How does chipping work?

What does chipping the engine actually do? Am I right in assuming it tells it to add more fuel at a given time or is there more to it?

The claimed better fuel economy I assume is through having to change down less. If this is the case then it may explain why my fuel consumption on a long motorway journey (at 55-65 mph) is not much different (maybe slightly worse) than before it was chipped.

Towing my 24ft caravan a few weeks ago did cause the engine temp to go in to the red twice (momentarily). Is this a side effect of chipping, was I pushing too hard?

Glad I've done it though, has made a massive difference to how it drives.

Twisted Performance chip ..... I'd recommend them.

lenb

slicing the potato into small long fingers of a square cross section and then frying, hardy ha ha.

no seriously. the way i understand things is this;
the government urban consumption figures are done at 56mph. and at 56mph engines generally do about 2500rpm.
at this engine speed the ecu injects slightly less fuel as to make the figures look good, this give's you a bit of a flat spot at that engine speed, you may put your foot down a touch more because of this, chipping the ecu stops this shortage and gives a much smoother power curve, not dropping at certain rpm.
this inturn tends to stop you from putting your foot down as much as it responds better to small changes at that speed
most horse power gains are reached when chipping a turbo engine but n/a engines are still "nicer to driver" than before.
from what i have heard the overhaul consumption figures are not that bad afterwards and most people are happier with the drivability so aren't bothered by it.

no doubt there will be someone who may explain it better but i think thats basicaly it..........

as far as getting that hot, the cooling system should be designed to accomodate all sort of work the engine is doing and shouldn't get that hot unless theres a prob somewhere, what do you drive? i have heard of the P38 radiator water ways getting partialy blocked due to age, this may be a prob as under load it cant cool a sufficient amount of colant? i have changed mine and the temp gauge never moves from just over half way, never no matter how i drive it, and its on lpg which i heard runs hotter!
i wouldnt have thought a chip could cause such temp increases!!

Thanks for your reply.

I drive a 1995 2.5DT Manual. It had a new rad before I bought it. Under normal driving around town etc the temp hardly moves above the blue, at 60-70 mph dual carriageway driving it will go up 1 division which is still under half way. Towing my c'van moves it up one more notch. I must admit I had done a few miles of nasty hills (inc 1 in 4's) so perhaps I should just slow down a little. One thought is that by staying in a higher gear the fan would spin slower and perhaps changing down to 4th rather than trying to stay in 5th (45+ mph) too long didn't help.

lenb

i think if your doing over 40mph the fan aint doing much anyway! i fitted an electric fan to mine, the difference when starting from cold is amazing, its soooooo quiet compared to the viscous fan it had!