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04ctd · 03-20-2013, 04:49 PM

Mike had this truck, and put a lot of parts on it (dizzy, plugs, wires) and it still idled rough, and cold idle was waaay too high.

Griffin Transmission & Small engine repair put the dizzy in, and it all looks good, and it runs GREAT on the interstate, and at any speed. just not at idle

looks like they put a 195 T-stat in it.

I have been working on it two months, and have fixed alot of small things: adjusted valves, adjusted timing half a dozen times, replaced dry rotted vacuum hoses, fuel pressure regulator, EGR valve, PCV valve, new tensioners & pulleys, new fan belt.

fuel filter looks recent, so left it.

pulled the IAC, and cleaned it. that's huge concern on the TBI forums.
http://www.chevytalk.org/fusionbb/sh...hp?tid/189758/
I took it out and cleaned it up, reinstalled it, that helped alot with the cold idle.

if you read here, you will see the EGR seems to be the culprit, this page is worth book marking:
http://www.chevytalk.org/fusionbb/sh...php?tid/258416

well...now the cold idle is dead on, perfect, and it runs GREAT at speed,
i have the timing at the lowest spot that works, and it does run good.
it pulls hard from down low, clear up to 80mph or so. runs 75mph with ease, set the cruise, and let that 350 eat.

but, when it gets warm...(when the EGR opens?) it idles about 20% rough.

it varies though, it used to idle about 45% rough, then it got to about 65%, where it seemed like it might die.

but now with the new EGR, and a few vacuum hoses replaced, it is about 20% rough, it don't feel like it's going to die, and it is not shaking the whole truck anymore, but you can feel it missing.

i was thinking get a set of vacuum cap plugs, and just plug off all the vacuum stuff, esp the EGR.

what do you guys think?

here's the scenario: you leave house cold, and it's smooth. hit on ramp at college park, doing 80mph by bottom, smooth all the way, get to work, it's warmed up, and sitting in traffic, it's missing.

same thing on way home: great on way, till get off I and into traffic, and it is missing.

so it's not a big deal..it's just annoying to run SO GOOD, and miss a little when it's warmed up

Edit: this truck did have a LONG start...which i though was fuel draining back into the tank, or the fuel pressure regulator leaking. with the new EGR, it cranks a lot faster.

03-20-2013, 04:49 PM	#1
04ctd Senior Member Join Date: Aug 2009 Location: Ladson SC Posts: 4,388	Anyone a TBI idle expert? Mike had this truck, and put a lot of parts on it (dizzy, plugs, wires) and it still idled rough, and cold idle was waaay too high. Griffin Transmission & Small engine repair put the dizzy in, and it all looks good, and it runs GREAT on the interstate, and at any speed. just not at idle looks like they put a 195 T-stat in it. I have been working on it two months, and have fixed alot of small things: adjusted valves, adjusted timing half a dozen times, replaced dry rotted vacuum hoses, fuel pressure regulator, EGR valve, PCV valve, new tensioners & pulleys, new fan belt. fuel filter looks recent, so left it. pulled the IAC, and cleaned it. that's huge concern on the TBI forums. http://www.chevytalk.org/fusionbb/sh...hp?tid/189758/ I took it out and cleaned it up, reinstalled it, that helped alot with the cold idle. if you read here, you will see the EGR seems to be the culprit, this page is worth book marking: http://www.chevytalk.org/fusionbb/sh...php?tid/258416 well...now the cold idle is dead on, perfect, and it runs GREAT at speed, i have the timing at the lowest spot that works, and it does run good. it pulls hard from down low, clear up to 80mph or so. runs 75mph with ease, set the cruise, and let that 350 eat. but, when it gets warm...(when the EGR opens?) it idles about 20% rough. it varies though, it used to idle about 45% rough, then it got to about 65%, where it seemed like it might die. but now with the new EGR, and a few vacuum hoses replaced, it is about 20% rough, it don't feel like it's going to die, and it is not shaking the whole truck anymore, but you can feel it missing. i was thinking get a set of vacuum cap plugs, and just plug off all the vacuum stuff, esp the EGR. what do you guys think? here's the scenario: you leave house cold, and it's smooth. hit on ramp at college park, doing 80mph by bottom, smooth all the way, get to work, it's warmed up, and sitting in traffic, it's missing. same thing on way home: great on way, till get off I and into traffic, and it is missing. so it's not a big deal..it's just annoying to run SO GOOD, and miss a little when it's warmed up Edit: this truck did have a LONG start...which i though was fuel draining back into the tank, or the fuel pressure regulator leaking. with the new EGR, it cranks a lot faster. __________________ 1 Timothy 3:16 16 And without controversy great is the mystery of godliness: God was manifested in the flesh, Justified in the Spirit, Seen by angels, Preached among the Gentiles, Believed on in the world, Received up in glory. Last edited by 04ctd; 03-20-2013 at 04:58 PM.