Engine hesitation/flat spot (Liberty 2.0R)

[Jeffreyy]

Why is that deep heat?

[Deep Heat]

Why is that deep heat?

Imprezaz's might be different but every 2.0R liberty I know of uses a Hitachi ECU which isn't supported by any of the tuning programs I know of.

Something about the type of memory they use or something.

[klam]

Let us know the outcome mate thanks!:) was is hard to clean? how much is a new egr valve? I used a mates Bluetooth and android device which said it maf sensor and the air intake temperature sensor! But I have drove the car with no maf sensor and the problem I still there! Does anyone know where the ait sensor is located!

new egr valve is 360$ (14710AA730). It's easy to take it off assuming the egine is not not and tear apart. does anyone know if it's ok to spray the uec into a throttle body from where egr sits?

[calais]

To be fair, when I really threw myself into fixing the issue, I went like a bull at a gate.

I have kept notes of what worked and what did, I had taken the car to Penrith Subaru and all they did was throw some UEC through it. (Which I had already done, but meh, it was done for free which was quite nice)

However, that doesn't assist the guys that are still having this problem.

I believe there is one culprit. The EGR.

The EGR is electronically controlled, and works just like an exhaust valve. However, as these valves are subjected to high exhaust temperature, they will wear.

One thing I noted between my original valve and the brand new one I swapped between was the amount of lateral float on the valve stem of my original valve. It was a marked difference which meant that if I attempted to depress the valve by hand and added any kind of lateral or 'off centre' loading, the valve would get stuck and fail to open fully as intended. The new one suffered from no such condition. it was smooth and easy operation every time.

I am currently running with my original valve in place after having cleaned it thoroughly in a cocktail of solvents, and also having placed a very thin film of copper grease along the valve stem. It was smooth as silk when I put it back together...... I was obviously looking for a more cost effective solution to just all out replacement.

I will also add this to the mix.

People have suggested KIDO tuning and the like to eliminate the issue. I disagree.

Subaru released the car, and they drove just fine. We can reset the fault codes and they drive just fine. After a cumulative effect of operating out of spec, the ecu will retard timing to protect the engine from an out of balance mixture in the combustion chamber. The ECU is doing its job, we had to find the component which was creating the issue, I am happy with what I have changed and what effect it has had on my wifes car.

The individual results may vary, because a number of faults can cause similar problems. A blocked fuel filter for example can cause similar problems. And the fuel filters on these cars are rarely changed because they are somewhat difficult to do. But it isn't outside the scope of any home mechanic. I did mine as part of a fault elimination exercise.

In addition, the coil packs have been blamed too, however, an ignition fault would typically be easy to diagnose by operating in a high load low rpm scenario. However, conducting the ECU reset which makes the hesitation disappear removed this as a potential cause in my opinion.

It is also my understanding that Subaru UK issued a service bulletin for this very issue where the service centres were directed to ensure that all vehicles were running the correct 5w30 oil and high octane fuels. This made sense to me being such a high compression petrol engine, start simple right?

Cheers fellas, I'm only too happy to help

[Jeffreyy]

Thanks for the great advice!

[klam]

thanks calais... I wonder what guys at Denlo will come up with today not much is expected except the 100$ bill for diagnostics haha ... well, I've noticed on my EGR that I has to put surprisingly a lot of pressure on the spring, but I've considered it as normal as I didn't have any new one to compare it to. That copper grease is a great idea. I'll take it off again, will try my own cooked solvents (some degreaser plus turp) and see what I get. I also suspect either injectors or the coils, but the decision will be made after a diagnostic today as be promised to check the injectors for any cracks/clogs they might have developed. Still up for a coffee at Parramatta ? anyone else can join as well if they wish !

[klam]

Guys, guess what... car had passed the diagnostic results perfectly fine no error codes, no problems with air nor fuel pressure, air flow, a/f ratio, o2 correction, roughness monitor perfectly fine, fuel injectors perfectly fine (he ran that through some test, I don't think he actually took them out, but maybe he did). Said the EGR values very fine, the MAP changes with the EGR valve opening which proves there is a flow, the ECU had the latest PAK updates already. He was clueless, he asked couple of other mechanics and they said that the 2.0R often have this, and it might be a result of the high compression ratio engine and fuel, and recommended to try some octane booster with the fuel (even with 98RON) as one option.. the other to change the compression ratio by rebuilding the engine (changing pistons, gaskets and god know what else he was talking about ) as the option 2. Money? around 3500$. No thank you I'd rather sell that
He said there was some dirty green (?) stuff at butterfly and cleaned it with 2 cans of UAC.

He then explained, and I might not be accurate here, that the ECU records all the timing (either advanced or retarded) based on how you drive and all the available information, and next time you start up the vehicle it uses these values to optimize the performance from the start. Thus the reset resolves the problem.

Best part of this was that they didn't charge me anything, therefore big THANKS to DENLO and James the mechanic who had all the patience with me and answered a lot of questions, I trust him he performed all the checks he said he had done. I'm kind of glad they confirmed what we are struggling

I'm going to do last two things and that is to clean the EGR again and possibly sourcing a new one cheap from overseas and change the fuel filter. And then I'm done with it if the flatspot re-appears.

[calais]

klam - you have mail.

[klam]

just found this... and the crack makes me wonder...

exhaust_pipe_crack.jpg (108.14 KiB) Viewed 5688 times

guys at the forums don't think this might be the problem as it's just the shield and shouldn't affect performance.. make me nervous though knowing something like that is sitting there. Check your exhaust pipe for any cracks just in case..

M

[Jeffreyy]

I will check my exhaust now! Haha
I am keen for a meet!

[Jeffreyy]

I have the same cack in the same position on my header/cat-conventer unit! Going to check a mate 2.0r tomorrow to see if he has it!

[klam]

what a coincidence.. post a photo and let us know tomorrow

[gen4cruiser]

I haven't checked my car yet, but judging by the location of the oil filter and the discolouration of the shield I'd say the crack is caused by the change in temperature when covered in oil after a filter change. If that's the case, I'd wager it's very common and likely in the higher models too. Might be worth asking some of the 2.5L or 2.0T folks if they have the same thing.

[calais]

Guys,

Had a bad enough day with work, and then driving home...... It just got worse.

My Subaru hesitation has returned. And its worse than ever.

So as soon as I got home, I threw it up on ramps and checked the exhaust manifold, and it looks solid.. no obvious damage or anything like that.

I have booked it in with Automotive Technical Centre in Penrith to have it diagnosed, I am over it, and just want someone who can go deep inside whatever the computer is doing and tell me what is reading out of spec. Anyone else care to do the same?

Sorry Fellas..... but it looks like it Subaru 1, Me none!

[klam]

I haven't checked my car yet, but judging by the location of the oil filter and the discolouration of the shield I'd say the crack is caused by the change in temperature when covered in oil after a filter change. If that's the case, I'd wager it's very common and likely in the higher models too. Might be worth asking some of the 2.5L or 2.0T folks if they have the same thing.

that discoloring could be just the cleaned part that I've done while wiping of the oil that had spilled over it ... the more I look at it the more I think it was hit by something, despite the fact that the undercover has no damage whatsover.

My Subaru hesitation has returned. And its worse than ever.

I'm sorry to hear that calais... and those were EXACTLY my thoughts after I've cleaned my EGR first time and it came back.. it was really bad :/ ... I've received a tip from a friend of mine to check for any valve cover gasket oil leaks .. check the sparkgplug cords if they are oily or not. He says it's quite common. I might check them tonight, but I'd rather let him to have a look at it. He seems to be up for a task to fix the car so I wonder currently it runs perfectly fine as I've done the reset of ECU on Friday.
And Calais, by any chance.. did it came back after a long "cruise control" drive or under a heavy load or drive more than 2-3h ?