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 EVL20T » Tue Feb 02, 2016 12:19 am

Cant believe no one has a fix yet, i'm having same issues with my 07 GTB EJ25. same hesitation between 2-3k rpm, but it comes and goes like 1 day it will be normal for an hr then problem will start for about an hour, then disapears without even turning off or resetting the ecu

Only thing i havnt done was front O2, AF sensor and clean the EGR
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Joined: Tue Mar 31, 2015 12:59 am
Location: Newcastle, NSW
Car: Liberty
Real name: Mikey

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

Postby alexeib7 » Wed Mar 16, 2016 9:07 pm

I previously had hesitation problems with my Liberty 2006 model. I used to reset the ecu by disconnecting the battery cable for about 5 minutes to clear it and reconnect it. The hesitation comes back after a while, but I found an easier way to fix this problem. Disconnect the maf sensor then crank the motor for 3 seconds then turn off, plug the sensor back on then start the vehicle.The engine light will come on, you can purchase a code scanner/ reader cheaply from eBay or buy the Carista app and Bluetooth Obd2 connector to reset wirelessly which is easier than battery disconnection.This method has worked for me so far without hesitation, it could be a faulty sensor but it's a quicker and less troublesome way of clearing hesitation for me.
Good luck you can try this, maybe it will make life easier for you too.
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Joined: Sun May 12, 2013 4:30 pm
Car: Subaru Liberty 2.0litre N/A 2006

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

Postby klam » Tue Jul 26, 2016 9:20 am

lz2nkm wrote: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).

this is one great, great write up on the problem and thanks for that. I've tried everything from o2 sensors, oil, throttle cleaning, maf cleaning, OCV's valves changing and the problem was always there and then I just gave up and sent the second hand ECU to Sasha. After his remap and then some fuel remap that was required considering the difference of the petrol 95/98 quality here, the car is perfectly fine and I must report that the fuel economy is actually better, not worse. Previously, I've rarely averaged less than 10.8, currently it's sitting on 10 (pure city driving, occasional hwy). The performance is great given it's a 2.0l NA engine and it's a wagon.
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Location: Sydney
Car: Subaru Liberty 2006 4GEN MY06 2.0R
Real name: Michael

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

Postby EMark » Tue Jan 30, 2018 9:09 pm

Hi guys,

I have a Subaru Legacy 2.0R from 2006. And like all other owners of a car with such an engine I also have problems with a flat spot between 2000 and 3000 rpm.

I have read a lot about this problem, in this forum, in other australian forums, few forums and blogs from UK and Europe. All this engines have this problem, all without exeptions. I have read about many different attempts and approches for fixing the issue, but without results. I'm familiar with the method of the russian guy Sasha to solving the problem. I have read about disconecting of the knock sensor as well, and other things like that. But I think all these solutions to fix the problem are just workarounds. Some theories say that the problem is in the AVCS valves, other that the problem is in the ECU, or in the mapping tables, but non of these are proven or certain. I know about few owners which have changed the AVCS valves but without result for example. I don't believe that the ECU has a hardware or software problem as well.

But there is one thing which is questionable, and I didn't read whether someone has doubted or assumed it - everyone looks for the problem in various details, but not in the engine. It is obvious that (even with a new knock sensor) there are knocks, and the ecu retracted the ignition advance upon this reason. Probably the problem is not in the ECU, or in the sensor, or the valves but in the engine itself.

It could be worn main bearings of the crankshaft. Does anybody check this? Because I have experience with different car and engine but with the same problem, and the problem was in the main bearings of the crankshaft. After changing the bearings the problem dissapeared.

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

Postby DracoKn » Sat Mar 10, 2018 9:16 am

Hi everyone,
I recently bought a 2006 Liberty 2.0R, at point of purchase I wasn't aware of the common hesitation issue with the car.
The car has been in and out of mechanic a few times because the throttle sometimes would not respond when it's cold started and the engine hesitates for a second or two at 2000rpm before it takes off.
As far as I know the mechanic has put in new spark plug fuel filter, replaced a split fuel pressure regulator, and cleaned air flow meter, and I was told there was no problem with the other sensors Every time I got the car back it drives really well, but the problem start to come back after a few days. I find that every time the problem comes back I can just disconnect the ECU and the car drives well again, which makes me think that it's not really a problem with the components but the ECU itself.
I really appreciate if anyone can share some insights to help me with alleviating this headache.
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