A bit boring with all this hp talk but... Anyone good with diesels ? I'm only getting 30-32mpg around town from my '99 Passat tdi. It's a 90hp model with a tuning box fitted (unknown make but looks like an Alpin, mpg unchanged when originally fitted). Mpg has been fine till the last couple of weeks, noticed how quickly the gauge has been dropping (compaired to normal) and carried out a proper (brimmed tank) mpg check. First check with mixed town and by-pass use (75mph cruising for around 60 miles) came out at 34mpg, followed by two town checks at 30.8 & 32mpg. Driving is mixed stop/start (i.e town traffic rather than being swithed on & off all the time) and not much over 45mph average. I dont drive foot to the floor, I let the turbo spool-up and do the work using about a 1/3-1/2 throttle tops. The MFA shows between 39-42mpg around town and mid to high 40's on by-pass and A-road work, but is certainly lying at the moment. The car gets regular service work (oil & filter 2k ago, air filter 6k ago) and recently passed it's M.O.T smoke test with flying colours. It pull's well and will easily pass 100mph if asked (of course that could be kmh officer ), it does'nt smoke heavily, stutter or have any flat spots or dragging brakes that I can feel. It is a bit miley (226k) but runs fine, never had the head off, original cat, exhaust, turbo, injectors etc. My initial thought was MAF (it's never had one) but it pulls fine and revs round to over 4k without any hesitation (I dont rev past that much due to not being necessary and in defence of the milage), or maybe coolant temp... temp gauge gets up to temp quickly though. Any ideas ?
when was the fuel filter last changed? I find that when its cold my economy drops off a little due to the denser air needing more fuel. also try chucking in some injector cleaner, i keep dumping in tescos cleaner in mine jst lately (i started off doing the mix properly but it didnt seem to make any ods so tonigght for the 4th bottle i have about 15l of fuel left and i just dumped a full bottles worth in! may make some differance)
Prob not changed for 25-30k, I know the recommended change is about 20k I think ?.. though I've run them way past that before without a problem... but worth a go. I've run cleaner through it in the past (Forte' trade stuff) without noticing much difference, but that was pre-problem so maybe worth another go. Thanks for yr reply...
