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View Full Version : tech tip: do not remove injector diffusers

88turboii
10-15-2008, 09:50 AM
on my new rebuild, i removed the injector diffusers, thinking with they were affecting the fuel flow from my bigger injectors. apparently they are very important, because it ran like crap, hesitations at cruise, AFRs all over the place, etc.

i pulled the injectors and replaced the diffusers and now she runs perfect. very smooth idle, no hesitations at all. apparently they help the fuel distribution in the air, stopping it from just hitting the opposite wall on the intake

just a heads up, incase anybody was considering removing them
SpooledupRacing
10-15-2008, 10:00 AM
Good info.. I knew that if I had removed them it would cause a problem with fuel atomization.. but I never wanted to test the theroy
Whizbang
10-15-2008, 10:29 AM
what i wonder is if they are still available from Mazda new
SpooledupRacing
10-15-2008, 10:30 AM
yes they are.
RotaryXperiment
10-15-2008, 10:35 AM
i made sure to put mine in and replace with new orings per my engine builders suggestion.
SpooledupRacing
10-15-2008, 10:51 AM
every time I get into an engien if they wiggle loose I pull them out inspect them for cracks, replace if nessecary and always put in mew o-rings.
Whizbang
10-15-2008, 10:53 AM
for me they always seem a bit....fragile....from 20+ years of heat cycling. Would be stellar is a nice aluminum reproduction.
need RX7
10-15-2008, 02:30 PM
Would be stellar is a nice aluminum reproduction.

:icon_tup: I like.
ZGN
10-15-2008, 09:01 PM
I pulled my secondary injectors ones when I installed my 1600. runs perfect!
classicauto
10-16-2008, 11:14 AM
Yeah I have none on my secondaries, primaries ABSOLUTELY.
88turboii
10-17-2008, 09:12 AM
I pulled my secondary injectors ones when I installed my 1600. runs perfect!
sweet, i still left my secondary diffusers out. i wasnt sure if they would cause problems too. Im going to tune it in boost this weekend, so hopefully no problems. im running 1600 sec, 750 pri
Whizbang
10-17-2008, 10:47 AM
1600s are big injectors though. Not sure how effective the diffusers are at about 3 times the fuel volume
classicauto
10-17-2008, 12:33 PM
1600s are big injectors though. Not sure how effective the diffusers are at about 3 times the fuel volume

I'm running a 750/1600 combo on mine. Only using primary diffusers....seems to work just fine.
ZGN
10-17-2008, 01:20 PM
I have heard under higher fuel pressure they could break off, and that would be bad. :(