Inexperianced and NEED help!!! Please
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From: Sad town of Hibbing,MN
Inexperianced and NEED help!!! Please llo everyone. So to get started I have an '02 Denali XL, .30 over LQ4, mildly ported 862s (I know I know, I'm workin in some 317s), Howards "ASA" cam and enough know how to change the cylinder volume with Hptuners. I really need help diagnosing something before I can start tuning and some advice on tuning if you have some input. My O2 in B1S1 just kinda does nothing and my fuel trims are just f***ed. Its a new sensor and I upped my idle 100 rpm across the board, with Hptuners, which slightly helped it not die but did nothing for my fueling issue on bank 1. B1S1 just kinda sits low and pours fuel in and B2S1 basically does what its supposed to. But another scan I unplugged the TPS (IAC at 310) and you can see B1 somewhat start to work and B2 hit damn near the bottom and start to flood that side. I have no idea what I'm working against here and would bring it to work (Dealership) and have the old (experienced) guys look at it but I can barely move it out of the garage let alone drive the 15 or so blocks to work. Someone please help me, I am new to tuning and haven't learned enough from work to help me. It dumps the fuel in so bad that I have to change the oil now. I'm very confident I have no intake leaks but will be double checking tomorrow. PLEASE someone point me in some direction to start.
Get a fuel pressure gauge on it and see if it builds and hold pressure when the engine is off. Im thinking u may have a stuck open injector. What are your fuel trims doing? Or maybe u havent ran it long enought yet? Will the engine rev up and clean up somewhat?
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From: Sad town of Hibbing,MN
Before I reset fuel trims bank 1 was off the charts, up to 53%!!! I can rev it to a point then in bogs down but just off idle it feels like it runs fine. Like the addition of the gobs of air evens it out though the scanner doesnt show it.
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From: Sad town of Hibbing,MN
Thanks for the info guys. This really helps me. I will be checking fuel pressure tonight when I get home. I talked to one of our A techs and he agreed. I figure the injectors are probably sticking. I can't rememer if I reused the injectors from the truck or the engine. Engine 120,000 miles, truck 303,000.
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From: Sad town of Hibbing,MN
So what would be an acceptable leak down for fuel pressure? I got 2 lbs in a minute. That seams exceedingly high! I remember in school doing the same test on a 96 Monte that was beat to hell, and having the gauge on an hour and it dropping maybe 2 lbs. Right now and its been about 5 minutes and 10 lbs its down. My fuel pump is brand new with maybe 4 to 10 hours of run time so I know its not the fuel pump check ball.
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Thread Starter
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From: Sad town of Hibbing,MN
So I didnt swap injectors becuase after posting remembered something then researhed LQ4 injector size. Figured out I had the bigger of the two sets In the truck. And also lost one of theother injectors... Otherwise I would have tried it regardless, .4 lbs difference would have at least shown me that it was the injectors. So minus the one injector I went to cleaning. I don't have a compressor so I couldn't use the cleaner from work, so I decided to Seafoam it instead. Well what I did was pull the rails, empty out the rest of the fuel and fill them with Seafoam. Then I triggered the injectors by jumping them and watching it drip on to white paper. I got some crud out and let them soak awhile. Well it seams to have worked for the most part, but I feel I have a different issue. My scans show B1S1 eventually starts working but jumps between 200 and 700 mv, which seems fairly normal. But as compared to B2S1 jumps between 20 and 950 mv, which to me would seem not abnormal for being untuned and the changes. My question is whats up the difference? I swiched the sensors and got the same result, and their the same Denso sensor. Could I have a bad FPR? PCM? Or maybe some F'd up wiring? I did port the heads myself so (if it's possible) could I have not gotten them even enough? I wouldn't think that little to cause such a large difference. Please any help or advice is better then what I've got right now.
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From: Denver, CO
Inexperianced and NEED help!!! Please Check for vacuum leaks and confirm good spark. If you get a misfire it'll look like a lean condition on the sensor and will trigger the engine to add fuel. Generally misfires will throw codes, but not always if it's intermittent.
That fuel pressure drop is normal, nothing to worry about there. The porting won't impact global trims that significantly, so don't sweat that either. If you have an exhaust leak upstream of b1s1 that could also cause and error in the readings.
We are all assuming a healthy engine here, but you may want to confirm that. A compression and/or leak down may give you some info or peace of mind. It sounds like the guys at work can help you with doing either and supplying tools if you aren't familiar with them. I'm assuming you are, but just trying to help brainstorm and rule things out without being there. Good luck man, you'll get it going soon!
That fuel pressure drop is normal, nothing to worry about there. The porting won't impact global trims that significantly, so don't sweat that either. If you have an exhaust leak upstream of b1s1 that could also cause and error in the readings.
We are all assuming a healthy engine here, but you may want to confirm that. A compression and/or leak down may give you some info or peace of mind. It sounds like the guys at work can help you with doing either and supplying tools if you aren't familiar with them. I'm assuming you are, but just trying to help brainstorm and rule things out without being there. Good luck man, you'll get it going soon!
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From: Sad town of Hibbing,MN
I believe that it's healthy, I have about 1800 miles or so on the rebuilt stock bottom end, minus the fresh 30 over pistons. I was having lifter issues so I put in new lifters a cam and ported the heads and new high volume/pressure oil pump since I had the top end apart. I will do a compression and leak down test anyway cuz then I can either rule them out or find the cause of those issues. I will start with number 5, found black sooty oil on the bottom of the spark plug boot shroud. Thought it was gas the first time I saw it cuz I touched it and it smelled like gas. Went back 3 days later without starting it and it was still there and wet. So I touched it, smelled it, then tasted it. Felt like oil, smelled like nothing (I have a poor sense of smell) and tasted like oil. So I'm gonna start there, also in that area I noticed a manifold bolt not seated all the way. So I have to figure that out too cuz it got torqued. This is all stuff I found in the last couple of days so I will do as suggested. Thank you very much for your help