I spent a couple of hours on the 250 this weekend and several unrelated tasks inadvertently resulted in a "happy ending." Still not sure exactly what caused what. The sequence of unrelated events:
I had noticed a small drip from the radiator drain bolt at the bottom of the radiator so was going to put a new seal and refill. Did that.
Checked engine oil, added a few ounces.
Checked Power steering fluid as I had noticed a little wetness on the hose below the reservoir. Added a little. Will attack the hose change etc at another time. Making a nice mess in the front of the engine.
While adding the power steering fluid, staring right at me was the thermo time switch. The cold start valve has not been kicking in when it should recently and to keep from cranking a lot, I sometimes use a jumper wire from positive battery to the CSV with the fuel pump running. Giving it a couple of seconds of activation. A while ago, when I was having Cold Start issues, I had cleaned up the connections on the TTS and it had started working, so thought I would give that a go again. Removed the connections, wire brushed all contacts, and put it back together.
While I was there, thought I would open the relays and make sure the relay points were clean. I could not recall which relay activated the CSV, so opened up both suspects, cleaned the relay points, and cleaned the connectors and put them back together.
While I was there I opened up the fuse box and checked that all "looked" okay and gave each fuse a nice twist and checked that each was seated well.
Cranked the cold engine over and it started immediately. Even in Southern California 23C/73F the engine takes a bit of cranking if the CSV doesn't kick in. The CSV did it's thing. I was thrilled. Success. But this was not the happy ending.
Now that the Pagoda was started and idling, I couldn't just turn it off and put it to bed, like I had intended. That would be like grabbing the dog-leash from behind the door and leaving fido, wagging his tail, without a walk and just putting the leash back. Not right at all. I could not do that to the Pagoda.
During the drive, I instantly noticed that the car had a lot more power. Thought it was just on that one street, but then it was clearly more powerful pulling up a steep hill, around bends and roads I know well. Difficult to put a percentage on power increase but I would say it felt 20% stronger. Clearly, without a doubt stronger. But I did not do anything that would improve power.
Now I pull into the driveway and I notice that the idle (car is fully warm) which usually sits at 700-800 is at 1100. Checked linkage and nothing sticky. WRD not stuck. Disconnected the CSV and no change. Checked side access at CSV and no leaking. Determined that CSV was not adding fuel when warm.
So what's going? Car has more power, like it used to have. Very happy about that. I was thinking the engine has slowly just gotten tired and that's why I felt less power.
Did the split linkage test at idle and car was running very rich. This was not the case prior to my fiddling. What did I do that made this change?
I went ahead and leaned out the idle many clicks on the Pump. This brought the idle back down to 700-800. It's still a little rich at idle (based on split linkage) but decided to leave it there, as I already dialed it back probably 6 clicks.
Happy Ending as I have significant more power - but what caused it?
I have some guesses on what happened, but not sure and would like to read your thinking.
Some history - a few months ago, the plugs looked suspiciously lean. This was sudden as they usually looked tan. I adjusted to make things a little richer as the plugs were too white. Did not understand how it could suddenly have gone lean and never found any air leaks etc.
