Facts about injector calibration figures.

**nutron** · 12th December 2012, 12:38

The manufatures acceptable variation in Bosch injectors for the 1.9CDTI 16v, max to min acceptable flow rate is over 30%. If you get a set of injectors or even one injector and fit it without correcting the ECU calibration figures, you could create upto a 60% variation in fueling between cylinders.

If you are running 60% more fuel than the ECU intends, you are likely to melt a piston.

If you run 60% less, you will have difficulty starting possibly and rough running definitely.

Even if you goto a company who uprates injectors and they do a good job of balancing them, without correct calibration figures, assuming the injectors you get are perfectly balanced, you could still have a 30% difference in fueling between cylinders.

Ensure you have correct calibration figures for your injectors this winter.

Merry Christmas X

**johp778** · 12th December 2012, 15:32

I have a 120 and have a feeling my injectors could do with a refurb and was considering getting them tested, so if I got them refurbed, would they got straight back in or need calibrating with the ECU?

**nutron** · 12th December 2012, 20:52

If they refurb them, they would be cleaning and possibly replacing bits, plus they may have worn over time. So I would suggest sending them to a place that could check and create new calibration figures.

**plasma** · 12th December 2012, 20:55

me and u need to chat about wots happening over xmas

**nutron** · 12th December 2012, 20:58

Oh sweety, yes please

**Chunklamb** · 12th December 2012, 20:58

So is there a laid down fueling rate for an injector, or are they all different, 1 thru 4 etc? (I have ZERO knowledge of this stuff! So as dumbed down as you can please.)
Can you see the flow rate with Tech 2 and recalibrate etc?

**Signum-Steve** · 12th December 2012, 21:01

So what is it your saying? Are you saying to run within the VX factory calibration parameters??

**nutron** · 12th December 2012, 21:11

The Bosch injectors have a tolerance range, I wrote it down today but do not have it with me. I believe from memory the acceptable range is 50.5cc to 67.5cc, something like that which a suitably knowledgeable Bosch specialist would know. That gives about 33% variation possible from a standard set of nozzles. The calibration figures are on the top of the injectors and are stored in the ECU for each injectors No1-No4, No1 being the right hand drivers side of the car where the airbox is. These figures can be changed with OPCOM or a Tech2 or any other suitable tool. People who change the injectors should change the figures to what is on the injector top if they are new; if they are reconditioned, they should have new figures. If you get a set of injectors uprated, they will need new calibration figures or at the very least, if you knew for sure they were balanced, the same figure should be entered for all injectors.

**cont1204** · 12th December 2012, 21:53

Interesting bit of information. That's a hell of a variation thinking about it.

**johp778** · 13th December 2012, 00:40

I wish I could just take it to a specialist and let them refurb the injectors, refit them and calibrate them. I don't think dealers would do this, they would just fit new injectors and then charge you.

Anyone know somewhere to trust in West Yorkshire who can do it, at a reasonable cost?

And is there anyway I would know if they need refurb? My mpg has not been above 45, even on a good run, which is low compared to some getting avg of 47-50. I'm not getting any smoke out the back tho.