Well i got the DSM datalogger, and currently the Laser has a big 16G, and i installed a Aeromotive FPR. The car goes through quite a bit of gas, and i can tell its running really rich in boost. I also installed a brand new o2 sensor. Idle fuel trims are pretty much maxed or very close to 139%. Mid trims are around 110%, high roughly the same. At the time of the FPR install, i set the base fuel pressure to stock setting of 37 psi, with no vac line connected. This resulted in ALL fuel trims at 139%! So now i'm running around 38-39 psi, WITH the vac line connected, at idle..What's the deal with this? I boost leak tested it, and no major leaks anywhere. NO exhaust leaks as well..i dont get it..dont know why i have to run so much fuel pressor over the stock settings, and even still the o2 trim values are not close to 100%..The car runs great though, but leaves quite a bit of black smoke under boost..I dont have any means for fuel control, like a SAFC, so its hard to tune..its getting a megasquirt, so i dont want to waste the money now..

are you still running stock injectors and a stock fuel pump?

stock 450's and a 255 walboro pump

Originally posted by XtremeRS
I dont have any means for fuel control, like a SAFC, so its hard to tune..its getting a megasquirt, so i dont want to waste the money now..

and what exactly do you need to know?.... :wary

Originally posted by eclipzGST

Originally posted by XtremeRS I dont have any means for fuel control, like a SAFC, so its hard to tune..its getting a megasquirt, so i dont want to waste the money now..

and what exactly do you need to know?.... :wary

Why the fuel trims are messed up...its not getting a MS for some time yet, and i'm forced to drive this daily through the winter, so i'd like to figure out why its doing what its doing..

I would imagine that the car is running wacked out rich because of the fpr. I would also assume that the injectors are probably maxing out too because they're stock and you have a 16g. My brother had that set up and his car would hit fuel cut very quickly... except he wasn't doing anything with his fuel pressure. You are going to need some sort of engine management to run the larger turbo or you are going to have sucking gas problems and that's the bottom line.

Originally posted by FluxCapacitor
I would imagine that the car is running wacked out rich because of the fpr. I would also assume that the injectors are probably maxing out too because they're stock and you have a 16g. My brother had that set up and his car would hit fuel cut very quickly... except he wasn't doing anything with his fuel pressure. You are going to need some sort of engine management to run the larger turbo or you are going to have sucking gas problems and that's the bottom line.

Why would a FPR make it run rich, providing its set at stock fuel pressure values?? Unless the stock FPR isnt a 1:1 rising rate FPR, then i dont see how that has any effect. I have hit around 15 psi boost so far, and has never hit fuel cut, in fact, its running pretty rich at that. I can run 18 psi on my S16G on my rs, with 440cc injectors, and those are prety much maxed, so the fuel is there, too much there lol..I know i need some fuel management of some nature, i just want to get it halfway decent with what i have for the time being. If i'm running stock injectors, with stock fuel pressure, idle/cruise fuel trims should be like stock, doesnt really matter what turbo is on it, esp not like there is THAT much difference between a 14B and 16G..a 14b to like an FP Red, ok lol..

I'm running roughly 12-15 psi MORE fuel pressure at idle than what it calls for stock, even then fuel trim data says it needs more fuel? So closed loop, computer says its a bit lean, but boost is super rich? Doesnt make sense..

the thing with the stock fpr is that when you start flowing more fuel to it, the little return hole can't keep up, so your psi rises as a consequence.

Originally posted by hookduphatch
the thing with the stock fpr is that when you start flowing more fuel to it, the little return hole can't keep up, so your psi rises as a consequence.

That's why he installed an afpr...it's an issue with larger than stock fuel pumps: they can overrun the stock fpr. Simply switching to an afpr shouldnt cause problems by itself. As a matter of fact, it should perform like stock. Your fuel pressure should drop when you hook up a vac line. Your base pressure is 37 and with a vac line hooked up, it goes up to 38-39. My guess is your fpr is bad. It should drop 1 psi for every 2 inches of vacuum.

Example:
Base: 37 psi
Vacuum 18 inches
Pressure with vac hooked up: 28 psi

Yours is 38...

Also, make sure you have a good vac source to the fpr. Bypass the fps if you have to.

Originally posted by eclpsmoneypit95

Originally posted by hookduphatch the thing with the stock fpr is that when you start flowing more fuel to it, the little return hole can't keep up, so your psi rises as a consequence.

That's why he installed an afpr...it's an issue with larger than stock fuel pumps: they can overrun the stock fpr. Simply switching to an afpr shouldnt cause problems by itself. As a matter of fact, it should perform like stock. Your fuel pressure should drop when you hook up a vac line. Your base pressure is 37 and with a vac line hooked up, it goes up to 38-39. My guess is your fpr is bad. It should drop 1 psi for every 2 inches of vacuum. Example: Base: 37 psi Vacuum 18 inches Pressure with vac hooked up: 28 psi Yours is 38... Also, make sure you have a good vac source to the fpr. Bypass the fps if you have to.

damn that's my bad. i completely misread and though he was using the stock fpr.

MAtt,
what do the O2 counts look like? This happened on my sisters 3g. Same exact issue, running pig rich. I scanned it with the scanner and the o2 was claiming very lean at idle. As a result the ECU raised the trims to 113% at idle.

When you look at the trims make sure they are cyclig back and forth. I noticed hers was pegged at lean. Even if the ECU is raising trims, the O2 should see a constant lean-rich-lean-rich ect.

Terry

Yeah the o2 cycles lean and rich, just like it should(its a new o2 sensor as well). I DID run the base 37 psi fuel pressure without the vac line connected at first, which brought the idle fuel pressure down to 27-28 psi like it should, so the FPR is working correctly. But when the pressure was that low, all my trims were maxed out at 139%.. wierd!

Originally posted by XtremeRS
Yeah the o2 cycles lean and rich, just like it should(its a new o2 sensor as well). I DID run the base 37 psi fuel pressure without the vac line connected at first, which brought the idle fuel pressure down to 27-28 psi like it should, so the FPR is working correctly. But when the pressure was that low, all my trims were maxed out at 139%.. wierd!

Well, im out of ideas. Is it reaching operating temp? Maybe its stuck in closed loop and those are the warm up enrichments...dunno

see thats what i was kinda thinking too, since i had put in a 180 stat during the motor build..but i swapped it back out for the oem 192 stat, and that wasnt the problem..hell i dont know..i guess i need to get the MS on it sooner than i thought haha..start making some power on this sucker :)

I'll tell ya what though, hitting 15 psi boost in the RAIN, and still hooking up like no other...puts the RS-T to shame traction wise lol..AWD is the shit :-o