pulled the exhaust off the EJ22 in the kombi to take some measurements to rework it and noticed that three pipes were nice and grey but the other one..front passenger whatever number that is...is black and sooty...haven't checked anything else yet...should i suspect an injector? and what to do about it

the plugs should look the same, if not something weird is going on. I'd expect a leaky / sticky injector. The good news is the economy should improve when you fix it

on the other side from the stater motor

you need parallel fuel rails

this is a common problem with the fuel rails in a subaru

can you explain a bit more Neil?

Rob , if you look at the fuel lines you will see one injector is some what distant in the fuel line .this injector never gets full flow in the fuel system , even when the system is under full pressure .

I have taken this from the RS forum , this is oversteers work under doing some testing of the rails on a test bench


Basically what the testing revealed is the difference in flow out of your injectors with the std rail set-up, after converting test bench to a Parallel rail set-up the flows were almost dead identical.

Testing was done using 02 STI rails and 440cc top feed injectors(GT forester). Rail configuration std is very simular to early std RS WRX etc(ie its series with a reg on end of one rail)....but they are probably more balanced that early rails, so results I expect would be worse with early RS/WRX rails.

Baseline data ;

Fuel quantity is measured in grams.
Was weighted on digital kitchen scales with a 2g resolution.
Vessel fuel was caught and weighted in was 26g empty.
100ml of solution in vessel weighed 102g
200ml of solution in vessel weighed 176g
300ml of solution in vessel weighed 250g
Base test fuel pressure was 47.5 psi, this is what the std O2 STI reg was tested at, and what parallel after market reg used was set to.
All tests were done with a 60 sec duration.

The Data ;

Testing was done using PWM circuit, going of the adjustable trim pot used 3 test modes were devised...tho they may be far from true DC, they are what was used for all tests, they are named from the position/range of the trim pot, so its was turned to ~ 25%, 50% and 100%(wide open no audible pulsing)

Test 1 - part A Std rail config -

DC Inj 1 Inj 2 Inj 3 Inj 4

25% 90 88 86 86

50% 204 202 190 190

100% 334 336 344 340

Test 1 - part B Identical set-up to part A - repeat for accuracy

DC Inj 1 Inj 2 Inj 3 Inj 4

25% 90 90 88 88

50% 204 200 186 184

100% 334 332 340 338

OK so we can see that around the middle duty cycle the flow rate is significantly different, so the position of the injectors in the rails was swapped...1-4 2-3 because I suspected it was the rails causing the discrepancy not the injectors them selves....
Also note at 100% DC the flow was higher on the rail that scored lower at 50% !

Test 2 - Part A same config as Test 1 except injector positions changed/opposite.

DC Inj 1 Inj 2 Inj 3 Inj 4

25% 88 88 92 90

50% 192 192 208 208

100% 310 310 302 302

Test 2 - part B Identical set-up to part A - repeat for accuracy

DC Inj 1 Inj 2 Inj 3 Inj 4

25% 88 88 92 90

50% 198 198 216 216

100% 314 314 304 304

...So after test 2 we can see thats it definitely the rails not the individual injectors themselves !



OK so now I made an adapter and converted the rails to parallel using 2 T pieces and an aftermarket FPR set the same 47.5 psi base pressure.



Test 3 - part A Parallel rails

DC Inj 1 Inj 2 Inj 3 Inj 4

25% 82 84 84 82

50% 204 204 204 204

100% 344 344 342 342

Test 3 - part B Identical set-up to part A - repeat for accuracy

DC Inj 1 Inj 2 Inj 3 Inj 4

25% 82 82 84 82

50% 206 206 204 204

100% 346 348 346 346

BINGO ! we have a winner, all with-in 2 g of each other !

wow! thanks Neil is that your longest post ever? makes sense tho so i'll have a little play and see if i can duplicate your system