injector readings

[sean71]

Hi all I had my 9 3 on op com today and the injector readings were as follows

cly 1 1.77 mg/stroke

cly 2 -0.51 mg/stroke

cly 3 -1.23 mg/stroke

cly 4 -0.13 mg/stroke

1 and 3 banjaxed? Just some advice before I start throwing money at injectors Thanks in advance!

[sgould]

Welcome!

What engine?  Size? Petrol? Diesel? Year?

And to be honest, I would not rely on a non-Saab diagnostic reader.  They can be very variable and may not be reading what you want or telling the truth.

Is the car running badly?

[sean71]

Sorry I should have listed years, engine size etc!

2004
1.9 tid
150
Not so much running poorly but more a little misfire around 1500-2000 rpm, injector 3 wiring kit done, egr blanked (with holes in the plate) manifold deflapped and cleaned....fuel economy good at around 49ish mpg.......maybe it's all in my head lol

[wrighar]

Numbers don't look that different to mine.

Are the correct injector coding number in the ecu matching the actual injectors?

Also, if you raise the rpm to say 1500 or 2000 rpm, do they level out?

Mine seem to adjust the other way then.

[sean71]

I didn't go as far into the detail of the codes to be honest but you're right when you say that the numbers swing the other way when the revs are taken up a little higher. I'll check the codes out tomorrow after work but by the sounds of it I don't have much to worry about, many thanks for your help

[phoenix]

It's normal. The ECU does somethign called cylinder balancing to make things run smoother:

The objective of this function is to balance the combustion pulses from each cylinder. This
is performed at idling speed to compensate for variations in the quantity injected into each
cylinder and the differences in the efficiency of each cylinder. Compensation under other
operating conditions is performed mainly for the differences in efficiency of each cylinder.
This is achieved by calculating and changing the injected quantity for each cylinder
individually.
The engine control module measures the speed of the crankshaft after each power stroke.
When the cylinder is about to ignite the next time, a calculation is ready to compensate the
quantity for the next combustion. This compensation quantity is adapted so that the next
combustion results in the same working pulse after combustion as that in the other
cylinders.

The average compensation quantity for the four cylinders is adjusted towards 0% so that
the idling speed is not affected by the cylinder balancing function. The limit for the range
of adjustment is 5 mg/combustion.

Cylinder balancing is not in operation:
- under 200 rpm
- over 2000 rpm
- under 2 mg/combustion
- over 40 mg/combustion

Calculations are performed with the following variables:
- Engine speed
- Injected fuel quantity