Engine dies on gas stomp - Page 2 - Subaru Forester Owners Forum
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post #16 of 20 (permalink) Old 11-19-2012, 05:47 AM Thread Starter
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Join Date: Sep 2012
Location: Canada, Quebec
Posts: 167
Car Year: 2000
Car Model: Forester Ltd S
Transmission: Manual
I don't mind changing parts its just I like to know why I'm changing it. Point made, if the car got this far and still runs fairly great you would expect it to have had minimal maintenance. The dude said he changed the Head gaskets 15 000km ago and changed a lot of parts while at it he named the plugs and wires...now that.said I guess anyone trying to sell would want to make believe theyve done tons of work on it ....
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post #17 of 20 (permalink) Old 11-20-2012, 09:03 AM Thread Starter
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Join Date: Sep 2012
Location: Canada, Quebec
Posts: 167
Car Year: 2000
Car Model: Forester Ltd S
Transmission: Manual
So I get a little better performance after the TB cleanup, new air filter etc. seems to be smoother in general and a little more torque..

What still puzzles me; The 0420 code for cat efficiency... I know this problem is a situation with many possibilities but I just want to start with what doesn't make sense to me.

On my OBD2 scanner (TORQUE app) My O2 (1x2) B1S2 shows voltage fluctuation I set up a graph and it goes from 0.2 when idle for a long time, and stays in the 0.5-0.9 range when driving. Yet the 1x1 (B1S1) seems dead on the readings stays at a stagnant 0V, and never moves. How can the car run if the B1S1 is dead(If thats the case) and how can the ECU throw a 0420 code when : 1) The sensor works fine in appearance, and 2) It has no B1S1 values to compare to. (Would this entitle to a direct CAT failure if the sensor is working fine(I think) and we get an efficiency code?)

Now I know many "backyard" jobs have been done to this rig, such as home made bushings on certain struts, clutch change but no flywheel reface (I figure as it shakes like hell when you pull off from a stop without giving it gas) there is also quite an apparent WELD around the joint between the first cat and where the two pipes come from the heads (Figured the flange must of been screwed)

Do you guys think its possible to plug the B1S1 sensor in the B1S2 ?


Where would you guys start probing for something feasible. Can I use my multimeter to physically read the sensor's voltage see if its working?
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post #18 of 20 (permalink) Old 11-20-2012, 09:34 AM
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Join Date: Dec 2011
Location: Juneau, AK
Posts: 3,314
Car Year: 2009
Car Model: 2.5xt w/ td05-20g
Transmission: 4EAT
Cat's fail. Might just be that. That would throw the code. After a certain amount of years they often need replacing. Or the after cat O2 sensor itself could be bad.

TD05-20g @ 24psi with Stage II AWDTUNING Block
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post #19 of 20 (permalink) Old 11-20-2012, 09:58 AM
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Join Date: Dec 2008
Location: old lyme Connectucut
Posts: 198
Car Year: 01
Car Model: forester s
Transmission: 5speed
Originally Posted by Plastickmat View Post
I love when people assume I'm a complete idiot because I ask a general question, of course I've done basic maintenance to it, the reason why I'm posting here is because I like my machines to run as good as possible.

Had my scanner plugged, seems theres a CAT efficiency issue, I've changed coolant and oil so far only had it for a week please allow me to take the time to go around it.

Throwing parts blindly to address an issue that can be much simpler is backyard mechanics trouble shooting, the reason I came to a specific forum was to see if there was a possible 'common' cause for these engines to act this way. Of course changing plugs, filters, pumps, wires, all fluids, clean intake, and injectors will make ANY engine run better than it was running, but as far as addressing the WOT throttle issue, I noticed my scanner does not "sense" my throttle position going to 100% when I do it quickly. Dirty TPS? Maybe.

Thanks SuperAcerC I will be looking at what you said, interesting post.
People will assume things if you don't include all the info. On that note, just bring it to a mechanic. Throwing parts at a problem is not good trouble shooting...... Cat efficiency issue (P0420) is your cat. you need a new one. ....

01 forester s jackson rally 1 inch lift
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post #20 of 20 (permalink) Old 11-20-2012, 10:05 AM Thread Starter
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Join Date: Sep 2012
Location: Canada, Quebec
Posts: 167
Car Year: 2000
Car Model: Forester Ltd S
Transmission: Manual
I spent a good 20 minutes "Looking around" in the hood, and realised the air intake tube is "tampered" It gets all the way to the snorkel but all the UNDERLYING round inputs are uncovered theres just the main tube....

I found a DENSO part 22012AA070 looked it up its the MAP sensor?

Its mounted with ONE bolt to a metal rack on the passenger's side front of strut frame. Shouldn't this part be 'IN' the intake flow??
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