Engine hesitation/flat spot (Liberty 2.0R)

[Kormoran]

Bit of an update;
Received the sensor from G88 but it wasn't the correct one
I recently noticed too that occasionally and only when the car was cold it would take a few extra seconds to turn over so I started googling again...

With all the other symptoms I came up with a possibility, a dodgy MAF but I really have NO idea anymore
It could still be O2 sensor or even a faulty knock sensor. When it returns I'll probably resort to getting it professionally diagnosed.

[dmh87]

Bit of an update;
Received the sensor from G88 but it wasn't the correct one
I recently noticed too that occasionally and only when the car was cold it would take a few extra seconds to turn over so I started googling again...

With all the other symptoms I came up with a possibility, a dodgy MAF but I really have NO idea anymore
It could still be O2 sensor or even a faulty knock sensor. When it returns I'll probably resort to getting it professionally diagnosed.

If your o2 sensor hasn't been replaced before I'd still think that would be one of, or the problem. I'm sure G88 can sort you out with the correct one.
Also no harm in giving your MAF a clean too, might get better fuel economy

[Deep Heat]

After having a little play with logging. I think its a fuel related problem. With one tank of BP ultimate I was seen FLKC regularly jumping to -3.75 and was getting the weird hesitation. After filling up with BP ultimate again, ECU reset I was getting FLKC getting to a low of -1.5 and the hesitations were gone.

[davejones2]

Hi all.

I'm from the UK and had exactly the same issue. I've posted on the UK Legacy forum about the same issue.

I've been following this thread with interest as despite having now moved on would be keen to know if anyone ever finds a solution!

Mine was babied its entire life, serviced every 10k etc, no expense spared, UK fuel (all 95 RON+). An absolute beauty of a car apart from this intermittent problem.

I tried:

- ECU update via main dealer (from Dec 2011)
- New knock sensor
- Different fuels, 95-99RON
- Cleaning MAF

Got to the point where I was resetting the ECU (an immediate but only temporary fix) every 1-2 tanks of fuel. Caught massively retarding the timing by dealer, but no error codes.

Dealer didn't have a clue what to do next. Seemed to think the ECU update should have solved it, which it seems to do in the majority of cases if you look on most forums. Gave the car to a family member to see if they could find a fix, no luck so far.

I was wondering if it could actually be something physical tricking the knock sensor into retarding the timing. Mine had a audible vibration coming from somewhere at around 3,000rpm. Never found out what it was (sounded like a heat shield / exhaust origin if I had to guess). Did wonder if it was near enough to the knock sensor to simulate engine knock vibrations. Sounds unlikely though I guess, but worth a thought.

Replacing random sensors seemed to be the next route, one that sounded like a bit of a money pit and as such I wasn't prepared to go down.

If anyone does find a solution it seems it will benefit a large number of people!

[klam]

Guys, not sure how about you but in my case it seems to be 'cruise' related (plus I suspect the fuel as well). Nearly each time when I drive with cruise control for couple of kms (10-15), the next day the cruise control light flashes, but ECL remains off, and no error code are logged in the ECU.

Does someone of you have an idea how (if) this could be related? Or, how I could possibly resolve this problem... I think of selling the car and getting the 2.5i instead, still sticking to Liberties of 2004-2008...

ECU reset helped.. I haven't had this flatspot for about 5 months an now they popped up couple of time in a month, with lots of cruise control driving, but I was running on 95 fuel lately.

cheers...

[alexeib7]

Dear Readers,

I've had engine hesitation with MY06 Liberty above 2,000 rpms. It could be that the air flow meter is dirty.I've fixed this problem: unscrew the air flow meter from the intake pipe- located between the air filter box and throttle body and using compressed air or you could blow the meter with your mouth on the openings/ sensors, then reconnect the wiring and screws, then disconnect the negative battery cable for 10 minutes to reset the ECU, then reconnect the negative battery cable, this procedure worked for me.

Hope it has helped someone.
Keep smiling and drive safe,
Alex.
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[Kormoran]

Hey guys,

Have finally bitten the bullet and taken the car to a mechanic to see if it can be sorted! 4 months nearly of no issues whatsoever and now its every week, if not everyday!

I will update as soon as I find something out.

So far I have tried;
- Cleaning the MAF
- PAK update from subaru
- injector cleaner
- new air filter
- cleaning the TB
- upper cylinder cleaner (a few times)
- fuel filter
- ALWAYS run on 98


Has anyone else had luck fixing it yet?

Cheers!

[Deep Heat]

Dieing knock sensor?

After a shit load of logging I think that's what's wrong with mine. I will be fine then randomly it will detect a huge knock, IAM drops to 0 from 1 and it starts to drive like a dog.

[Kormoran]

Dieing knock sensor?

After a shit load of logging I think that's what's wrong with mine. I will be fine then randomly it will detect a huge knock, IAM drops to 0 from 1 and it starts to drive like a dog.

This is something I have wondered too and I will mention it next time I talk to the mech! Its so f**** frustrating!!

[dmh87]

When was the last time you got it serviced? Possibly spark plugs? Strange that after 4 months of no issues that it came up again. Did you recently change something over that could have made these issues come up again?

Once again, I believe it could be the knock sensor or o2 sensor.
I feel your pain, but so far since the update from Subaru and replacement of my o2 sensor, I have had no issues.

[Kormoran]

Small update: without resetting the ecu and a fresh tank of fuel the flat spot has all but disappeared. The fook man?

[TimN]

Ive had the same a few times. Its intermittent and annoying but goes away rapidly. Ive noticed that the issue often changes (good to bad or bad to good) significantly when i refuel...I always run 98, from various brands but usually shell. I will start to log when the problem happens and what fuel i'm running at the time. Mostly it occurs 2200-3200 revs, but occasionally affects power off idle to 3200, I wouldnt say its significant, maybe a 20% loss in power and laggier response. The mechanics have seen it 3x and have never found any mechanical issues, and say its in great mechanical condition. The mystery continues

[davejones2]

To posters above.

Just to reiterate, just in case anyone was reading the recommendations above, I replaced the knock sensor on my car to no avail.

In fact, the garage that replaced it thought that the knock sensor in-situ looked newer than the rest of the car and may have been replaced before..... probably for the same problem!

I too was told that the rest of the car was perfect. In fact, the Subaru main dealer said it was the best example at that age he'd ever seen and driven (when working properly!)

I strongly suspect that an enormous number of these cars are being sold second hand because of this apparently unfixable problem!

As stated earlier, I also cleaned the MAF.

[Telf]

Hi all I'm new on here but I'm so glad I am. I had the same problem I disconnected the battery, did the peddle thing, left the battery of for half an hr. it had a bit of trouble starting straight up but once it did I have a brand new car. 1 that is once again a joy to drive. So thanks again for the help. Cheers Telf

[klam]

fellas ... I have just replaced the sensor and will let you know whether that helped to resolve the problem. fingers crossed.

I've source the sensor much cheaper than here, plus the work I've done myself.