1995 legacy 5spd. I just put in a new radiator as the old one was dripping faster and faster. The car's been in the garage since last friday and now when i drove it today it's developed a sputter. On the way to work, it would buck and sputter after releasing the clutch. As I after that it ran fine until the next stop sign. Then on the way home it was sputtering and bucking also when I'd give it extra gas. Then by the time I got home it just about couldn't drive steady.

 

I put it in the garage, and operated the throttle from the throttle body. It runs smooth as silk without load, but when I crack the throttle somewhat quick it sputters like it did on the road.

 

I have another 95 legacy 5spd so I did some swapping. I swapped in:

 

coil pack

plug wires

MAF sensor

 

Checked the IAC valve.

Fuel filter was changed a year ago

plugs are a year old

o2 sensors are a year old. It also does this problem immediately after starting, when I'd assume its in open loop mode which would rule this out.

 

any ideas? When the engine cools later on I'm going to take the plugs out and see what they look like. I'm thinking it could be clogged injectors, or fuel pump

I swapped plugs with my other car and the car runs fine now.

 

One of the plugs had oil on it, not dried or burned oil, but wet fresh oil. I did a compression test on that cylinder and first instant it jumped to 150psi then to 180. Which is odd since I tested it about a year ago and all the cylinders were around 120.

 

Any ideas what happened?

sounds like classic cylinder misfire. it often doesn't show up at idle because there's nearly no load on the engine.

 

compression readings can vary so those numbers don't scare me normally. if compression is a concern, which it might be given the oil on the plug and initial low readings, then do it again. be sure to prop the throttle open, remove all the spark plugs and leave them out for the testing, and make sure the battery is in tip top condition or you have another car jumper cabled to it. compression readings vary by rpm's which can vary a bit by available battery power.

 

EJ's i believe are supposed to be around 180, so sounds good! oil on the plug doesn't sound good though, replace the PCV valve?

I know what "buck and sputter" means for a carburetor engine, its usually a little different for a closed loop engine.

 

Its only in "open loop mode" while the O2 sensor is cold. Restarting the engine may go into closed loop very quickly.

 

A dirty, or fouled, O2 sensor is often very laggy, and the closed loop control breaks down. Some of your description points that way. It might be worth visually examining the upstream sensor. The Bosch web site has some good pictures of what different kinds of fouling look like.

 

You didn't mention the condition of the donor of the swapped parts.

 

During a true cold start it should be not only open loop, but mapped very rich, to the point of a smelly exhaust. If not, check the coolant temp sensor.

 

If you can get your hands on a cylinder leak down tester the answers are more useful than a standard compression check. You mentioned a radiator swap, and sometimes the root cause is a cylinder leak. Dirty coolant can be a hint, but not every time.

 

You also haven't mentioned anything about the air filter, cleaning the throtle body, cylinder carbon cleanout (SeaFoam), or injector cleaning (Lucas, Mystry Oil, Techron, etc.) Any of those could cause the problems mentioned.

 

In my personal experience, dramatic bucking and stumbling with a closed loop engine that idled well has been due to a bad O2 sensor, but I'm picky about what I call a good idle.

One of the plugs had oil on it, not dried or burned oil, but wet fresh oil.

Did you sniff it? Was it black?

Carbon + gas + misfire = wetplugs that might look like oil fouling.

Did you sniff it? Was it black?

Carbon + gas + misfire = wetplugs that might look like oil fouling.

 

No smell of gas.

I know what "buck and sputter" means for a carburetor engine, its usually a little different for a closed loop engine.

 

Its only in "open loop mode" while the O2 sensor is cold. Restarting the engine may go into closed loop very quickly.

 

A dirty, or fouled, O2 sensor is often very laggy, and the closed loop control breaks down. Some of your description points that way. It might be worth visually examining the upstream sensor. The Bosch web site has some good pictures of what different kinds of fouling look like.

 

You didn't mention the condition of the donor of the swapped parts.

 

During a true cold start it should be not only open loop, but mapped very rich, to the point of a smelly exhaust. If not, check the coolant temp sensor.

 

If you can get your hands on a cylinder leak down tester the answers are more useful than a standard compression check. You mentioned a radiator swap, and sometimes the root cause is a cylinder leak. Dirty coolant can be a hint, but not every time.

 

You also haven't mentioned anything about the air filter, cleaning the throtle body, cylinder carbon cleanout (SeaFoam), or injector cleaning (Lucas, Mystry Oil, Techron, etc.) Any of those could cause the problems mentioned.

 

In my personal experience, dramatic bucking and stumbling with a closed loop engine that idled well has been due to a bad O2 sensor, but I'm picky about what I call a good idle.

 

It started doing the bucking again on the way to work. Not nearly as bad as before, but still there. A guy at work said oil could be coming through the pcv valve (blowby or bad pcv valve?). Which is possible because the cylinder with the oily plug is the one rear one on the passenger side, right next to the pcv valve.

 

I don't think its o2. I drove it immediately upon starting it and it had the symptoms (after sitting cool all night). The donor parts should be good as they came out of a good running car. I haven't done a leak down test. I'll look into seeing how much a kit is.

 

Air filter looks clean. Not sure about the throttle body or injectors. Is it easy to remove the injectors and check them? I've never done anything with injectors.

 

Thanks everyone for the replies

Edited September 2, 201015 yr by destey