When i had problems with the cambelt a couple of years ago the local garage couldn't get to the bottom of the problem and i eventually had to sort it myself. In there attempts to find and sort the problem they had several attempts at diagnosing the problem using electronic diagnosis tools and had a couple of mobile electronic "experts" look at it as well, it was also sent to Gurney's at Benson twice who also failed to diagnose the problem with thier Tech2 and i'm begining to wonder whether in all thier messing about with things they didn't understand they reset something in the hope that it would cure the problem.
Is it possible that they altered the Fuel Trim while they were looking for a cure ?
The thing was running very rich at the time and alsorts of things were changed, MAF sensor, Air temp sensor next to the MAF, Coil pack, HT leads, Plugs, Crank sensor etc al to no avail. As a last resort i took it to my mates barn and decided to start striping everything out looking for the problem and thats when we found that the cambelt had slipped due to the bottom R/H idler/adjuster wheel had been put on back to front when plod last changed it, the cambelt had supposedly been checked by the local garage but obviosly hadn't. Cam belt kit was fitted and normal running was returned.
I had never bothered to check the MPG since then until recently as i haven't done any real journeys in it. Before the cam belt issue i could get 25mpg pulling a trailer with a Mk1 Escort race car on it (Didcot-Lydden Hill- Didcot) without even trying but as i haven't been there since then i hadn't bothered checking mpg but i'm now getting less mpg without the trailer and race car.
Could the fuel trim have been altered or interferred with to mask the problem ?
Could it be something like the Purge valve or Carbon canister at fault ?
Any other suggestions ?
Driving everywhere at 56mph is not really an option, I was getting 33mpg driving on motorways and dual carriageways at 75mph before, now getting 24/25mpg.