So I got something practical but fast

[Xeron]

Just remember the toughest of tough toolboxes don't have ball bearings, none of mine do! (look up faber toolbox on google)

[angryrobots]

things are bolted together.



and back running.



with some fresh kicks.

[General Geoff]

She looks mean. I like it.

[angryrobots]

Still have a CEL issue. Without getting into (boring) detail I think it is an ECU problem.*

I'm contacting a company that does (pretty much exclusively) volvo tuning and ECU flashing (full custom stuff) to detail the problem I'm having to make sure it is the ECU.

Then I will send them my spare ECU and get a nice upgraded tune.


*Computer insists there is a TPS circuit problem, even though I have fully bench tested the TPS, changed it out with another known good one, and can even view the TPS on my scanner's live data reporting perfectly to the ECU which seems to indicate that the wiring is also not faulted. Also strange is that the DTC that sets never sets like every other code I've had on it - it disappears when you shut the car off and comes back after ~5 seconds of engine running when I crank it back up. Otherwise, the car runs like a top, no more misfires (knock on wood).

[General Geoff]

I freaking hate electrical/electronic problems.

[angryrobots]

Today on the way home from work, I was stopped waiting on traffic to turn left, and the engine idled down low, then came back up and the CEL went off and has been off since.

OK.

Maybe the IACV was hung up? I tried cleaning it (and I think also switched with the other car) to no result, but I'll take whatever progress I can get.

[boxvic]

If an ECU is anything like the systems I work on (I've never actually looked at one, so it might be totally different) then it probably has a microcontroller with onboard flash or a DSP with a separate flash chip. combination. I've seen both "lock" in an error- especially if its been run for a while with that error. Sometimes I have to reprogram some of our radar units with a totally different program to fully flash the chip and reset all of the registers to remove the error.

So reprogramming it might be the only surefire way to ensure the problem goes away, but at the same time it might have just taken a while for the chip to clear itself. Could have just taken this long to finally write over the old registers.

[angryrobots]

Possibly, but now that I think about it, this problem first surfaced after the initial tune-up, in which I found and fixed a large vacuum leak.

I bet that the ECU noted the change in MAF relative to TPS output and assumed that the TPS signal was at fault. After driving 40-50 miles the ECU assumed the change was permanent and compensated and removed the DTC.

I'm guessing here, but this is certainly within the realm of ECU programming.

[angryrobots]

Drove it about 100 miles back and forth to work, had some concerns about the cooling system; it seemed to be running a little hot and the coolant kept getting backed up into the expansion tank. These cars are notorious for being hard to bleed the air out of the system thoroughly (although I never had a problem with the NA car) so a worked on it and *thought* I got the air bubble out that I *thought* was causing my problem.

Drove it about 40 miles on the interstate, temp was fine on the highway but started going up when I got on side roads (I had my OBDII scanner on it looking at the coolant temp sensor) and when I got to the neighborhood that was my destination and stopped, it was starting to boil. I shut it down and let it cool down for a bit while I fretted about what was going on (at this point I was really starting to fear a bad headgasket).

Had a few beers and looked at it again. Took out the thermostat and found that it was a 195F, stock is 180F. And even more importantly, I found that the air vent hose from the thermostat housing to the expansion tank was plugged! #@()#*$&^%$^

I managed to clear out the plug with a finishing nail, and just for good measure, I cut out the guts of the thermostat and re-installed it with just the exterior ring and gasket. Refilled and managed to make it home without incident.

[angryrobots]

Well it was fun for a while. Headgasket went a couple days ago, had to haul it home last night. It is craigslist fodder now, just have to accept that I am going to take a wash on it.