PDA

View Full Version : Legacy station Brighton 99: delays (hesitation) on accelaration



chinookcpt
05-26-2009, 12:30 PM
Model: Sub. Leg. Station Wagon Brighton 1999 AWD
Motor: Boxer 2.2
kms: 207 000 (miles: 130 000)

Hi,

my legacy has an intermittent problem when I accelerate. The motor will freeze at 1500-2000 rpm for a second or two before kicking up to 4-5000 rpm. After that, I can shift all 5 gears without to much problems if I stay over 3000 rpm. Sometimes, it can take as much as 4-5 secs at 1500rpm (something like 4-5 mph lol) before it kicks in. At a stop sign or at a red light, it really is annoying! Does it cold or hot, with low or full fuel tank, almost everytime I start from 0 mph or sometimes downshifting at ~3000rpm.

I also burn some oil, more or less half a pint each thousand mile since I bought the car last year, and I'm pretty sure I drink more gas since I have this problem. No check engine on. I had a P0440 3 weeks ago, figured out it was because of the fuel tank cap, deleted the code and it hasn't re-appeared since 300miles (~500kms)

Here are the things I've changed in the past year or tried:

Changed my two oxygen sensors and knock sensor(I had a check engine before that).

Changed my mass air flow thinking that it could be the source of my problem, disconnected the battery a couple minutes, reconnected, let motor run on idle to enable the mass air flow to reprogram, but still no change.

Changed the air filter and gas filter two weeks ago.

Added a can of cleaning additive after fueling to clean motor, injectors, exhaust and all, but it didn't do much.

Flywheel and clutch rebuilt last month, at least now the transmission works great :D

Anybody has a clue? Could it be a problem with the electronic injection? Fuel pump? Dirty something due to oil burning? Throttle position sensor? Damaged head gaskets?

Any kind of information will be very welcomed, I am pretty new to car repairing... so be very a ease to tell I me wrote something stupid! Sorry also for my medium english...!

Chinook Cpt.

Scorpion8
05-27-2009, 12:34 AM
Subaru has a service bulleting on "Hesitation on Acceleration" number 11-58-99. The summary is attached.

51


Military, eh?

rutech
06-21-2009, 11:55 AM
I agree with scorpion, sounds like an ignition timing problem to me, as long as it runs good at the higher rpms.

chinookcpt
06-22-2009, 08:34 AM
Indeed, it runs smooth at higher rpms (from 2500-3000 to red line) Intermittent problem though, I reckon the ECM could be working only part-time...

As it is suggested in the service bulletin posted by scorpion, I'd like to check for low fuel pressure and/or low air pressure, but how can I do that? Still no CEL by the way...

I've already checked the MAP level with my OBD2 reader in live data mode, and it seems to be running correctly, moving from 29 to 4-5 when stepping hard on the pedal. Is that an effective low air pressure test or sould I do some other tests?

How can I check the fuel pressure?

Thanks

Scorpion8
06-23-2009, 07:13 PM
How can I check the fuel pressure?

There should be a test pressure fitting on the fuel rail near either the first or last injector on the fuel rail. You can hook up a test guage to that fitting, and then run the engine and observe.

Also, you can try swapping another ECM from a salvage yard pull. That would save the most money by confirming an ECM fault before you get too far into it.

rutech
06-24-2009, 12:12 AM
I don't think that car has a pressure test port on the fuel rail like scorpion was talking about. The best way I know of to check it is at the outlet of the fuel filter. use an inline guage between the filter and fuel rail. I think the spec is about 32psi. You will also want to disconnect the vacuum line off the pressure regulator, the pressure should increase. The pressure regulator is a round metal thing, located on the passanger side of the engine at the back and is mounted to the fuel rail. I would also check your mass air flow sensor readings. Possibly your throttle position sensor as well. Does it act up only in that rpm range or does it have anything to do with your throttle position?? I have found it is best to rule out all sensors and the wireing harness before messing with the ecm. Hope this helps and keep us informed.