Subaru Legacy 2001 bad acceleration

AAlir
10

Asked by AAlir Aug 10, 2013 at 03:59 PM about the 2001 Subaru Legacy GT

Question type: Maintenance & Repair

Well i have subaru legacy 2001, My problem is when shift the 1 or 2 Gear and then press
the accelerator the acceleration RPM slowly slowly increase when it reach to above 1500
RPM then take pickup fine i dont know how to solve this issue i got 2 error fault codes
Knock sensor and CO Resistor.

38 Answers

Nick Eidemiller
3,055

sounds like you need to replace the 02 sensor and run a fuel system treatment through a tank of gas. that would be a good place to start, I would need a little more info on the codes to tell you more, does the knock sensor code say the sensor is bad or say it is sensing knock and does the O2 sensor code say it's bad or it's reading outside of its acceptable parameters. One last question, what grade fuel do you use?

1 out of 1 people think this is helpful.
AAlir
10

we have 2 types of fuel in saudi arabia 91 and 95, 91 is thin and 95 is bold 95. I just recieve this code by scan tool the guy provided me it is written like 22 - Knock Sensor 49 - CO Resister 53 - Key Communication Failure 24 - Open/Short in ISC Valve Circuit

1 out of 1 people think this is helpful.
AAlir
10

one more thing i forgot to tell you the when i release the Clutch or stop the CAR the engine make high RPM sound for example like i am pressing the RPM. then it come back to normal. Most of my friend say this is MAF and IACV problem

Jeff Smith
1,145

A knock sensor code will put the car in limp mode, which means it retards timing and consequently power in order to try to prevent damage to the engine. I would recommend getting further detail on that code and replacing the knock sensor if necessary.

1 out of 1 people think this is helpful.
AAlir
10

You mean Knock Sensor is very sensitive part if i didn't change it my engine will Die???

Nick Eidemiller
3,055

well not the sensor itself, the "knock" that the knock sensor checks for is what could ruing the engine. Knock is when your fuel is detonating to early in the combustion cycle and is definately a bad thing. If the sensor detects knock then as stated above it puts the car into limp mode if it's too bad.

1 out of 1 people think this is helpful.
AAlir
10

Nick you told me that i need to replace the o2 sensor which one front or Rear ?? if you don't mind are you really understood my problem?? whihc i have mentioned above??

Jeff Smith
1,145

Post up the actual codes, and it will be much easier to help you troubleshoot this.

AAlir
10

Some error code i found in ODB scanner ( 22,49,53,24 )

Jeff Smith
1,145

Those aren't actual codes, they would be things like P0042, etc.

AAlir
10

HOw it is possinble?? that codes are actual and are mentioned in the webiste check the link given below legacycentral.org/library/literature/codes.htm

Nick Eidemiller
3,055

Well if they show up there, read what they mean.

AAlir
10

so how did you predict me about the o2 sensor Problem???

Nick Eidemiller
3,055

the CO (carbon monoxide) resistor is part of the O2 (Oxygen) sensor.

AAlir
10

so what it does???

AAlir
10

you guys are not understanding my problem!

Nick Eidemiller
3,055

If we are not understanding the problem it is only because you aren't really giving the info needed to truley diagnose this. Without being there in person to diagnose it first hand all we can do is make suggestions unless we have dealt with the same exact issue before. I'm not geting paid to do this but I am trying to help you anyway. If you don't like how I am doing it or what I am telling you I suggest you find a mechanic to take your car to and stop complaining. As far as what the O2 sensor does; it reads the exhaust gasses as they pass through the exhaust system in order to make sure the engine is geting the proper ammount of fuel and is burning it correctly and that the catalytic converter is doing its job. the CO resistor specifically reads the ammount of Carbon Monoxide in the exhaust, if that is bad of course you would be geting a bad reading, you could also be geting a bad reading if the Catalytic converter is bad or if another part of the emssions systems are bad.

1 out of 1 people think this is helpful.
Jeff Smith
1,145

AAlir, are you in the USA, or another country?

AAlir
10

i am in saudi arabia

AAlir
10

Thanks Nick very nice explaination now i understood what is CO resister another mechanic also told me to change the O2 sensor so definatley i am going to change it with knock sensor. soon update you!

Jeff Smith
1,145

It's possible that your trouble codes aren't the same as the OBD2 codes for the USA cars then. I would recommend searching for the meanings of your codes online or checking with your mechanic. Nick and I are used to USA OBD2 codes, like P0042 and similar.

AAlir
10

Hi, very strange news actually i have bought this used car from my friend of my friend! i was searching the O2 sensor location in the exhaust area but there was nothing i think the old car owner removed the complete exahust set and replaced with the local duplicate set???

Nick Eidemiller
3,055

has the car been acting like this since you bought the car?

AAlir
10

Yes, the first owner also had told me that you have to change the Flywheel the pickup issue has concern with it my gear alomost stuck when i am shifting so i am planning to change the clutch with flywheel! what you suggest??

AAlir
10

some time my car take pickup fine and some time car like dead

Nick Eidemiller
3,055

well with you're exhaust having been changed and not having the O2 sensors that explains why you're having the issues with how it runs. it's not geting the data that alows it to run correctly. As far as the clutch goes it is usually best to replace the flywheel and clutch at the same time.

AAlir
10

Thanks Nick, as for o2 sensor issue what i have to do now i have to change the full exhaust system components or some sets?? and where is location of o2 sesnor exactly can you guide me i want to recheck the location.

Nick Eidemiller
3,055

well the foreward O2 sensor should be threaded into the 1st catalytic converter where the pipes Y together from the heads, the 2nd O2 Sensor should be in a secondary catalytic converter further back in the exhaust about halfway back the car. Now there's a few ways this can be remedied, find and install a factory exhaust again, this my not be the cheapest way but will usually be the most reliable and easiest option if you wanna do it yourself. another option is to have an exhaust shop put in 2 catalytic converters at the points I mentioned. and a 3rd option is to have an exhaust shop weld in a couple bungs and have the O2 sensors put in without cats, however the O2 sensors will degrade faster and without the catalytic converters the exhaust gasses still wont be reading quite right for what the car expects and could still cause issues.

AAlir
10

if i found the location of o2 sesnor then how many sensor i have to change both?? or only front o2sensor???

Nick Eidemiller
3,055

the codes you were geting should specify primary (front) or secondary (rear) O2 sensor, if you only have one coming up then just replace that one, if both come up replace both. Personally I would also pull both to begin with and just try cleaning them with brake clean or an electrical solvent and a rag to remove any potential carbon deposits that could be fowling the sensor, if it then works you're good, if it is still acting up replace as nessiscary.

AAlir
10

:) even code don't know about my co resister bcoz both are missing!

AAlir
10

Hay! I went to the mechanic today and explained him about the problem after investigate he said that this car has no o2 sensor because this is outside usa or maybe some one changed but he has also told me to remove the exhaust through welding and check. but confusion here in subaru company I have checked about my model and they have o2 sensor they said I have to buy both components 4 exhaust set and 2 o2 sensor front and rear but was very expensive. What you suggest me here?

Nick Eidemiller
3,055

what you found out from the Subaru company sounds more correct to me, I wouldn't expect it to not have O2 sensors just because it isn't in the US. It's a fairly importaint part of your system for your engine to run properly.

AAlir
10

Yeah you are right! i will find used parts that will be cheap for me but today one more thing i have notice the mechanic just aligh the throtle body or air vlave position after that my rpm little improves! and running smoothly

AAlir
10

My engine is 2.0 http://estore.subarupartswarehouse.com/ is this website is good for buying parts are they compatible with my subaru

Nick Eidemiller
3,055

Well from what I know the site is reputable, but there's a potential issue. This company is based in the US and only has parts for US models which used a 2.5L, not the 2.0L you have so parts may not swap across the same. I'd recomend you give them a call to verify whether they will work or not. Try to find parts that are specific to the 2.0L you have.

AAlir
10

Nick, very strange issue if you remmember i have told you that old car owner told me to change the flywheel, if i press the rpm normally in neutral mode it works fine but when i changed the first gear the rpm is not going up i have notice my check engline light suddenly disappear when i heard the sound like (kut kut kut) ????

AAlir
10

actually this car is japnese version the engine 2.0 legacy 2001 B4

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