Grand Vitara XL7 2.7L H27A fuel octane

Started by Anthony755, June 01, 2017, 08:05:56 PM

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One more..

I have only filled my 'new' XL7  5 times, but it looks as though there may be a fuel economy benefit from using 95 octane over 91 octane. I can't comment on 98 octane as yet.

My car has done 160 000km, manual.

I live on the sunny coast which involves more free driving than start stop driving, but there's a bit of up and down hills, and I'm seeing low 9's in L/100km on 95 octane and around 11L/100km on 91 octane so far. I need to look at it longer to be sure the fuel comparison is really fair however.

Have others found any benefit to using the premium fuels?



yep, if your is tuned to use the higher octane you will see a difference.

check that the ignition timing is set to spec, or a little advanced if you will run Premium all the time.

Not sure what year they put the smarter ignition timing in them, the sq625 didn't have a knock sensor so they ran just be pre-set ignition map, when the similiar engine was put in the JB627 ( the newer body shape) it came with a knock sensor so it continually hunts for the best ignition timing (just before pinging) so premium makes more difference in them. Not sure which ECU will be in yours.


(Don't laugh, but) armed with that info...... a review of knock sensors on ebay and finds that the 2.7L H27A engine as used in XL7's from 2001 to 2006 does indeed have a knock sensor. Also a 2.0L suzuki engine in (at least) the same period used the same sensor.

In fact on ebay Supercheap auto will sell you one for $170AUD, whereas you can buy them on ebay in the USA for USD$10 !!

As this points to my car having the smarter ignition ECU you mentioned, in your opinion is it still necessary to "check that the ignition timing is set to spec, or a little advanced if you will run Premium all the time." ?



I do get some benefit (1998 V6 Prado) bit more torque and better range
and I've bumped up the base timing on the Vit to run it but have not measured anything, (because it's flat out doing 2k per year if that atm)
I'm lucky our local Shell (cnr Herston Rd and Kelvin Grove Rd) sells Vortex 98 for only 13-15 cents more than 91 octane so probably winning maybe!! cheers


Hi Anthony,

probably not so important, but any with the old cam style pick-up might be worth doing as any I've checked have never been correct. If it feels doughy it would be the first thing I'd check.

So to clarify, the older style ECU has the timing pick-up on the back of the cam on the passenger side, and the newer style uses a crank angle sensor which reads the crank position directly from the crank. So the later really shouldn't need checking as unless the crank sensor fails it will consistently read the actual crank position. The earlier style is driven from the cam, so any slack in the cam chains, or wear any wear will move the relationship of the cam timing to the crank, with thus impacts the accuracy of the timing.


Great information.

Supercheap sell a tridon crank angle sensor for the XL7 JA627 2001 to 2006, and it appears that the JA series XL7 engine has the same knock sensor and crank angle sensor as the JB series you're mentioned.

Thanks again. The local RACQ had suggested premium unleaded for it but didn't say why


Well well well. After looking at the hardware on the car, there is indeed a cam position sensor on the passenger side cylinder bank..... and the location where the crank position sensor would bolt in behind the main pulley at the front of the engine has a small blanking plate on it.

There are photos here that helped me realise this:

Makes me wonder why supercheap auto have tridon crank position sensors for sale, as on ebay, and Tridon themselves do too            for JA627 H27A engines XL7 2001 to 2006 ?!?!

If I have the older ECU would it mean my H27A engine doesn't have a knock sensor also?, would it be visible if I looked and if so where?


June 06, 2017, 08:53:50 PM #7 Last Edit: June 06, 2017, 08:58:43 PM by Anthony755
So I'm getting better at answering my own questions .applaud. .applaud. I found this reference to knock sensors on suzuki V6 engines.

Armed with the last photo I was able to quickly identify that my:

Suzuki XL-7, with
2.7L H27A engine
5spd manual
Built Japan October 2003, Australian compliance plate affixed November 2003, and sold in Australia in April 2004
that has a cam position sensor for ignition timing (no crank position sensor fitted, the port is blanked off)

has a knock sensor of the type, and in the position as described in the last photo of the forum thread indicated above.


hopefully this helps. this is the section from the SQ manual about setting timing on an engine with the crank sensor on the back of the head.

and yes if yours has timing setup like this - check it I'd put beer on it being out.