The fuel consumption I'm just living with. A different exhaust system might help - so might electric thermofans, free wheeling front hubs, new oxygen sensors etc. But I'm sure the expenditure would out weigh the gains.
Has your brother got the same series XL-7? The first series, with the older front end, is supposedly more fuel efficient (going by the published figures.)
I run mine permanently on BP Ultimate. It costs more but I just fill up when fuel is cheap. I'd much rather pay the extra for fuel than risk damaging the engine. You could try retarding the ignition timing (via the cam sensor- I believe their is some adjustment). Colder spark plugs might also help with detonation?
You'd be better off buying/ borrowing a stand alone air fuel ratio meter to check the mixtures. I assume you're in Australia? None of the XL-7's here seem to be OBDII compliant.
I have read few of your post and wanted to find out if you ever found a solution to common issues you experienced:
1. Fuel Consumption - Currently I'm getting average fuel consumption of around 13.5l/100km - mostly metro but highway is not much better . My brothers XL7 gets worst 12.5/100 and best of 11/100.
2. Detonation - If I fill up on standard unleaded and put the engine under load (driving uphill) I can hear detonation (pinning), if I use BP ultimate it doesnt happen.
3. ODB scanner - I have tried couple of the ODB tools and I'm unable to communicate with the ECU (tried different protocols and still nothing). I was hoping to use the tool to check fuel mixture which could explain the detonation.
I do have experience with detonation and know it can can cause engine failure if the cause is not discovered fast enough.
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