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Hi all, I recently purchased the liberty already knowing it some minor issues. There seems to be a low rev hesitation when you plant the accelerator. The car has been recently serviced and it imaculate under the hood. new plugs air hose and filters as well as battery. It is running standard unleaded and I have put injector cleaner through it. It is in the doctors today getting the ridiculous canon removed and a standard muffler put back on it. Would there be any merrit in resetting the ECU after the muffler replacement?

I'm not sure if the muffler will make much of a difference to the ECU, but regardless the ECU will relearn on its own and shouldn't need to be reset. Throttle position sensor cured the hesitation/surging in my Liberty.

Never heard of having to "reset" the ECU after changing the Muffler unless you have a bunch of old codes it there

Hesitation could be fuel issue.. pump or filters?

Hi
I have experienced similar hesitation (2010 Impreza RX manual) when I'm stopped at the lights for sometime then go to move off quicker than normal. The car accelerates then pauses for about half a second then picks up and goes.
defeats the purpose when wanting to get away quick.
it only happens if the car is still for say a minute. If I stop and go it's ok so I figure it wasn't my foot work.
I thought it might be that the injectors are getting too much fuel feed to them while stationary then floods for that split second.
I asked this question last week at the subi dealer and was told it's best to run 98 octane all the time and not mix 91, 95, and 98.
the engines should run ok on 91, maybe try 95 or 98 for a few tank fulls and see if the issue goes away.
Ian

I have driven it around today after the muffler replacement and it's still the same. I didnt think changing it would really do anything but thought that the ecu might be doing something weird. The car still hesitates quite badly if your in say 3rd and doing 30-40 if you plant it the car does nothing then a second later it revs as it should. Air hose was rat shit so that has been replaced and it did make an improvement. The car has dual fuel with LPG although since I picked it up last night I have not had a chance to try out the gas. It sounds like I'm going to have trouble shoot from start to finish on both the ignition and fuel delivery ay

I'll try that Ian cheers

[quote="Tezwah"]

LPG = A critical piece of info missing from the OP

Take it an experienced duel fuel mechanic - would suggest this where your issues start and finish.

Mmm i think your right.. I ran it on gas today and something srange happened.. I had to slow down to avoid a car and when I accelerated there was a loud pop sound kind of like a back fire, turns out that noise was the air box blowing apart! needless to say i turned it straight back to fuel and connected the airbox back up and it ran ok. Yesterday I, for what ever reason reset the ECU... now the car refuses to idle below 1500rpm.. I am going to take it in to get looked at regardless but just wondering if anyone has any insight into why that would happen?

Plugged the readout connectors together today and got a readout of 23 and 32 which are the Mass air flow circuit and o2 sensors..

Well I have changed the AFM and the o2 sensor both of which changed nothing.. took it and asked two mechanics who both suggested replacing these items also..

Oh and now the car has a constant error 32 (o2 sensor)

Did you replace with a new or known O2 sensor?

Yeah I bought a brand new Bosch 3 wire o2 sensor. Performance is identical with the new o2 sensor and the 'second hand' AFM. at a bit of a loss :S

LPG intake side backfire is known to root expensive efi sensors. LPG relies on correct mixtures to avoid lean backfire, signals based on O2 sensor output. OK so you have a smogger LPG as vapour injection eliminates backfires. A backfire is harsh on all sensors, ducting and all the little vacuum hoses etc. Every little bit of intake needs to carefully looked at to find splits, breaks, holes etc.

I have replaced the AFM and the o2 sensor but those didnt change anything. If you were me who would you take it to, a gas specialist or a normal subaru pro?

personally a gas expert there are performance gas specialists or gas tuners about that do this stuff all the time with ease, The backfiring thing can be a common issue with some setups i.e. the AU fords used to come with special clips in the gas kit for the airbox so it wouldn't blow them apart! Also it might be an idea to have the transmission looked at if its an auto.

Ok i think i will take it to a gas specialist. I'm sure it had to run fine on gas at some point. It is a manual also. I will post on here how it all pans out!

i have had this problem. after alot of investigating and hunting round for info and with those 2 particular error codes the tps throttle position sensor causes hesitation but will cause those 2 error codes to come up.. warning though for a brand new1 its 800 plus it will have to get built.. i picked 1 up from the car wreckers taking the risk for 100.. i got it tuned properly with the computer and it has been good ever since.. .. try that..

i have just bought a 1992 liberty with similar issues as yours,tps was the cause of hesitation.$5 from wreckers.runs perfect now.your idle issue could be related to air idle controll which is located on the manifold just under tps.cheers