This weekend I did a leakage test on all the intake system, from the turbo to the engine manifold.
I pressurized it at around 3-4bar, much higher than normal pressure, the hoses were hard like steel, but there were no leaks
So, intake system is 100% ok and proven.
For now, this is what I'm sure about
- MAF OK. I have two, the used one I had bought few weeks ago from a scrapyard is in very good condition and AR original, It shows very similar readings, just +-50mg differences.
- Turbo ok, 1bar at 1800-1900rpm. I have removed the spring valve for now and it's running at 1bar always.
- Intake hoses/intercooler good, no leaks even at much higher pressure.
- MAP ok, bought a new one and got same readings.
- No serious errors on the ECU, just EGR and sometimes glowplugs.
I've read scary stories here about similar symptoms: low power, smoke on heavy load, and still strong in higher rpm but feeling rough... also engine starting nicely even when cold and idling pretty good, and it in the end was a bad compression issue! (bad valves/piston rings).
Now I'm getting worried again. May be that intake sound be normal or maybe it's a inlet valve that leaks at high pressures, like when the cylinder fires?
I'll try to disconnect each injector at once and listening to the intake noise, maybe I found something out. I have no idea why I didn't do this before!
And anyway, I'll do that compression test. I hope they don't want a lot of $$$ for that!
If the compression tests show something bad, I'll let the engine stay like that. The engine still runs pretty good, and if I drive like an octogenarian the MPG isn't too bad.
Then it'll be time to start saving for another car...