99 legacy outback 2.5L

 

So I had a loose spark plug, and retightened it. Every time I would start the engine it went in reverse fine. When I put it in forward and begin to accelerate, the engine would drop RPMs to way below idle RPMs, then a few seconds later, begin to accelerate normally. So I figured it had to do with the loose spark plug problem. I took it in to get a Heli-Coil for the #2 plug, and had plugs and wires changed as well. $350 later...the engine is a lot smoother, but still drops RPMs (and feels its about to stall) when I switch from reverse to drive and begin to accelerate. When the engine is warm, this doesnt happen. What is going on?

 

Thanks,

Andrew

(Note - The following assumes this is happening all the time. Not just when switching from Reverse. See last comment in that case.)

 

I had this problem twice on my 97 OB. Low rpms only... like 600 rpm to 1000. It got worse as time went on to where I was feeling it while driving with the engine running at about 1500 rpm (almost like a misfire). You can probably find posts if you search.

 

My problem... carbon. A MotorVac fixed it the first time. Gas cleaners kept it in check for about 3 years. Then it came back and I couldn't get rid of it. However, I suspected my O2 sensor by this point. I had it changed. The hesitation cleared up considerably right away, then slowly disappeared over the next several weeks of driving. No return of the problem since then.

 

One other point. I find my transmission takes half a second to engage (R to D). I don't hit the gas immediately. I wait to feel it "catch" and then accelerate.

 

Commuter

Thanks, I'll take a closer look and try some gas cleaner if necessary.

If you do have a carbon problem, the over the counter stuff is probably not good enough to clean things out. I had tried that and it didn't do much of anything. The MotorVac however, did. After that, the over the counter stuff was able to keep it in check, until the O2 sensor caused the problem to get worse.

 

Commuter