I've got a 1999 Ford Ka, with some choice engine modifications (and yes, that means more than a filter and a backbox, this is real modification) Currently i'm only getting about 20mpg. The place that did the mods say that it should get more than that, maybe 10-15mpg more. They have had the car back and can't find a problem with their installs, but can't figure out whats the problem.

I'm considering getting it re-tuned, as i'm hoping that its just outta whack sorta thing. Can anyone reccomend any mobile tuners?

Problem will be in the ECU, basically. Either it isn't remapped to take into account the mods, or one of the sensors that supplies it with info is telling it porkies, causing it to do its sums wrong. Did the place that did the mods remap the ECU? And has it made any changes since? Bigger injectors or a more hard-core fuel pump for instance? basically, it sounds as though it's overfuelling. Have you had a turbo conversion done? Because one trick is to let it overfuel to stop it going lean on petrol. Which causes the engine to run hot and go bang.

Please tell me the tuner wasn't Severn Valley down near Birmingham?!

Oh, and first look at your air filter. Is it a cleanable kind, and is it mucky? That would mess up the air-fuel ratio...

Yes the ECU has been replaced by a Ford Racing one. The air filter is clean, as that has been cleaned recently.

I have been told it could be a few things, like spark plugs, HT leads, Coilpack, Lambda sensor or O2 sensor, and I was told all these things should show up as an error code on the ECU.

I was told I need to find someone with access to an ODB-II Scanner, or get in contact with ford.

I got in contact with ford and they want £75 for the diagnostics!!!!

I'm concerned that if the problem doesn't show up on the ECU, I'll have been stung for £75!

And no, Severn Trent haven't had their hands on it, its not a tubby,
The guy who did it is a friend of the family who maintains all our cars. Used to work as a mechanic at some performance car centre