LT1 383 fuel trims.
Thread Starter
Joined: Jul 2005
Posts: 5,898
Likes: 255
From: Ft. Wayne, IN
LT1 383 fuel trims. Hey guy's. I just recently had a mailorder tune done and the long term fuel trims are +25 at idle? Part throttle the trims are +2 +5 and wot 0. I figured a mail order would get me close, but it almost seems like something mechanically might be causing this idk?
Mods are 10.1cr 383, 54cc ported stock lt1 castings 2.02 1.60 valves, ported lt1 intake, 58mm tb, 44lb injectors, comp custom grind 230-236 540-550 114, 1.6 promag rockers, 1 3/4 lt headers no cats, m6, 3.42 gear.
Also fuel pressure reads 42psi idle, vacum is 18psi at idle. The egr is deleted in the pcm, but I have not removed it yet. I just disconnected the egr solenoid from vacum(not sure if this is the cause). Also no dtc's and the o2's seem to be functioning correctly. I have two small exhaust leaks coming out of the exhaust band clamps connecting the y-pipe, but that's after the o'2s, so i don't think that's the problem. Most likely it prolly needs more tuning, but i figured that I would see what some of you guys think!!!
*Also if I reset the fuel trims the car runs it's best, once it learns the trims a lil surging begins to occur around 1800rpm in 4th and 5th gear.
Mods are 10.1cr 383, 54cc ported stock lt1 castings 2.02 1.60 valves, ported lt1 intake, 58mm tb, 44lb injectors, comp custom grind 230-236 540-550 114, 1.6 promag rockers, 1 3/4 lt headers no cats, m6, 3.42 gear.
Also fuel pressure reads 42psi idle, vacum is 18psi at idle. The egr is deleted in the pcm, but I have not removed it yet. I just disconnected the egr solenoid from vacum(not sure if this is the cause). Also no dtc's and the o2's seem to be functioning correctly. I have two small exhaust leaks coming out of the exhaust band clamps connecting the y-pipe, but that's after the o'2s, so i don't think that's the problem. Most likely it prolly needs more tuning, but i figured that I would see what some of you guys think!!!
*Also if I reset the fuel trims the car runs it's best, once it learns the trims a lil surging begins to occur around 1800rpm in 4th and 5th gear.
Last edited by kinglt-1; Aug 31, 2008 at 01:40 AM.
Thread Starter
Joined: Jul 2005
Posts: 5,898
Likes: 255
From: Ft. Wayne, IN
I will post logs soon as my new laptop battery shows up! Battery took a **** on me today while I was trying to log.
Also I only have proscan right now, it does not support enhanced pid's. Im going to be purchasing Jet dst/mxscan soon tho!
Also I only have proscan right now, it does not support enhanced pid's. Im going to be purchasing Jet dst/mxscan soon tho! Thread Starter
Joined: Jul 2005
Posts: 5,898
Likes: 255
From: Ft. Wayne, IN
Well after talking with the tuner today, Im leaning towards the o2's being the problem! I had to replace my o2's two seasons ago and I bought the bosh unit's! Well I am finding out from more people that these are junk! So I ordered some new ac delco afs75's today!
Thread Starter
Joined: Jul 2005
Posts: 5,898
Likes: 255
From: Ft. Wayne, IN
As of today, still same issue! Tried new delco o2's and fuel trims still +25 +25 at idle! I even swaped the bbk tb out for a stock unit and the fuel trims remain the same. Although the drivability did get better. I also fixed my exhaust leaks, still no change. At this point Im clueles to what's wrong. Still have not seen my new battery for my laptop, so I cant post any logs yet.
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Thread Starter
Joined: Jul 2005
Posts: 5,898
Likes: 255
From: Ft. Wayne, IN
I did get a few minutes to scan before my battery took a ****! The fuel trims are now +15at idle which is better. I noticed my maf is reading around 13 gps at idle? Thought the maf was suppose to show between 5-10gps at idle?
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