17 replies to this topic

[Subaru_Bloke]

Hey guys, up until the other day, my car never backfired at all, now it does when cold, but is fine when warmed up.

It's always taken more turns to start than normal petrol engines and never thought anything of it, but with the backfiring I'm wondering if they're connected? Some searching suggests an injector may be leaking? I have no idea.

Btw wrx turbo engine if it helps

[glenisanutter]

Mind does the same thing. Its the engine telling you to be nice until its warmed up!

[Subaru_Bloke]

It never used to though! I also got a backfire when I backed off from high rpm and high boost... does yours take longer to turn over and start than normal?
Oh I should add if I turn the key a little, stop then turn it again, my car starts straight away

[El_Freddo]

Oh I should add if I turn the key a little, stop then turn it again, my car starts straight away

Sounds like a leaking injector to me. The test is: When cold prime the fuel three or four times by turning the key to the "ON" position, wait a few seconds, then OFF to ON wait a few seconds... you get the drift.

Then try starting it and seeing if it starts quicker/first go.

As for the popping - you'll have a cylinder either not firing properly or a small leak in the exhaust that's allowing air into the exhaust on off throttle deceleration, this allows the fuel mix that's passed through the cylinders unburnt to create the pop. Or this is also a side effect of the leaking injector - now it's just leaking worse...

Cheers

Bennie

[Subaru_Bloke]

Thanks freddo. My fuel pump runs constantly, but I don't think it's connected to the ecu, so I can't tell if it's pressurising the fuel line or not. I read that even if the fuel line doesn't pressure up, the ecu will cut the pump after 5 or 8 seconds or something. Mine never stops

[Subaru_Bloke]

This is a picture of my injector. I think sti are side feed right? What size do I get? 555cc? I don't have any mods other than full exhaust and a boost controller atm

[El_Freddo]

Thanks freddo. My fuel pump runs constantly, but I don't think it's connected to the ecu, so I can't tell if it's pressurising the fuel line or not. I read that even if the fuel line doesn't pressure up, the ecu will cut the pump after 5 or 8 seconds or something. Mine never stops

That's not right! ADRs make them so the fuel pump stops. Dunno that the ECU does it or if it's a pulse signal after initial prime to keep it going, haven't looked that up in ages. I'd be trying to rectify that!

Dunno about the injector sizes. I'm an NA bloke, may get a turbo someday, but for now I'm happy with NAs and old school subi's

Cheers

Bennie

[Subaru_Bloke]

Yeah. I need to look into it for sure mate, apparently it used to have plug in engine management, but was returned to stock. I also can't use obd socket because it's not connected. Oh the joys. Thanks for your help though Bennie

[El_Freddo]

No worries mate. I've just realised you're in benders. I frequent that place and am looking forward to moving back soon! Shepp sucks!

I'll keep an eye out for you when I'm in town, but it's a big place now

Cheers

Bennie

[Subaru_Bloke]

Oh yeah? I'm working in Shep every now and then. Hard to miss my car ha ha. Give us a toot

[Jimbo]

Yellow injectors are 440cc's.

[allpaw4]

If you need a set of spares, I have a set here, just need to remove them from the manifold.

[Subaru_Bloke]

Thanks fellas.

So a set of 555cc would be an ok upgrade? Also, just to confirm, I have side feed injectors right?

[Subaru_Bloke]

Ok i've done some research, and unless I can get a tune (I can't with stock 98 ecu) then I need to get the same sized injectors. If my injector is stuffed, can it be rebuilt?

[allpaw4]

Yep, yellow tops are a side feed injector. And yes, if you can't tune, you won't be able to up the injector size. No idea about rebuilding of injectors sorry.

[Subaru_Bloke]

Just thought I'd do an update. Cleaning the injectors and replacing the o rings have stopped the misfiring and backfiring

[Beckers]

Great news.

 

Might be time to bring it down to Melb for the next Docklands meet.

We had a few of the Bendigo boys @ the last months meet.

[Subaru_Bloke]

It's on like a Wednesday night isn't it? I'd love to, but I'm a tradie and up early in the morning Beckers. Maybe though...