Hey guys,

 

I've got a 1999 Legacy wagon 2.2L that loses power during acceleration. The RPM's fall for about 5 seconds, then the engine suddenly accelerates hard (if you keep the gas pedal depressed). This happens at about 2,500 rpm pretty consistently. The problem seems to go away after the car warms up for about 20 minutes of driving. A second (potentially related) problem is a wandering idle. The car idles at 750 sometimes, but wanders up to 1500 or even 2000. 

 

I'd appreciate any thoughts!

 

Thanks,

 

John

could be the IACV is gummed-up/sticking i guess.

 

is the CEL on?

Plug wires can do that. sputters and trips all over itself until it gets above 2500 rpm or so and then acts like nothing happened. Are the wires new? Anything but NGK and Subaru can cause problems right out of the gate. Good starting point if the wires are questionable as it's good routine tune up maintenance anyway.

^^^ good post - any dew/moisture around will cause arcing until the egine compartment heats-up/dries-out.

Edited August 27, 201510 yr by 1 Lucky Texan

Someone on another forum had almost the same problem with his XT6. After replacing a ton of stuff, turned out the problem was caused by a failing O2 sensor. Just something to consider especially if the sensor hasn't been replaced in years.

02 and knock sensors can do that, but typically will throw a check engine code.

 

If no check engine light - plugs/wires and possibly the IACV or MAF.

 

If there is a check engine light it may point in the right direction. Most national parts stores like auto zone, oreillys etc. will pull the code for free.

Thanks for the ideas! 

 

Forgot to mention, there has been no engine code so far. Plugs and wires are less than 1 year old. I'm sure the O2 sensor has never been replaced. I'll start with the IACV and see if a good clean out sorts it out. 

 

Thanks for the ideas.

99s had a TSB about the MAF sensor. If it has a MAF you can try cleaning it. A scanner that reads live data can be used to check the MAF flow rate to determine if its reading too high.

Fair - are those also the MAFs prone to a poor solder connection inside?

No. The 99-01(I think) have an issue with a sealer of some kind getting on the sensor element and causing it to read incorrectly.

 

This seems to apply only to models with the phase 2 style MAF.

 

The older square top MAFs have the solder joint problem.

Cleaning the IACV and the MAF fixed the trouble for about 2 days, then the car returned to "normal": losing power on acceleration at about 2500 rpm, wandering idle from 750 - 2000 rpm. The CEL is came on though, and the codes are P1100, P1507, and P0443. 

 

I went through some of the service records from the previous owner, and it looks like something was done regarding the MAF and a recall; the service sheet is pretty faded but it mentions the MAF and a recommended defect service.

 

Thanks,

 

John

check the wiring and hoses again. a coupla those codes are IACV-related I think.

 

almost seems like a bad/missing ground under the hood too. Clear the codes and see if all 3 come back immediately.

 

I searched google "  subaru P0443 " (and the other numbers - looks like you could read-up a little on those codes and how other folks dealt with them.

 

could be 2 problems I guess.