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2001 Forester engine lurching


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4 replies to this topic

#1 bend9999

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Posted 06 December 2003 - 01:20 PM

Automatic transmission. 45k miles. Engine has been lurching more and more lately. Dealer said it was impossible because "the computer controls the engine". Today, stepped on accelerator and had NO power. SCARY!

Pulled over to side of road and into park. OK. Back into gear same proble. First no power, then lurching, then rocket off.

HELP!!

#2 CROSSTBOLT

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Posted 06 December 2003 - 04:11 PM

I know some of the guys & gals are gonna groan when they read this but give it a try anyway since ya can't hurt anything: Reset the ECU. Two methods exist 1) Remove battery ground for 30-45 minutes and reattach; 2) Remove ECU fuse for the same amount of time. May be marked as ENG IGN on your fuse panel. Plug fuse back in. Start and idle for 15 min to warm up everything. Drive it off smoothly for 1/2 hour. Do NOT engage cruise control during this learning drive especially with MT. See if it improves with this reset and learn. Get the codes read for free at AutoZone if it does not. Let everyone know what happens. I had a 2001 Forester & traded at 51K miles-never did what you got.

#3 Commuter

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Posted 06 December 2003 - 08:24 PM

Could be many things... but I believe you. Others have had similar problems.

Didn't this year have trouble with bad Oxygen sensors?

And wasn't there a recall on the ECU (reflash?) around this time too.

I'm sure others will be of more help.

Commuter

#4 alias20035

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Posted 07 December 2003 - 02:59 AM

Originally posted by Commuter
Could be many things... but I believe you. Others have had similar problems.

Didn't this year have trouble with bad Oxygen sensors?

And wasn't there a recall on the ECU (reflash?) around this time too.

I'm sure others will be of more help.

Commuter



As others indicate, reset the ECU. See if any codes pop up.

Check to see if throttle position sensor (TPS) is loose and moved out of place (it is adjustable, but you should note a "dirt line" denoting the original position (hopefully!)).

EGR can cause some driveability issues including lurching. I would clean and check the EGR and its related vacuum system. While your at it check the air intake for any leaks or disconnected vacuum hoses.

Oxygen sensors can cause problems, but "bogging" is usually not one of them. It is worth investigating though.

A defective mass airflow (MAF) or Manifold Air Pressure (MAP) sensor will cause "bogging" which you may be referring to as "lurching". If you open the thottle completely and get no power, and then reduce throttle and get power, the MAF/MAP may not be working. Sometimes the ECU will detect a bad MAF/MAP, but not always. Often people get "bogging" due to changes to the air intake, in particular the removal of the air intake resonator. Did you make any changes to the air intake?

See this possibly related thread:

http://usmb.ultimate...=&threadid=8236

#5 alias20035

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Posted 07 December 2003 - 03:09 AM

Originally posted by alias20035
As others indicate, reset the ECU. See if any codes pop up.

Check to see if throttle position sensor (TPS) is loose and moved out of place (it is adjustable, but you should note a "dirt line" denoting the original position (hopefully!)).

EGR can cause some driveability issues including lurching. I would clean and check the EGR and its related vacuum system. While your at it check the air intake for any leaks or disconnected vacuum hoses.

Oxygen sensors can cause problems, but "bogging" is usually not one of them. It is worth investigating though.

A defective mass airflow (MAF) or Manifold Air Pressure (MAP) sensor will cause "bogging" which you may be referring to as "lurching". If you open the thottle completely and get no power, and then reduce throttle and get power, the MAF/MAP may not be working. Sometimes the ECU will detect a bad MAF/MAP, but not always. Often people get "bogging" due to changes to the air intake, in particular the removal of the air intake resonator. Did you make any changes to the air intake?

See this possibly related thread:

http://usmb.ultimate...=&threadid=8236



Your 01 Forester uses a MAP sensor which is to the left of the throttle body on the "clean" side of the air filter box. MAP sensors are usually more reliable than the MAF sensor. I would verify that it is correctly plugged in. The ECU is much better at identifying MAP problems than MAF problems, so hopefully it will detect something on the reset.

There are two service bulletins (recalls) that may apply to your 01 Forester, one is for ECU reprogramming, and the other for air/fuel ratio sensor (oxygen sensor? or MAP?). Check with your dealer or Subaru customer service to see if they apply. I think you can also enroll in a service on the Subaru.com website that will indicate the recalls.




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