Acceleration Hesitation MY07

myarken · Post by **myarken** » Tue Aug 17, 2010 1:55 pm

I own a MY07 Liberty (Dec, 89,000k's on clock.) it was only serviced approx 1500k's ago and have been displaying smyptons of fuel issues since about 100k's after the service.

I did get the injector's cleaned, and I've just had my mechanic say, that he does it with every Subaru.

The issue is that it has really bad hesitation on acceleration up to approx 2500, then over this, it works fine.

I don't believe it's the carbon build up because:
(It normally has the carbon build up problem and this is different)

1) The mechanic said that he did this, I totally trust him, known him for years.
2) When the car is filled up with fuel, to full, the problem 'almost' disappears. Insert octane boost and injector cleaner prior to filling up with 98 octane fuel.
It takes approx 40km's for the issue to totally disappear. It runs for approx 200km's without issue before starting to come back.

3) Hesitation in acceleration ... Problem starts to come back when the tank gets down approx half.

4) When lower than half a tank, the car is very painful/ unsafe to drive, especially, at a T intersestion .

5) only ever use 98 octane fuel, have tried different branded fuel stations.

I think that it's fuel related, I can re-produce the problem immediately, when the tank is below half.

But, after some research, it was mentioned that the TGV sensor, may not be working as well ?

It doesn't make sense, when I have it at full tank the problem goes away, then under half a tank , it comes back.

Anyone have any ideas?

Really appreciate your help on this.

myarken

Post by **TOONGA** » Tue Aug 17, 2010 2:04 pm

Tumble Generator Valves ....otherwise known as my car won't accelerate past 2500 rpm.... or my car drives like a piece of fecal matter up to 2500 rpm

a common problem with the newer subaru motors

http://www.scoobymods.com/mod-tgv-tumbl ... ht=FPR+MOD

Im trying to find subarinos thread on his GT forester that had this problem

when I find it I will add the link to the post

edit : read this thread it may help

showthread.php?t=16210&page=9

TOONGA

myarken · Post by **myarken** » Tue Aug 17, 2010 2:26 pm

thanks, for all the info

Mod: Sorry, I noticed, I posted it under general, then changed it to troubleshooting. Pls merge.

myarken · Post by **myarken** » Mon Aug 30, 2010 9:05 am

TOONGA wrote:Tumble Generator Valves ....otherwise known as my car won't accelerate past 2500 rpm.... or my car drives like a piece of fecal matter up to 2500 rpm

a common problem with the newer subaru motors

http://www.scoobymods.com/mod-tgv-tumbl ... ht=FPR+MOD

Im trying to find subarinos thread on his GT forester that had this problem

when I find it I will add the link to the post

edit : read this thread it may help

showthread.php?t=16210&page=9
TOONGA

Thanks for the offer but, only Turbo's have the TGV. This is a non Turbo model. Sorry, I should have mentioned that.

The mechanic has confirmed that there is no TGV in the car.

Also, he removed some crap/dirt whatever, from inside the fuel pump. the car is much smoother now and running as expected but, he's going to also replace the fuel filter in it too. Generally replaced at 112,000k's but, mines currently at 90,000. So may as well.

bobbyjimmy · Post by **bobbyjimmy** » Mon Aug 30, 2010 12:06 pm

This is a 2.0 SOHC, 2.0 DOHC, 2.5 or 3.0?

Does he use the upper cylinder cleaner every service? Or just says he does but really couldn't be effed?

If you use 98RON all the time - you shouldn't need to clean the injectors or have any build-up on them.
Genuine Part number of the Subaru fuel filter kit is SAS1055, RRP is $110.25, PM me if you want one of these on the cheap.

Octane booster fouls your plugs quicker than normal - stop using it.
Change the plugs and leads - if that doesn't help find a known to be good coil pack and swap that in for a test.
If that doesn't work find a known to be good AFM and try that.

myarken · Post by **myarken** » Wed Oct 13, 2010 9:31 am

2.0 SOHC

We had the mechanic clean out the fuel pump and replace with a genuine fuel filter.

After a few days went to crap again.

We then did another service and the mechanic did a upper cylinder clean and he said compared to the previous one, it was so dirty. He let it sit for 10mins before turning it on again. When it turned on again a massive plume of black smoke came out the back (was never this bad during other cleans) ... he thought someone was going to ring the fire brigade ....

The car is running as new now. We have both put it down to a bad batch of fuel... amazing how much damage it can do and the cost.

Post by **Alex** » Wed Oct 13, 2010 10:30 am

agree with a bad batch of fuel....never ever ever fill up when theyre re-filling the servo. It stirrs up all the crap in the tanks at the petrol station and increases the chances of your car picking up shit.

i have the 2.0 sohc also, i usually just run standard unleaded and then run a tank of bp ultimate thru her every 3 or 4 tanks. I do notice a significant increase in power and fuel economy when i run 98 octane.

but yeh..makes you think about petrol and what they actually put in it!

AndrewT · Post by **AndrewT** » Wed Oct 13, 2010 12:04 pm

I'd find out a bit more about what your mechanic actually does when he cleans the injectors. Does he just run some kind of snake-oil injector cleaner through the tank? Or does he fully remove the injectors and clean / flow test them?
If he fully removes them it's quite possible he may have stuffed up the re-installation. Even if he's done it many times before it's still possible, they are very very finiky and very easy to mess up getting the rubber o-rings to seat properly. If they aren't sealing properly then you get these kind of problems.
I'd look into this before branching out to other things. The fact that the problem started almost immediately after the service is a strong indicator it's been caused by something in the service.

If you hear hoof beats, think horses, not zebras

***edit - lol, just re-read your last post. Totally missed that the problem was already solved haha.