96 VDP - compression test / 13.9mpg mixed

This is about my new-to-me VDP.
It concerns me that it only gets 13.9mpg in mixed rural/city/highway driving in Normal mode and only bit of ‘racing’ (my other VDP gets 17.9+).

So, I bought a HF compression tester and did a dry test just now.
Pulled the fuel fuse, but didn’t hold the throttle down while cranking for 6 seconds.
All were 152 +/- 2 PSI

Should I go back and do a wet test?
If so, how much oil in each cylinder?
Are these good numbers?

Would this indicate why I am getting low mileage?

I’m a newbie about inside-of-the-engine stuff and am currently obsessing over my new-to-me VDP.
: - )


Why do you suspect compression is the problem? I would first do a complete engine tune-up, new filters, new sparkplugs, check that the timing is correct and that the ecu is operating correctly. Check if it is running too rich. Once all that is done, if no improvement, do a wet compression test.

Probably a little more information.
How many miles/kilometers, have the plugs been changed, what state is the air filter?

All good questions!

  1. I had found in the paper work that 5 & 6 were low by 10/15 pts (175 vs 185) - test done in 2019, so I wanted to check it, but didin’t know about wet vs. dry before i did the test. [smacks forehead]
  2. 150,000 miles
  3. I’m going to change the plugs, air filter (if it looks dirty at all), check the timing, and and the ECU (now I’ve been asked and it makes sense anyway!).
  4. check the mileage again.

Thank you all!

Not a lot you can do with the timing as it is governed by the reluctor wheel and Crank Shaft Position sensor (CPS)

Isn’t the CPS mounted with slots in the housing so it can be tweaked a bit?
Or am I mis-rememebring from some car I’ve wrenched on in the past?

No its fixed in relation to the reluctor. There is a bracket called the ‘Andy Bracket’ @kirweekid fitted on to his x300 3.2 this advances the ignition by <>5 deg, I modified my old XJ40 (AJ6) by rotating the reluctor wheel and re-pinning it to replicate the bracket, (just because I could)

Ah! The old ‘Insider tricks’
: - )
Thanks for the education (there’s a lot to learn . . .)