Emissions Problems on a Le Mans – High CO levels

Hi Guys

Can anybody enlighten me on how to identify the difference between an ECU for a D501 engine and a D502 engine?

The reason is I am having Carbon Monoxide emissions problems that have caused the Le Mans to fail its MOT. On the test it was measured at 4.5% a full 1% above maximum permitted levels. Today I took it to a local guy called Gavin who is very good with diagnostics and indeed has many local garages send cars to him for diagnostics and repair. To cut a long story short we would like to know how to identify between the two ECU’s as my Le Mans has previously had its D502 engine replaced by a D501 engine, but all ancillaries from the D502 engine seem to have been installed onto the D501 engine. Therefore at this time Gavin and I believe that as well as the D501 engine an ECU from a D501 has been installed and this is not functioning correctly with the engine due to the D502 ancillaries, such as the Lambda Probe from the D502 being present, but no CO potentiometer as would be fitted on a D501 GTA Turbo. We are getting up to 5 volts at the Lambda Probe when it should be approximately 450mv, but 5 volts should be what is present at the CO potentiometer suggesting a D501 ECU that cannot function 100% correctly with the D502 ancillaries.

Alternatively if people could send me by email, see below for address, photos of their ECU’s showing the label with all the numbers and stating whether it is for a GTA Turbo or a Le Mans I would be grateful and could analyse the photos to find the numbers etc.

Does anybody have any wiring diagrams of a D501 engine and a D502 Engine? I have a M.R. 273 manual but that does not seem to have any wiring diagrams. Again if anybody does have wiring diagrams please email them to me.

My email address is: paul.cowley4@ntlworld.com

I have included the photo I took of the ECU currently installed in my Le Mans at this time.

Regards

Paul.

PM all ready sent with info

PM all ready sent with info

Thank You

is this a secret mr turbodog

Not at all Andrew

Paul, I think your best and cheapest option would be to remove the wires from the oxygen sensor and then connect them to a CO pot. The engine and ECU fitted to your car was meant to run with a CO pot. Have a word with Martin as he may have one on one of the cars he is breaking.
Best of luck
Andrew.

Paul, I think your best and cheapest option would be to remove the wires from the oxygen sensor and then connect them to a CO pot. The engine and ECU fitted to your car was meant to run with a CO pot. Have a word with Martin as he may have one on one of the cars he is breaking.
Best of luck
Andrew.

Hi Andrew

I will take that on board, will you still be sending me those wiring diagrams please?

I will PM you my email address.

Paul.

Has the CAT been removed?

Has the CAT been removed?

Yes it has, and a stainless exhaust fitted.

Call me simple, but surely that's the problem.

The ECU now fitted to the car is not compatable with an oxygen sensor the voltage is incorrect so the ECU will misread and over fuel the engine If the cat was still fitted then Paul would have no choice but to get the correct ECU and use the oxygen sensor

Call me simple, but surely that's the problem.

Yes it is one of the problems, but Gavin the man who is looking at it wants as much info as he possibly can have so he can proceed after weighing up all of the pros and cons.

As Andrew, Turbodog suggests a CO Pot could be a route to follow.

[mettersl]

Old enough not to need a cat, so it sounds like the CO adjusting pot is the way to go as d 502 ecu must be as rare as hens teeth...and you get an extra 30 bhp too (200 vs 170) sounds an easy choice....adaptronic could be a more expensive and complex alternative....

Old enough not to need a cat, so it sounds like the CO adjusting pot is the way to go as d 502 ecu must be as rare as hens teeth...and you get an extra 30 bhp too (200 vs 170) sounds an easy choice....adaptronic could be a more expensive and complex alternative....

Indeed.

UPDATE and part number check.

I had a chat with Gavin today and relayed all of the comments received from the forum members and he is leaning towards fitting a CO potentiometer so I will drop the car off at Autocraft tomorrow morning for it to be there Monday morning when Gavin will remove the leads from the Lambda Probe and attach them to a gizmo that replicates a variable resistor as a substitute CO pot and analyse the CO emissions. If this works we will then wire a CO pot to the Lambda Probe leads and send it for an MOT.

I have checked the part number catalogue and have found on page numbered, (or so it seems), 17.401 what I believe to be the CO Potentiometer numbered as 3 in the diagram and 77 00 722 068, can anybody confirm this or provide the correct information, please.

Regards

Paul.