MoTeC Global Forum

Help required.
I hope someone can help me here!

I have a race car using a Motec M8 ECU. The car was always a good starter until recently; now it simply will not start.
I have (I hope) eliminated all issues such as fuel and spark etc as I have 4 Bar fuel pressure and a good spark on all four plugs.
So, I have to assume that some sensor is down on the engine?

When I have managed to get the engine running (with some easy start!) it seems that it is running extremely rich for some reason. The plugs are fouling and it will not tick over (it seems the mixture evens out at higher revs).
The engine must be flooding when trying to start.

I have connected the ECU to the software and laptop package that came with the car and ran the diagnostics / errors check. The injectors all click away when testing them.
The only error i am getting is AT Error. Which is the Air temperature sensor.
This being faulty or even disconnected would not cause the engine to run so excessively rich would it?

Would anyone have any other ideas I could look into? Is there some give-away in the software that would indicate what it wrong?
I am afraid that I really am new to this kind of thing, so laymans terms please!!

Thanks for your time.

I am not familiar with the M8, however if you have a AT sensor fault, the AT sensor value could be causing the ECU to add fuel from the AT Comp table (or equivalent compensation table)

This also assumes there is actually an air temp sensor fitted of course....there may or may not be

But either way, it is highly unlikely to be causing the problem unless air temp corrections are very strange. A few seconds with the software will tell you exactly what they may or may not be

With the software open and ecu connected press the F3 key, that will bring up the errors screen, double check here that your AT sensor is the only error showing. If AT sensor is the only error showing then you can esc out of that screen and hit "T" (to bring up the trims screen), this will list all trims that are being applied to fuel & ign so you should be able to see how much effect the AT trim is causing.

Thanks guys.
The Air temp sensor is present but looks obviously broken.
this was no doubt in the same condition when the car was running fine 2 miles down the road at my friends house!

Those short cuts to view the trims are handy, thanks. I literally know nothing about mapping/ecu's so I wont be touching/adjusting anything.
My only hope is that I will find something obviously wrong or strange.
What kind of values should I be looking for to indicate something strange?......

Would the best idea be to get the engine running (if i can) and view the software then? I assume that simply connecting the ecu to the software and not running the engine wont tell me much.

Thanks again chaps.

sambo wrote:Thanks guys.
The Air temp sensor is present but looks obviously broken.
this was no doubt in the same condition when the car was running fine 2 miles down the road at my friends house!

Those short cuts to view the trims are handy, thanks. I literally know nothing about mapping/ecu's so I wont be touching/adjusting anything.
My only hope is that I will find something obviously wrong or strange.
What kind of values should I be looking for to indicate something strange?......

Would the best idea be to get the engine running (if i can) and view the software then? I assume that simply connecting the ecu to the software and not running the engine wont tell me much.

Thanks again chaps.

So you're saying you can see that the air temp sensor is physically broken ?

You dont need the engine running to see the air temps, or look through the software to see what trims may be applied at any given air temp.