Mileage Question.

[dennis]

Hello all.
Just got the Caddy on the road, and was expecting hugh mileage numbers but Im only getting 33-34 mpg over roughly a 100 mile jaunt. Engine is an 85 TD 1.6 out of a Jetta. So far Im only lookin at a speedo, and fuel guage. I timed it to spec for the Jetta using a dial indicator prior to puttin the engine in. Runs great, no complaints there. I had hoped for 45-50 mpg though. The only mods are a 2.25" exhaust and big intake tube, and filter. Just wondering what others are getting with similar set-ups? Guess the first thing to do is re-visit pump timing.

[maxfax]

How old are your injectors???

[8v-of-fury]

well.. hold on here.. you used 29 year old gauges to test your mpg? First problem lol.

Get a Gps to track your mileage, and fill it to the brim, drive 50 miles hwy, and see how much fuel it will take to get it back to that exact spot when filling it. If it takes a gallon you just achieved 50mpg.. do the math from there. 1.25gallon.. 40mpg, 1.5gallon, 33mpg...and so on

New injectors never hurts.. what do you have it timed to right now?

[dennis]

Injectors are probably original. It is timed to 1.0 which is mid range for the 85 Jetta the engine came from. I can get injectors from worldpac for about 38 bucks. Have to wait a bit though, alternator took a crap last night. I have found that if I stay off the interstate, and drive 55-60 that mileage improves somewhat.

[8v-of-fury]

what transmission code does this thing have? it is located right on the bottom of the bell housing on a machined spot

[dennis]

ASF Tranny. Nothing special out of a late 80s Jetta Gasser. I like the tall gears.

[8v-of-fury]

with the AFS, at 55mph you should be turning ~2150rpm.. there is nooo way you are getting 33mpg crusing a diesel at 2100.. unless you got some big problems elsewhere.. lol

Bump the timing up a bit, maybe to 1.05mm.. and try the mileage test again when you get the alt fixed. ( like how i said before )

its the only really conclusive way.. because not every odometer/fuel gauge tells the same thing

[dennis]

I'v been calculating it based on odometer readings per mile markers on the interstate. I lose .05 per mile, so I calculate tatal miles times 1.05 devided by gallons. Got my alternator in now so I will re-check topped off with fuel and try to maintain a reasonable speed. My last Caddy got 50 at times but was an NA motor. This is my 6th Rabbit diesel so far. I will also re-visit pump timing as you suggest as soon as I get time. After working on customer cars all week I sometimes find it hard to work on my own. Got a dead TDI Jetta outside (probably coked up), an 06 BMW 750li, Power steering pump pn a 325i, an oil leaking Volvo S80 ect....................... Better get to work, but it is STILL FRIDAY!!!!!

[burn_your_money]

Check your valve lash, brakes, alignment etc. You are best to gauge your mileage from full to empty. That way it averages out inconsistencies.

If you have original injectors I would be tempted to try running 0.90-0.95mm advance.