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 HardwareBoB » Mon Dec 22, 2014 9:48 pm

Buy a GT they have no problems*







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

Postby Cambie54 » Sat Jan 10, 2015 11:09 am

Hi there,
Im in my first year of owning my liberty, and am currently studying so money is very tight.
Was hoping that someone had actually come to a conclusion about the issue?
Was thinking of just sending it subaru's way and having them deal with it.
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby rolltosave » Thu Jan 29, 2015 12:00 pm

I had this same issue on my 06 Impreza 2.0R. I had it at my mechanics on and off for months and tried everything. Replaced maf, AFR sensor, full fuel system flush, upper engine cleaner multiple times, logged all sensor voltages eg crank angle, can angle etc. It would sometimes work okay for a while but that all seemed to be due the ecu being reset.
I eventually bit the bullet and decided to take it to a Subaru dealership and I explained all of what I had done. They applied a patch to the ecu for around $150. It has been running flawlessly ever since. The only thing was it did slightly change the character of the engine. It doesnt seem to be as rev happy. But much much smoother.
I recently sold the car to my brother in law and he hasn't had any issues either.
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby Ezzymay » Sun Apr 05, 2015 7:54 pm

Hi all.
I have been experiencing the issues with since 4 weeks after I purchased my late 2005 manual liberty back in June 2012.
The first thing that that happened was disabled cruise control accompanied by flashing cruise light. This would be intermittent and I could bypass it most times by disconnecting the battery terminal for 10 mins. A number of scans showed it was a fuel to air ratio sensor fault.... But it developed the stumbling and hesitating issue as well, however this was intermittently separate to the cruise fault.... First thing I did was replace the fuel filter as it is not a recommended serviceable item on my car and had never been done according to the servicing history. The filter looked like it had had a hard life.
But faults returned with in a week.
I have basically put up with the issues until 3 months ago when I bit the bullet and replaced the sensor when I had the car in for its D service. It cleared the fault and the cruise has been perfect ever since, but the stumbling, hesitating and flat spot all returned within 3 weeks. I was frustrated but not surprised. I have spoken to Subaru and a number of in dependant subaru specialist mechanics and the all deny knowing anything about this problem. To make matters worse the car wouldn't throw any fault codes when running like a dog. Codes would only show if the cruise light was flashing.
All in all I have been told it is a great car and very tidy well maintained.

I would like to know what has been the outcome for everyone else's vehicles and would it now be worth contacting Subaru again to get my ecu updated? It has been 18 months since I bothered speaking to subaru.
What other recommendations can you al give that won't cost an arm and a leg and that I can do myself. I like to be hands and see first hand that a job gets done.
I'm frustrated with being palmed off by mechanics and if I have to keep hearing "it's your O2 sensor" I'm going to lose it. Being a woman does not make it any easier I'm sure.
Thanks for reading my novel, I hope to hear back from you guys.
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby klam » Fri May 22, 2015 8:24 am

NS_SHERLOCK wrote:Hey all.

I want an actual fix, something that will be permanent.

I was thinking an aftermarket ECU.

Any thoughts?


my car is hassle free since. except the dash rattle! :lol:
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby west_minist » Fri Jun 12, 2015 11:32 am

Any car over 5yrs or so should really have checks for leaks on the intake system and exhaust system. A smoke test or pressurised test will show issues.

Once the spark plugs are new and under 1 yr old, its good to apply the first statement above.

Get a mechanic who is willing to take the time to perform such test.

I would do all of above before changing ht e AFR's. But 2005, I would prepare to change them and check for leaks.

I can tell you, as a tuner working with 2005 model cars, I always have to ask for above and always find the issues noted.
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby Yourfather » Sat Sep 05, 2015 9:23 am

Hi everyone, I'm from Singapore and do own the 2007 Subaru Legacy 2.0r which your country calls it Liberty.

I'm registering to inform u all that it has been solved in my car with regards to this issue.

The problem continues after so many parts that was thrown at it and it didn't worked, it turns out to be the knock sensor that is the problem- over sensitive to be exact.

There are 2 solutions to it:

1) buy a new knock sensor as a replacement. Replacing it will be tricky as there is a certain way the knock sensor must be aligned or it will cause premature wear.

2) this is the route I took. Unscrew the knock sensor and zip tie it somewhere in the engine and be sure it's not going to knock anything. Problem solved as long as you don't pump any fuel below ron95.

I know the 2) solution might sound crazy but in Singapore I pump ron98 anyways and it the engine were to knock, it most likely wouldn't be due to fuel. Knocking would affect turbo charged cars more than a NA car anyway.

So there it is, my solution and hopefully yours.
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby Kormoran » Sun Sep 13, 2015 10:59 pm

Update, its been a while now and since changing spark plugs and rotating coil packs and replacing the resonator behind the throttle body (it had a hairline crack) I have been issue free :)

Will update again in the future!!!

PS; also started using lucas upper cylinder lubricant in each tank, 2 tanks with it so far. 4 tanks without an issue, since changing spark plugs etc.

Edit: flat spot still present so I bought a bike instead. Giving up unless someone has a breakthrough!
Last edited by Kormoran on Thu Oct 15, 2015 3:55 pm, edited 1 time in total.
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby Telf » Thu Oct 15, 2015 10:38 am

Well after 1 and a half years off off having a troublesome car, i finally took it in to get a diagnostic at subaru Tweed. I'de done my research and came up with a self prognosis that my OCV (Oil Control Valves) were sticking. They also came up with the same diagnosis at $800 to renew the OCV'S and replace the oil. Since then i sorced 2 second hand ones and fitted them, but i think they were faulty so the problem arose again. So i refitted my old ones back in Its about a 20 min job each side, a little fiddly but quite easy.
In the end i thought fcuk it. I took it in yesterday they fitted the parts and i drove home. Finger crossed that is the end of it and i have my old car back to new. Ill keep you posted
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby Limphlibby » Sun Nov 29, 2015 12:57 pm

Hi Guys,

Sorry to bump this on another topic but I have been following this forum for yonks! Copied a lot of work done on your guys cars with no luck Koroman I feel your pain, do you have any updates?

I really need some help slowly going crazy. I have always had new subarus. My most recent is a 2.0r 2006 Liberty.
I have had the cruise control flashing and Ecu come on and off for 4 months now.

In that time I have had new 02 sensors, Cadillac converter, secondary airpump, primary airpump, new realay, upper engine cleaner, Exuast Carbon cleaned, new throttle body, sparkplugs, new battery.
And a few other small things cleaned.

A total of $6200 the reason been is the car has flat spots between 2000r & 3000r every time I reset the ECU the car drives amazing then after 1-2 days goes back to a flat spot jolting heavy feeling crap! The light comes on every morning on a cold start outside temp around 15-20 degrees.
I am slowly going crazy as I have no idea what could possibly be wrong. It has been into Subaru Frankston 6 times now and even they are stumped. I just can't afford to continue, It seems to be a wide spread problem on these cars. Please, please ANY help or advise would be greatly appreciated!
Ps always used 98 v power fuel, petrol caps good
Thoughts on a pak update!!? I have no idea cheers in advance guys
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby lz2nkm » Sat Dec 19, 2015 9:42 am

Hi all. Im following that 2.0R issues from a week as I experience something similar on my car.

The most serious theory we have about that issue is the Russian one - AVCS is advanced by stock tune too much, causing rattling noise from the camshaft to be interpreted like knock by the knock sensor and ignition is retarded making the hesitation (me personally don't hear any rattle noise from my engine when it hesitates). This happens on most of EJ204 engines around 100 kkm. We know also that this is fixable by tuned ECU (klam confirms it above) with modified AVCS timing.

However a few of the last posts here suggest to change the Oil Control Valves of the AVCS cams, and one coming directly from Subaru. I had an impression that Subaru knows that this issue is related to those valves. Can somebody who changed the OCVs confirm does this solves the issue? From what I see in that topic: http://www.romraider.com/forum/viewtopi ... 066#p96066 the original Subaru tune is 50 in the zone where the engine hesitates. Sasha from the other forums cure it by slight modify of AVCS advance table. Nice, but what if it can be cured only by change of the oil valves? ECU tune is not impossible but not easy, will not be cheap, and there are some risks also.

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

Postby Telf » Wed Jan 20, 2016 12:24 pm

Hi all well after about 1500ks its still going well. The cruise light has flashed twice and reset itself after turning the car of and back on again. It has had no hesitation as yet. Not sure changing the OCV will work for you but it has for me. To me the car worked fine when it came out of the factory and over time things degrade or break, so if some thing is on its way out, how could renewing ECU's work? Good look to you all. Hope you find the answers.
Cheers
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby Jordan.k » Wed Jan 20, 2016 2:23 pm

Filled up with shell vpower , experienced flat spots, switched back to bp98 and the flat spots dissapeared!
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby Kormoran » Wed Jan 20, 2016 2:24 pm

Telf wrote:Hi all well after about 1500ks its still going well. The cruise light has flashed twice and reset itself after turning the car of and back on again. It has had no hesitation as yet. Not sure changing the OCV will work for you but it has for me. To me the car worked fine when it came out of the factory and over time things degrade or break, so if some thing is on its way out, how could renewing ECU's work? Good look to you all. Hope you find the answers.
Cheers


Great to hear Telf, keep us updated! I reckon if you can go 3 - 4k km without trouble then your worries are over. Longest Ive gone issue free was 2500km with just a reset. My update; Now that its Summer the problem is noticeably worse/more frequent. Has anyone else noticed this?
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Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby lz2nkm » Wed Jan 20, 2016 7:25 pm

I'm in contact with the Russian guy Sasha (the one who managed to flash the ECU first). There are some very big thread in Russian forums about the issue and his hypotheses is that the false knock is coming somewhere around the cams - he thinks the noise is from the cams when the AVCS angle is high (above 40 or so) - when I check my logs it goes to 50 degrees on wide open throttle between 2-3k rpm. I asked him what about if we change the OCVs and even the AVCS sprockets but he thinks this is not sure to fix the issue as the noise is coming (according to him) from cams or somewhere there - you know that with this angle the intake/exhaust valses are overlapped and definitely the sound changes. The common agreement among Russian people is that only ECU re-map can solve it once and for all. All the rest is just temporary (soldering capacitor to silence the knock sensor, official ECU update, etc). Maybe only the knock sensor removal (as somebody mentioned here) can also cure it but that is more or less dangerous as it can foul the ECU to pull timing advance which can cause real detonations and this is much worse compared with hesitations. Anyway the Russians just fixing it by ECU flash - Sasha made over 1000 cars in the region and his know-how is spread among other mappers, so there are a lot of people in Russia, Ukraine, Poland, etc. with such re-maps. However nobody there done any extensive verifications to confirm what is the root cause, as it's a lot cheaper just to map the ECU. :) In my opinion on the high levels in FHI they know pretty well what is the problem, but that information is not available outside. Even the dealers does not know it except the service bulletins which in that case says to put 5W30 oil, clean the throttle and update ECU. If somebody have a way to find info from high levels of FHI, then we can eventually know the root cause, but I doubt that info is somehow secret. :)

What was the status with my car? Immediately after I bought it I got the issue (it has 115 kkm on the clock). Then I read here the info and start digging, then bought cable to do myself diagnostic and confirmed I have drop in the ignition timing. Then it fixed itself, and after 200 km made it again but not so bad, then disappeared and appeared again. The last time it was pretty bad with -10.5 knock correction. Anyway, I asked Sasha to tell me if I have all updates and he wanted to send him the ROM (it's possible to download it with USB Vagcom cable) and he told me I have one of the updates but not the last one. He thinks that if the first didn't solved it, then the second cannot help much but it's ok to try, so I installed the last update in Subaru dealer. The car runs fine now for about 1000 km without hesitations. Also after the update I had to reset the ECU as the learning tables for knock corrections are stored in the RAM, not the ROM which they updated. For now I will drive it to see when the hesitations come back (hopefully not soon). Sasha gave me good price for ECU remap (he can even send me ready to plug ecu) and when it start giving issues again I will probably move on with that. What he is basically do is to decrease the AVCS angles from up to 50 degrees BTDC to max 35 degrees (as you can see on the table on my previous post), then he turns off the EGR and secondary air system (if there is one, from MY2008 there is no such) as that is also giving issues. And I think he also do some re-map of fuel maps (probably to make it runs fine without EGR). I read also some feedback for his patch and generally it's good - most of the people report better and smoother torque in low revs, although some slight increase in consumption. Also they continue to confirm all is ok 3 years later. He provide modified vagcom cable which can be used for later upload of updated maps, so some complains can be fixed if it's not ok.

So for me after the tons of info I read, I think the only option we have for final solution is unofficial ECU re-map, since FHI do not care after the warranty finished. That is why they made ECU updates - just to keep the car without complains in the warranty period. Also I can speculate, the other reason is that this problem is not dangerous for the engine (since it retard timing, not advance it) and cannot lead to a lot of broken engines etc., which is worse for their reputation. Everything else is pretty expensive for them, and re-map by doing what Sasha do will probably make the engine ecology worse, which they cannot afford even more (in the context with VW scandal).
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