MoTeC Global Forum

Hi

this is my 1st Motec ecu M4 pro

my engine setup as below

SR20det
GT3076R turbine
FIC 1050cc low ohm injector
Greddy intake manifold with 70mm throttle body
big FMIC kits
std cam shaft
walbro pump with 20psi w/vacuum

the problem is the air fuel ratio too rich (11af ) at idling after I change my 510cc injector to this FIC 1050cc injector .

I know we can reduce it at fuel map right , but even I reduce the loading point ( idling ) to 0 it still too rich .

but once the vacuum loading point near to 0 vacuum everything go find .

the problem stared when the loading point go below -0 vacuum .

can anyone here help me out of this problem .

Thanks a lots

Have you adjusted the settings in the Motec for the new low impedance injectors ? ( assuming previous were high impedance ? )

And are you operating fully sequential injection ( ie you have a crank and cam/phase sensor ) ?

Also, not that it should affect this, that throttle body is huge for that engine.

wenya wrote:Hi

walbro pump with 20psi w/vacuum

Please clarify what you mean by that. Because 20psi is a totally ridiculous fuel pressure to be using in an efi car. it is far far far too low.

IMO never go less than the typical 35-40psi or so ( with vvac )

stevieturbo wrote:Have you adjusted the settings in the Motec for the new low impedance injectors ? ( assuming previous were high impedance ? )

And are you operating fully sequential injection ( ie you have a crank and cam/phase sensor ) ?

Also, not that it should affect this, that throttle body is huge for that engine.

yup set it to low impedance

yup fully sequential injection

for the 70mm throttle because we are looking for 480whp for this motor , ( a pair of Tomei Procam 270 is ready to drop in once settle the fueling problem )

stevieturbo wrote:

wenya wrote:Hi

walbro pump with 20psi w/vacuum

Please clarify what you mean by that. Because 20psi is a totally ridiculous fuel pressure to be using in an efi car. it is far far far too low.

IMO never go less than the typical 35-40psi or so ( with vvac )

yup I know it is very low for EFI motor ,

but if I set it to 30psi it will much much too rich at below 10A/F you see.

and at the fuel map it is no way to reduce anymore ! even go as low as 0 value it still too much fuel .

is there any other way to reduce it ?

70mm TB will support double that power.

And the injectors will never work properly at such low pressure which could be contributing to the problem. They will just dribble fuel out, not spray it as a fine mist as is required.

What are your actual injector pulse widths at idle ? Are they wired correctly in firing sequence ?

And fitting bigger cams will only make the situation worse, so you really need this sorted first.

In the picture, the first injector looks like the seal is not fitted correctly, are they all like that ?

Restore fuel pressure to a sensible level, then try and tune for an idle at say 2000rpm and see if that works. If it does and you have control, perhaps adjust injection timing to see if it helps and then reduce the rpm's slowly

Although if you have a zero in the main map and the engine still runs, something else is badly wrong. The engine should stop, as no fuel should be injected. So confirm there are n strange settings within the ecu and confirm at zero fuel pulse widths are zero.

stevieturbo wrote:...
Although if you have a zero in the main map and the engine still runs, something else is badly wrong. The engine should stop, as no fuel should be injected. So confirm there are n strange settings within the ecu and confirm at zero fuel pulse widths are zero.

How do you set the dead time for the injectors?

stevieturbo wrote:70mm TB will support double that power.

And the injectors will never work properly at such low pressure which could be contributing to the problem. They will just dribble fuel out, not spray it as a fine mist as is required.

What are your actual injector pulse widths at idle ? Are they wired correctly in firing sequence ?

And fitting bigger cams will only make the situation worse, so you really need this sorted first.

In the picture, the first injector looks like the seal is not fitted correctly, are they all like that ?

Restore fuel pressure to a sensible level, then try and tune for an idle at say 2000rpm and see if that works. If it does and you have control, perhaps adjust injection timing to see if it helps and then reduce the rpm's slowly

Although if you have a zero in the main map and the engine still runs, something else is badly wrong. The engine should stop, as no fuel should be injected. So confirm there are n strange settings within the ecu and confirm at zero fuel pulse widths are zero.

wiring all correct
will fix the fuel pressure and try it out .
the injection timing is RPM 1000 ~250 , RPM 1500~275 at the moment .
the pulse widths is 0.2 at idle .

I'm not going to install the cam yet , now trying to get the idle done 1st .

Holmz wrote:

stevieturbo wrote:...
Although if you have a zero in the main map and the engine still runs, something else is badly wrong. The engine should stop, as no fuel should be injected. So confirm there are n strange settings within the ecu and confirm at zero fuel pulse widths are zero.

How do you set the dead time for the injectors?

the dead time is 12v ~1140, 13v~1060

wenya wrote:

Holmz wrote:

stevieturbo wrote:...
Although if you have a zero in the main map and the engine still runs, something else is badly wrong. The engine should stop, as no fuel should be injected. So confirm there are n strange settings within the ecu and confirm at zero fuel pulse widths are zero.

How do you set the dead time for the injectors?

the dead time is 12v ~1140, 13v~1060

I would suggest that you need to measure that yourself.
if you wind that right back to zero, and wind back the fueling cells at idle to zero, then it should not be running rich.