Detonation Ej25

taza

taza

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Joined
Oct 30, 2010
Messages
3,820
Location
Perth, Western Australia
My convereted EJ25 Foresters has some pinging. When I strippes the motor for the head gasket job a month ago there was no signs of detonation damage.
Im running the standard computer qith Ej25 manifold and injectors.
Since building this motor and having it in the foz (14months) it has always been ran on BP98 fuel. Except for an odd occurance once or twice.

I noticed today that while under slight load (60kmhr in 3rd gear), up hill there was slught pinging.
I tried running the car on octane 91 for the first time 2 weeks ago. While the car ran very well, with very little difference in performance it detonated like no tomorrow. Even when driving carefully.

The standard ecu is not programmable at all. Infact my particular one is a completely sealed unit.
Non the less I need more fuel! I was going to uograde trom the standard fuel pump to a Walbro 255. Which flows at 250l per min. While the standard one runs at 180l per min.
However if I uograde the fuel pump will I see an increase in pressure after the fuel pressure regulator? So at the injectors. Or will I still be limites to around 43psi at idle?

If I upgrade the regualtor and not the pump, this might be adequate. However I am unsure if I should go to an adjustable fpr or rising rate fpr. The rrfps adjusts 10psi with ever psi in vacuum.

Last option is to upgrade the injectors to 280cc from the standard 220cc(ej25).

My goal is to run octane 91 fuel comfortably without detonation.
Thoughts?
 
The amount of fuel doesn't affect pinging. It only means it burn lean, rich or spot on. Pinging is caused by the octane rating of fuel, ignition timing and compression ratio. Too low an octane and it will ping. Pinging on 98 means something else is wrong as these engine run fine on 91. Increase in compression ratio can cause pinging. If the head was shaved during the head gasket change and a lot was taken off, then it would increase the comression ratio.. Also running 98 fuel in a car the doesn't need it has the potential to build up excessive carbon which increases the compression ratio. Not sure on Foresters but I think the ignition timing is controlled by the computer, so a duff computer is a possibility.
 
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The way I look at it is that it's leaning out. Thus needs more fuel. I cannot tune the ecu and am not spending 2+ grand for an aftermarket option on a n/a motor (that I'll only have for a few years).

Ignition timing is higher than your car for example because the ecu is designed for a 2.0l comopuer. Which runs greater timing.

Compression would be around 10.5:1 as thats the 3rd time the heads have been skimmed on this motor.

I'm limited with options here. I just want the engine to last another 100, 000km max. It's only got 18k on ot.
 
Sorry I thought you were running an EJ25 computer. Getting one might be the cheapest option. Fuel would be sorted along with ignition timing.
 
Sounds like your shaved head and possibly the new HG's are thinner than the last set that allowed your EJ20 computer to run the EJ25 ok without pinging.

Ultimately you'll be chasing your tail until you get an EJ25 computer together.

Might be time to track down an EJ25 computer and loom as well as a loom that matches your foz then send it off to Al at AMauto to have the two merged.

Once you get it back it's just a case of swapping over the loom in the dash of your Foz to the one you sent to Al then mount the ECU and you're off.

Also check things like your knock sensor, if that's off line you'll have all sorts of issues ;)

Cheers

Bennie
 
I thought about that Elfreddo however then I have to use two separate keys as the immobilizer is linked with the ecu on both a gen 3 outback and sf forester.

The biggest peoblem is getting an outback with maching key to make it run. A wreckes vehicle is an option but very harf to come by for what im after.

I only plan the keep the engine for a few more years then move on to a turbo( or diesel). So again I don't want to through thousands of dollars at it when it won't be around for ever. Itd even be cheaper for me to change the heads and head gaskets, if I left it. I just don't want to be standard anywhere from a blown bottom end.
 
^ Taza, I agree with Bennie about this. Check your knock sensor. It could have been damaged with the recent work.

Other than that, Bennie's right. Get the proper ECU.

Mine doesn't ping ever, even at 800 rpm in 2nd/LR, with the fully loaded trailer on behind, and two adults on board ...
 
After a Google it seems common with Bosch spark plugs. Which im running. I'll change them back to NGK and see how I go. Never had an issue with ngk before.
Might through in some wrx 330cc injectors and see how I go. If the major of then pinging is gone I'll live with it.
 
Knock sensor is 2 years old. Genuine. However it's on it's 3rd motor. The last two were pretty ****** as we all know.
Ive got 5 or 6 spares.
Will try that too.
 
^ I've never been a fan of Bosch plugs.

Ross always uses NGK in our cars, even though he's a Bosch service centre.

I've never had a single problem with ngk in 40 years.

From my Batphone
 
Might of gotten hold of a 04 SG forester wiring harness, immobilizer, barrel and ecu. Will find out today. It's a wrecked car that will be parted. I am thinking I should just buy the whole car, then I'll have everything I need.
 
Taza,

It is a pain to rewire etc if it was ok and now it isn’t - so close to getting away with the mods.


Have you tried the United 100 fuel - yes I know it has ethanol and we can debate that all day but if it solves your problem it will be better for the motor than detonation. Alternatively have you tried some octane booster - you used to be able to get it from Repco.


You need to get the detonation under control so you have time to deal with the cause detonation will kill your motor in very short time.
Injectors and fuel pumps are not going to help this problem - they will help at your top end if you are leaning out


Just a thought but are the cam pullies the same on each head on that car is it possible you have them on the other head or are ½ tooth out on the timing belt - that could be enough to advance the timing by a bees ..... whisker and now you have a problem.
 
Running 100 octane will just shift the pre-igntion threshold and yes it will help but not fix this problem.

Problem is Taza's 2.0L ECU still wont be able to retard timing enough, even with a new knock sensor installed so its substandard with this current setup. With those engine mods, new AFR / ignition and timing maps needs to be implemented to cater for the higher VE output of his motor.

No need for fueling mods if the ECU management is not capable and I think you will find the stock fuel setup more than sufficient for this purpose.

Stock 2.5 ECU or piggyback and get it tuned Taza.
 
you can get second hand aftermarket ECUs for the $800 to 1500 range. Should be ample for a turbo 4 down the track too. Probably not a bad investment for the car, and can always be sold for a good price too.
 
Ive got a piggy back haltech system which was installed but I don't like it... will look at my options.
Can buy a whole SG Foz for $1300 thats got the front end busted in.
 
taza said:
Ive got a piggy back haltech system which was installed but I don't like it... will look at my options.
Can buy a whole SG Foz for $1300 thats got the front end busted in.
Click to expand...

Who tuned it?
 
I'd do what you said with NGK plugs & knock sensor for starters.

Crazy Dave has a good point with the timing belt. Are you 100% certain it wasn't put back on 1 tooth out? That would def cause your problems.

If you can get a 2nd hand aftermarket computer for under $100, that would be a great way to go & as Venom said you can transfer it to your new turbo down the track (or dune as the case may be lol)
 
Yes 100% on timing belt. Will go back to NGK plugs and run octane 100 for time being.

Picking up the 04 SG Foz next weekend. Airbags have been deployed. Front LHS damaged. No damage to engine but radiator is bent (not leaking).
Has 150, 000km, manual (need the gearbox as a spare) and can use other stuff from it.

Will be good to uograde to OBD II amd have a tunable ecu.
 
I deffinately think putting sg wiring and manifold is the best way to go. The 2.0 computer and sensors are so limited vs a more modern 2.5 set up. It will never run the motor how it is meant to be run.
 
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