stuttering, stalling, non-functional O2 sensor, etc.

So, I've long had the 2300-3300 RPM stutters with my 05 LGT. 6000 miles ago I had the ECU reflash, and afterwards had stutters not a 1/4 mile down the road from the dealer. I wasn't really surprised given what others experienced here. After ECU learning, I think it improved a bit. Either that, the colder weather, or I adapted my driving.

 

Now, about a month ago, with the onset of cold weather, I started experiencing occasional stalling while approaching a stop sign. (Foot off the gas, foot on the clutch, RPMs drop below idle, warning lights flicker, maybe stall while still moving at 20-30mph.) This seemed to happen when the car was transitioning from the high idle cold mode to the normal idle as the car warmed up. I had at least 5 stalls in one week during my normal commute. However, I would say I had about 3 such stalls between June and October in various temperatures, but they were so rare I didn't really think about it.

 

Now, I didn't like the stutter, but I REALLY disliked the stalling and considered it a safety hazard to lose power steering and brakes regularly while the car was moving. I took it into the dealer, and the tech took it for a spin with a computer of some type hooked up to the OBD2, and he said the O2 sensor input was non-reactive. 3 days later they get one in stock (why are these NOT stocked more locally--come on it's a current car).

 

The car went in a couple days ago to get that installed and that doesn't help. They discovered that an ECU pin must have been bent and that the O2 input wasn't being properly read by the ECU. I ask them if my engine has been running "open loop" for the past three months since the ECU reflash (or even longer), and they say probably. I ask why it didn't throw a CEL and they didn't know. They eventually got some explanation from SOA's tech line that they were satisfied with, but I am fairly annoyed my car has been running this way for months without anybody knowing. I asked if it was running rich or lean all this time and they say very lean. I asked if this was potentially damaging to the engine and they say yes if it was for a long time. I mention three months. Hmm... Well, if it wasn't pinging it is probably fine. Hmm...

 

So, what's the deal? Does it make sense my ECU would not be reading an O2 sensor input for months and not throw a CEL? What has this done to my engine? Should I demand a more careful examination of the state of the engine?

 

Anyways, back to the stutter: I think it might be gone. I tried my hardest to recreate it today, and I couldn't detect it at all. Of course, the reset ECU may relearn bad habits, but I don't think my engine has ever run this smoothly, especially in the 2300-3300 RPM range under light to moderate throttle. That was almost guaranteed to cause stutters/surges before.

 

I wonder how many other LGTs are driving around with inoperative O2 sensors/connections.

 

--Lee

 

PS: They want to replace the neutral safety switch for some reason. Apparently, SOA says it is linked to some stalling incidents. Apparently, the ECU can get some erroneous neutral indications and it adjusts the AFR, potentially causing stalls. I doubt that is a factor for me, but what the heck. My dealer said that will take...you guessed it 3 days...to come in because there are only 8 in the USA. 8 switches in the whole country. What's the deal with Subaru stocking parts of current cars? They don't have boatloads of such parts at the IN assembly plant?

After being in the dealer three days last week and one this week for the stalling issue, I picked up the car last evening. What do you know, it stalled at my second stop sign this morning. At the first one it nearly stalled, flickering all the warning lights. At the second one, it dropped the idle too far, flickered the warning lights, it then seemed to blip the RPMs up, and then they dropped to zero for the stall. Twenty minutes later, after a 10-mile highway stretch on cruise control, approaching backed up traffic and pushing the clutch, the RPMs again dropped precipitously causing at least one warning light to flicker. The car was warmed up at that point for sure. Temperatures were 25-28F indicated.

 

Ugh! I'm really getting frustrated. It is going in tomorrow again. That will be 5 days in the shop for the stalling, 3 days for the ECU reflash a few months ago, and 1 day for another warranty item in the summer. That makes 9 days in the shop for 7 months of new car ownership!

 

I would like to go in armed with a list of things they should be looking at tomorrow. Suggestions? I've heard about the OCV and AVCS systems. Compression? Anything else? I wonder if the variable valve system is not quick enough reacting to idle, leading to roughness and intermittent stalling. I am completely stock.

 

Thanks.

 

--Lee

I'd start a Lemon law case. Force a buy-back. This is a $35K car in the year 2006. There shouldn't be an issue with a stalling car.

 

How many times did they attempt to fix the stalling?

 

I'm assuming absolutely NO mods....right?

After several talks with dealer that didnt fix my problem - lack of throttle response or very non-linear response and stalling, I gave them a big serve at 25k service yesterday. Finally got some action - they said they inspected with a boroscope, saw lots of carbon buildup inside, soaked the chambers in carbon remover, and now its behaving like it should - pulls any gear from low down, smooth response etc. Well see how long it lasts. The rep did mention that it might be worth moving up to premium fuel (98Ron), as people report improvements with it, and extra cost is offset by improved economy...

jp

Absolutely no mods. It has lived exclusively on 93 octane (premimum).

 

Well, still in the shop today, getting my total up to 10 days. The frustrating problem is the dealer has equipment to data log only up to 4 parameters at a time while driving. They've got a tech doing repeated runs to log more parameters, and they've done the same with a supposedly good LGT for comparison. They clearly do not have sufficient equipment to diagnose our cars.

 

The service rep tells me that SOA has told them they will all be getting laptops that can log many more parameters simultaneously, but they do not yet have such equipment. This seems ridiculuous. If I bought a $80 Tactrix cable I could log with the Tari software. I might just do this.

 

This might end up heading to lemon law. I don't think I am there yet depending on how one counts some of my visits. 15 days in the shop in the first year is a pretty clear threshold according to my reading of MA Lemon Law. I really hope it doesn't come to this. I feel like the dealer is genuinely trying, and they are noticing abnormalities. They've been on the phone repeatedly with SOA and Subaru of New England. They've also had me in new loaners for all the warranty work.

 

I'll have to tool around in the B9 Tribeca (92 miles) over the weekend. I really don't like it. I want my GT back.

 

Is anyone else experiencing occasional stalling when it is cold while coasting to a stop with the engine idling?

 

--Lee

Update: business day 10 in the shop for the stalling, they think they've tracked it down. It turns out the dealer did have equipment to log all relevant engine parameters; they just didn't know it. (Their equipment could only display 4 parameters at a time, but it could log all/most of them.) A Subaru of New England technician came and they were able to capture various stalls with logging on a few days ago and then have SOA analyze the logs. They found that right before a stall, they could see the ECU adding fuel, but there was a hesitation in the throttle plate, sometimes long enough to cause the stall. Apparently the throttle plate was sticking. They swapped throttle plates with a new car on the lot, and it appeared to work fine. The car they swapped with was not working fine with my throttle plate in it.

 

So, I pick it up at the end of the day, and keeping my fingers crossed my car might finally be fixed. The dealer has treated me fine with new loaners etc., but it is still a bummer to have my car in the shop for 14 business days total in my first 7.5 months of ownership. Perhaps SOA will do something to keep me happy. Not only was it out of commission a lot, it was never really running properly either between the defective throttle plate and the inoperative O2 sensor.

 

Anybody have SOA give them anything like extended warranty, Subaru $s for the shop and/or accessories in situations like this?

 

...Picked it up and drove around locally for almost an hour. I am cautiously optimistic. It would appear the throttle plate fixed the stall and the new O2 sensor/unbent ECU pin fixed my stutter. I won't pass final judgement for several days as it is fairly warm here these days. I hope my ECU doesn't relearn bad habits, which is always possible, but previously I was stuttering right after the ECU reflash.

 

--Lee

 

PS: Care to guess how long it will take to get a new throttle plate? 2-3 weeks (!), with it coming from somewhere like Peru (so said the service manager). Hopefully I'll just keep the one I now have and not have to have another swap.

Sorry to bring this back up again, but I wanted to include a final update.

 

I drove it for about two weeks and 800+ miles on the borrowed throttle body. A few days after getting it, I experienced some significant wailing sound that was related to boost. However, after about 20 minutes of driving, that went away. I called the service manager, and he said when they swapped throttle bodies, they didn't have any new gaskets and had to reuse the old. They told me when the new throttle body came in, I'd get all new gaskets.

 

Two weeks later, they installed the new throttle body and gaskets today. I gave it a vigorous workout, and my engine is simply amazing: no stutter, no stall, just smooth power delivery, even from 2300rpm. Beautiful. Too bad this car wasn't like this for the past 7.5 months since I bought it.

 

Altogether, my car has been at the dealer 15 business days (and one weekend) in my first 7.5 months of ownership. 1 was for TMIC replacement right after purchase because many fins were damaged before I bought it. 3 were for the ECU reflash in NJ. And 11 were spread out over a few weeks for stalling, several days of which were due to waiting for parts to come in. I really do not understand SOA's part stocking policy. They didn't even have a single O2 sensor in the area for a current model.

 

While I am dismayed it has been out of service this long, I give credit to the dealer, Village Subaru in Acton, MA, for taking good care of me. I was always in a loaner, usually a car newer than my own. That included basic Outbacks, a 3.0R LL Bean Outback, and a Tribeca with 92 miles on it, all 2005-2006. I felt like with some pushing on my part I was able to get good information from the service manager, and when I requested to speak to the tech working on my car at one point, they didn't hesitate to get me in touch with him. The dealer put a lot of time into working on my problem, including approximately 300 miles on the road reproducing the problem and data logging. A Subaru of New England tech made a visit to the dealer at one point to help with data logging. When I picked up the car today, it had been washed, cleaned inside, and an oil change was done at no charge.

 

I have heard rumors that SOA will likely offer to pick up a month of car payment for me.

 

As long as it keeps running like it is now, I will be very happy. This car is intoxicating to drive now, even stock. I hadn't realized what I was missing with a defective throttle body and inoperative O2 sensor connection. It is much smoother than it was for the past 7.5 months. My CEL was never lit nor did it ever throw any codes during this whole process.

 

--Lee

So you have absolutely no stutter at all now....?

As far as I can tell, yes, mine is gone. I was very sensitive to it, and I have been probing for the past two weeks, but I am unable to reproduce what was reproducible previously.

As far as I can tell, yes, mine is gone. I was very sensitive to it, and I have been probing for the past two weeks, but I am unable to reproduce what was reproducible previously.

Please report back in 100, 500, 1000 miles, etc. Changing any intake or exhaust part is known to change stuttering, only to have it discovered again a little differently.

ILH-Glad everything is ok.

EEK!!!! I hope this is not what may car is beginning to do. :eek:

I am pretty sensitive to the stutter as well.

 

It is interesting that your fix seemed to include a new throttle butterfly..

 

I've been trying to figure out what the hell could cause the stuttering.

 

In stop and go traffic the car is a pain. The throttle is so sensitive at the beginning of the travel, so I was thinking the throttle by wire tuning was horrible or the throttle butterfly was sticking or the butterfly stepper motor doesn't have enough steps to be smooth.

 

I hate driving the car in traffic. Thank god I have a 5 minute commute to work. Last night I had to drive in traffic and the combination of the hessitation, terrible throttle tune and shit clutch is a real problem. I have no clue how Subaru let this car into production like this..

 

I need to send a letter to Subaru ASAP. Dammit, it is going out this weekend.

I'm not sure which of the throttle body or the O2 sensor ECU pin, or both, were responsible for fixing my stutter in the 2300-3000rpm range, but I think it is gone. I've now got 1000 miles on it after removal of my throttle body, 600 or so on the borrowed throttle body and 400 on the new one, and so far so good.

 

The sticky throttle plate was definitely the cause of the stalling and poor throttle response, especially in stop-and-go traffic. I too had that same feeling starting from a stop: little throttle...nothing...little more...bam too much power. It was really annoying and made me look and feel like an idiot who couldn't drive a manual smoothly, and I've been driving manual for 24 years.

 

If I didn't have the car stalling in cold weather while coming to a stop, I doubt I would have gotten the attention that I did, at least from SOA. Presumably, they couldn't deny stalling as a major problem, arguably a safety problem (since stalling would occur while still moving). Difficult to drive in stop and go with 5MT they could blame on poor technique, etc. Nearing MA lemon law thresholds probably didn't hurt to focus SOA's attention either.

 

The fact is, my car is MUCH better with the new throttle body. The old one definitely stuck closed, often enough to affect drivability. Too bad it wasn't this way from day 1.

 

Good luck.

I wonder if mine is sticking too..

 

For example..

 

If I give ever so slight throttle, then release, the car continues at the same power level for about a second, then goes back to idle. If you mess with the throttle a little I can get the car to buck roughly..

 

My stutter is so bad now I should have no problem demonstrating the issue.

 

I just wish my center console would stock squeaking.. ha

 

Oh, and I hate my clutch. I have to say that again. The damn thing slips and dumps at random times.. not consistent AT ALL.

 

My castor is off by one degree from left to right, so I fight the car's right drift - dealer says its the tires! ha it's It's been like this since day one. It's funny, the alignment sheet shows the castor off by one degree and it says "green" within spec. The service manual says they should both be equal, no +/-.

 

Anyway.

 

Did your new throttle come off an 06? Can't remember if I read that or not.

 

Ok, enought bitching for a while.. I just gotta write the Lemon Law letter and move forward.

That sounds familiar with the non-linear throttle response.

 

I have no idea if my loaner throttle body was off an 05 or 06. My final throttle body is new and took 2-3 weeks to make it to the dealer. During that time I drove with the loaner throttle body.

 

Thankfully my car tracks straight with no pull whatsoever.

My car continues to remain stutter and stall free. Yea!

 

Because my car has been in the shop so much in its first 7.5 months of life, SOA has offered to provide me with a 7-year / 100,000-mile / $0 deductible extended warranty. I am happy with this offer. It will make me less nervous given my car's history and how expensive repairs like this can be. I intend to keep this car 100,000+ miles.

I'm not familiar with the Studdering problem. I always thought it was just the little jolt/hesitation under acceleration. Is it?

 

A few times last week I was just cruising on the highway, car was half way to normal running temp and it's like it missed a cylinder or something and was fine after that.

 

Is this the studdering? It's a pretty serious jolt, it's more than just letting off the gas. I've already had my ECU replaced for the Fan issue.

 

No Cel, so I'm not going to bother taking it in until there's a CEL or it's not running, or doing it often.

My stuttering felt like the throttle was fluttering about 5-6 times over a span of a second or two, generally with the onset of boost in the 2500rpm range. It felt like accelerate/coast/accelerate/etc at a high rate. At worst, it would sometimes buck the car, but usually it wasn't very severe (but still annoying). Mine generally happened in 2nd or 3rd gear while starting acceleration after coasting in gear. It might have happened a few times cruising on the highway in 5th, but with the higher gears the acceleration jolts were not as noticable.

My stuttering felt like the throttle was fluttering about 5-6 times over a span of a second or two, generally with the onset of boost in the 2500rpm range. It felt like accelerate/coast/accelerate/etc at a high rate. At worst, it would sometimes buck the car, but usually it wasn't very severe (but still annoying). Mine generally happened in 2nd or 3rd gear while starting acceleration after coasting in gear. It might have happened a few times cruising on the highway in 5th, but with the higher gears the acceleration jolts were not as noticable.

 

This is exactly what I am experiencing, but with an 06.