94 Legacy Gt randomly loses power while driving

[Guest]

Ok I have this problem where basically the car occasionally looses power when going up hills or at a sustained speed.

You will be driving along and then there is just nothing there for 2sec - 20 sec's, then the car comes right and drives like normal.

Ive been told the legacy motors have a common problem once over 200,000kms with the valves sticking open, and the loss of power is the valves staying open hence I loose all compression, till the valves stop sticking and work as normal again.

Has anyone had this problem before? - Loose all power then comes right after some time and drives like normal. Car has done about 232,000kms.

[Durty-Sanchez]

Even more common though is the AFM going tits-up in them. Search some of my older posts for a DIY AFM fixup guide, it'll steer you in the right direction

Edit: Here it is

[log1call]

Hmm...

If the AFM was playing up bad enough to cause total power loss at a steady throttle setting like this, wouldn't it set a trouble code... for O2 if nothing else?

I'd suspect the main relay or a power or earth connection myself.

[Guest]

 log1call said:

Hmm...

If the AFM was playing up bad enough to cause total power loss at a steady throttle setting like this, wouldn't it set a trouble code... for O2 if nothing else?

I'd suspect the main relay or a power or earth connection myself.

Absolutely would log1call. How them cactus?

Just a quick question daxter, have you noticed if you are using more fuel lately?

This is unrelated to my question but I also think it could be Low voltage/current, stopping the fuel pump from delivering the required fuel flow rate. Could just be gravity lol just kidding.

[Guest]

I get about 450kms driving around town per tank. Which I think is good for a 4wd turbo car.

Thanks Durty-Sanchez for the AFM fix up, that could help it alot.

So far Ive done a engine flush and oil/filter change, radiator fluid change, new fuel filter, and cleaned the AFM with ARC AFM cleaner. I also pulled the intercooler off and put a bottle of turps thru it to clean all the blow-by oil out that comes from the rocker-covers - All this has help to reduce how often the problem occurs.

Also I have a friend who has the same car and on similar kms, and his has the same problem, he changed the fuel pump on his legacy and didn't help much at all.

I'm beginning to think it could be true about the valves sticking open due to sludge and carbon build up stopping them from closing. It does feel like the motor looses all compression - hence valves stay open when they should be closed.

I guess the only fix would be a couple of engine flushes in a short time between oil changes and put a few bottles of injector cleaner in.

[dubbedup]

SUbaru upper engine cleaner maybe....

[Guest]

Right ok, so I guess Subaru knows about the sticky valves and have brought out a product to fix it.

Do you know any dealers that stock this stuff? thanks!

[Joker]

coils?

[Guest]

I thought coils but the car would run rough as the coils crap out. What I'm getting is a total loss of power, then after a few sec's it all comes back and drives normal again.

I just brought some Subaru fuel additive and upper engine cleaner so ill give them a go, if it is the valves sticking open this should fix it.

[Durty-Sanchez]

When my AFM's died I experienced power loss on hills, on the flat, any time, any throttle.. my moneys still on that being the problem. Check your error codes, the AFM problem doesn't always throw an urgent code but there may be one stored in memory that can be dug up when you check.

[Guest]

Ok serviced the car with Subaru fuel additive and Subaru Upper engine cleaner on the weekend. Made a big difference, car runs a lot smoother. The legacy use to have a heastation after changing gear but this is now gone, very smooth car to drive now.

Highly recommend doing this, it actually works. Was about $50 for both products from my local Subaru dealer.

[log1call]

Power loss is not usualy quite the same as no power at all for several seconds surely?

If the AFM stops working, or goes out of range, the ecu uses revs, TPI and temp to calculate IPW and the performance should still be fairly reasonable.

It does sound to me more like an electrical fault somewhere. The older cars had dodgy main relays that caused symptoms like this and never set a code.

Ignition ignitor breaking down could also cause those symptoms.

The ignitor is easy to get at and swap if you can borrow one.

[Guest]

I no-longer have the issue after a good service, and using the Subaru Upper engine cleaner - which made the biggest difference. I believe it was the valves sticking open.