OK so this week I had some more time to spend with the Sera.
It drove quite good from the day i bought it but it wasn't very easy on petrol to say the least. I had to do my very best to get 1 liter to 12 km and regardless of how I drove, it would smell like petrol / oil whenever I parked somewhere.
I decided a basic engine tune up would do no harm so out with the timing light and the "special tool" for shorting the diagnostic terminals. Idle was a bit high as well when warm (1200 rpm) so I also wanted to sort that out.
Well, to start: Timing was way off, without the terminals bridged it was only 10 deg BDC, someone obvious adjusted the timing without bridging the terminals...
Next problem: Idle speed.
I checked all vacuum hoses for cracks but although some ends started to tear they were only on the very end outside of the pipe so no leak through there. (will be getting new ones anyway)
I checked the Idle speed valve (at the opposite end of the throttle body and that one was working OK. Nevertheless I took it out and gave it a nice clean with some degreaser and cotton swabs. new O-ring and opens and closes just fine.
At this point I tried adjusting the idle speed screw but that one was already completely screwed in!
Next suspect were the aircon VSV's. My A/C isn't working so I figured maybe one of these VSV's is stuck open, even when switched off. I disconnected all 3 lines from the T/B & manifold and capped them off but to no avail.
Then I noticed the cold idle control valve under the throttle body. On the 4A-GE, these will accumulate all sorts of gunk, especially if oil and coolant have touched at some point. There are 2 coolant hoses going to this valve, one was hot and the other.... only slightly over ambient temperature. My money is on this valve but I will pick up some new gaskets from the dealership tomorrow before I try and take it apart.
It's a nice opportunity to flush the complete system with fresh water and fill it up with some nice new coolant as well.
Thinking of doing oil and filters as well, and get myself some new plugs. Dizzy rotor and cap have already been ordered.
Will do a compression test and a leak-down test tomorrow while I'm at it!
Results will be available here once I'm finished with her!