Official Engine Stalling Thread

Walleye · Post by **Walleye** » 13 Dec 2006, 11:48

Not sure if this will help...but I have a 94 850 and I too had stalling problems recently. It started stalling once in a while, probably every couple months, and usually when I would decelerate at a stop sign. I thought nothing of it until my car began stalling more often. During this time, I also noticed my engine and gauges were acting weird. By this I mean, I would be driving and all of a sudden my engine temperature would drop to 0 and the engine felt like it was running rough. As soon as I would decelerate or come to a stop, the engine would stall. At times, the car would start up again, but others times I would have to let the car sit for a while. I brought it in to a Volvo specialist to check it out (before the car would stall at the most inopportune moment), and he couldn't find anything wrong with it. There were no codes suggesting anything was wrong, as well. He advised me to come back when the problem got worse. Sure enough, my car stalled in the middle of the intersection and it would not restart. I had it towed to the garage (which was closed by the way), so now I'm stuck trying to find someone to pick me up. I decided to try and start the car and sure enough, it started with no problem. I began driving home and of course, it felt like the car was going to stall again. I quickly pulled into a nearby parking lot in case it did stall. After a couple of trouble shooting ideas in the parking lot, I FINALLY discovered the problem....

It turns out, my coolant temperature sensor was failing. It makes sense to me now why my car would stall. Because the temp sensor provides information to the engine via the computer, it would make sense that any wrong info from the sensor would make the engine run differently. Hence, a temp of 0 would result in the engine thinking it was a cold start. A cold start would result in the car providing more fuel to the engine, essentially flooding the engine if this false reading persisted. This is why the car would only stall during slow speeds or at idle.
I ended up fixing the problem myself, which ended up costing me $115 CAD for the sensor, and it only took 15 min. to fix....definitely a do-it-yourself project. My car has been running perfectly fine since. Hope this helps......

Post by **matthew1** » 13 Dec 2006, 13:47

Walleye, interesting and informative, thanks for the post. I put it in the Volvo Repair Database.

mdebel · Post by **mdebel** » 04 Jan 2007, 16:44

We just bought an 93 850 for my 16 year old son. Car drives well, idles nicely but it stalled on him once while slowing down for a red light. Another time it stalled at the mechanic when they just let the car idle after they replaced the radiator fluid. It was idling for quite along time, then they noticed it just cut off. I am wondering it this maybe the same problem with coolant sensor.
Which part did you actually replace. Is it this one at the below link

http://www.eeuroparts.com/productdetail ... &code=8123
How did you replace it ? Or is there more to it.

Post by **MadeInJapan** » 04 Jan 2007, 18:41

That would be the coolant level sensor.
You really need to look for the coolant temperature sensor. It screws into the thermostat housing. www.fcpgroton.com has both on the same page so you can see a comparison.

mdebel · Post by **mdebel** » 05 Jan 2007, 07:12

MadeInJapan wrote:That would be the coolant level sensor.
You really need to look for the coolant temperature sensor. It screws into the thermostat housing. www.fcpgroton.com has both on the same page so you can see a comparison.

Thanks. Is there a way to test that the one you have is bad ?

Post by **MadeInJapan** » 05 Jan 2007, 07:40

Once the car warms up the temp gauge on your dash should be exactly at the half-way mark (3:00 for the S70...not sure for 850). Anyway, if there is any deviation, I would suspect it. You should also get a code for this part being problematic. Actually, I'm still trying to figure out why you suspect the coolant sensor. Do you have flooding issues on start-up (ECU thinking it's cold outside when it's not?) like the previous poster? Especially if your car won't start at all, your best bet is to read the codes and go from there. Even if it does start, I would still do that. Either way, if the temp. is whacky- replace both the temp. sensor and the thermostat- it's an easy 15 minute R&R and will cost you less than $45 in parts.

mdebel · Post by **mdebel** » 05 Jan 2007, 08:05

I am not sure it is the temperature sensor. Just from reading this forum, it seems like the closest thing. It cut off on my husband twice yesterday, once on the highway as he was trying to speed up and car was dead, another time as he was slowing down coming off the ramp. I have not noticed anything odd with the temperature gauge, it typically is nicely in the middle, by the time the car is dead, all gauges are down as there is no power. Car starts up immediately except for the last time when it happened yesterday when he had to turn the key over tree times before it started up again. Car runs fine otherwise, idles nicely, no hesitation, runs smooth, this just happens out of the blue.
The only thing I noticed a couple of times was the temperature next to the clock that I assume measures the outside temperature showed in a few instances a temperature that was way too high e.g it showed a temperature of 98 degrees while it was more like 70 outside ( this was around sunset time) The car is in Florida where it is has not been cold yet, but it definitely was not that hot. Maybe it is the fuel pump relay ??? I am new to all this so I am looking of what it may be as the mechanic could not find anything wrong with the car that may explain the cutting off.

Post by **MadeInJapan** » 05 Jan 2007, 08:58

For the outside temp. setting (temp read out on dash) the sensor is buried in the plastic air dam below the front bumper. It has probably become dislodged, sitting further under the engine, so the temp reading is higher than it should be. This would be a quick thing to fix. Even if this is off, I would not suspect it as the reason for your car stalling. From your description, I am more apt to think that an electrical glitch is causing this. Check all leads from your battery as well as the wire braids (ground wires) that are behind and around the engine connecting different points with only a screw. If these are corroded or are making bad contacts you could be shorting as you make a turn (even a wide turn off of the interstate- by ramp), or over bumps. Just a hunch but I've heard of this before more than a few times.

Walleye · Post by **Walleye** » 07 Jan 2007, 16:19

The symptoms you described are similiar to what my car was doing except it had never stalled on the highway. What I noticed was prior to the car stalling at low speeds or idle, the temp. sensor gauge in the car would start acting eratically, or drop to a reading of 0. If I was on the highway, I would notice the same behaviour, except the car did not stall. I kind of figured that since your car requires more gas while travelling at highway speeds anyway, it wouldn't stall (the engine would not flood). However, I did notice the engine behaving differently. The way I diagnosed the problem for my car was I fiddled around with the wires leading to the probe in the thermostat housing (I figured there must be some sort of correlation between the coolant and the engine stalling). By doing this, I was able to do a "controlled" stall. Before I replaced the coolant temp. sensor, I would wedge the wires so there would be minimal play from the vibration of the engine. This helped greatly in reducing the number of times my car stalled, but it didn't eliminate the problem. I eventually bought the coolant temp. sensor and replaced it myself. It's been almost 7 months and my car has not stalled since. If you do decide to replace the part yourself, make sure to drain some of the coolant to just below the thermostat housing. Let me know how it works out for you.

volvo virgin jinx · Post by **volvo virgin jinx** » 10 Jan 2007, 09:09

hey guys, just wanted to add a question to the obvious stalling issues;

I have a 93 850 with the classic fuel relay problem symptoms: stall after startup, car runs fine after warming up. Here's the ringer though, it will only start if I leave the MAF unplugged. Bought another MAF, same thing. I have a theory on why this is the case, but just wanted to back that up by asking all of you seasoned vets. Btw, thanks again for posting all of this info, you guys are a heaven send.