P1171 issues

[Zorak412]

So I bought a 01 s60 t5 the other day. It ran beautifully. Battery was dead so I replaced it and it had about a quarter tank of gas in it. So the next day I put 10$ of 89 octane in it and the thing ran so rough and started stalling out. I owned a t6 xc90 and it only would run on 87 and nothing else but I figured I’d try 89 in my s60. I got the p1171 on my code reader. I don’t have a cel on the dash but once warmed up the car will not run right. Rough idle and stalling out. I can clear the codes and it runs great for a little bit then it will come back. When it runs rough it will spit out a bunch of smoke and I get about 2 miles to the gallon. I read about the code and either a maf or o2 sensor. I don’t have any other codes and I cleaned the maf and the plug for the maf. I haven’t looked much into the ETM yet because of the weather but if I clear the computer the car runs great for most of the day then the bad idle comes back then I park the car start it up in the morning and it still runs super rich and rough. Until I clear the computer. I don’t have too much money to start throwing parts at it so I don’t know if anyone here has an idea. I read other posts about their p1171 codes and their problems are not like mine. I know gas has a big part to play since my xc90 did the same thing when I put 93 in it the day I bought that thinking a turbo car should always run 93 but I was wrong with that. I filled up my s60 with 87 when my fuel light cam on after I put in the 89. I am just lost at this point.

[abscate]

The octane of the fuel isn’t causing trouble, all of those will work fine.

With poor running, the P1171 code tells you little, it’s just a fuel trim limit error which isn’t surprising given your engine is running rough. You need to slowly go through your vacuum lines and air induction lines and hoses looking for leaks, splits, holes, and loose hoses.

On a new to You Car, a compression test to make sure all cylinders are pulling is a good idea , too.

[93SCMax]

I've had my 2001 V70 T5 since new and have always run 91 to 93 octane fuel. The only time I had a problem (once only), was when I accidently put low test (87 octane) in the tank. Ran like crap and knocked.
I double checked my owners manual. For fuel requirements, it states "Volvo engines are designed for optimum performance on unleaded premium gasoline with an octane rating AKI of 91 or above. AKI (Anti Knock Index) is an average of the Research Octane Number, RON, and the Motor Octane Number, MON. (RON + MON/2). The minimum octane requirement is AKI 87 (RON 91)."

If I were you, I'd add a can of octane boost and then go with high test on your next fill up. You may also want to call the original seller and ask what they were running. If they always ran high test, the car's performance will decline if you go with a lower octane.

This may not be your solution, but you would at least eliminate fuel as a contributor.

Also, do you know when the fuel filter was last changed? A clogged/dirty fuel filter could also cause rough running and stalling.
Good luck.

[Zorak412]

I asked the PO and he said he ran nothing but 87 in for the 3 years he owned it. Same thing with my xc90 the original buyer of the suv only ever ran 87 in it. I know when I drove the car for the test drive and when I brought it home it took me almost 2 and a half hours of driving through city traffic to get home the car ran fantastic. All the way up till I put 89 in it. About 10 minuets when I put the gas in is when it ran really rough. And it ran about 1 mile to the gallon I watched the fuel needle slowly go down to empty and I threw in 87 and drove that for a little bit and the roughness was not as bad but still there. But never got a cel on for anything but when I plug my tester in it I get the p1171 fuel adaption bank one

[93SCMax]

Now I'm thinking you bought some bad gas (when you put in the $10 of 89 octane). Do you normally buy gas at that station and are they a reputable chain? I've bought bad gas before (not with my Volvo), and needed gas line antifreeze treatment to clean it up. If there is water in the gas, she will run like shxx. I still think a tank of high test wouldn't hurt.

I've never heard of 1 mile to the gallon, almost like your injectors are just dumping fuel and not spraying. With that kind of mileage, I'd be concerned with washing the cylinders (overfueling with incomplete combustion). Maybe this was the core problem requiring the catalytic converter to be replaced. Best to check your engine oil level. If too high, you may have fuel in the oil. Not to be an alarmist, but something isn't adding up.

Did I miss how many miles are on your "new" car?

Also, the recommendation of a compression test and checking vacuum lines for leaks/cracks, appears sound.

[Zorak412]

Vacuum lines are ok a bit crusty but no cracks or chips. I did get a second code today o2 sensor bank one sensor 2. So I’m waiting to get the money and buying a new o2 sensor and see what that does. It’s definitely dumping gas because the whole car will real of fuel and the exhaust smells real rich. I keep the mpg on the dash so I know about what I’m getting. But basically I will have to drive it with my code reader plugged in and clear it every so often just so it will get me to where I’m going. Once clear it runs amazing. No bad ticks or noises. Oil is and clean and where it should be. I’ve had bad o2 sensors before and the car never ran as bad as this one. I’m nervous about running 93 in it because I know my xc90 would not run with anything but 87. It ran worse than this thing if I put any other fuel in it. Also about the o2 sensor I’m also not wanting to waste the money on it just yet if that isn’t truly the issue since all the bad exhaust coming out when it runs bad maybe could have dirtyed the sensor. I’m getting kinda bummed. The car has 200k on it. It’s not a long term car for me just something to get me and my kids through the winter. Until I can pick up something else.

[abscate]

Have you tried unplugging the MAF? That makes the car run on the lookup table rather than trying to adjust the fuel mix on the fly. If it runs better disconnected it doesn't mean the MAF Is bad, it means the engine is getting faulty information.

Overwhelmingly, faulty information is usually unmetered air not being seen by the MAF but getting into the cylinders via vacuum leaks

The O2 sensor adjusts long term mix.

We typically budget $1500-2000 to get an old P80/P2 Volvo running well from an unknown, high age/miles condition.

These are high end cars with expensive parts, but they look like new after 20 years. For a short term runner, there are much cheaper options.

[Zorak412]

I found a write up to replace all my vacuum lines which I am going to do over the weekend and see how that goes. I know most of them are crusty but pain inspection of them they all seem intact no cracks or tears at the ends. But that was one of the things I wanted to address when I bought the car. I usually do most of the normal maintenance plugs oil and vacuum lines on all the cars I buy since who truly knows when the previous owners did it last.

[Zorak412]

Ok so I ran the fuel low and filled up with 93 and then pulled the spark plugs and they were shot so I replaced them. But the car still runs like garbage. I was hopeful since it ran fantastic for a few days. Pulled the plugs again and they are good. Now the only code I get is the o2 sensor bank one sensor 2 and the p1171. So I guess I’m going to replace the o2 sensor and hope it doesn’t need a new maf. I pulled the maf and everything looks intact on the sensor itself. I used maf cleaner so I’m hoping it’s just the o2 sensor.

[abscate]

The good-bad running modality is telling us you have a bad component like a coil, fuel pressure problem rather than engine management issues from the OXS