Subaru Forester Owners Forum banner
1 - 6 of 6 Posts

2006 Forester XT 2.5 SG9 Manual
4 Posts
Discussion Starter · #1 ·
Hi everyone, I'm writing to you because I have a problem with my Forester XT 2.5 06 and I can't find a solution.

The car has 205,000km, I bought it used 4 months ago, the car has an LPG system but the car runs on petrol only for about 1000km.

Main symptoms:
  • Acceleration hesitation between 2500rpm and 3500rpm
  • 0.3Bar turbo pressure => 0.8Bar
  • Ceck Engine warning light off
The car started to have hesitations in acceleration, first weak then more and more present. note that the engine warning light has never turned on.
I replaced the sparks, the situation improved but after a few km (200/25) the car presented the same symptoms,
I replaced the ignition coils, same result.

I thought that the improvement after replacing the components is caused by the reset of the ECM, because I disconnected the battery when I replaced the components. I did some tests and noticed that resetting the ECM actually does improve.

I thought maybe the problem is sensor so I bought an OBD2 reader with Torque PRO to read the data and discovered various things.

Supercharging pressure that changes from 0.3 bar to 0.8 bar
Strange behavior of the A / F sensor between the OPEN LOOP and CLOSE LOOP cycles and consequently STFT with wide variations.

I use the car every day for the journey from home to work (10km + 10Km) with a quiet pace, then sometimes I have fun and I sink with the gas, one night I noticed that the car didn't push as usual, through Torque PRO I notice that the turbo pressure reaches 0.3bar, I do other accelerations up to 5000rpm and the pressure returns to 0.8bar. I immediately notice a general improvement of the delivery, the car is more ready when I go to press on the accelerator and the car is fine, no hesitation in acceleration. When I return to the quiet driving after a few miles back to having the same problem.

The car gives me these symptoms with the tank completely in reserve, at 1/4, with half tank and full, I checked inside the tank is the filter is not badly placed there is no dirt
on the bottom.

I started looking for the problem, I think it's a matter of the ecu or some sensor that deceives the ECM. Analyzing the OBD2 data I noticed a strange behavior of the carburation system between OPEN LOOP and CLOSE LOOP especially in the values O2S1Eq, O2 1x2 V, STFT1% and LTFT1%.

In CLOSE LOOP, the front O2 sensor controls the carburation, in the various situations, O2S1Eq = 1, O2 1x2 V = 0.9V with STFT1% which varies up to + 10/11%.
When I accelerate to the bottom the car changes from CLOSE LOOP to OPEN LOOP and the values change: O2S1Eq = 1.4, O2 1x2 V = 0 and STFT1% = 0.
When the ECM returns to CLOOSE LOOP, STFT1% has a peak of + 11%, O2S1Eq and O2 1x2 V return to normal values.

I ask you, can acceleration hesitations be linked to this anomalous behavior in CLOSE LOOP?
Could I have some faulty injector?
Catalyst to be replaced?
Front O2 sensor to be changed?
Why does the car have that pressure variation? does the ECM go into protection mode? or is the sensor gone?

The problem is that I have no errors in the ecu. I looked at the values of MODE $ 06 I get:
Id component $ 01
TID $ 41 111 110 / pass
TID $ 81 0 / 65535 pass
TID $ 84 467 / 3211 pass
TID $ 89 5945 367 / pass
Id component $ 02
TID $ 41 0 / 50 pass
TID $ 89 26214 635 / pass

I enclose some screenshots, if you have any advice

engine idling

I'm going crazy, what do you think it could be? Is there any test I could do to better understand the problem?
Thanks to everyone and have a nice day

Premium Member
2008 Forester Cross Sport AUTO
4,698 Posts
I had an outback with lpg.


It had serious hesitation and a couple of brown underwear moments.

Took it to the Subaru Garage nothing wrong with the petrol set up.

Then took it to Lpg place, nothing wrong with it.

Chopped it fir a Golf.

My other half met the new owner of my Lpg outback at a product recall. Said he took it to a mapper who fir £250 sorted everything out apparently there are 2 ecus and they can work against each other.

Good luck.



2007 XTEn Manual
117 Posts
I had a similar sounding problem in my 2007 XTEN which I struggled to find a solution for. Eventually I booked it in for a rolling road session which identified a faulty turbo boost solenoid. Power was down from 250bhp to 185bhp, boost was half what it should be at 2k-3krpm. I replaced the solenoid & they re-initialised it in the ECU which cured the problem.

2004 Forester STi
73 Posts
Faulty turbo boost solenoid would cause consistent max boost to be at actuator pressure ~0.5bar, & it doesen't sound like that's the issue the OP has.

OP, hard to understand your post - it reads like it's been through an online translator?
Can you confirm if the running issues after an ECU reset reappear when running on LPG, or on petrol, or all the time? A modern sequential injection ECU-controlled LPG system is essentially completely out of the wiring loop when it is switched off - the only 'intercepts' it does is for the fuel injectors to switch them off when running on LPG, but it is a pass through device when turned off.

2006 Forester XT 2.5 SG9 Manual
4 Posts
Discussion Starter · #5 ·
Grazie per le risposte, mi vergogno ma il mio inglese è pessimo, uso il traduttore online.
Sto usando l'auto solo a benzina, per escludere che potrebbe essere un problema di GPL.
Il problema (esitazione) si verifica 200/250 km dopo il ripristino della ECU. tra 2500rpm e dopo 3500rpm ..
Nessuna luce del motore accesa.

Penso che un sensore (o più) invii i dati errati all'ECM, se si trattasse di un problema di scintilla e / o bobina di accensione apparirebbe anche dopo il ripristino dell'ECM.

il sistema GPL è un PRINS VSI 2 (Vapor Sequential Injection)

molte grazie

2006 Forester 2,5 XT, LPG automatic
20 Posts
got a 2006 SG9 with LPG, in a past got similar problem, solve it with a new LPG ewporetor. since then (cca 1 year) no problems (knocking on wood)
regular service every 10.000 km (one year) with overall service, filters change and map check.
Daily driven about 10 km + 10km.
1 - 6 of 6 Posts