I am using a 1996 XJ6 air flow meter on my 1966 S Type with Megasquirt injection. I pulled the flowrate vs voltage data from the service manual and entered that into the computer and it is a long way off. I had to reduce the fueling by 35% at idle to get a reasonable air-fuel mixture for example.

This has me thinking that I have entered the calibration curve for the XJR's flowmeter, rather than the XJ6 ( which is what I am using). The curve I have shows a flowrate of 0.284 kg/s at 4.7 V
Could someone send me the flowrate vs voltage numbers for the 1995-1997 XJ6 please?

 

Hi Jagboi64,

The only reference I can find in my library is this page from the AJ16 Engine Management System Dealer Training Manual. I don't know if it will be of any help at all. I'm also attaching a pdf which may be a little higher resolution.

Cheers,

Don

 

From the service manual- Looks like the same curve you have! I guess he Megasquirt must allow you to put in the non linear curve and it handles linearizing it. Since the curve is highly non linear, I suppose you should not just apply a calibration constant, huh

 

Yes, that's the same curve I have. The question is does that apply to the XJ6 or XJR, as XJREngineer has stated that they are not the same curve. The AFM's are different part numbers too.

Megasquirt does not linerize the cure, it creates a best fit curve based on those values. A fair bit of math is involved. I attached the document if anyone is interested.

However, it appears that Jaguar wires the ECU differently than other typical AFM's (what a surprise! ), so I have to add some components to my megasquirt board so the signal output from the MAF isn't just noise. After looking at the diagram in the service manual an Electrical Engineer friend of mine noticed the difference and the pull up resistor in Jaguar's circuit.

 

Yeah, I was going to point out that down at idle air flow, you are "in the noise" of the electrical signal's voltage. Even a small voltage loss on the return could make a 35% error, much less not having the input circuit right.