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#7252 of 19336 Re: Subaru forester (2006) Catalytic Converters [gaucho1]
Jan 16, 2007 (4:08 pm)
Sounds like you have 'discovered' one of the many wonders of OBDII. Problems logged by the system fall into one of several categories. Some will trigger the light and it will stay on for up to 40 "drive cycles". Other more transient issues will trigger the light, but it will only stay on for 3 cycles if the problem does not re-occur and go off.
Oxygen sensors can fall into the latter set. The front sensor deals with fuel/air ratios and the raw exhaust. The rear sensor assesses how efficient the cat is at futher reducing it. If feedback from the front sensor strays for a fraction of a second it can throw a code, but the light will clear itself if it does not happen again. But the system captures the code and a 'snapshot' of conditions posted by a dozen other sensors for a total of 40 cycles so that it can be read out by your mechanic.
Interpretation of what the codes mean, and what to change, is very much in the hands of the mechanic. It could be that the sensor itself is bad, a wiring problem, or something else that the CPU is misinterpreting. Remember that there are no dedicated sensors 'watching' the performance of sensors. The total system is monitored, and when certain conditions are met, a logic table dictates what code to show. It is not always right or absolute, which is why sometimes they end up having to change multiple things until it does not re-occur.
#7253 of 19336 cold start up engine squeal
Jan 17, 2007 (6:57 pm)
The noise is probably not a belt (but could be?) It only lasts 2-3 seconds and only when the engine is cold (perhaps alittle more pronounced during our subzero mornings right now in Colorado). If it's not either of the belts what would be the most likely candidate: idler pulley, power steering unit, air conditioning condensor, etc..? I probably need to have someone start the car while I listen carefully but if anyone has had this similar issue? 98 Impreza OBS 118k+
I've installed a Perrin lightened pulley but again, no squeal sound at all during revs, turning or warm engine starts. Please, don't make me call the Car Guys with another Scooby question thx Jon
#7254 of 19336 Re: cold start up engine squeal [98obster]
Jan 17, 2007 (9:11 pm)
Well, I vote for a pulley, as both my '07 is and my '96 was prone to such noises (I fondly call them "objections") when started on cold days. I do not notice it at or above about zero, but colder than that and it is there... lasting longer the colder it is. The sound, though, is distinctly different from a belt.... which is more of a shrieking squeal. This sound is, well, more of a buzzing squeal. Not sure if that makes any sense, but if that is it then I doubt it is a problem. I had the '96 through (most of) 7 winters and I do not feel like anything took excess wear as a result of the noise. I did replace my timing idler pulleys at 192.5K miles and the bearings were getting fairly worn.
#7255 of 19336 Re: cold start up engine squeal [xwesx]
Jan 17, 2007 (10:12 pm)
Most likely cause of a 2-3 second squeal is a "loose" fan belt. Unlike most substances, rubber actually expands as it gets colder. When it gets warmer (as in being spun around a few pulleys until the friction heats it up), the rubber belts will shrink.
If the belt adjustment is just outside acceptable -- you'll hear a squeal,until it shrinks back to the right tension.
A bad pulley bearing would squeal quite often, if not continuously. They don't get better with added friction.
#7256 of 19336 Re: Subaru forester (2006) Catalytic Converters [fibber2]
Jan 17, 2007 (10:36 pm)
I am discovering a lot of wonders.
Instead of waiting on delivery of the replacement Catalytic converter,I took off on my scheduled vacation trip --CA to western FL.
Gremlins have a mean streak. About an hour after I took off,the Cruise Control disabled,and the CEL came on steady. That condition remained until about thirty minutes before I checked into a motel for the night.
Next day, same thing. Day after that, same thing. Now that I have been in the same locale for about a week? No problem.
I have a manual shift; I tend to keep the rpm between 2.5k and 4k. While cruise control is more accurate than my foot, I do try to keep the same rpm range (when the damned CC is working, that is).
Temps all along Interstate 10 were about the same range; the only difference is the higher humidity as one approaches the Gulf Coast.
I'm in a relatively civilized area on the Gulf Coast; CC isn't needed that much, so --it's now available.
I'll learn more when I head back to CA in about five days,I guess.
#7257 of 19336 Re: Subaru forester (2006) Catalytic Converters [gaucho1]
Jan 18, 2007 (5:49 am)
It's probably your cat. The reason why it's not coming on until 1/2hr is that the cat takes time to heat up. Thus in local driving it doesn't have time to heat up.
#7258 of 19336 Re: Subaru forester (2006) Catalytic Converters [gaucho1]
Jan 18, 2007 (6:29 am)
Time for you to take some notes as you drive. Sounds like the light is going off quite quickly, so you are probably having a brief, single incident that does not repeat for a while. As I mentioned, hard or repeating fails would typically keep the light on for 40 full drive cycles.
A drive cycle is a cold start, full warm-up, and a certain set of speeds and distance (like 5-10 miles or so). A brief, one-time incident would turn on the light and set the code and snapsnot in memory, but the light will go back off at the start of the 4th drive cycle if it never happens again.
Did you note any performance change when the light went on? Sag or buck in power? Did you make a sudden change in throttle position?
Just guessing, but I would think that a rear O2 sensor (that monitors the cat) would trip more often than once in a great while, and the light would be on constantly. More likely the mixture, as measured by the front sensor, is occasionally out of spec. Why? Could be actual fuel or spark, or a measurement error (the O2 sensor itself). This is where it gets dicy, and the computer might have it right, or send your shop on a witch hunt.
Please, keep us posted on what they find. I learn also based on what you come up with!
#7259 of 19336 Re: Subaru forester (2006) Catalytic Converters [fibber2]
Jan 18, 2007 (10:49 am)
It is probably tripping the P0400 code (that is caused by mixture reading out of spec, is it not?). Mine was tripping that code periodically for 2.5 years and each time I had my emissions inspection performed the tailpipe readings were nearly identical. I have a hard time imagining that the cat was below threshold if this is the case, so I was leaning toward aging sensors. I planned to address it this spring along with a recent P0420 (EGR system) code, but was saved this headache.
#7260 of 19336 Re: cold start up engine squeal [gaucho1]
Jan 18, 2007 (10:55 am)
Nah, you would have to hear the sound to know it is definitely not a belt. Completely different sort of squeal. It is not bad bearings that are squealing, just cold... complaints. I should not have thrown that timing bearing bit in my last post as it was completely unrelated and apparently served to confuse the issue. I noted it only to say that the complaints coming from the pulleys (or whichever moving part(s) that tends to do the complaining) do not seem to lead to less longevity.
As for the rubber, it does lose elasticity when cold and therefore is more prone to squealing, but again, a different sort of squeal.
#7261 of 19336 PLEASE HELP - MAJOR SAP PROBLEM
Jan 18, 2007 (6:10 pm)
I've lived in an apartment complex for the past four years where I have no choice but to park under very large pine trees. I have a black Subaru Forester. When the spots first appeared, I ran out and purchased bug and tar remover which did nothing. I then tried the infamous clay bar and again, no luck removing the sap. I've tried alcohol (for the sap, not me) and even lighter fluid applied with a Q-tip and NOTHING will take this stuff off my car! I inquired at an auto body shop as to what options I have other than paying for a new paint job and they laughed at me. Now my car is polka-dotted with old crusty sap spots. If anyone has a trick up their sleeve for removing old crusty sap I would be VERY appreciative. Thank you in advance!