With the various issues I've recently had with the SV8 resolved (MAF sensor out of spec, leaking (vacuum leak) EGR, out of spec O2 sensor, clogged catalytic converter, tired transmission), I'm back to making decent power.

The new issue: I'm hitting some sort of fuel cut when making peak power in 3rd gear, and a P0103 CEL is thrown at the same time. Full power in the lower gears is fine, it's the 3rd gear pull when the MAF sensor values seem to exceed acceptable parameters.

I data logged with the iCarsoft 930, and my airflow is peaking at 52.9 lb/min, which back of the envelop equates (I think) to 500 to 525 hp (which I think is not actually possible given my setup). From a voltage perspective, assuming I can extrapolate Subaru MAF voltage to airflow tables to the Jaguar, the voltage on the table would be over 5.1 volts which of course is well into the maxed-out MAF zone of things. While the car is very fast, I do not believe I'm making over 500 hp. So.... my replacement MAF is immediately suspect.

I went with a generic MAF sensor from a national parts chain because it was available to me quickly as I was trouble shooting my air/fuel problems. I am now concluding that the high end of this sensor may not have enough resolution for the Jaguar ECU. So... some questions for the community:

1. Are there any general recommendations for the 'best calibrated out of the box' MAF sensor? For now I plan to grab a Denso because I've had good results with them over the years, though I am open to other recommendations. I want new versus remanufactured.

2. Does anyone have a voltage to airflow table or graph for the X350 supercharged cars? Would be interesting to understand what the ECU expects.

3. Does anyone know whether there is a particular, specific MAF voltage that will trigger a fuel cut, or what the necessary criteria are for the ECU to throw a P0103 error?

Thanks all. Overall the car is 'back' and a blast to drive, just have this last little thing to solve. If it turns out I am truly maxing out the MAF, then the solution may be go to a slightly oversized MAF housing. A 76mm ID housing would give me 4% more airflow than my stock 74.55mm ID housing, which would lean out the stock maps slightly and provide some cushion on the MAF voltage. Though for now I think the sensor itself is the issue.
- Scooter

 

Denso 197-6040

my last vietnam special denso maf was randomly throwing p0101s

 

I had to get an OEM MAF for my car a few years back. First tried an aftermarket Delphi, thinking it was a known brand sensor manufacturer, but it made problems worse. OEM Denso got it back to normal.

 

I replaced the MAF with a Denso tonight and no more CEL or fuel cut. Peak airflow on a couple runs was 49.2 lb/min, below the 52.9 that the other MAF read.