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98 S70 Experiencing Random Stalling

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Posted

Hello,

As of the past two or three weeks my '98 S70 has been stalling, with little warning on a completely spontaneous basis. The car will run fine for anywhere been 20 minutes-2 hours, of actual running time, but will start to bog and the revs will drop coming to a stop. Sometimes the car will stall, and other times not, but the revs end up bouncing between 400-600 with higher spikes to upwards of 2000. Found a vacuum leak of two hoses involved with the intake and replaced both. Mechanic also said there was a chance that one of the O2's was going bad so had that replaced by him as well. These repairs seemed to fix it with no problems after several days of short and long driving, but now the problem has returned. Also, should note car is not throwing any CEL codes-- however three weeks ago it threw a P0171 for half a day before turning off on its own.

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16 answers to this question

Posted

Hello,

As of the past two or three weeks my '98 S70 has been stalling, with little warning on a completely spontaneous basis. The car will run fine for anywhere been 20 minutes-2 hours, of actual running time, but will start to bog and the revs will drop coming to a stop. Sometimes the car will stall, and other times not, but the revs end up bouncing between 400-600 with higher spikes to upwards of 2000. Found a vacuum leak of two hoses involved with the intake and replaced both. Mechanic also said there was a chance that one of the O2's was going bad so had that replaced by him as well. These repairs seemed to fix it with no problems after several days of short and long driving, but now the problem has returned. Also, should note car is not throwing any CEL codes-- however three weeks ago it threw a P0171 for half a day before turning off on its own.

Me s70 N/A

My idle was rough, recently bouncing 200-400 RPM at idle. I believe my code was PO172. And " Bank 1 running rich" Possibilities also considered were bad o2. I used the "hot start " ether spray around my (cold) engine to find my intake manifold gasket was sucking air.. So found it pretty quick'

During research I remember reading on s70 there is a "J" hose, to the air canister that was famous for cracking. The unit is hidden well and hard to find. ( under driver side F Fender? ) But I never had to go that far.

That's all I got man

Oh yeah . Bad MAF sensor would throw a code,, right?

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Posted

I'm kind of inclined to think you still have a vac. leak somewhere. Check the hoses that go into the IAC Valve.

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Posted

Definitely sounds like a vacuum leak. As for the MAF, it would through a code.

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Posted

Thanks for the good answers guys I'll definitely be checking for more vacuum leaks tomorrow. I also talked with some friends, although not Volvo owners, who suggested the possibility it might be the fuel pump starting to go? Wouldn't this also throw a code though?

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Posted

Thanks for the good answers guys I'll definitely be checking for more vacuum leaks tomorrow. I also talked with some friends, although not Volvo owners, who suggested the possibility it might be the fuel pump starting to go? Wouldn't this also throw a code though?

Not likely, might throw a lean or misfire code but as far as I know there is no code for failing fuel pump.

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Posted

The search continues....I can't find anymore hoses that would be causing a vacuum leak. In reference to the fuel pump possibility...it isn't throwing ANY codes and the P0172 is a lean/misfire code isn't it?

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Posted

The search continues....I can't find anymore hoses that would be causing a vacuum leak. In reference to the fuel pump possibility...it isn't throwing ANY codes and the P0172 is a lean/misfire code isn't it?

I had the exact same experience. In my case it turned out to be a bad power module. It's that little potted assembly that feeds the coil. It would intermittently stop firing the coil. I also had checked everything in the book including replacing the MAF, with out a fix. I replaced that module, and the problem never presented itself again. Intermittent problems are the worst!

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Posted

So after taking the car into our trusted Volvo specialist the car seems to be running okay, I drove it about 50 miles over two hours with no bouncing in RPM's or stalls. However, towards the end of my trip I stopped for something and when going back out and turning the car on the revs bounced around 400-450 for a couple seconds then went back to the normal idle. The 'specialist' cleaned all the electrical connectors, checked evap and the idle air control as well as searching for any vacuum leaks but found none.

^ Where is this power module located and how you were able to test it to determine whether it was faulty or failing?

Thanks again everyone for the help because this intermittent issue is being a real PITA especially since I'm mainly doing city/turnpike driving in and around West Philadelphia-- stalling in the left lane of US-1 feels like playing russian roulette.

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Posted

Try replacing the fuel pump relay. My 850 was doing the same thing a few months back with the random dying which was bad during rush hour! The relay on my 850 (don't know if it's the same for an S70) was under the fuse box under the hood on the driver's side of the car. You had to remove 4 torx screws and lift off the lid. The relay was marked "103". You can jumper a wire and drive your car around and see if it doesn't stall anymore. If that's the case, your relay is bad. The part costs about $40 from the local auto parts store. Anyway, good luck and hope you can find the problem.

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Posted

Well guys, another update to this absolutely infuriating issue. Car got checked over AGAIN and still found no problems with any of the suggested parts in question. However, the symptoms are a tad bit different- the car did not completely stall but the revs dropped below 500 and was struggling to not stall. The difference this time is the car was moving, instead of stopping, and when pressing on the gas pedal to try and keep it alive/keep moving it did absolutely nothing. I'm beginning to wonder if its the throttle body sticking closed, but at least its throwing a CEL now so hopefully I can go get the code pulled after I get out of classes. This problem is becoming quite serious because no acceleration when making a left turn in Philadelphia is like asking for serious injury.

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Posted

My 94 had same symptoms, random stalling. A new FPR did the trick. If your still desperate you could try it.

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Posted

MAF it will not throw a code until it is absolutely did. But with the randomness of it sounds just like mine and it was the maf..

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Posted

Used to have the same symptoms about the transmission and the RPM dip and the near stalling (or stalling when braking suddenly). Apparently what had happened was the metal shavings from the transmission wasn't getting caught in the magnets inside the transmission pan. This eventually clogged and jammed valve body passages and this lead to fluid pressure issues. I thought it was the solenoids but after opening up the old transmission (before sending it back as a core), it wasn't pretty inside.

In the end, I bought a new Volvo transmission for $2600 and the problem never came back and the car drove like new again.

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Posted

Did you have a 171 or a 172? You have made reference to both and 171 is lean and 172 is rich.

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Posted

You mentioned an aftermarket MAF. People have not had very good luck historically with non-Bosch MAFs. Any way to get your hands on a known good MAF?

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