I am trying to tune my car and am not sure what my fuel pressure should be at for idle and boost. Right now I have the GM SC, Adjustable FRP, Cartech FMU, 320 CC injectors, 2.6 inch pulley and soon to be installed alky injection. I have my fuel pressure for idle tuned to 45 PSI and at boost it jumps to 60PSI. As it sits I think I am a little lean by just looking at my plugs. They are not white, I cleaned them and put them in and they are still shiny, with a little whitish haze.
Also I need to ask and sound like an idion but I dont know how to adjust the cartech FMU, to you do anything with the top screw or the side one with your fingers?
So I think I need to upgrade to bigger injectors, with the SVO 370s do you need to modify them at all or is a direct replacement in size for a 1998?
Thanks
Chris
http://members.cardomain.com/vertz24 1998 Z24 Convertible
at idle- 50 psi. ( 0-100psi guage tapped into my rail)
i am on a stock 2k2 FPR (them have higher fuel pressure then the pre 2k ones from what i noticed).
walbro pump and cartech fmu / stock injectors.
under boost- i havent a clue. i know i pinched my return line once and the fuel pressure shot to 100 psi fast and the car died. haa
to adjust for more fuel on the fmu, turn that little screw in. not the one on the top.
Im running a turbo setup... But my idle fuel pressure is around 38PSI and while under boost it is raised to 80-85PSI with cartech FMU...
2004 Turbo cavalier 11PSI and blown!
mine idles at 30 psi , and about 45 psi under boost
ive got 36lb injectors
get a wide band o2 sensor and gauge , before you hurt something
i ran low 13's with the 320's , even with the fpr set all the way up , so i went with the 36lb and droped the pressure
now ill run mid 11's , and car runs alot better
center screw adjusts base fuel pressure, the vacuum fitting that is inline with the center bolt is signal line, at atmospheric pressure (line unplugged) it should run the 50 mark. GM base fuel pressure with -20 - -18 vacuum is 38-45 (mine is 43psi)
so set the main bolt for 0psi, then you can adjust it from there, you will likely run 4:1 or 3:1 and it should boost FP (at eg. 10psi up to the 80ish mark) around 100-125 psi your injectors will stick open, so be careful.
HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED
Jake wrote:i am on a stock 2k2 FPR (them have higher fuel pressure then the pre 2k ones from what i noticed).
are you sure about this?
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- Sold my beloved J in April 2010 -
How far will the side bolt come uunscrewed until it comes out? I cant get it over 60PSI in boost, thats scary. Anyone have bigger injectors they want to sell?
http://members.cardomain.com/vertz24 1998 Z24 Convertible
^^ The side bolt wont come off when u unscrew it out all the way....Only way to get if off is unscrew the whole housing that its in. 60 psi you could be ok. You really should get some type of wideband so you know whats goin on.
On mine I have idle pressure at 40......and in boost its 60....my a/f's are mid 11s with the alky and low to mid 12s without the alky.
Car is for Sale!Supercharger kit is for sale!
Oh and also......that is on the s/c injectors.....
And also I was originally running 80psi in boost..........but then I turned down the fmu to see what would happen and now im at the 60psi in boost.....and still running the same a/f's......I dunno whats up with that but whatever works I guess....
Car is for Sale!Supercharger kit is for sale!
You're ADJ FPR and Cartech FMU are able to do the same things to base fuel pressure, so you don't need both, and should only be adjusting one.
My base is set to 58psi via adj fpr, and goes to 64 at WOT (no boost).
Yes the '99.5+ (newer , smaller injectors) run a higher base fuel pressure than the older ones with bigger injectors.
15.3 @ 89.97mph, 14's on the way?
58PSI Is a very high idle fuel pressure isnt it? I had my car running at 50 PSI idle and it was richer than trump. Also it made the car idle like crap, 45 PSI seems to work great. The point of the FMU was to add more fuel when in boost, I would like to get it to 65 PSI or better in boost over my 60. Anyone know how to do this? Also I just bought SVo 36# injectors to help out the engine, are they direct replacement?
http://members.cardomain.com/vertz24 1998 Z24 Convertible
My base or idle fuel pressure with the 370cc Brown Tops is 30psi, anything more than that and my car doesnt idle smoothly. Even at 30psi the car is still a bit too rich. I'm also not sure what my cars runs as far as fuel pressure under boost but I do know that the a/f ratio's are in the mid 11's under boost with the Alky, I run my alky 100% of the time so I have no non-alky numbers. I also have a vortech FMU set at 3:1 and the Apexi SAFC2 which I use in conjunction with the wideband to take fuel out at different rpm incremements according to the wideband charts I have.
"Horsepower is the Ultimate Accessory"
It sounds to me like your onset screw (the one on top) is set to low. Basically, pull your vacuum line off the fmu and watch your fuel pressure, if nothing happens then most likely it's set to low. The way mine is set, I see 60 PSI at only 2psi of boost, so you should have no problems gettin to 65.
As for the question about stock idle pressures, my 2000 idled at 53 psi stock.
2000 Turbo Z
Interesting what you said about the top screw, I have no clue what it does. It seems to be all the way down, but I tried unscrewing it and it just unscrewed. How can I adjust this?
Hey Jimmy, I will give you 50$ if you let me use your wideband at the track on the 19th. Are my 320s enough for my engine, or do you think they are beeing pushed too hard? Remember I have about the same engine as you (9.0.1 compression, ported exhaust runners, eagles H's, JE pistons, and the .020 over). So with the 2.6 pulley and alky, and stock fuel pump could I lean the car out, or will it keep up (I understand without a wideband I just have to check my plugs to get the best measurement, I dont care if its a bit rich).
I am registering the car on the 17th, and going to the track 20th, spencer the 19th for a short run. I have been letting the car run and driving it a little to break in on the normal oil, then I am switching to royal purple.
So will the 320s hold up? And any more on how to tune with the FMU???
http://members.cardomain.com/vertz24 1998 Z24 Convertible
i would think the 320's should be sufficient for you setup. As for tuning the FMU i dont use the adjustable ones, i've only ever used the ones where you switch discs out (vortech) my wideband isn't portable man sorry
The cable is ran through my car and loomed into my harness, if i could let ya use it i would
"Horsepower is the Ultimate Accessory"
Okay, I thought I would ask I have heard of some being portable. So the 320s should be enough, then it has to be the FMU. I think I just need more adjusting. Still not sure if I adjust the top or side bolts though. The top screw I am unsure about. I am finishing the alky today so hopefully I will fire it up and see how it runs.
Jimmy you going to the track for the street meet? I think it is sunday the 20th, I gotta check.
http://members.cardomain.com/vertz24 1998 Z24 Convertible
Hey Chris sorry man i won't be there on the 20th, I have an area show that i'm going to be promoting the club at that day. I plan on hitting up NYIRP in June sometime after I get the new clutch and flywheel in the car, as of right now when i speed shift im slipping still in 4th damn gear
Damn centerforce dual friction didn't help me much
I'm going with spec stage 3 and lightened flywheel now.
"Horsepower is the Ultimate Accessory"
That makes me nervous, I had the spec stge 1, and "Upgraded" to the centerforce stage two. I hope it holds up, it looked to be a lot beefier. Actually NYIRP is the 21st for the 1/4, I will be going, if I dont get in the 14s I am going to hang myself. They sent me the wrong switch for my alky kit so I have to wait to finish it up, but I hard wired it and man is it cool. I cant believe how well it mists the methanol. Will I really feel a difference with it?
http://members.cardomain.com/vertz24 1998 Z24 Convertible
Also one more question, will the methanol also aid in cooling of the incoming air fuel mixture, thus decreseing the chance of overheating and detonating? That would be sweet, I am afraid to blow this biatch up.
http://members.cardomain.com/vertz24 1998 Z24 Convertible
Chris Fontana wrote:Also one more question, will the methanol also aid in cooling of the incoming air fuel mixture, thus decreseing the chance of overheating and detonating? That would be sweet, I am afraid to blow this biatch up.
It will help with detonation, but not overheating per say.
15.3 @ 89.97mph, 14's on the way?
the alky and methanol will lower your IAT temps. My temps are usually a bit below ambient unless it's extremely hot outside. The point of the alky injection is to "chemically" intercool the supercharger so in that regard it does aid with cooling and also virtually eliminating detonation. Without alky it's simply not safe to run high boost numbers on the gm s/c. You will feel a bit of an increase throughout the rpms with the alky turned on, however it's not nitrous or anything so don't expect anything that drastic lol.
"Horsepower is the Ultimate Accessory"
