Could be. The previous owner thought it would be really cool to lower it, so it's running on custom springs, and probably smaller tires as well (it doesn't look as cool as intended, by the way). I intend to put the springs and shocks back to stock someday, but that's pretty low on the priority list right now.

 

whats the tire size? stock on a 240 was, IIRC, 185/70R14 (or 195/75R14 on a wagon), and compatible sizes (with +1 or +2 rims) are 205/60R15 and 205/55R16 ...

these tires are all about 24-25 inch outer diameter, and deviating more than a small amount from this is what determines your speedometer error.

p.s. I don't really recommend the 205/55R16 kinda sizes if you value ride comfort, while it probably handles better with a sports-tuned suspension, the ride comfort goes away, and you feel the road much more. How do I know this? I drove a 740 T-wagon with that size on Hydra rims for several years and a lot of miles.

 

Tires are the proper size. I'm still getting a weird surge-drop-surge-drop cycling idle when I come home and put it in park before turning off the key. I've reset the Self-Diagnostic codes 3 times now before I go to work, and I haven't gotten any rich/lean codes at all anymore after getting home, just the 3-1-1 and 3-2-2.

 

3-2-2 still points to a missing/bad signal from the AMM. 3-1-1 should not affect idling when standing still. 3-1-1 will affect drivability - such as stalling when coming to a stop.

Have you gone through and double checked there are no air leaks in the big accordion hose that runs from the AMM to the throttle body? Any holes will let in unmetered air that will cause all kinds of idle issues. Also, make sure the throttle position switch is adjusted properly and the idle air controller is clean and functioning properly

 

The listing I see for 3-2-2 is that the burn-off function isn't working, right? Not sure how that affects the idle. Or could it be a false code?
I will pull the hose and double-check, I didn't see anything the last time I checked, but I'll do it again. If there's extra air getting in, wouldn't that also trigger a code for running lean? I haven't had any troubles with driving so far.
The throttle position switch is good; I checked it with a multi-meter and with the self-diagnostic routine.
IAC is brand-new, and is working per the self-diagnostic routine.

 

This is what the FAQ over at Brickboard says about the 3-2-2 code:

Code: 3-2-2
Fault Condition: Air Mass Meter wire burn-off signal absent or faulty
Causes of Fault: Wiring break between FI terminal 8 and AMM #4
Symptoms: Various driving problems due to dirty AMM wire

Not very conclusive but I doubt it would cause idle issues.

When at idle, the throttle body should essentially be closed and all air flow needed to keep the idle at ~750 RPM goes through the idle air controller. When the throttle position switch is closed, the ECU activates the IAC and controls the amount of air through the IAC to keep the RPMs at 750. If you have a fluctuating idle, then the problem can be anyone of the following:

1) The ECU has not activated the IAC which would be caused by a mis-adjusted TPS
2) The IAC is active but air is still getting in through other paths. This can be caused by the throttle plate being improperly adjusted and is letting air in.
3) Air is getting in past the throttle body through other paths. Leaky intake manifold gasket, etc.

 

I got a new speedo chip, and after a mysterious loss of coolant with no corresponding leak and no water in the oil, I got a new water pump and thermostat, AND a new lower coolant hose because a previous problem with leaking seals (now fixed) got oil all over the hose where it connected to the water pump. I suspected that coolant under pressure was getting past the weakened hose, which is why I never saw coolant in the driveway; it was leaking while I was driving.
Spent the weekend with solder and wrenches, and got everything hooked back up. Cleared the codes and took a spin down the block, a mile or two on the freeway, and back up the hill to home. The top hose was leaking a bit at the thermostat housing, so I gave the hose clamp another twist or two until the drip stopped.

Checked the codes.

1-1-1.



Now lets drive it for a few weeks and see if that actually cured it...

 

Just out of curiosity, does your cruise control work again?

 

Nope, and never has since I bought the car. I suspect the Cruise Control relay is shot, but I can live without it.

Anyways, I have a new dilemma, see here: https://volvoforums.com/forum/volvo-...timing-103550/