Hi,

I recently installed a comptech sc+ac and I'm ruining stock injectors, I was at the dyno today, unfortunately from around 4k rpm's the car runs too lean it's in the low 13's.

Now we adjusted the fpr with no success (was around 60-65psi) it didn't make an ounce of difference, I have a single pipe exhaust, tracySports header, testpipe, and vafc2.

We believe it's either...

A. A fuel pump problem could be a fake walbro?

B. We did measure voltage from the car battery and fuel pump, my tuner friend says there's too much voltage being lost, it's 16v at the battery but only 12v at the fuel pump even just when the car is idling. My friend thinks wiring in directly from battery with a relay and thicker wire should help?

C. Fpr can't cope with my mods and with 7psi pulley? I believe I woild be getting towards maxing out the stock injectors but would be ok on my setup?

I'm pretty pissed off at the moment

What do you think?

Cheers

AJ

 

ur friend is right rewiring the pump will help. its a mod people do on the site but ussually when they are much higher hp. since your stock injectors it couldnt hurt.

the comptech rising rate fpr might be bad. 60-65 psi aint much over stock 50ish so i dont really think its doing much right now. your gonna see more in the 75-80 range. i really think thats the problem right now.

but i hate those things. get eman ult + 550 injectors and call it a day

 

Hi

thanks for that, so your saying I should had adjusted it to 75-80psi range?

I have a synapse missing link installed, should the little filter but facing the front of the car? - but doubt that's a problem?

Thanks

 

if the missing link was installed wrong, stock ecu would see positive map pressure, and woulda freaked out. seeing lean is becuase theres not enough fuel. and you are adding fuel by increasing Fuel pressure. 60-65 is damn near stock. its what you would see if you had bigger injectors and stock FPR with no rising rate thing installed. stock one is 1:1, the comptech is adjustable. my opinion is your gonna need 75-80 to get that car to run safe at WOT @ 7psi boost. might be a bit less. but its just my guess.

hopefully someone can chime in that has actually done it. i went to 650 injectors and aem ems the moment i went boost.

i had a really had experience with rising rate fpr's and said to hell with them.

 

I spoke to my friend he said he wound the fpr up to around 90psi and it still didn't enrich the afr, he says his moneys on the fuel pump voltage issue with the battery being 16 but pump only being 12v in idle.

Thanks for your help so far

 

if pump was hitting 90 psi not so sure its broken. most of our cars run lower voltage at the pump then at the battery, so still not sure.

i personally think your just running outa of injector. try the other stuff first, but in the end its still just bandaids over the fact that your running stock small injectors not designed for the fueling needs of a boosted car.

 

Hi,
Sorry i should say i have a fuel pressure gauge on the Fpr, when we alter the fpr it does alter the psi - this is what we are viewing.

Maybe your right, problem is i cant view the injector duty cycle otherwise i'd know for sure.

I would of thought it would go lean much further up the rev range than 4k rpm??? - this is the point where it hits 13.1 and will not go down.

 

7psi...an 60psi of fuel? turn the fpr in a few turns don't be a wimp about it...I was at 10psi with stock injectors and the comptech fpr but with water/meth you should be able to get the fuel you need for 7psi through the fpr ignore the battery to fuel pump voltage for now...crank the fpr bolt down!

 

unplug your vafc first and then try and adjust the afr with JUST the fpr...once you get that into spec use the vafc to fine tune...I'm a thinking its your vafc

 

Hi vafc2 is zero'd out

the fpr was set at 55-60 psi an rose to around 90 on WOT it made no difference to the afr, it didn't budge.

Maybe with this said a 7psi setup with header, testpipe and single exhaust it's just too much for stocker injectors.