Ever since my engine has been built and running there is a overfueling issue that I can’t get to the bottom of spec is as follows:

205 block
7:2.1 low compression pistons
Standard head and cams
UtT38 turbo
Siemens 3102 55lb injectors
3 bar map sensor
071c plugs
MSD chip to suit
Fuel pump rewire
Twin fan rewire

i have replaced every sensor, had the TPS set up ,checked fuel pressure regulator, changed ecu even tried another loom (second hand) and it’s still emitting
black smoke out of the back when you rev it my next step is to check the fuel return pipe to make sure it’s clear beyond that I don’t know what to do? New engine loom? I want to get it set up on a rolling road and a custom map but while it’s overfueling I can’t get a MOT on it so I’m limited

 

Hi, have you reset the mixture screw on the ecu?
I had a similar problem and it was down to the mixture screw not being reset and setup, on L8 it's 5 turns clockwise and approx 2 1/2 turns anticlockswise for a ball park figure, and L6 i think is opposite but you will need to ask as i'm not sure, you MUST check fuelling after doing this as you you don't want to melt your engine if it's running lean.
Hope this helps.

 

The CO pot is known as the 'global' mod and works by altering the voltage to the MAP sensor, it trims the fuel table by an overall percentage, hence the comment about it potentially running lean at the top end.

A couple of things to check is the MAP reference host is connected/not split!

The CTS is also a corrective factor for the CO and if not giving the correct input will result in rich running.

You say you have checked the regulator, but what about the fuel pressure?

Another common thing is the reg diaphragm can go, which results in vacuum drawing fuel into the plenum via it's reference hose.

Martin

 

I’ve reset the co screw made new difference, fuel pressure regulator is new and pressure if fine no splits in any of the hoses all brand new

 

Could the thermostat be stuck open?, does it get up to temperature normally?
and coolant Sensor might be thinking engine is still cold?

 

Gets up to temperature fine fans cut in and work fine new thermostat and cts

 

Get it booked in for for tune and book an mot for straight after (day or so), if you are unlucky to be stopped explain that you are having fuelling set for mot and they can check that you are booked in for mot with the garage.
seems reasonable.