Z3M Coupe Built 02/99 S50 engine failing emissions at MOT

[colb]

Had a rather nice Z3M Coupe in the Zedshed Cymru today for diagnostics as to why its failing emissions and can't get through its MOT.
Readings at MOT were
CO Limits 0.30% Actual 0.00% PASS
HC Max 200ppm Actual 16ppm PASS
Lambda 0.97 -1.03 Actual 1.14 FAIL
Same results on Fast idle test and Second idle test

Health check using Launch scanner revealed some historic codes so they were all cleared and the car rescanned which threw up the following codes
03 Fuel Injection Valve Cylinder 1
07 Inductive Sensor on Intake camshaft

Carried out activation tests on all injectors and they could all be heard operating.
Wiring to inlet camshaft sensor was found to be damaged but was showing live data from it.
Exhaust camshaft sensor was static but responded when engine given revs.
Maf showed up as working in live data.
Attention turned to Exhaust sensors but only able to see a digital readout from them and both static at 0.99 would have preferred to view them in graph form to see if there was any movement with a rising and falling voltage trace but software couldn't display them in that form.
WE did disconnect the Maf so it ran on default settings and it did change the engine note slightly but codes remained when scanned with it disconnected with the addition of a Maf code being set so have ruled a bad Maf out as to a cause to the rich running. No signs of any air leaks and since seeing the codes were related to other sensors we didn't smoke test the car on this occasion.

I do suspect the root of the rich running problem is the exhaust sensors so going forward going to replace the inlet cam sensor and the exhaust sensors and if they don't sort it look at replacing No1 injector since it threw that code.
Vanos was rebuilt by Mr Vanos earlier this year so ignoring that at present.

Will report back when we have results after installing the new parts but open to any suggestions if anyone else has had similar troubles with the S50 engine.

 

[Lulubell]

Some great new Zed-shed Cymru..
It was the DME (ecu) which was the issue.
The drivers on bank 1 & 2 was faulty .
The DME was serviced replacing the drivers inc checking everything with a detailed printed inspection report.
Car is now running perfectly, not constantly at closed loop now , open loop with o2 sensors finally working..
I highly recommend this company to service your ECU.
Remember these fragile electronics are 25 years old now so get these checked out beforehand as it gets very expensive othewise

used these guys very happy , very professional service throughout..
And of course the amazing work the main man does at the Zedshed

COMMON ECU FAILURES ON RANGE ROVER, CITROEN, MITSUBISHI AND OTHER EUROPEAN AND ASIAN CARS.

Common ECU failures on Range Rover, Citroen, Mitsubishi, BMW, Volvo and other European and Asian cars. ECU repairs and remanufacturing

avilec.co.uk

 

[Lee]

Thanks for updating us, these updates help more than you realise when it comes to diagnosing our zeds going forward.

 

[Althulas]

I was thinking after seeing a couple of threads on this to send mine off just for a health check and service while someone is still there to provide one.

 

[Lee]

I was thinking after seeing a couple of threads on this to send mine off just for a health check and service while someone is still there to provide one.

Or at least get them to refresh all the soldered joints to future proof it

 

[Pingu]

@bertiejaffa could tell you a tale or two about his problems getting the ECU on his M Roadster fixed .

I'm not sure if the swear filters on here are up to the job, so it's maybe better he doesn't

 

[Argyll Andy]

@bertiejaffa could tell you a tale or two about his problems getting the ECU on his M Roadster fixed .

I'm not sure if the swear filters on here are up to the job, so it's maybe better he doesn't

Or that folks have long enough between now and Xmas to read the rants