what causes car to run lean?
what causes car to run lean?
I have a recently installed ca18det, headers 3'' exhaust, sr turbo, fmic, and spectre airfilter. My fuel pressure is around 35 lbs and idles decent. From a stop the car revs fine and acts normal but under load the car is very sluggish and I was told running lean. I am running a Ka maf and stock ecu, should my car run ok with that combination of parts? do I need a 255 fuel pump do you think? Thanks z
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rsmithdrift
- Posts: 1984
- Joined: Fri Jan 27, 2006 2:18 pm
- Car: 1993 240sx fastback se.
Re: what causes car to run lean?
Ok I see the problem already. the stock fuel pump should put out about 44 psi. And that's for the KA.
If you have a upgraded turbo charged CA then their is no way that that is an adequat fuel preassure. My near stock KA wouldn't run with 20psi so yeah, 35 is prolly just enough for it to run at idle and rev, but under load you'll just get nasty detonation from running lean and that'll kill your power and cause sputtering/hesitation right their, and detonation will retard your timing which will kill your power even more. So yeah, that's the problem. Not enough fuel.
Your stock pump is dying and it wasn't good enough to begin with. Replace it with a Walboro 255 lph one ASAP. Then if it's still having problems you can start looking elsewhere like fuel maps and injectors and whatnot. But until you have proper fuel preassure you can change every part under the hood and it'll still run like crap.
If you have a upgraded turbo charged CA then their is no way that that is an adequat fuel preassure. My near stock KA wouldn't run with 20psi so yeah, 35 is prolly just enough for it to run at idle and rev, but under load you'll just get nasty detonation from running lean and that'll kill your power and cause sputtering/hesitation right their, and detonation will retard your timing which will kill your power even more. So yeah, that's the problem. Not enough fuel.
Your stock pump is dying and it wasn't good enough to begin with. Replace it with a Walboro 255 lph one ASAP. Then if it's still having problems you can start looking elsewhere like fuel maps and injectors and whatnot. But until you have proper fuel preassure you can change every part under the hood and it'll still run like crap.