99 OBW engine bogs down

[Rooster2]

Engine has been running great, until last week, when engine started to bog down, but doesn't stall. It is worse when the engine is less then fully warmed up, and accelerating from a stop light. If I slightly pump the gas pedal, I can get the engine to "catch" to get beyond the bog down problem. Driving at 30 mph+, I have no problem. I have NO CEL to tell me what the problem is. My thought is that I may have gotten a bad tank of gas. Maybe some water came with that tank of gas. Since then, I have refilled the tank, but still have the problem. I am thinking of adding a can of "dry gas." Maybe that will fix the problem.

 

Is it possible to have a bad cold temp sensor? Should I be cleaning the MAF sensor? I just need to fix this before the driveability gets worse.

 

Thanks for any advise.

[idosubaru]

gas treatment sounds like a good first step.

 

cylinder misfires can happen without any check engine light, doesn't happen often but i've seen it before.  it's usually due to non-NGK plug or non-OEM or low grade ignition wires.

1.  brand and miles on the plugs and wires?

 

in my experience the knock sensor is the most common problem I've seen on EJ engines.  if they don't throw a code yet, remove it and look at the bottom of it.  they're usually cracked or the rubber is sort of corroded/separating from the inner metal bushing.  it's a bit awkward to get to but can be replaced via one 12 mm bolts in 15 - 30 minutes...add a bit for your first time maybe.  they're available on ebay for like $20 or less.   they have an orientation and torque value that are good to follow - orientation meaning the pigtail from the sensor faces a certain way - i think sort of pointing to the drivers side strut tower from memory, but the diagrams are easily found in an FSM or online they've been posted.

 

CTS - yes that's a good thing to check too.  they are cheap and not terribly difficult to replace, i believe you can test them if you'd like.  i just replaced one recently and i don't recall having any issues with it, it's a bit tight but no big deal.

[Rooster2]

gas treatment sounds like a good first step.

 

cylinder misfires can happen without any check engine light, doesn't happen often but i've seen it before.  it's usually due to non-NGK plug or non-OEM or low grade ignition wires.

1.  brand and miles on the plugs and wires?

 

in my experience the knock sensor is the most common problem I've seen on EJ engines.  if they don't throw a code yet, remove it and look at the bottom of it.  they're usually cracked or the rubber is sort of corroded/separating from the inner metal bushing.  it's a bit awkward to get to but can be replaced via one 12 mm bolts in 15 - 30 minutes...add a bit for your first time maybe.  they're available on ebay for like $20 or less.   they have an orientation and torque value that are good to follow - orientation meaning the pigtail from the sensor faces a certain way - i think sort of pointing to the drivers side strut tower from memory, but the diagrams are easily found in an FSM or online they've been posted.

 

CTS - yes that's a good thing to check too.  they are cheap and not terribly difficult to replace, i believe you can test them if you'd like.  i just replaced one recently and i don't recall having any issues with it, it's a bit tight but no big deal.

Thanks, I will add "dry gas" first. I am still strongly leaning towards water in the gas tank, as the problem.

 

My plugs are Bosch Platinum, and wires are Bosch top of the line. I know people complain about Bosch, but I have never encountered any problem. I have about 10K miles on the plugs after driving on them for 1 year, maybe 5 years on the wires.

 

The knock sensor I replaced less then 2 years ago, and knew not to over tighten the bolt, and do remember the awkward bolt on angle.

 

What is CTS. TS probable means Temp Sensor?? Right?? Don't know what "C" stands for. What is it, and where is it located?

 

Thanks grossgary...........you have given me great advise in the past. Thanks for your imput on this problem.

 

Regards................Rooster2

[Gloyale]

CTS= coolant temp sensor

 

I'd replace those bosch plugs with NGK pronto.  Bosch are junk for subarus.

[Giovara]

I had the same problem and it ended up being my throttle position sensor. I was able to remove mine and clean it and it fixed the problem. It had a lot of nastiness on the end of it which was making it give the computer a wrong reading and causing the car to bog. Its located on top of the throttle body, held on with two phillips head screws. Easy to remove and clean.

[idosubaru]

CTS - coolant temp sensor as Gloyale said.  Common to have issues

 

EJ engines are not very forgiving in terms of ignition components as Gloyale suggested, mostly to cheap wires and you got good stuff.  NGK is highly recommended for plugs so i'd keep those in mind if it continues.

[1 Lucky Texan]

throttle body cleaning might be helpful.

[heartless]

spending the extra cash on "platinum" plugs is a waste of hard earned money, imho - the standard NGK's (owner's manual should give the specific type for your car) work very well in these cars.

 

but, getting back to the bogging issue - if it started suddenly after a fillup, then yeah, I would suspect bad gas as well. depending on the amount of water you got, it may take more than one treatment to get it cleared out.

[ivans imports]

front o2 senser they go bad and set no ce light

[Rooster2]

Update...........the motor is bogging down less and less over the past several days. I added about a half a gallon of E-85 ethenol fuel to my unleaded 87 fill up. E-85 I think is prolly about the same stuff as "dry gas" in its ability to absorb moisture. I am still thinking I got a tank full of gas tainted with water. I have had this happen over the years, and remember it took driving a while to clear up the problem.

 

Thanks for all the good advise.