Volvo Forums - Volvo Enthusiasts Forum - S80 T6 stalls at low speeds, no fault code

Hello! I'll introduce myself later but I wanted to get this posted since my car is currently at the dealer and I'm a bit worried that what they're doing won't actually fix my problem. So, I have a 2001 S80 T6 with roughly 122,000 miles. About two years ago, at I guess under 100,000 miles, I noticed that occasionally my car would stall when I was turning left into the parking lot at work, which has a ditch in front of it that you have to drive through. I thought the bumping and breaking was an issue so I changed the way I came at the driveway, so that I was hitting the ditch head on and I didn't really experience the problem again for maybe a year. In the past year, however, the problem has slowly gotten worse, almost always in traffic, to the point where my vehicle will stall once and then will work for maybe 10 seconds, stall again, and repeat this until I'm able to increase my speed or turn it off and walk away. In traffic it stalled three times in two minutes, once on the off ramp, and then six times in the parking lot. I've noticed that before the car stalls, the RPMs will be just below 1000, the engine will surge with a very noticeable vibration to just above 1000 and drop again, and will do this a couple of times. It appears that when the RPMs drop to 500 the car stalls, the check engine light and the oil light come on and then all of the warning lights illuminate. I turn the car off and have no problem restarting it and all of the lights go away. But then, as I said before, it will do it again and again. This seems to happen when I'm breaking, as in stop and go traffic, or cruising at low speeds and am not using the accelerator, also as in stop and go traffic. I did notice once that the warning screen flashed something about low oil pressure but since it didn't stay on and the car didn't stall at that point, I don't know if it's related.

I've taken it in to three different dealers and none of them seemed to 1. want to make a concerted effort to figure out what was wrong and 2. couldn't figure out what was wrong when they tried. But now it's gotten to the point where it's pretty much undrivable and useless, unless I'm in a rural area with no traffic. I took it to the dealer again two days ago thinking it might be the ETM and no one, including me, could make it stall, although we did get the engine to surge a couple of times. Based on things I've read on the forums, it sounded a lot like the ETM to me but the technicians also can't find any fault codes, which is making it very difficult to diagnose. They told me that they're going to clean the throttle and update the software, but I'm not entirely convinced that that is going to fix the problem and then I'll be out $350. Any help you have is appreciated!