Help Required Please on setting fuel pressure on regulator

[peter_reid]

I have just fitted my new 550 injectors, walbro pump and SARD regulator and was wondering what I should set the regulator at ??.

Cheers

Pete

[scoobaroo]

I`m sure it should be set at 3.5 bar, but not 100%.

Somebody more technically gifted should be around to confirm this for you []

Marty.

[AlanG]

 

I'd set it at 3 bar (atmospheric) initially. This will give good enough atomisation. When you tune and max out the injectors, you can increase it to give more scope, but will need a re-map to suit.

[peter_reid]

Tried 2.2 as per his Furrieness and 3 bar but car is misfiring like running on 3 cylinders. Any clues chaps?

 

Pete

[cusco kid]

sound like its overfuelling m8 or the mapping is not able to cope with this pressure or over stressin the injectors  ,loads of reasons could apply check if its the same cylinder all the time thats missfiring if it is change injectors from cyl to cyl if miss goes with it it could be faulty injector   geo

[the squiggle]

You still on the std ECU?

I was thinking you had 440's in there as per Phase 1.5 manifold and not as big as 550's

I am thinking the jump from 550s to the 380s that the ECU will be looking for is too much

Best bet while on the std ecu is fit some 380's (cheap from any breakers) and let the ECU control injectors of a size it is capable of insteaad of getting it to flow 2 sizes bigger than the ECU is expecting

AlanG, Pete runs an early WRX that is fitted with a Phase 1.5 engine while still on the early 4 port ECU

[AlanG]

2.2 bar is too low imo. If you have set it for 2.2 bar, then when vac pipe is re-connected to FPR, fuel pressure will drop, because engine is below atmospheric i.e. you will be in vacuum. Fuel pressure varies with vacuum and boost pressure, so must be set initially with vac pipe off.

Also, the larger sized injectors will need sufficient pressure to gain a good nozzle spray pattern (atomisation) and with 550's, i think you'll struggle for good atomisation with a pressure as low as 2.2 bar (if that is with vac pipe disconnected)

However, you say it sounds like you're running on 3 cylinders. If it was alright before, then i suspect it's something to do with the injector install, or the injectors themselves.

My car was a '99 admittedly but i could idle and rev my 2.5 with 740's on a std ecu with no problem, that's why i kept the std ecu, to check issues i had with the car to eliminate or confirm any ecu or map problem.

As a suggestion, i would check you maintain some form of fuel pressure after you have switched the ignition off.

[AlanG]

sound like its overfuelling m8 or the mapping is not able to cope with this pressure or over stressin the injectors  ,loads of reasons could apply check if its the same cylinder all the time thats missfiring if it is change injectors from cyl to cyl if miss goes with it it could be faulty injector   geo

 

This is a very strange site....

I replied to this thread this morning after Squirrel, now it's this afternoon and the above post from cusco kid is in the thread from last night,[:^)] it wasn't there this morning on my pc. On the scottish scoobies forum page it's now stating the last post was by cusco kid last night.... though i expect it will change now i've posted this reply. [8-)]

[the squiggle]

2.2 bar is too low imo. If you have set it for 2.2 bar, then when vac pipe is re-connected to FPR, fuel pressure will drop, because engine is below atmospheric i.e. you will be in vacuum. Fuel pressure varies with vacuum and boost pressure, so must be set initially with vac pipe off.

Also, the larger sized injectors will need sufficient pressure to gain a good nozzle spray pattern (atomisation) and with 550's, i think you'll struggle for good atomisation with a pressure as low as 2.2 bar (if that is with vac pipe disconnected)

However, you say it sounds like you're running on 3 cylinders. If it was alright before, then i suspect it's something to do with the injector install, or the injectors themselves.

My car was a '99 admittedly but i could idle and rev my 2.5 with 740's on a std ecu with no problem, that's why i kept the std ecu, to check issues i had with the car to eliminate or confirm any ecu or map problem.

As a suggestion, i would check you maintain some form of fuel pressure after you have switched the ignition off.

2.2bar was with vac pipe connected, so 2.7bar disconnected.

Originally Pete contacted me be cause the car would not pull any boost at all and would eat a full tank in about 100 miles.  Upon checking the fuel pressure it was found to be at something silly after a FSE reg had been fitted and not set with a guage.  Car was subsequently rolling roaded and the operator pointed out the car was badly over fuelling.

 I would source a Phase 1 manifold and fit that in the short term, then the ECU will fuel the car as expected.  Match the injectors and manifold to the ECU and it ill make it easier to diagnose the fault

[AlanG]

No probs squirrel. There's more to the problem than what was mentioned originally,so I'll leave it in your capable hands fine sir, sounds like you've got it sussed. [Y]

[peter_reid]

Guys thanks for all the great replies,

I did forget to mention that I have a Z4 ecu fitted.[:$]

 

Grant.

Thanks for all your help,I have taken your advice on the injectors and have put on the standard ones,after I refitted them it was still running like it had a missfire so removed the plugs and gave them a clean,started her up and she was idleing perfect but then the CEL came on [:S],checked for fault codes and it came up 22 which is the Knock sensor,had a look about and the wiring to the sensor was bare from what looked like a previous badly done solder job (slowly going from bad to worse [:@])

I cut the wire,recrimped it then checked for faults again,Success all well now,started her up and now she,s idleing perfect and driving better than before.

Dont suppose the dodgy wiring had any thing to do with initial problem would it?? (although CEL didnt come on before)

Anyway I suppose I need to start saving for the new ECU to allow me to fit the new injectors,so now I need advice on what is the best one to get.APEXI etc,etc

Thanks again guys for all your help

Pete

 

 

[RA Dunk]

im going to be selling my apexi soon from my MY95, 1 year old been mapped once from andy.f

[peter_reid]

Would def be interested (if I have the pennies saved) how mich would you be looking for it

Cheers

Pete

[WUZ]

Better save like mad Pete - Apexi don't make the Power FC for the 93-96 cars any more so 2nd-hand prices have gone through the roof!

Russell