Compression Test Readings, can anyone help?
 

Hello there!

Just bought myself a used 8, not knowing what I was getting myself into :D.
It was also very cheap.

I took it for a compression test at the dealer's before I bought it and they said the engine was in perfect condition. It is an '04 231hp (I'm from Europe).

Here are the readings on the 2 rotors. Something does not look right.. but they said these were good figures, showing just minor engine wear. It has 48,000 km on the odo.

rotor 1 : sampling time - 7sec; speed of rev - 167 rpm

Measurement / Compen.(250rpm)

port 1 536 / 743.89

port 2 567 / 774.89

port 3 522 / 729.89

Diff. port 45 / 45.00

Diff No.1/No.2 522 / 522.00


Data trace

Time No.1[KPa]

6.89 164
6.90 211
6.91 267
6.92 331
6.93 400
6.94 468
6.95 527
6.96 566
6.97 568
6.98 541
6.99 478


rotor 2 : sampling time - 7sec; speed of rev - 220rpm

Measurement / Compen.(250rpm)

port 1 836 / 902.08

port 2 817 / 883.08

port 3 808 / 874.08

Diff. port 28 / 28.00

Diff No.1/No.2 808 / 808.00


Time No.1[KPa]

6.89 152
6.90 213
6.91 289
6.92 396
6.93 516
6.94 645
6.95 770
6.96 826
6.97 804
6.98 686
6.99 524


Also, the guy I bought it from had just flooded it. He had just changed sparks/cables/coils - the dealer charges $1,600 for these here (Romania) :D

The car had a rough idle, and vibrated when it exited idle, until about 1200rpm. Also, the engine cel was lit and a universal motor test indicated missfires on the second "piston".
Also, even though it is winter and -6 C, the smoke had a very strong petrol smell and the tank was 3/4 empty after just 100km.

I took it in today, they changed the engine mounts, and claim to have updated the software to the latest one.

The car runs incredibly smooth now, no vibrations whatsoever, there seems to be less smoke, much better fuel economy and also a stronger kick.
Even so, before arriving home I floored it to 8000rpm in 3rd and the engine cell started flashing again but went away.

My question - Should I keep it or sell it? I am willing to put up with everything, as long as the engine doesn't die on me. It has no more warranty and an engine change would cost me $7,500 here.

Flashing cel is a misfire so bad coil or spark plug somewhere. Shouldn't be too bad to fix since I had that and I changed them out and it fixed my problem. If you like how she drives keep it, if you don't then sell it.

Thank you for the confirmation on the CEL.

But can someone accurately read the compression numbers above and tell me if the engine is ok or not?

I do agree with Charles and being from europe myself there are 2 things that i would like to add:
If you don't want to spend a lot of money on the OEM coils + wires and spark plugs BHR is the way to go. You will end up spending just a little more than what you would pay the oem set-up in europe but will have a lot of benefits.
7500$ is a lot more than what you can pay a good remanufactured engine, PM me and i'll tell you what to buy and where to go.

CAUTION!

Weak coils have lead to rich fuel conditions which equals dead Catalictic converter.

Those are expensive.

Thank you for all the suggestion!

Will get a full BHR ignition set and try and rebuild the engine.

Even if the current ignition set only has 100km, I don't really know what the guys at mazda did under there...