Sudden change in fueling motec m48

[Mick]

Has anyone got any idea what would cause sudden over fueling. Have had no problem using the M48 on closed loop after dyno mapping over the last 9 months, however over the last month had to replace plugs as they have been fouling constantly ecu doesn't show any errors, change the TPS, plug leads etc. is it possible one of the other sensors is causing the problem but no showing an error or perhaps a fuel pressure issue? Anyone got any idea what could cause the problem.

Mick

 

[Ian Anderson]

Mick
I do not run Motec but a Rover based system
When a sensor sees a strange reading it can go into limp home mode where to protect the engine from running lean it over fuels something stupid.

With the rover system a power disconnect and reconnect resets the ecu.

But I am surprised it is not showing an error code

Ian

 

[Mick]

Yeh can't understand why there are no errors either. I have a battery isolater that is turned off when ever its parked. It may be a bad connector hoping some could tell me which sensor may cause the problem.

 

[Ricky]

Hi Mick
If you are running closed loop it is quite likley a bad or failing o2 sensor. Can you borrow a known good one to check before spending $ on a replacement

 

[Mick]

Hey Rick nice to hear from you long time no speak, I have a spare O2 sensor suspected that it's the problem but not sure why it didn't show up as an error?

Mick

 

[Clayton]

Hi Mick
I have an M84 and while it was in closed loop it would hunt at certain rpm's. Tried all sorts of things to fix it, but in the end I just turned it off and it now runs sweet in open loop. Go figure.... (Lambda readings are still good)
Can you turn that function off in the M48 for a trial run ??

As Ricky said, it could be the O2 sensors.

Clayton

 

[Mick]

Hi Clayton mine does a little hunting at low rpm but that interesting I might try it with the lamda on. Are you running dual Lamda,s. I have only one might be worth a try.

Mick