01 V70 Possible Catalytic Converter Failure?

zero324 · Post by **zero324** » 08 Mar 2011, 10:45

I am wondering if these might be symptoms of my catalytic converter about to fail or if I need to look in another direction on my 01 V70 non-turbo.

1. Recently I have noticed a decrease in performance that is especially noticeable at speeds between 0-50mph above that it isn't as bad but noticeable. I also notice a foul odor from time to time.

2. Also have found that I now have a small oil leak again near the crank seal. About 3 months ago I replaced all the seals and flame trap box and hoses. Yesterday after I pulled in the driveway I turned the car off to check the oil and noticed smoke coming out the dipstick tube which never happened before till I noticed the decrease in performance.

3. Back in November we started to notice a rattling noise at exactly 2k rpms but would only do it at exactly 2k rpms and at speeds below 45mph. Now we hear a rattle at 2-4k rpms which starts out loud but gets softer as the rpms go up but it only happens when the car is in drive. It almost sounds race exhaust like on WRX's but not quite as loud.

4. Since the performance issues started my gas mileage has gone down dramatically. I am now getting only 19-20mpg in the city and max of 23mpg hwy. Before I was getting 22-24mpg city and 30-32mpg hwy.

5. I did get a CEL about 7 months ago and was told by the independent Volvo shop that I use to go to that the code pointed to a bad catalytic converter. They cleared the CEL and it has not come back.

I wanted to see what you guys might think before I throw alot of money into buying a catalytic converter and new o2 sensors.

FCPEURO · Post by **FCPEURO** » 09 Mar 2011, 15:15

Your symtoms do not sound like a cat. convertor. It sounds more like bad compression and/or a clogged up PCV system. I would get a compression test done on the engine to make sure the engine is still within spec. If that checks out ok, then check the PCV to see if it clogged up again.

zero324 · Post by **zero324** » 09 Mar 2011, 21:54

As you suggested I did a compression test and found all cylinders were getting between 150 and 148.

One thing I did notice when I pulled my ignition coils out that # 3 and #5 had really hot coil boots. the #3 coil boot seemed the worst and also noticed the spark plug in that cylinder was worn differently than #1,2,4 and 5 was similar to 3 but not as bad. I pulled the boot off #3 and found the spring was very thin compared to a normal one. I went out and purchased a new coil boot which has a new spring with it. After installing everything and starting the car the first think I noticed was that it sounded like it was running alot smoother than before and my wife agreed. Upon driving the car I now have my acceleration back and also the shift lock is gone which may have been a misfire that would happen if we had to quickly slow down due to a car turning and we would speed back up. We also noticed that the car ran alot quieter while going down the road than prior.

I'm thinking about replacing the coil boots on the rest of the ignition coils this weekend since they are all the originals. I may also go ahead and replace the plugs as well even thou they were replaced only 6 months ago.

zero324 · Post by **zero324** » 14 Mar 2011, 07:08

I forgot to mention that the plugs and cylinders looked like they had decent amount of unburnt fuel.

I did go ahead and replace the rest of the boots and springs to see if it made any difference but in the end it didn't. I did notice that my fuel economy did improve a bit compared to before but still not as great as it was. One thing we have noticed is that it is now randomly having power loss as before it was constant. I'm thinking about replacing the ignition coils to see if that changes anything but another thing i'm wondering is if it may be the MAF. I've read in a few threads that this can cause the same issues and not throw a CEL. I'm kinda confused as how to test the MAF because I've read if you unplug it while the car is running and it stays running then the MAF is bad and if it dies then the MAF is ok. When I unplug mine it stays running and almost seems to me that my idle smooths out a bit. Is there any other way to test the MAF?

Post by **precopster** » 14 Mar 2011, 07:23

PLEASE never unplug a sensory device while the car is running!! I don't know which thread gave you this idea but remember that the MAF is connected to the car's ECU. Switch off the ignition and then unplug it.

If the symptoms (of bad idle & poor acceleration, poor starting) disappear install a new MAF.

Your compression is low for a N/A car with compression ratio of 10.5:1

Did you test with a warm engine?

Your readings should be over 190PSI

If a high volume of smoke is coming out of your dipstick you have a blocked PCV system and/or worn rings or excess carbon build up at the rings. Your compression readings certainly point to either of these directions where rings are concerned. You may want to look up how to perform a Seafoam treatment to attempt to restore lost compression.

Let us know how you go.

zero324 · Post by **zero324** » 14 Mar 2011, 07:53

There are numerous threads about unpluging the MAF while the car is running and none have ever said anything about this being an issue but I do see your point about that causing ECU conflicts or issues due to that being done. Should I try to clean the MAF if it indicates being bad before buying a new one or would that be just fighting a losing battle?

The car was driven for about 20 min before running the compression test and went thru 5-6 revolutions of the motor to get my readings.

There was not a high volume of smoke coming out of the tube but a very very small amount. I did do seafoam in my gas tank over the weekend and now no smoke is coming out of the tube. I hope to run some seafoam thru the intake later today but have to wait till i'm outside of the city so I don't have angry neighbors. When I did my 245 a few months ago my neighbors thought my house was on fire and called the fire dept so I don't want that to happen again

.

Post by **precopster** » 14 Mar 2011, 16:39

Sorry I should have qualified what I said a little better like this:

If the symptoms (of bad idle & poor acceleration, poor starting) disappear after having it disconnected then install a new MAF.

An unplugged MAF will allow the car to run on a set of preset values for air/fuel mixture (though inefficiently)

A bad O2 sensor combined with a bad MAF can throw the engine into running very rich, though you still need to have a psi of 188 psi minimum (straight from the Volvo Pocket Book which states b/w 1.3 & 1.5 MPa or 13-15 kp/cm2 )

The Seafoam may just do the trick, though that may fix the symptom and not the cause. Now that the rings are clogged with carbon you will need to find out why this happened. What grade of fuel do you regularly run? This will be a factor. If the front O2 sensor has covered more than 100k miles replace it. Also use some MAF cleaner and clean the throttle body and see how you go.