I have a 93 240, the car is in great condition except that it's had a history of stalling problems. For a long time, it would stall coming to a stop, sometimes going around a turn, and completely lose ignition momentarily but not stall when going full speed and hitting a bump. Stalling was never a big problem, would always happen at low speed and would start right back up. Note: hot and humid weather always consistently made it act up far more often. It threw check engine lights a few times, and it was always the MAF code. I replaced the MAF about a year ago and did the recommended engine air box mod that removes the preheat hose so you're not frying the new MAF with hot air. The problem has always persisted but very incosistently, running great one day then stalling frequently another day.

Just today, the problem changed. Car starts then immediately stalls, even if the throttle is opened up. However, unplug the MAF to use "limp home mode" and it runs perfectly with no stalling (albeit in the weird limp home mode sort of running). So, at this point it consistently doesn't run with MAF plugged in, then consistently runs without it. I've read someone saying that this scnerio is definitely a bad MAF. But is that necessarily true? Especially given my MAF is fairly new and "shouldn't" be fried by hot air, could it not be the plugs or wires connected to the MAF?

Also, I have checked the sound of both of the fuel pumps and they seem to be consistently running.

 

Not being able to give it throttle and running better when unplugged are the classic symptoms of a bad MAF. When you replaced it last year did you use a Bosch brand MAF or an aftermarket. From what I have read the aftermarket MAFs are of dubious quality.

I keep known good spares that I pick up from the junkyard. They cost somewhere around $35. The junkyard by me will allow me to return it for another if the purchased one is faulty. So far I haven't got a bad one and I have two spares.

The rest of your post tends to make me think there might be some loose wire or something else going on as well. Dying when coming to a stop can also be related to missing the speed signal to the ECU. However, that will throw a 3-1-1 code (if I remember correctly).

Other item to check is your crank position sensor. It's located on the top of the bell housing where the engine and transmission are mated. It has a black coax wire running to a connector on the firewall. Check this wire for cracked and flaking insulation. If it is flaking off then it's due for replacement.

 

its quite possible your 'new' MAF is no good. they aren't making them like they used to.

 

Great, thanks for all the info! It is aftermarket and definitely not near Bosch quality, but fortunately it's from FCP Euro and covered by their guarantee. The CPS wiring looks like it is in great shape, as do the rest of the visible wires. Interestingly, I just went out to do tests on the MAF and its plug with a digital multimeter, after doing some teats it's seemingly come back to life and the car is starting perfectly. It's hard to find junkyards with Volvos where I live, but I'll either end up getting one from a local used car dealer that has a few 240s, or having FCP replace the one I have.