injector swap question

[Redfwdsm]

i had stock injectors in my car when i swaped my motor to another shell but the blown motor i swaped it in for had 550 rc injectors so i just put them in and now that the car runs its running super rich i also have a walbro 255 pump stock fuel lines and rail anyway will the 550s and other mods make the car run to rich? stock fpr

 

[UofACATS]

Yes, the larger injectors will make your car run too rich if you provide no fuel management for those injectors. This is because the fuel system is treating those 550s like 450s because it does not know they are there.

Additionally compounding the rich condition, the 255 pump has been known to overrun the stock FPR on some cars. This will cause the rich running car (on the 550s) to run extra rich until sufficient boost is achieved. This is because base pressure is higher than stock and the proper pressure is not achieved until some boost is present and the car needs equal than or greater to that pressure. This is somewhat irrelevant if the 550s continue to fuel the car, as stated above.

Try to find stock injectors to start. If you're still running rich at idle and "lowish" RPMS, swap in a stock pump. Otherwise pick up some proper fuel management and knock yourself out.

 

[nuclearr]

You either need to put the 450's back in or take some time to tune the air/fuel ratio.

Also do you have an adjustable FPR (fuel pressure regulator)? That could be part of the problem.

 

[Gooberlog]

Some fuel management is recommended now that you added more fuel with the 550's, other than swapping your stock parts back on, your cheapest temporary fix would be to adapt a 2g mass air flow sensor to your 1g. These are known to just about even out the fuel ratio on a 1g with 550 injectors. Some people run a 2g maf on a 1g with 550's with no fuel management. Might work for you. I have a 2g maf for sale if your interested email me or check the classifieds on here.

 

[toofast82]

Either put your stock injectors back in or get something to compensate for the injectors (chip,safc,dsmap,dsmlink,etc)
I've heard the 2g maf being pretty close with 550s but i would still recommend something to tune with also

 

[Gooberlog]

Either put your stock injectors back in or get something to compensate for the injectors (chip,safc,dsmap,dsmlink,etc)
I've heard the 2g maf being pretty close with 550s but i would still recommend something to tune with also

agreed, or atleast monitor it like a logger

 

[Redfwdsm]

ive got a logger and a safc-2 but im just going to put in the stock injectors and wait till i have the money for a wideband and fpr kit