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post #1 of (permalink) Old 09-27-2003, 10:47 AM Thread Starter
 
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93 350 TBI Acting up....

Well its been quite a while since i've been on here, and even longer since i've made a post. Well anyways heres my problem. My truck when in Gear has low idle around 400 and when at stop lights its starting to die, now when its in P its seems to idle alot better. Not perfect but a whole lot better. Now my question is what could be causing this. I have new plugs, cap, rotor, ICM, pick up coil, fuel pump, TPS. The idle seems to change when i step on the brakes some, not alot but some. what could be causing my low idle while in gear? Any help would be great.
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post #2 of (permalink) Old 09-27-2003, 11:33 AM
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Re: 93 350 TBI Acting up....

hmm, if it changes when you step on the brakes, that makes me kinda think of the vacuum system for some reason. anyway, check all your hoses. for kicks, check your EGR valve. i realize you would be drawing a code if it were EGR, but, you never know.

also check your throttle cable, make sure it doesn't have too much slack in it. if it does, adjust the little screw thingy there at the throttle body.
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post #3 of (permalink) Old 09-27-2003, 12:53 PM Thread Starter
 
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Re: 93 350 TBI Acting up....

i've checked the EGR and it operates correct. i'll check the throttle cable here in a bit. One thing i forgot to mention above was that it only seems to run rough when the engine is at normal opertating temp. when the engine is cold it seems to run ok.. I just put a new fuel pump in yesterday. Untill i put a new pump in my truck would never acutally die at a stop light. seems like it just did that after i put the pump in. don't know if its just a fuke thing or if its related... it still idled really rough when warm before i put the fuel pump...
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post #4 of (permalink) Old 09-28-2003, 01:06 PM
 
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Re: 93 350 TBI Acting up....

When the engine is cold, the computer is in a different mode than when hot. If there is no problem when its cold, but it warms up and there is one, you probably have a bad sensor or two somewhere. When cold, the comkputer doesnt use info from the sensors. I would replace the O2 sensor, could be getting wierd readings and causing it to lower RPMs
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post #5 of (permalink) Old 09-28-2003, 02:20 PM
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Re: 93 350 TBI Acting up....

yup, i second the O2 sensor. also, check your cooolant temp sensor (CTS).
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post #6 of (permalink) Old 09-28-2003, 08:04 PM Thread Starter
 
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Re: 93 350 TBI Acting up....

i have replaced that bout 4 months ago... i also replaced teh coolant sensor.... [img]images/graemlins/confused.gif[/img] [img]images/graemlins/confused.gif[/img] [img]images/graemlins/confused.gif[/img]
one thing i haven't replaced are the plug wires. they look ok...
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post #7 of (permalink) Old 09-28-2003, 08:47 PM
 
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Re: 93 350 TBI Acting up....

maybe the IAC motor...the big sensor on the pass side of the TB...you can sort of clean it out with carb cleaner...if it helps, i'd replace it. They are about 30-40 bucks
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