420R emissions

[Bucko]

Hi,

My 420R has just failed the mot on the emissions in cataclysmic style. It's so far out that I don't think replacing the cat will make any difference. There must be an underlying issue yet there doesn't seem to be any misfiring or rough running, I do intend to check the plugs and leads, etc first of all but was wondering if anyone could offer some advice? 
 

I'd like to check to see if there's any faulty codes present that would point me in the right direction. Could anyone recommend an obd reader to check, diagnose and reset fault codes?

[aerobod - near CYYC]

What are the values for HC, CO and Lambda at the test RPMs? There are all sorts of potential issues that can give different values for those measurements. With a Caterham using an MBE ECU, the only device that gives good diagnostic info is the MBE 985 interface to a laptop running Easimap software.

[Jonathan Kay]

And do you have any previous values?

Jonathan

[Bucko]

The fast idle results are:

CO - 11.37%    HC - 1405ppm    Lambda - 0.7

I believe the limits are:

CO - 0.3%    HC - 200ppm    Lambda - 0.97-1.03

I don't have any previous results, this is the first mot in my ownership. I had just refitted the cat for the mot as I have had a decat pipe fitted, so I don't think the cat will be shot as it hasn't really been used.

Rick

[aerobod - near CYYC]

Hi Rick, it is running extremely rich, a failed Lambda sensor or jammed fuel injector would be a couple of possibilities. If all plugs are evenly sooty I would unplug the Lambda sensor, give it a good hard run and see if they are a tan colour afterwards. If one plug is very sooty compared with the others there is either a jammed injector or poor ignition from a bad coil or plug, swapping the plug and coil to another cylinder would eliminate them as the problem, although fractured ignition wires are another possibility.

[Bucko]

Cheers James, that's very helpful. I'll check the plugs, connections, etc. I may just replace the lambda sensor too, just to rule out.

I'm beginning to suspect a faulty coil, although I would of expected some signs of hesitance or misfire, there's the normal lumpy cold running and then it seems to run just fine once warmed up. Is it possible to diagnose a faulty coil?

Rick

[Amos91]

Most likely to be the lambda with those values. 

[Bucko]

I suspected the lambda sensor and checked the wiring plug connection as the first and easiest place to check first. It just seems hard to imagine a sensor like that failing with so few miles.

[StevehS3]

I don't know much about the MBE ECU but would it allow the mixture to be changed by such a large amount even if called for by the lambda? 

[Benton]

Have had  previous experience with failed lambdas.......

#8 With my 420R the first lambda sensor failed before the first 600 mile service! Replacement was fine and still working 17,000 miles later when I sold the car.

#9 When the lambda sensor failed in my 620R the "default" map running meant the car smelt like an oil refinery and sooted the plugs etc., confirmed the failure by using Easimap,  Original  sensor failed around the 1,200 mile mark.   
Photo below showing left non working lamdba, right working!  
Replacement is still working fine 7000+ miles later.

 

 

[7 wonders of the world]

don't forget to check for a coolant temp sensor failure.... or failed thermostat too

with that much fuel I'm surprised the cat wasn't cherry red

[Bucko]

Had a poke around today and all plugs were equally as sooty and all the coils seem to be ok. So as it seems to be a common fuelling issue and not restricted to a particular cylinder, I've opted to change the lambda sensor.

I've gone for a Bosch 0-258-003-229, as I've found reference to this sensor elsewhere on the forum. Hope it's right as it does appear different to the one fitted and google is not coming up with anything referring to the number on the lambda sensor that's currently fitted (P463P).

[ducatidentist]

#12 any updates on this? Did the new Lambda sensor sort things?

[Bucko]

I'm currently out of the country, so unable to swap the Lambda sensor. Unfortunately I'll not get to it for another couple of weeks now, I will post a reply once its sorted.

[Bucko]

New lambda sensor fitted and emissions are back to acceptable conditions, mot passed.

Thanks all for your advice.

[Jonathan Kay]

Well done.

And thanks for adding the answer.

Jonathan

[rob spencer]

After two engine rebuilds in 10,000 miles (due to issues before I bought the car ), when the car seemed to have been filled with kangaroo petrol and black smoke came out of the exhaust when I revved my 420R on the way home from a week's touring in Brittany, I was anticipating the worst.  Driving up the M1 it would accelerate fine but would not cruise at an even 70mph without juddering, kangarooing etc. and making the diff sound like maybe that was even the problem. 
I found this thread when I got home, checked the plugs (all sooty) disconnected the lambda (thanks James) and went for a blast.  Now running well, so checked the plugs; now a beautiful light tan colour. Result!
So thanks to Bucko for sharing his problem and to all you lot who helped him (or her etc ) which helped me out and probably others too. 
Lambda sensor now replaced (£55 from Sparkplugs.co.uk) and plugs still looking lovely and no engine rebuild again ... yet.

Rob

[rob spencer]

Forgot to mention that the solution all happened the day before a booked MOT, which thanks to you lot, it passed.