my 89 gt is running reallly lean...my set-ups in my sig...should i bump fuel pressure up? cars getting tuned but not till the 21st of june ( they are booked)...thanks

yea thats a temp fix, it just makes it rich at lower rpms, but will keep you from leaning out in upper rpms

do you have a FPR (fuel pessure regulator)? Whats your idle Fuel pres. now?


Mine runs at 41psi @ idle 45psi @ 5800rpm on dyno-- in which i do have a n20 kit and 30lb injectors and dif heads, so therefore my engine needs more fuel.

hes got a mallory regulator in his sig.
start with 39 w/ vac off, then work your way up.

didn't see that part... Whoops. Do like Stinkin' said. you'll be fine. Buts it's a temp fix. A dyno tune will tell you how much the injectors are working at what % @ what rpm, and will also be able to squeeze out some more ponies i'm sure.

I'm just curious on how you determined that you are running lean

ok i got the fp up at like 44....pulled out number 1 plug out when installing my new rocker arms ( to find tdc) and my dad showed me i was lean....so i pulled number 5 out today and it was the same as number 1 so i bumped the fp up to 44 when vacum off..

remember..it's not as easy to read plugs on an efi car when it's running okay vs a carbed car......efi cars generally will show a whiter plug than a carbed car.....correct way to tell on a efi car is have a wideband set up to monitor a/f through whole rpm range and under all conditions;)

yea..well tuning shop is booked and im scheduled june 21..theres another mustang place img onna call tomorrow and see if they can do anything( i didnt go to them because i heard a lot of badd stuff) but i'll see what hapends

best bet would be to retard your timing a bit

+1--- like i said 89mustangfive0--- My car has some decent mods (read sig) plus some fuel upgrades and i'm at 41psi @ idle... and after checking my plugs every 3-4months i still get that grey'ish tint to them, but my tune says it's all good.... Just wait for the tune... When your car is warming up. Do you smell the exhausteasily?- Kinda like gas fumes--- you know like a rich burning car? if so, it's not lean.... just need a tune.

yes lol i can smell fuel on start-up now that i bumped the fp up...

its rich at idle put itthrough the rpms--- who knows until you tune it. Fuel Pressure should go up w/ rpms.---- Lean will actually pop head/piston pretty much blow up... you can never go wrong with being rich--- There is such thing as being too rich... Wait for the tune you'll notice a diffrence.

yea i was just worried about wrecking stuff its my dd so im gonna be carefull driving it till the tune

i drove mine for about 1yr w/out a tune.... although i have the Zex n20 kit-- so therefore really no need to... and the guys that built knew what they were doing. Once i got stationed here, thats when i forked out the $$$ and got it dyno tuned. tune time + 3 pulls (on pump gas)was $475... Car runs betters, still has a rough idle (due to the cam), lill better gas mileage (although i dont care its a weekend car), and it ever revs a lill faster. Race gas tune was $300- pretty much the same as above (exceot the mileage part)but itpulls harder onracew/ n20-

514ftlbs race gace- n20
491ftlbs pump- n20

492rwhp n20 race gas
474rwhp n20 pump gasn20

321rwhp N/A- pump gas
331ftlbs N/A- pump gas

You'll prolly notice some of the same changes.

yea deffinelty better to be rich then lean, they have all told you correct, id just leave your fuile pressure between 41-44 till your tune and just be easy with it, you might have a injector issue or clogged fuel rail, (happend to me) also whats the cobra injectors? are they 24lb if i rember? or 30lb. make sure the mass air is correctly calibrated, good luck :)

cobra is 24lb injectors.

i have 24s on the car and a cobra maf for the injectos...i picked up a c&l maf and i have 30 pounders on the way ( got a sickkkk deal on them)