Engine hesitation/flat spot (Liberty 2.0R)

Posts specific to the 2.0 litre NA engine

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby calais » Fri Apr 18, 2014 7:37 pm

I feel quite confident to now report that my Subaru hesitation issues are gone.

It has been 9000km since the hesitation has reared it's ugly head.

The car is performing beautifully and as it should.

I used the Lucas Upper Cylinder Lubricant in every tank of BP98 and it has made a world of difference. The cylinder tops are clean whereas before they were coated in carbon.

I urge people who are having this issue to use a fuel additive upper cylinder lubricant and let the cleaner do its job over time. I don't believe the Subaru upper cylinder cleaner is as effective over such a long time. Its a one time hit, whereas this fuel additive is cleaning more gradually during every combustion cycle.

Please, give this a try before giving up.
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby Kormoran » Sat Apr 19, 2014 12:15 pm

Thanks Calais! Glad to hear someone had some luck, are you 100% it was the upper cylinder lube doing the work or have you tried other things during these trouble free 9000km?!

Off to buy some either way!
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby calais » Mon Apr 21, 2014 10:27 am

I used nothing other than bp98 and the lucas upper cylinder treatment.

It was a gradual cleaning process. In the first three tanks I reset fault codes once per tank as a preventative and it has never come back.

I used an inspection camera to check before and after what the cylinder faces looked like.... It is night and day.

It helped solve my issues :)
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby Deep Heat » Mon Apr 21, 2014 5:10 pm

calais wrote:I used an inspection camera to check before and after what the cylinder faces looked like.... It is night and day.


What do you mean, Lucas fuel additive made it cleaner? My experience is that most fuel additives coat the cylinders in a white layer.
Jack_Keaka wrote: I like my women like subarus, box explodes and does a head easily.
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby klam » Tue Apr 22, 2014 10:54 am

I've used the same cleaner for last 3 tanks. done over 1500kms and runs ok, with A/C on occasionally. It hesitated once or twice in really steep and long climbs, fully loaded, with the car pod on the roof but it corrected after 3-5 minutes. will report in another 3 weeks.
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby klam » Fri May 02, 2014 9:44 am

ECU playing up again. was the longest flat-spot free run though :)
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby gen4cruiser » Fri May 02, 2014 11:41 am

I've used the Lucas treatment in two tanks so far without issue. I wonder though, would a piggyback tune be able to override the issue?
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby LEG45Y » Tue Jul 01, 2014 11:19 am

Had same flat spot issues with my 2.0R recently, ran Subaru Genuine upper engine cleaner through then blew Air sensor, disconnected negative terminals for 10 mins to reset.
Reconnected and drove any further gunk out of cars system.
Lastly as a little extra add half a Bottle of octane booster with half a tank of 100 octane to make sure all clean. Hasn't skipped a beat since.
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby Snappy » Tue Jul 01, 2014 7:27 pm

Hey Guys,

I've been reading this post for some time now (over the last 6 months) as I developed the same problem of flat spotting from 2200 to 3300rpm - outside of this rev band the car was fine, but like yourselves a horrible car to drive in and around the city. Found that resetting the ECU (by unplugging the battery for a period of time and reconnecting) the flat spot would be resolved for an arbitrary amount of time - could be 2 days or 5 weeks, before returning.
My mate is a motor mechanic and he hooked up his diagnostic tool, but failed to report any error codes - so he suggested changing out the O2 sensors; clean the MAF sensor - did that and the flat spotting went away for some weeks....before returning.
All the things that you guys had suggested I had tried: changing out the O2 sensors, cleaning MAF, replace fuel filter, replace spark plugs, including changing fuel suppliers (I have always used premium 98 since new) and anything else I could think of that was fuel delivery system / engine sensor related to no avail. Instead of continuing to replace items that may not be guilty of any wrong doing, I ended up booking into Subaru to see if they could diagnose the fault - I was very hesitant to do this as the charge was $155 per hour and every hour afterwards! But, this was my last attempt to try to resolve the issue before I sold the car out of pure frustration!

I took the car into McGrath Subaru at Liverpool and the guys there were excellent! They did some conservative checks/replacement of items first (eg. fuel filter) test drove the vehicle, found out that this did not resolve the issue, so next step was they hooked up their laptop to collect some realtime data. The guys collected about 10mins of drive data before sending it off to Subaru Australia where they analysed the data and reported back (which you guys have mentioned) that the ignition timing was being retarded between the 2200 to 3300 rpm range. Subaru Australia immediately knew what the issue was and advised that the 2.0R engine has two OCV (Oil Control Valves) that control the ignition timing for the variable valve timing and that these were most likely faulty and not allowing the timing to advance. They replaced two OCV (as both had failed) and I drove the car home and it was fine! Hooray! I couldn't tell you happy I was to drive a car without that hesitation!!!!

A couple of days later I drove the car on a long distance trip and the car was fine and drove the car back...then the issue came back again! My joy had now returned to frustration as I'd thought the issue may have been resolved once and for all! I gave McGraths a call and they said 'no probs, bring it in and we'll check it out' - took the car in and the guys hooked up their laptop again to collect drive data; sent away to Subaru Australia and was advised that one of the OCV had failed! Subaru replaced the failed new part under warranty and I've not had an issue with hesitation since (touch wood) having this done which was a couple of months ago. I refrained from posting a reply as I wanted to make sure that the second OCV replacement actually did resolve the issue.

I can't tell you how good it is to drive this car now! My recommendation is to take your car into Subaru (McGraths Liverpool I would highly recommend) for these trickier types of issues as they have the advanced tools and resources to investigate the issue...I had only wished I'd done this earlier!!

Hope this post helps!
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby klam » Mon Jul 21, 2014 1:28 pm

interesting that Subaru Australia "knew immediately" what the problem was but when I've contacted them, or Denlo Subaru did, then I did not get such an advice ?!

FYI : in the meantime, I've replaced the ECU with the benched-flashed one by the guy in Russia (you'd have to ask him what were the mods, but from what I know he basically deleted (on circuit) the EGR valve and secondary air valves and corrected the map against the knock). So far no issues, runs perfectly fine, he noticed though that one of my OCV's is acting up and recommended to change it. I've since done a oil change and can't see any issues in the logs anymore, the VVT advance angle difference between the left / right are within +/- 4 degrees and the OCV duty is difference is max 7% (rarely), normally 1%. This whole process of getting the second hand ecu, sending, receiving, installing and reflashing with the new maps definitely killed some nerve cells.
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby Kormoran » Mon Jul 21, 2014 6:08 pm

Threw my first code today, p0030 - bank 1 sensor 1 HO2S sensor. Figure Ill get a af sensor and some ocvs as well. Hope everyone else is having some luck!
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby klam » Tue Jul 22, 2014 11:16 am

Kormoran wrote:Threw my first code today, p0030 - bank 1 sensor 1 HO2S sensor. Figure Ill get a af sensor and some ocvs as well. Hope everyone else is having some luck!


I'm having luck since new ECU ;) shall I recommend, buy the parts @ partsouq.com, though I think I've bought the AF sensor from http://www.sparkplugs.co.uk/ ... admin, if this is against the rules please modify the post but let me know. cheers
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby Kormoran » Mon Sep 15, 2014 8:07 pm

Unfortunately afr sensor didnt fix my issues (fuel economy has improved though).

Over the weekend I cleaned and swapped over my ocv's to see if it makes a difference after snappys recommendation, will update in a month.

Out of curiosity does anyone else have an odd noise from one side of the engine between 1 - 2.5k rpm? Mainly when its hot but it can be intermittent. Sounds sort of like a clap clap clap and increases/decreases with rpm.

Cheers!
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby Bradice_2046 » Fri Sep 19, 2014 9:47 pm

Hey mate i work for subaru and have had the exact same problem with my 2.0R engine in my liberty.
I reset the ecu and the problem went away and came back after driving for a while. Exactly what is happening with your car. I updated the ecu and the problem is solved. Subaru them selves made an ecu update for this type of engine for this particular problem and its been 4 months since ive done the update. Car drives perfect now. So my advice is take it to a subaru dealer and get the update done it will fix all your problems :)
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby gilesy » Tue Oct 07, 2014 10:25 am

Sounds like the same problem I've been having with my 2.0R Impreza, it started off as an on and off thing. Sometimes it wouldn't happen for weeks, then wouldn't stop for a few days, but recently it's started happening more and more.
I took it to get the computer scanned at Subaru because I'd eliminated just about all mechanical issues and was left with electrical fault, turns out the airflow sensor is failing so the car thinks there isn't enough air being mixed with the fuel so it limits the fuel flow to avoid flooding the engine, causing that hesitation and power loss.
Apparently through them its a $716 fix, so I'm looking at my options but probably getting it sorted out on Thursday.
Will post on how successful or otherwise this is.
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