MS3X running mega ricj

[cobra351w]

Hi guys ,

hoping you can help, as in a bit of a desperate state, on an AC cobra replica tour in Spain , and the EFI has developed an issue.

I had the engine mapped a few months back all was perfect, I have been noticing over the past few days the afr reading are getting lower and lower, and fuel consumption is down to 12 MPG, AFR goes below 10 at times, already killing a wide band sensor.

Not sure why all of a sudden it should do this, it's very simple alpha N , on Borla ITB's running wasted spark fully sequential, no AFR correction.

The only difference is i have racked up nearly a 1000 miles of motorway cruising, where between the rolling road and now , has been short trips.

I can modify the map, but seems it needs about 25% less fuel at the lower left of the map, anything below 2500rpm, and 10% throttle means that on cruise this is where I'm struggling.

I cant really judge too well the upper regions, but nothing goes drastically lean above this.

Any ideas appreciated

[cobra351w]

That should have said mega rich!!

[nathaninwa]

2 things that come to mind. Its possible the air temp correction table needs tuned based on real world driving and temp swings, and if you have a wideband why not use it to control ego and get some correction and possible autotuning? You have a powerfull ecu, and ego control is a great addition to any efi system

edit, your setup to use "not include afr target" so if I think of that correct the afr table is not really used at all, but if you click to use afr target andenable ego control, make sure to change the load percenton the afr table, right now its at 30% throttle to start which is in the 12's for afr and 100% has you running 14 afr's

[cobra351w]

Nathan,

thanks for the response, at the moment no afr target is included, due to what seems unreliable afr signal, the gauge reads stable , but the afr on the megasquirt gauges are swinging all over the place, and also as so rich, it's already killed one lambda sensor ( wide band bosch) via zeitronix controllers.

it looks like a possible over fuelling issue, as possibly the pressure regulator is possible over fuelling, but need a pressure gauge to test that.

or possibly a few injectors are sticking open?

it' s the fact all was good upto recently, so something seems broken.

the only recent change was turning over the pressure regulator on the fuel rails, so I can fit a filter plate on the throttle bodies, but can't see why it would not work in any orientation?

Still working on it...

[DaveEFI]

How are you deriving the vacuum supply to the regulator? I'd certainly check the pressure - especially since you've altered things. Pressure has a big effect on the fuelling.

[cobra351w]

Hi,

It's a standalone regulator, so just uses fixed rail pressure

Regards

[cobra351w]

SOLUTION:

the TPS was knackered, when reading over the low range, replaced later with a Penny and Giles Hall effect unit.

Since then entire EFI solution rewired, Isolated all signal from HT & injectors.
Moved to fully sequential spark (virtual COP)

Only issue (new thread ) P & G sensor seems to be losing sensitivity with engine running at "off throttle" take off , possible sig to noise ration, but tbc.