Has anybody on the group had either good or bad experiences of this fuel economy device ? From what I can gather, it allows a small amount of air directly into the inlet manifold and creates extra turbulence in the air flow. Looking at the manufacturers web site, Car Mechanics seems to have confirmed a fuel saving.
Steve
!! Not this again, please...
This comes up periodically, a google will bring back many, many threads on the subject.
I had a bad experience with this device, oddly enough all the feedback on their website is good...
Why would anyone want to increase turbulence in the airflow? Engine tuners/designers etc go to great lengths to do just the opposite.
Car Mechanics have a long and distinguished history of being the only mag to find snake oil products work...
Thanks for the feedback, as you all say the financial returns may well be questionable. I have to admit the units concept did intrigue me because my automatic Zafira is set to run slightly rich to prevent the chance of stalling etc. But thinking about it, if extra air is admitted into the manifold then surly the engine management system would detect either the extra oxygen in the exhaust gas or perhaps the lower vacuum level in the manifold and inject more fuel into the cylinders ?
Steve
How have you checked this? Most modern cars would fail the MOT if this was so.
The Vauxhall dealer who reprogrammed the engine management system following a running fault and the published emission values for auto / manual same model cars. Automatics appear to pollute more which is strange considering the engine / gearbox operation is totally out of the hands of the driver if left in 'drive'. You would expect the manufacturer to program the car for maximum economy when not in 'sport mode' but even with the torque converter locked up and on a motorway, the fuel consumption is worse than a manual car on the same run. -Yes I know I have an extra hydraulic pump etc in the auto box but that should not offset the 'ideal manufactures mapped settings' compared to an everyday general diver in a manual model.
If you mean the published figures for tax reasons, this is the CO2 emissions which are rather a different matter from the actual mixture settings, ie rich or weak.
Apart from the position of the accelerator pedal...;-)
On my last BMW auto it was better, by the figures quoted in the handbook.
It will depend to a large extent on the actual gearing in top for steady state fuel consumption, and on many cars this is different between manual and auto.
Dave Plowman mumbled:
It'd be interesting to see whether there's a real life difference between auto and manual consumption...simply 'cos people with automatics may drive differently. IF they're generally more relaxed then it's possible that they'd get better consumption.
In response to you both Dave and Guy, our last holiday to Europe in July / Aug featured just that. We covered 3,000+ miles door to door with a friend and his family driving his manual 1.8 and us in our auto 1.8. Both cars were purchased new in Jan 02. We drove each others car on different legs of the trip to try and rule out any major variations and still found we were consistently 10-12% down on his manual cars fuel consumption. One obvious difference was the gearing. Ours does
70mph at 2750 rpm, the manual in 5th does almost 1000 rpm more which I expected to put the consumption in our favour. Hence my interest on getting 10 % better mileage.Steve
Hmm. 3750 at 70 is only 18.6 mph/1000 rpm which seems awfully low for a modern car - your 25.5 is nearer the mark.
10% overall worse in mixed driving might well be normal for some autos - it would depend on how much work the torque convertor is doing. I'd not expect that sort of difference at a steady 70 or so, though.Be interesting to get both cars MOT'd at the same place and compare the emission figures.
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