Car using twice as much petrol after MOT

doobyden

Hi, some advice would be gratefully accepted.

My little 1.3 Fiesta usually gets through about £12.50 a week in fuel. However, since I got it back from MOT (passed but with 5 advisories) last weekend, the fuel consumption has skyrocketed. It's just used £22.50 in 5 days, with usual mileage! _pale_


Is there a way the garage could tamper with something to make this happen? I'm not sure if I have a leak in the tank as the needle seems to drop while I'm driving and not overnight, but I could be wrong about that...

Thanks in advance

BeenThroughItAll

doobyden wrote: »

Is there a way the garage could tamper with something to make this happen?

Yes, many ways, but why would they and what makes you suspect they have?


Have you encountered more traffic than usual? Has the weather been colder/warmer? Has the car been reaching operating temperature slower than normal? Are all the tyres inflated to the correct pressures? Have you accidentally driven with the handbrake on? Has the fuel price gone up?


Rather than all this 'about £12.50 a week', you need to fill the tank to the brim, drive the car, fill the tank to the brim, note the mileage when you fill up and calculate the fuel consumption. Do this repeatedly and you'll be able to monitor your usage much more accurately than on the basis of 'a tenner gets me xx miles' so many people seem keen on.


My money's on a difference in driving conditions before I'd start pointing fingers at the MOT tester.

stator

He probably adjusted the idle timings to get you through the emissions test, but that wouldn't be responsible for double the fuel usage, unless you leave your car sat with the engine running for hours at a time.

atrixblue.-MFR-.

stator wrote: »

He probably adjusted the idle timings to get you through the emissions test, but that wouldn't be responsible for double the fuel usage, unless you leave your car sat with the engine running for hours at a time.

how would he do that with a EFI system, IDLE control valve firmly placed on the inlet manifold and a throttle position sensor placed on the side of the throttle, gone are days of idle screws on a carb the only basic thing you can do is adjust the screw for the throttle to compensate for wear it really doesn't affect the idle.

I assume were talking about a 1.3 (KENT) Endura E/FE engine here mk4 and mk4.5, or the (rocam) 1.3 8v duratec if 2002-2008 mk5 model fiesta. Not the carb operated KENT Crossflows of the 70's/80's.

keith1950

The Mot consists purely of a brake test, and emissions test and visual inspection.

They are not even allowed to remove covers that on some cars restrict these visual inspections.

StartAfresh

Go back to the garage and ask them to check for you. I would have thought they would do that for free if you explain what has happened.
They can check connections for the fuel pipe are not loose. Also look at the engine whilst the car engine is running - which may show where petrol is leaking from - if in fact it is a leak.

Stoke

You can't check your fuel consumption without brimming.

specialboy

Stoke wrote: »

You can't check your fuel consumption without brimming.

Yes you can but it involves carrying a gallon of juice with you and deliberately running out of fuel.

Stoke

specialboy wrote: »

Yes you can but it involves carrying a gallon of juice with you and deliberately running out of fuel.

Dumb idea, but whatever floats your boat.

BeenThroughItAll

Stoke wrote: »

Dumb idea, but whatever floats your boat.

No one said it was a good idea. It is, however, accurate.

torbrex

The car will have been idling during the test and probably revved up a few times as well so fuel will have been used without any miles being clocked up. You don't say what the advisories were, if it was emmission related then he may well have ran the car longer than usual to see if he could get a pass result.
The price of fuel also went up a penny or two last week so that will affect your figures as well.

Try it again and see what the results are.

If the garage has 'tampered' with your car during an MOT then they have broken the law and can lose their testing licence.