injector problems? something not right

toyota85ae86 · Post by **toyota85ae86** » Fri Jul 31, 2009 9:53 am

need to start from the top lol. its kinda complicated

first setup was an MSD external fuel pump, stock ecu, stock boost, stock injectors.

car ran fine, drove good. then one day it died on me. what the hell lol.

ok so in my frustrations with external fuel pumps, had an issues with some carb fuel pumps lol, so i decided to drop the tank just to make sure its all dandy in the back.

i drop the tank, to find.........a kinked up return line.

ok logical choice, is for me to un kink hose and see what happens. test fuel psi with my inline gauge, i got 40psi. good.

fire it up, no go....runs so dead lean, wideband doesnt even read AFR its so lean, and then i cant even rev it, runs so bad. ok, so kink return line to boost fuel psi to around 55-60 psi, car runs good. little rich but it does run. and drives fine!

so im tired of external pumps, i buy a walbro 255 in tank, convert back, hook it all up, does the same. 43psi runs like trash, 60 psi runs good.

NOW everything from the pump, to the filter, to the hard lines, to the rail, even to the regulator is fINE. its been replaced OR changed. i even swapped regulators just to rule that out. so really the only thing is my injectors. they are 20 years old, sitting outside, rain, snow, who knows. and when i re did my head, i reused the O rings and injectors. chances are they could be dirty and clogged, and clogged or dirty injectors require more fuel psi to run right.

2 things, i A install brand new 550cc injectors i have on my desk, OR swap in another set of USED 370cc oem ca18det injectors and test that. at this point i just want the car to run like stock, and run the 550cc injectors up the boost and tune later.

what do you guys think is going on? my last thing is injectors, even know they OHM out ok, they could be clogged, and when i was re building my cylinder head i had the injectors just sitting on my bedroom floor with the rail, and by re using the O rings wasnt the best either. so should i swap injectors? 550cc or another set of 370cc?

Projectgofast · Post by **Projectgofast** » Fri Jul 31, 2009 10:12 am

I would get an adjustable fuel pressure regulator, then you can raise fuel prerssure and unkink the return line

ga_goosh · Post by **ga_goosh** » Fri Jul 31, 2009 2:03 pm

whats the injector impedance and are you using an injector resistor?

mooreofit · Post by **mooreofit** » Fri Jul 31, 2009 7:00 pm

i bought used injectors when i supercharged my monte and they toasted my motor.

#3 cylinder ran lean and chipped the pistons. i first noticed this when i would idle down from a wot run and and i would be on five cylinders. the spark plug detonated the gap shut on 4 seperate occasions. on the 5th i pulled the plug and there was no porcoline left to the center electrode on the plug and there was large flakes of piston coating what was left of the plug.

point is you probably didnt drop all your injectors at one time and when they fail you will notice your car runing foul before hand.

what motor is this? the 4a?

i would start looking into the air metering device or something sensor\ecm related. as it sounds like (if all else is really good.) like the extra fuel pressure is compensating for a lack of injector pulse width.

good luck.keep us posted.

HondaRue · Post by **HondaRue** » Fri Jul 31, 2009 9:06 pm

mooreofit wrote:what motor is this? the 4a?

He has a ca18det swap...

mooreofit · Post by **mooreofit** » Sat Aug 01, 2009 8:58 am

i'm not familiar with to many nissans.

good luck!.

also swapped a walbro in my little bros montecarlo and it built 60 psi but had no volume. turned out the stock pump was a two stage and flowed as much as the 255lph so we put it back in.

toyota85ae86 · Post by **toyota85ae86** » Sun Aug 02, 2009 12:48 am

thanks guys for opinions.

heres what i think im down to. i have a GREAT pump, all my lines are fine, my fuel rail is not damaged doubt that would make ANY difference. Also i have swapped regulators so im sure that fine.

obvisouly the motor wants more FUEL. my wideband is reading lean, and by boosting fuel psi im compensating and making it run smoother.

anyways, bumping up fuel pressure is a band aid, and im not going to just buy an adjustable regulator. so....whats that leave me with. i need to put in bigger injectors.

I have a set of BRAND new 550cc injectors to swap in tomorrow..... anyways its my best solution, i doubt my stock 370cc injectors are bad BECUASE, they ohm out great, and having 4 equally clogged or dirty injectors is not logical. so i will just put in my 550cc injectors and see what happens!

mooreofit · Post by **mooreofit** » Sun Aug 02, 2009 10:36 am

are you running stock boost\turbo?

toyota85ae86 · Post by **toyota85ae86** » Sun Aug 02, 2009 5:36 pm

mooreofit wrote:are you running stock boost\turbo?

no.....10psi waste gate is set to and then i run an HKS 2530 turbo, which is a .64a/r exhaust and a T3 compressor housing with a .64a/r

stock turbo is only a .48 a/r intake and exhaust. its a dinky little thing.

also using a mild sized front mount and piping, full exhaust.

mooreofit · Post by **mooreofit** » Sun Aug 02, 2009 5:53 pm

thats a big differance.

they say 300whp will be maxing out 450cc injectors.

370 to 550cc might be too big a jump and injector pulse width out of boost might be too large for the 550cc injectors.couldnt hurt to try though.

although it should idle and run fine off boost with the stock injectors.

toyota85ae86 · Post by **toyota85ae86** » Sun Aug 02, 2009 7:09 pm

mooreofit wrote:thats a big differance.

they say 300whp will be maxing out 450cc injectors.

370 to 550cc might be too big a jump and injector pulse width out of boost might be too large for the 550cc injectors.couldnt hurt to try though.

although it should idle and run fine off boost with the stock injectors.

yeah, turbo is HUGE.

550cc injectors will support 345whp. turbo is good for 320ps, i want to break or hit right around the 300whp mark.

the turbo came off an sr20det, he was running bigger injectors, an safc2 i think and some other stuff it was pretty healthy.

well i plan to get a Nistune done at vip performance in oregon as soon as i get back. car is loaded up and ready to be put on the trailer and leave. leaving for washington on monday!

mooreofit · Post by **mooreofit** » Sun Aug 02, 2009 7:19 pm

good luck i hope all turns out well.

Post by **dr.occa** » Mon Aug 03, 2009 7:51 am

it appears you may have solved your problem.

my initial guest would have been injector size after you indicated you were going to a larger turbo. stock the CA18 didn't even see close to 300 so factory injectors and non-adjustable fpr would be your weak point. the pump wasn't a consideration since you've gone to the walbro 255.

check out rceng calculating proper injector sizing here.

mooreofit · Post by **mooreofit** » Mon Aug 03, 2009 7:42 pm

he said they were 375's or something like that.