Xantia Fuel economy

[DoubleChevron]

Yep it's got the plastic inlet manifold of the CX N/A GTi too.

Any car will spin the wheels if your brutal. First thing, get rid of the god awful TRX's. If there's water on the road they'll have less traction than a racing slick...

Get the clutch out *then* give it to her, I can usually feel both front tyres scambling for grip & squirming a bit in 1st & 2nd gear, certainly not "lots of spin & not moving". If you drop the clutch in 1st and floor it I have no doubt you'll be sitting there all day with the wheels spining... But hey a crappy BX/405 will the strut suspension will do that will hardly any power (in comparison). Same from 1st to 2nd gear, get the clutch out then give it to her, don't have your foot down hard *as* your letting the clutch out. Really they do get the power down exceptionally well for a 2wd car. It's chalk & cheese when compared to the BX/405 with a fraction of the power struggling not to spin.

seeya,
Shane L.

 

[DoubleChevron]

The 8 valve petrol is supposed to run on 96 unleaded. It does have a knock sensor connected to the ECU that is supposed to detect 91 and retard the ignition so that you CAN run on 91, but with reduced performance.

In my experience, from accidentally filling dad's one with 91 when he first bought it, the knock sensor never works that effectively and with the 91 there were always signs of pinking during acceleration for as long as that tank of 91 lasted, and worse performance, so I would stay away from 91....

Here in NZ 91 is in the process of getting replaced with 95, and 96 is getting replaced with 98, and as an intermediate step the cheeky buggers in SOME service stations have replaced 96 with 95 without telling anyone - they still advertise as 96 on their signs and charge the same prices but the pump handle clearly says 95

So for the last month or so my one has been running on 95. I don't notice any knocking problems but I had noticed performance was slightly down...

Will be interesting to see whether 98 is of any benefit or not.

By the way it takes the ECU quite some time to "learn" the characteristics of your fuel and if you change from one octane to another, especialy 91->96 it can be quite stubborn to make an adjustment, so your best bet is to run the tank right down close to empty to minimize mixing, then after filling up with the new stuff, disconnect the battery for 15 minutes to force the ECU to go back to factory defaults, then take the car for a 15 minute "spirited" drive, and it will readjust its parameters to the new fuel much more quickly.

Regards,
Simon

I don't believe it, I drove the Xantia this morning and every time I touched the throttle around the local car park, it pinged like crazy just off idle :nownow: I've never noticed that before (I had window down, it was *very* obvious).

I'll try the 95octane again and unhooking the battery. I've used high octain fuel several times in the past with no difference in fuel economy or power

seeya,
Shane L.

 

[Mandrake]

I don't believe it, I drove the Xantia this morning and every time I touched the throttle around the local car park, it pinged like crazy just off idle :nownow: I've never noticed that before (I had window down, it was *very* obvious).

Is that running on 91 ?

Yes thats what I noticed with Dad's car... but not quite as bad as your describe, typically anything over about half throttle would result in a little bit of audible pinking.

I wonder if its possible for the knock sensor to be faulty, and therefore have the ECU not retarding the ignition to prevent knocking when it should ? Perhaps your knock sensor has recently failed ? With 96 the knock sensor would probably have nothing to do, and a failed sensor may go unnoticed while running on 96.

I'll try the 95octane again and unhooking the battery. I've used high octain fuel several times in the past with no difference in fuel economy or power

The difference in power is not a lot, but it is noticable. About the difference you'd expect on an old car which hasn't had a tune in a while...

Regards,
Simon

 

[JohnW]

I get around 9 - 10L/100 klms around town and about 7.5 on a trip although I did once get 6.8 over a couple of hundred klms using Optimax.
Worst consumption I ever got was when I tried it on standard ULP although I filled up on 95 octane the other week and was pleasantly surprised by the results.


Alan S

I'm about the same as Alan with our 8V manual.

JohnW

 

[DoubleChevron]

Just filled the tank with optimax. I'll try resetting the ECU's tonight.

Fuel economy 100% around town, all cold start, no highways. Normal 'around small'ish' town driving. 11.97litres/100kms or 27mpg ... Not good... Certainly it sounds like way to little. I'll check the Optimax fuel economy when the tank next need filling. Highway was *indentical* between standard ULP and PULP

seeya,
Shane L.

 

[Mandrake]

Just filled the tank with optimax. I'll try resetting the ECU's tonight.

Fuel economy 100% around town, all cold start, no highways. Normal 'around small'ish' town driving. 11.97litres/100kms or 27mpg ... Not good... Certainly it sounds like way to little. I'll check the Optimax fuel economy when the tank next need filling. Highway was *indentical* between standard ULP and PULP

seeya,
Shane L.

Hi Shane,

I don't get any better than that with around town driving even with 96 octane.... I just put it down to the inefficiences of 1st and 2nd gear around town due to the torque converter...and the foot down driving style that an auto encourages to get any kind of "performance"...

On the other hand at 100Km/hr on the open road or a country road where you're mostly in 3rd or 4th where there is little torque converter slip in 3rd and none in 4th, I can get quite respectable figures, provided that I use a manual change down to 3rd when it is warranted rather than planting my foot to get a kickdown, or letting it labour at low revs...

Regards,
Simon