After replacing grounds today, I decided to take her out for a spin. In 3rd gear, I didn't have any knock but at around 55mph thru 65mph, Scanmaster O2 numbers were 770 and 780 and 765. I am running a TT 93 octane chip and 1st and 2nd gear would go to 20psi then settle in 3rd gear to 15-16psi. I also noticed that at around 60psi fuel pressure, my gauge was fluttering. When I saw the fluttering, I took my foot off the gas. I'm not sure if I should bump up fuel in the chip or does the fluttering needle mean my fuel pump can't keep up with demand? All other Scanmaster numbers looked good.
Leaning out mid-top of 3rd gear-Please advise.
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toomanymodz
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60psi fuel pressure is normal for 16psi boost. (43 base + 1 for every # of boost). How do you know you're leaning out? By the O2 numbers? 765 - 780 isn't lean at all. I run mine all the way down to 740's - 750's at the end of a run (the wideband is set at 11.2 to 1 AFR). You mention the needle fluttering. How much are we talking about? A slight amount or is it bouncing from say 50 to 60 psi?
If you're gonna run lean, it will be when your boost is at 20psi, assuming you've tuned it for the 15-16psi. Need to get a handle on your boost being all over the place in my opinion.
If you're gonna run lean, it will be when your boost is at 20psi, assuming you've tuned it for the 15-16psi. Need to get a handle on your boost being all over the place in my opinion.
I've ordered a RJC Boost Controller to get a better handle on the boost. It makes me nervous to see 20psi in 1st and 2nd to drop to 16 in 3rd. The car seems to loose steam when this happens. I was looking at Scanmaster O2's to let me know of lean through it's recall. I thought mid 700's was too low? The needle was bouncing around about 6psi in the fuel gauge at about the 60psi mark when 20psi started in 2nd gear. The fuel filter is new and no leaks.
I'd be looking at my pump if wiring and electrical are verified as you stated ie: grounds, hotwire, filter, etc. Good alternator voltage? Those O2's are ok without knock and no alky but the NB is a guess and varies with temp and pressure so different boost levels show different O2s at the same AFR.
Bingo!
dw from nick at www.arizonagn.com
3.8L V-8 eater
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Try this if you have an adjustable regulator with a gauge on the rail...Lossen the nut on the regulator and slowly start turning the stud to increase pressure...The pressure should go all the way to 100lbs...If it gets to say 70lbs and the needle starts bouncing and can't get near the 100lbs you have a bad fuel pump...
You do this key on engine off, correct ?
3.8L V-8 eater
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I've never adjusted fuel pressure with key on and engine off....Start the car and verify it with the engine running....
Mike Licht
I was here first
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I doubt an intank will get to 100PSI usless the overpressure valve is shimmed or tapped closed. Just jump the FP test port with the key on engin off and run it up to 70 PSI and see if it is steady, My guess is the pump is fine and the gauge is seeing the pressure waves in the rail from the injectors opening and closeing. Lots of gauges do that. Your not geting lean 750 is fine. You don't seem to have knock which you would if the pump was bad.
Mike
Mike
3.8L V-8 eater
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I've done this on two different cars it will go to 100lbs....When my buddy diagnosed a bad pump it would go to about 55 to 65 fluttering around....Car ran horrible super lean on the wideband surprizingly with no knock?? The alky was keeping away the knock....
I hope you get the fuel delivery problems sorted out. From my own experience installing an rjc boost controller and bypassing the factory boost solenoid solved some issues for me (boost would spike to 20psi then settle to 16). And this was after I had already replaced all of my vacuum hoses from advice I had received here on the board (which was still very good advice). Lots of learning experiences with these cars. Mine started out bone stock and was parked for 15 years so I've had lots of other bugs to fix too.
Yea, I hope my gauge just needs to be replaced. I've replaced all vacuum lines and even put in a new engine harness when I purchased the car 12 years ago. She's been sitting the last 5 years in the garage. I just re-did the grounds to 10ga. and changed the fuel filter. I've also upgraded injectors and turbos about 3 times so far! The need for speed is strong with these cars
