Found on a forum: Subaru Hesitation Problems
I own a 1999 Subaru Legacy Outback - this is actually the second Subaru I have owned, both of which have had the same problem. I bought the first one (an Impreza L 1994) used, and just assumed that I was having problems as the result of buying a used vehicle. However, when my 1999 started acting up at 12,000 (10 Months) I knew then that this was a big problem.
Simply put, I have a major hesitation problem in the engine. It seems to be most tempormental in the rain, but doesn't discrimante the rainy weather only. 1st and 2nd gear are the worst, although 3rd and 4th cause problems also. The RPMs get to about 2000 and then the engine more or less feels like it needs the choke ripped out and then at about 2700 - 3000 the thing takes off like a jet engine. I refuse to put my toddler (daughter) in the car, nor will I let my wife drive it. Not being sexist - I just don't think the vehicle is safe to drive.
I cannot seem to get the problem to reproduce itself regularly, hence I have never been able to get the dealership to reproduce while under warranty. Well here I am at 40,000 miles and it has become exponentially worse, I needed to tow it to the dealership... ---------------------------------------------------------------------------------------- My wife's 1998 Forester (32K) just started having the same problem that you described almost to tee. It an intermittent and when I test it out - no problem. Just today after a 2nd visit, the dealer said
that its a bad speed sensor ($188) which had to be ordered. ---------------------------------------------------------------------------------------- Found this TSB, Bulletin 11-58-99. Ask your dealer to check it out..
Subaru: 1999 Legacy and Impreza with 2.2L or 2.5L engine and manual transmission
Subject: Hesitation on acceleration from low rpm may be caused by the ECM commanding retarded ignition timing. Under certain driving conditions, the knock sensor may be excited by engine vibrations, which the ECM may interpret as ignition knock and retard the timing to -10 degrees. The bulletin includes a long list of other possibilities that may cause ignition knock, and they must be examined first. If no other problems are found, road test the vehicle to duplicate the hesitation while watching the knock sensor signal on an appropriate scan tool. If the cause of the problem is confirmed to be engine vibration and not ignition knock, the ECM must be replaced. The bulletin includes a table matching ECM part numbers with vehicle model/engine combinations.
Bulletin 11-58-99
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