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91 5.7 tbi idle problems cant figure it out please help
Ok when truck is cold high idle then starts to idle down. Then as it warms up it idled down then dies. If u give it a little gas it will stay running. Starts right back up if it dies no prob. I have a scan tool and checked everything. Has new egr iac cts intake gaskets new fuel presure regulator and spring. map checks perfect rock steady vacuum. Checked for vacuum leaks none. Cleaned tb and all ports are open and clean. Shows rock steady 20 vacuum at idle. Map shows 4.76v with key on motor dead at idle shows 1.11v. Iac pulse is around 23 or so fluctuates some as with the map it fluctuated a little as the iac tries to keep it running. The iac moves in and out to try to keep it running. Runs great everywhere else except idle it dies.
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ok heres what ive checked. tps shows .48 volts at throttle closed and volts go up smoothly as throttle is opened. map checks good 4.76v with motor dead 1.11 at idle flucuates some from 1.30 to .90 at idle. set timming dead on 0 with wire unplugged. iac moves out at high idle and moves back in to slow idle down and at idle shows pulses around 23 fluctuates from about 15 or so to about 30 as its trying to keep the idle steady moves out when motor starts to die to try to give more air but dies anyways. cts ive ohmed it and read the scan tool and showed exact temps where it should be. checked egr no leaks its new. checked everythinhg for vaccum leaks none that i can find. no codes. 02 sensor shows good volts fluctuates shows around .44 volts and fluctuates above and below as the idle is trying to be maintained and the scanner shows its fluctuating from rich to lean. spray pattern of the injectors shows a nice conical pattern. i can flatten a cig but and put it on the throttle stop and it idles great brings the rpms up to around 1000 or so.
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still messing with TBI crap around Hamilton, wow. Got a spare distrubor setting around, I remember they gave some stumbling idle issues, off top of my head. Do you have any trouble codes.
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ya theres alot of them around here lol. im actually in oglesby working on my motherinlaws truck she got for real cheap lol. i have an extra one in hamilton just not with me. is there anything wrong with the readings i gave? or any other info or readings i can give for a better understanding.
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it doesnt realy stuble just idles down and gets lower and dies. if u give it gas just to barely bring it off idle it runs like a top.
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Does it puff any black smoke when this is happening
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I had similar troubles with my 350 tbi. I replaced every sensor on the top of the motor amd it didnt fix the problem. I replaced the distributor cap and rotor and plugs wires and i ereased all yhe codes from the computer and it consistently threw the codes of everything id replaced. I got tired of fooling around so i got smart amd installed a 5.3 out of an 02 in it! Solved all my problems. (Not to mention the tranny was getting a little tired at 250000 miles) but i had talked to some folks around here amd i was told that as much as id replaced and worked on it was probably the computer for the tbi. Im not saying thats the problem but its a possibilty.
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Ya I understand that not my truck just want to make it run and not just put parts on it it don't need. That's why I'm running diognostics on it and checking wiring and all that good stuff.
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what is the fuel trim #'s look like and are there any codes, you could knock out plug on base idle adjustment on throttle body and adjust screw up a little, TPS a little low to my liking but IAC counts look good. Adjust screw up a little see what happens, doesn't cost anything. I think TPS should be somewhere between .60 to .80 V
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