a reverse thread or anything like that is it ?

Thanks

[martyn]

It has a normal direction thread.  Mine was quite tight the first time I removed it. Needed a friend to hold the cat while I pulled on the spanner (whole lot was removed from the car by this point).

If that fails, then try heating various bits up with a blow torch.

[TJG]

They can be very tight but never had one seize or break (where's the famous last words smiley)

I have a hex lambda socket with a cut out for the cable and a bunch of other gear if you get desperate, I'm lurking in Hoddesdon.

Tony

 

 

 

[Dr Slotter]

Loads of penetrant, a shock TIGHTEN, and then untighten worked for me recently. 

[paul richards]

Yes

A tighten and then loosen seems to help.

[jmracing66]

Thanks, I was trying to undo it in situ. I'll try to disconnect the other end of the cable and get the whole lot off the car.

[jmracing66]

My lambda sensor must be welded in ! I have thrown everything I have got at it included a lambda socket and I still can't shift it.

i don't want to damage the cat so I think I'll take it to a professional and see what they can do with it.

[SM25T]

A long lever is normally your friend after a dose of PlusGas the day before.

[Smithy77]

Did you try applying heat?

 

[simon_h]

Or you may strip the thread and ruin the sensor and cat!

If doing something like fitting a cat delete probably better to get a new sensor and leave the old one in. They don't like being removed too often, especially if they have been in a few years.

[7 wonders of the world]

Spend a good few mins tapping it with a toffee hammer withthe odd spray of penetrant juice, then lambda socket plus breaker bar or if its inside the care extenstion with decent T bar for better control.

If you have access shock it with a windy gun.

[jmracing66]

That is exactly what I have done. Probably the most expensive way to fit a cat bypass pipe but that's my only option realty ! 

[martyn]

If you do buy a second lambda sensor (to save the hassle when switching pipes) don't, whatever you do, go to a ford parts counter.  They wanted £211 for a like-for-like replacement!

[SM25T]

eBay is your friend

[jmracing66]

I ended up getting another lambda sensor from Caterham. It was £112 which doesn't seem to bad after hearing the price from Ford ! 

[Dr Slotter]

The UK Duratec cars (i.e. those with basic narrowband lambdas) often use Rover lambdas.

[jmracing66]

My new lambda did come in a box with MG Rover stamped on it which I did think was odd but now I know ! 

Anyway, what was supposed to be a simple job turned into a small nightmare but finally the bypass pipe is on and everything is working again !

http://i1054.photobucket.com/albums/s496/jm_racing66/F037E464-FFC4-4E3F-996E-D4E7C5D5FADF_zpszr2ujyxb.jpg

[martyn]

To be honest, I don't really think the lambda sensor does much. I was driving around for probably months with a failed one. Replacing it for a new one I couldn't tell any difference in either driveability or fuel economy. The car even passed the MOT emmisions test while it was broken!

[Dr Slotter]

On a standard Duratec roadcar setup the car runs in closed loop (i.e. takes notice of the lambda and other sensors) for the first 40 seconds of engine run to modify the air/fuel ratio, otherwise they run open loop (i.e. ignore sensors). IME a dodgy lambda on a Duratec does the following:

- When the ambient temperature is pretty cold, the car needs quite a bit of throttle on starting to run properly for the first 40 seconds.

- When the engine is properly hot (i.e. after significant track use) application of throttle during first 40 seconds causes very uneven running and lots of hesitation.

Shouldn't have any influence on passing MOT emissions tests other than prolonged running with a dodgy lambda will speed up the decay of the catalyst matrix and therefore increase the liklihood of a test failure.

[martyn]

That's interesting, are you sure you have that the right way round? The sigma is the exact opposite. It runs open loop for the 30 second warm-up timer then switches to closed loop.

[aerobod - near CYYC]

I agree with Martyn, MBE 992 ECU factory fitted to my 2012 R400D runs open loop under the following conditions:

First 30 to 90 seconds from start (until oxygen sensor heats enough to drop sensor output voltage below 1.3V).

Coolant temperature equal to or below 60°C.

Engine speed below approximately 4100 RPM (inferred by data logging, as map is encrypted).

Throttle site below approximately 10.0 (inferred by data logging, as map is encrypted).

May also be put into open loop by other parameters, such as MAP pressure, but difficult to tell from data logging.

 

[Dr Slotter]

Those specifics I mention is what CC told me recently when they were diagnosing some faults on my 2009 Duratec. I was surprised to discover that the ECU runs in open loop when it is off the start map as it is usual for most engines to run in:

- closed loop at low load i.e. idle or at part throttle (e.g. cruise) (I would say that is what Aerobod describes in their second two bullet points) to optimise economy/emissions. I guess that during startup the ECU is monitoring the lambda sensor so it knows when it is up to temperature (by the voltage change mentioned by Aerobod) and then uses it, so is technically still operating in closed loop.

- open loop when under load i.e. accelerating or engine braking.

In the process of looking at my engine with CC, I suggested that the cause of the hunting at idle/part throttle when it had got hot was that the lambda was feeding the ECU duff information. The CC guys said that wouldn't matter because it is in open loop at that point. I also mentioned about temperature compensation and got a similar response.

Note for other Duratec owners: the above is seperate to the classic hunting because of a dodgy TPS issue.

 

[aerobod - near CYYC]

I believe there are a couple of issues with the standard R400D map relating to the throttle site when the throttle is closed. One is sensitivity to throttle position and cable tension. To get the car to idle evenly, the default throttle stop position takes the TPS voltage over 1.30V, which takes it into throttle site 1.0, as opposed to 0.0 to 0.9, this causes the map to see the throttle as being open, increase the revs, then drop back again. This is not helped by the normal lambda probe oscillation in closed loop at about 0.3Hz. Throttle cable tension also has to be set carefully, as there needs to be a couple of mm of slack when cold, so that it doesn't crack the throttle open when hot. With a bit of fiddling to minimize the throttle voltage by winding the stop back as far as possible and adding a bit of slack in the cable, I managed to get my car to a 1.20V TPS voltage and to idle evenly at 950 RPM instead of hunting between 950 and 1250 RPM when hot or requiring throttle input when cold.

Another interesting issue with the standard map is that it only gets to throttle site 14.0 on my car at full throttle, as the TPS can only rotate to give 4.68V before it hits the non-adjustable stop at full throttle, so the car never gets to site 15.0.

Due to the issues with the standard map on the 992 (especially as it totally ignores any barometric sensor input, which I need at my 1250 metre altitude), I bought an MBE 9A4 from SBD. Unfortunately this week I had to ship the 9A4 back to SBD for a re-flash, as Windows hung while running Easimap when I was writing a new chip file with enhanced wideband lambda control to the 9A4, bricking it.

One other interesting thing about the standard map on the 992 is that it is very aggressive in advancing ignition, to over 50 degrees in some high load conditions in the 5000 to 6000 RPM range and in the mid 40s at redline, I'm not convinced there isn't some pinking, but will need to have some analysis done with a knock sensor to be sure.

[Dr Slotter]

Interesting stuff.

[martyn]

Aerobod,  do you think it is because of your altitude that the idle throttle stop needs to be opened so far, therefore putting your TPS voltage out of range (> site 1.0).

Also, not reaching throttle site 15 suggests that there is too much slack in your throttle cable or the stops are set incorrectly.  Have you tried rotating the throttle linkage by hand all the way to its stop?  What site do you get then?   I don’t want to sound patronising. It sounds like you already fully know what you're doing!