Poor Acceleration after oil and trans fluid change.

[Julian Rodriguez]

I recently purchased a 98 Subaru Legacy with a 2.2 L engine manual 5 speed transmission. When I got the car it already ran pretty good, just a few things here and there that needed tidied up. Engine ran great though. I know the guy who previously owned it hadn't change the oil in a while so I took it to my shop at Honda to change the oil and I figured while I was at it I'd change the trans fluid. I followed the amount of fluids I should put in the vehicle recommended by the owners manual. I drove off and got home. When I got to the house I noticed there was some smoke coming out of the tailpipe. I figured maybe I overfilled just a little bit on the engine oil. I checked the dipstick and it was barely over the full line so I didn't think anything of it. About a week went by and I started noticing that when I begin to accelerate at a dead stop and get to about 2500 RPMs it starts to hesitate until I get past 3000 RPMs. Then it seems to take off rather quickly and continue to accelerate.

 

I already checked the wiring to the right of the bellhousing to make sure I didn't disconnect any of the cables, I noticed that I had accidentally unplugged the O2 sensor at the front of the car. I've since then plugged it back in with no improvement on driving. The rear O2 sensor has been out since I've had the car and it was driving fine with that one being bad. Someone suggested that maybe I put the wrong weight in trans fluid but I made sure that I put the right kind in and that's not the issue. I've already ran a scanner on it and the only codes that pop up are O2 sensors which have already been there since I bought the car. I haven't changed too much to the car besides change fluids so I'm kind of stumped besides maybe putting too much oil. Also I've since then checked the dipstick and it's right where it needs to be.

Edited June 22, 2022 by Julian Rodriguez

[laegion]

I'm sure others will have some good suggestions; but I would first inspect your plugs and wires, see if they are good, see if they have oil or have been running hot. Also, your knock sensor, I would pull it and inspect for cracks, make sure to torque to spec when re-installing. Also, if you haven't done so yet, since you reconnected the O2 Sensor, you might try disconnecting the battery for a bit to reset the ECM. I'd also check your PCV valve, and air filter. It sounds a lot like either bad plugs, or a vacuum leak of some kind.

What color was the smoke coming from the tailpipe? Also, how does your coolant look?

Edited June 23, 2022 by laegion

[lmdew]

All good suggestions.  Also make sure the IAC hose coming from the airfilter box is correctly installed as well as the vacumm lines on the passenger strut tower!

1+ for comments from leagion.

[el_freddo]

How much oil is in the gearbox? You can check this on the gearbox dipstick. If you’ve got too much in there that could cause drag through the gearbox, but not in the way you said the engine behaves between 2500 and 3000 revs. 

It could be a coincidence that you did the oil changes and now you’ve detected this issue. That or your Subi is pissed it was forced into some maintenance at a Honda place   

Other issues it could be: a dirty MAF, needing a new air filter (unlikely to be root cause but a clean filter is always good!), dirty TPS contacts, and that’s about all I can think of atm. Laegion covered many good points to start with too. 

Cheers 

Bennie

[1 Lucky Texan]

always check and refresh ground connections on older OBD cars.

possible dead spot in TPS range

 

less likely would be a timing belt slip....?

[Julian Rodriguez]

On 6/23/2022 at 2:39 AM, laegion said:

I'm sure others will have some good suggestions; but I would first inspect your plugs and wires, see if they are good, see if they have oil or have been running hot. Also, your knock sensor, I would pull it and inspect for cracks, make sure to torque to spec when re-installing. Also, if you haven't done so yet, since you reconnected the O2 Sensor, you might try disconnecting the battery for a bit to reset the ECM. I'd also check your PCV valve, and air filter. It sounds a lot like either bad plugs, or a vacuum leak of some kind.

What color was the smoke coming from the tailpipe? Also, how does your coolant look?

The plugs and wires on it are fairly new I'll check them again though. I did disconnect the battery to reset the ECM and it fixed the problem for maybe 15-20 miles or so then came back. I think that by resetting the ECM if put it back to its factory settings, then is trying to correct itself later on causing the issue again. I don't necessarily hear any vacuum leaks but I will look again. The smoke was kind of whitish I don't really remember it doesn't smoke anymore though. I feel that if I did overfill it it's already burned off what it was overfilled.

[Julian Rodriguez]

On 6/23/2022 at 8:16 AM, el_freddo said:

How much oil is in the gearbox? You can check this on the gearbox dipstick. If you’ve got too much in there that could cause drag through the gearbox, but not in the way you said the engine behaves between 2500 and 3000 revs. 

It could be a coincidence that you did the oil changes and now you’ve detected this issue. That or your Subi is pissed it was forced into some maintenance at a Honda place   

Other issues it could be: a dirty MAF, needing a new air filter (unlikely to be root cause but a clean filter is always good!), dirty TPS contacts, and that’s about all I can think of atm. Laegion covered many good points to start with too. 

Cheers 

Bennie

I thought that maybe I put too much or that maybe the weight of the gear oil was too heavy so I replaced it with the correct weight. I didn't overfill it though. Problems still exist.

[Julian Rodriguez]

On 6/24/2022 at 1:02 AM, 1 Lucky Texan said:

always check and refresh ground connections on older OBD cars.

possible dead spot in TPS range

 

less likely would be a timing belt slip....?

A friend of mine has a couple TPS from old 2.2 laying around says he'll bring them in come Monday to see if that's the issue. Thanks.

[Julian Rodriguez]

On 6/23/2022 at 8:16 AM, el_freddo said:

How much oil is in the gearbox? You can check this on the gearbox dipstick. If you’ve got too much in there that could cause drag through the gearbox, but not in the way you said the engine behaves between 2500 and 3000 revs. 

It could be a coincidence that you did the oil changes and now you’ve detected this issue. That or your Subi is pissed it was forced into some maintenance at a Honda place   

Other issues it could be: a dirty MAF, needing a new air filter (unlikely to be root cause but a clean filter is always good!), dirty TPS contacts, and that’s about all I can think of atm. Laegion covered many good points to start with too. 

Cheers 

Bennie

Also just to clarify I just work here all my tools are here lol. I was just trying to show my suby some love.

[laegion]

4 hours ago, Julian Rodriguez said:

The plugs and wires on it are fairly new I'll check them again though. I did disconnect the battery to reset the ECM and it fixed the problem for maybe 15-20 miles or so then came back. I think that by resetting the ECM if put it back to its factory settings, then is trying to correct itself later on causing the issue again. I don't necessarily hear any vacuum leaks but I will look again. The smoke was kind of whitish I don't really remember it doesn't smoke anymore though. I feel that if I did overfill it it's already burned off what it was overfilled.

Well, also, looking at the plugs might give some clues as to what is happening. Also, I've had very nice looking wires that were leaking spark...it doesn't always look obvious. I used to look at the engine in the dark while running, it makes it really easy to spot. Also might test the resistances on your ignition coil to see if it's gone bad. Also, I've had problems with a partially stuck PCV valve that presented similarly.

Edited June 25, 2022 by laegion

[ronemus]

Overfilling oil may have overloaded your catalyst of damaged your oxygen sensor.  Has your fuel mileage changed?  If engine oil was overfilled, you can probably find evidence of it in the vent lines and airbox.