A "very special" Stutter/Hesitation Thread...

[rvanhell]

Hi All,

 

I've looked through the forums and have not found a precise description of my problem, so here goes:

 

I have a '99 Impreza Brighton 2.2, 5 speed. I have had hesitation problems in the past, and they have temporarily resolved themselves to some extent over the years. Lately, though, things seem to have changed.

 

Up until yesterday I was under the impression that because my car burned a small amount of oil (not enough to show up in the exhaust) the plugs were getting fouled. So, I would clean/change them and that seemed to resolve the issue for a time (about 6 weeks).

 

Yesterday I replaced the plugs, and the car's hesitation/stutter actually got worse.

 

Let me describe it: At idle I will get the occasional "bump", like it misses. If I rev it, it will cough on the way up sometimes. When I accelerate at low rpm and then pin it, the car will hesitate and then lurch violently. Often when I accelerate from a standstill, but not hard the car will just misfire (or so it seems, but I get no check engine light), and not accelerate but rather lurch. While it is doing this if I keep my foot on the gas, I hear a chirping sound coming from the back of the car. Lately at highway speeds, if I accelerate hard, no matter if it is reving high or low, it will not respond very well and the engine will feel like it's running a bit rough. This can happen cold or warm.

 

I have adapted to the acceleration from a standstill by giving a bit more gas before I lift the clutch. Most of the time this works, but sometimes there's nothing to do but disengage the clutch and try again until the engine decides to cooperate. I don't often accelerate really hard, because of how I expect it to respond.

 

The chirping sound has always intrigued me, but I've gotta say that this hesitation in general really bums me out.

 

Anybody with any ideas or is this just a standard "plugs/wires, MAF cleaning, fuel/air filter replacement etc." hesitation problem?

 

Thanks!

[Skip]

I vote for a plugged fuel filter

 

the chirping may be the fuel pump

dead heading against it

 

or

 

the fuel pump itself is going south and the bearings

are doing the chirping song of death.

[porcupine73]

Are the spark plug wire connections on the coil pack corroded at all? Sometimes certain ones will disintegrate over time due to the waste spark setup or whatever it's called.

[1 Lucky Texan]

Any OBDII codes stored?

 

I'm gonna suggest a SeaFoam or other similar treatment. Cheap and maybe some carbon will be knocked of a valve that's sticking.

 

How did the plugs look when you pulled 'em?

 

obtw - how many miles on the vehicle?

 

Carl

[Commuter]

What brand of plugs did you put in?

 

Have you changed the O2 sensor in recent years?

 

Commuter

[rvanhell]

I'm ashamed to admit to having had the plugs changed when I had my summer tires put on... so I don't know how they looked.

 

The spark plug wire connectors look good.

 

The car has about 120,000 miles. I'll look into SEA foam. Who knows?

[subaruplatt]

I vote for a plugged fuel filter

 

the chirping may be the fuel pump

dead heading against it

 

or

 

the fuel pump itself is going south and the bearings

are doing the chirping song of death.

So if you replace the fuel filter and it gets better but not perfect then you know maybe your heading into a fuel supply issue.

You would be surprised how faulty idle stabilization will mimic most of these symptoms. I used to run gas line antifreeze through the pcv draft,even the maf.

to cure those clogged from oil burning recirculating blues.

[porcupine73]

Maybe your cat is plugged/fouled?

[1 Lucky Texan]

?????

 

bump - repaired yet?

[unibrook]

My fix turned out to be the front 02 sensor. Here is my review from a diff thread: I have a 2001 Forester L with 85k miles on it. I have been chasing an intermittent hesitation under load problem for the past year. Only occurred when engine was warm. The front 02 sensor had been replaced once at 40k miles. I suspected it again this time, but since the only codes thrown had been cyl's 2&4 misfire ( p0302 & p0304) I assumed it must be ignition related. So I replaced plugs and wires 8 months ago...no effect. Did the dollar bill test over exhaust pipe, it was fine. Misted the coil, no sparks. I mentally sort of ruled out the fuel filter since it only happened when the engine was warm. Finally, a week ago while cruising on hwy at 65 mph, I felt the hesitation again (I wasn't even accelerating this time) and a new code was thrown....p0172. AutoZone read it for me, I described the symptoms to the guy and asked if he thought it might be the front 02 sensor. He said, "absolutely." So I decided to replace it next. Cost me $100.75 incl tax for the oem part# 22791aa00a from Cityside Subaru. I asked the Parts guy there if his experience was that this model engine needed a new front 02 sensor every 40k miles. He said, "no, these sensors are good for 100k miles." Well, bullsnot on that. I replaced the new front 02 sensor in 1 hour reaching from the top over the passenger side of the engine using an adjustable wrench. Be sure to use the thread lube so you can get it out easily next time.....after another 40k miles. I took out the air channel assembly first for better access. That seems to be the fix. No further hesitation since. Car runs like new.