1996 Volvo 850 non-turbo P0171 P0103 Stalling MAF bad??

ketchup3821 · Post by **ketchup3821** » 20 Jan 2014, 06:29

Hello.

I bought my 850 this past June, with 155,795 miles on it. Now at 163,xxx. Since then, other than oil changes, I have drained and filled transmission fluid twice, replaced power steering fluid, replaced timing belt (all components) and water pump, both air filters, spark plugs, spark plug wires, distributor cap, and distributor rotor. All replacement parts were OEM from either FCP or IPD.

When I replaced the rotor, I was unable to tighten all the screws completely, because I dropped my hex key and lost it. I got them as tight as I could with a small flat-head screwdriver. It was my intention to go in there the next time I did work on the car (the next oil change, at ~166k). This was in on December 1.

The problem started about a week ago. My car would lose power and have lowered RPMs, but only for a split second, then go back to normal. This was usually when idling at a stop light. It was concerning, so I pinned it on the loose rotor, and slated that as a weekend project. It got worse throughout the week, once stalling out completely in a parking lot, but after a few tries, I was able to get it going again. I was also getting abysmal gas mileage (I have an UltraGauge). In the 15-16MPG range (~21-23MPG is normal for my commute this time of year). However, occasionally, everything would be perfectly fine, and I would get normal mileage.

Yesterday, I went in and tightened the rotor screws (got a new hex key). Then, feeling good about everything, drove (~10 miles) to my parents' house. Everything seemed perfect until it started acting up to the point of stalling out completely again. Took a few tries to get it going again. Then about a mile later, it did it again, but I was still able to get it started up again. Then about half a mile after that, it stubbornly died again. This time it was very difficult to start it again. It seemed to like it more if I started and then quickly shifted into Drive and gave it some gas. I got to my destination, and then on the way home had no troubles, or for the rest of the day yesterday.

Clearly the distributor rotor was not the problem. Reading the codes, I have a P0171 and P0103, along with my old P0442 and P0455 leak codes, which I plan on fixing this summer.

It looks like P0171 and P0103 tend to be related to MAF issues, although I also saw someone say it was related to the airbox thermometer. I did disassemble and remove the airbox when I did the distributor cap/rotor back in December; is it possibly I did something in there that would have only made itself apparent a month and a half later? Should I just clean the MAF to rule that out? Is there anything else I can do diagnostically to figure out what is going on?

Thanks.

Post by **rspi** » 20 Jan 2014, 08:39

Sounds like you have a MAF problem that has gotten worse. I would look into replacing the MAF. Some have found wire issues at the connector but that is rare compared to a MAF going bad. Only use a Bosch

Sounds like you have been doing a good job caring for the car so far. What condition is your PCV in?

ketchup3821 · Post by **ketchup3821** » 20 Jan 2014, 09:42

rspi wrote:Sounds like you have a MAF problem that has gotten worse. I would look into replacing the MAF. Some have found wire issues at the connector but that is rare compared to a MAF going bad. Only use a Bosch

Is there a way I could go about verifying this? A new MAF sensor looks to be about $140 (FCP). That's not the end of the world, cost-wise, and a new sensor in an 18 year old car is probably never a bad thing, but I would prefer to be more certain if it would solve my issue. It seems like replacing the MAF would be pretty simple unless there's some gotcha I'm not thinking of. Also, if this is the case, how urgent of a clock am I on? I'm still driving this car to work every day.

rspi wrote:Sounds like you have been doing a good job caring for the car so far. What condition is your PCV in?

Thanks. Like I said, I got the car last June with 155k on it, and despite it seeming to be in really good shape, it did not have any maintenance records except for a Jiffy-Lube sticker. The previous owner only had the car for about 6 months and 5k miles. He was a foreigner that had bought the car from the original owner, who it seems took very good care of it. He knew enough to get oil changes done, but he wasn't a "car guy" or anything. As I want this car to last me a long time, over the course of the rest of last summer and fall, I made it a point to go over most of the maintenance to be able to comfortably "reset all the maintenance clocks". The only truly neglected maintenance item I discovered was the old cabin air filter. It was pretty gross. It was also a nice way to get a feel for my car under the hood. My last car was a 3-cylinder 1988 Chevy Sprint (a bit of a different animal).

I know the PCV system is a big commonly neglected concern with these cars. I did what appeared to be the common checks last fall. I pulled out the dipstick with the car running and no smoke came out. I also ran the engine with a nitrile glove over the open oil cap without any obvious symptoms of pressure. I think that pretty much covers my bases, but I might look into it again sometime this summer just to be sure.

Post by **JimBee** » 20 Jan 2014, 21:24

Search this site for how to test an MAF. There are a couple of posts. Basically, you use a multi-meter and some thin wire nails to back probe the wires where they go into the plug.
The MAF increases micro-voltage output corresponding to increasing airflow. Those values are on here, too. It's a bit of fussy work, but you might find that your MAF is okay. It's kind of heartbreaking to replace it and not have a fix.
I suggest first checking your oxygen sensor connectors to make sure they're firmly secured and clean. They get a lot of road exposure. They have a lock tab on them which you can loosen with a flat blade screw driver (insert and twist). That's probably useful to do, anyhow, as a preventive measure.
Otherwise, check for air leaks. Look at the accordian hose (airbox to throttle body). Check it all around. The thin film plastic over the wire winding can easily perforate and can cause stalling.
Good luck.

Post by **jreed** » 21 Jan 2014, 05:05

I have experienced intermittent stalling a couple of different times on my '97 855 GLT (~170K miles). The causes were a dirty and sticky IAC valve and a bad positive battery cable between battery and starter.
If you haven't checked these potential causes, it might be a good idea before buying a MAF.
I wrote up a quick DIY for the IAC here:
https://www.matthewsvolvosite.com/forums ... hp?t=47533
And the battery cable here:
https://www.matthewsvolvosite.com/forums ... =1&t=47706

Good luck!

ketchup3821 · Post by **ketchup3821** » 21 Jan 2014, 06:18

Thanks for the additional input.

I'll look into testing the MAF tonight. I bought some MAF cleaner last night, so if nothing else I can clean it. I'll also look into the IAC and battery terminal tonight if I have time. If I clean the IAC and it doesn't solve the problem, at least I'll have a clean IAC. I like this tactic of doing things that probably should be done anyway.

One thing I noticed yesterday that does point to a MAF issue. My Ultragauge said I have 3.57 gallons left last night. Usually it's right around 3.6 when the gas light comes on. My gauge says I have 6 gallons left. The Ultragauge uses the MAF output to calculate gas mileage, etc. So it looks like I wasn't getting the crap gas mileage I thought I was, but the MAF and Ultragauge sure thought so.

Possibly related, but this all started a little after it got the coldest here it has been in a long time (it's since "warmed back up"). Outside air temperature was -27C on the coldest morning. No idea if this is actually relevant.

ketchup3821 · Post by **ketchup3821** » 26 Jan 2014, 14:36

Finally was able to clean the MAF today. Had a busy week of furnaces blowing up and weird stuff going on at work.

I'll see how it acts with a clean MAF, and see if the problem persists. If it comes back, I'll test the MAF and go from there.

Post by **erikv11** » 26 Jan 2014, 15:01

By far the easiest test for a bad MAF, is to unplug it. The car goes into a default mode (it will run rich) and you'll get a CEL, but the engine will not chug or hesitate. GO for it, unplug it then start it up. Give it a few seconds to smooth out, then drive it around like that. If the stall goes away, the MAF (or the connector) is the culprit.

That's how it is supposed to work, and most people can complete that test sucessfully. Occasionally the car gets very fussy with an unplugged MAF, I do not know why that is, but you will know right away if that is the case.

I will not hesitate for a second to put in a used MAF from the junkyard. Virtually every MAF at the yard is working perfectly. Cost should be more like $40 or less. Get two if they are cheap, one pick and pull I visited last summer wanted $11 for a MAF. They only had one 850, though, and it was too old (all 95-98 850/x70 cars have the same MAF as yours).

ketchup3821 · Post by **ketchup3821** » 29 Jan 2014, 05:54

Well, after cleaning the MAF, I still got the stalling problem.

Yesterday I disconnected the MAF and the problem went away. Without the MAF, the car seems to be have less power until it's warmed up, which to me would make sense. Also, it's been around -17C here the past few days. I think I'm going to pick up a "new" MAF from the junkyard sometime in the next few days. Is there anything wrong with driving sans MAF for a few days? I know I'll get lousy mileage.

Post by **erikv11** » 29 Jan 2014, 09:40

Just the lousy mileage. Over time it could be bad for the catalytic converter but for a couple days no problem.

Sounds like you got it figured out, nice.