I have a 1998 V70 AWD with 178,000 miles on it. I live in Colorado, and bought here. I've had it just over a year and it has run perfectly. Today I noticed the engine hesitating and stuttering. It occurs while driving and idling. There is no noticeable difference in the RPM. Is this an O2 sensor or a filter that needs changing?

 

put in V70 section

 

This section of the forum is open to any Volvo models. While it would be more beneficial to post questions in vehicle-specific forums, people are free to post questions related to any Volvo models here. On the other hand, I direct certain posts to here, especially those that are either quiet or has no one except Tech and another member supporting the all owners (the XC90 section is a good example).

If you did not receive replies within the next 2 days, I would move this post to the V70 section for you. Or, I can leave it here should you wish to.


JPN

 

Generalized answer from one who has maintained various cars and clunkers for many years under the ol' shade tree.

In the old days of mechanical parts, your formula for problems like this was fuel + air + spark = good running engine with appropriate mix. These days, there's a fourth factor: electronic sensors. You can check fuel pressure (there's threads on this here) and air intake (start with the obvious, the air filter, then the tubes routing air to the intake for leaks, kinks, etc.) and spark
by doing the old ground it to the block test looking for a nice ice blue spark and not a yellowish one). And look at the condition of the plugs. You can also do the poor man's blocked catalyst test hy disconnecting the exhaust (be prepared for excessive noise, mind you) and seeing if the idle smooths out. This is all mechanical work that you could do on a '66 Volvo or a '66 GTO (except the cat, of course). If there's a problem, fix it. Button up the car and see if its cured. Baked on oil or wet oil on plugs, for instance, indicates possible ring/compression/valve guide problem, creating the need for a compression/leakdown test. At 177K, its possible they're just worn out.

But, you'll need some help if its some electroscrewup with a sensor, computer, etc. That's what you onboard diagnostic computer II hookup is for. The problem with those is that they suggest problems, but don't always tell you exactly what's wrong. Think of it as a suggestion box. You'll need to locate the codes as a "1933" or the like won't give you valuable information even if you have access to an OBD reader. Or have the dealer do it as long as it will give you the code readouts in plain English and not Swedish.

Your problem could be as far back as bad battery grounds or fuel pump pressure, or as far forward as the radiator. Or anything in between. That's a lot of territory, and you don't want to get into a deal with a "well, maybe we'll replace this thingamajig" type of mechanic which is what you'd end up with me!

Good luck



I'd suggest a diagnositc computer run first unless you're into fighting rusty bolts, etc.

 

Thanks for the input. JPN, yes, please move it to the V70 section. I didn't take the time to look at all the different sections, sorry.

I'm going to take it to the mechanic, hopefully tomorrow. It has gotten worse, with the rpm now being affected, and the car shudders. The Check engine light now is on, and blinks for a few seconds every few minutes.

 

OK, I moved the post.

Since V(S)70s are similar to the 850s, I'll try giving you some things to look for.

In 850s, such trouble can be boiled down to:

- Faulty MAF (Mass Air Flow) sensor; it calculates how much air is being fed to the intake manifold.
- Faulty ECT (Engine Coolant Temp) sensor
- Faulty Cam Position Sensor (usually causes no-spark/no-start).
- Faulty ignition components.
- Faulty fuel pump/pump relay.
- Faulty fuel system relay (if so equipped).
- Dirty throttle housing.
- Neglect.

I do not believe clogged filters would cause such symptoms often. I once changed the fuel filter for Ford F350 and the original filter was there for 10 years & over 130,000 miles. No noticeable changes to the performance with the new filter. Filters really have to be clogged to cause fluctuating RPM (but they sure do affect gas mileage).

If you wish, you can visit Autozone or other auto parts shop to see if they still offer free OBD-II diagnostic service. I used to take advantage of this, but also bought lots of consumables as a courtesy. If their OBD-II scanner can read a faulty sensor(s), you can try buying the OEM parts from FCP Groton or any reputable on-line vendor and replace the sensor to see if it cures the trouble. Should you decide to take this route, make sure that the ignition is off (in some cases, removing the negative battery cable is required).

This is for 850 maintenance, but some items may be similar to V70s:
https://volvoforums.com/forum/volvo-850-16/new-volvo-850-owners-read-important-thread-also-applies-s-v70s-9266/

I hope this is of some use. Wait for V70 experts to chime in.


JPN