Idle issue.

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un4givn85

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hmm, so is something wrong with mine then? its pretty audible under the hood. dont hear it when its shut.
 

DerekTheGreat

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Well an upload of it in progress would be great but if it's like what you mentioned, it's most likely the IAC stepper motor being all wonky like someone else mentioned. When I verified base idle on my truck by grounding out the ALDL pins and such I could hear a bunch of noise from under the hood until I disconnected it per procedure. So, you could just try unplugging your IAC and then starting your truck to see if anything changes.
 

un4givn85

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Well an upload of it in progress would be great but if it's like what you mentioned, it's most likely the IAC stepper motor being all wonky like someone else mentioned. When I verified base idle on my truck by grounding out the ALDL pins and such I could hear a bunch of noise from under the hood until I disconnected it per procedure. So, you could just try unplugging your IAC and then starting your truck to see if anything changes.

Was this meant for this thread?

I can get a video of the noise, but no one has mentioned an IAC yet.
 

un4givn85

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Got home and pulled the vacuum line, idled perfect.
I'll throw in a new EGR and see how she acts .
Thanks for the tip.
 

un4givn85

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Got the new EGR in, idles much better, tho still stumbles a bit on occasion, but I'm pretty sure it did that before the really bad idle.
This stumble is almost like a miss, but very random and sporadic.
I'll see how it handles traffic tomorrow and report back.
 

DerekTheGreat

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Yeah, the IAC is certainly something to check. They can make noise if messed up. Stumble could be due to that and maybe the TPS. Back in December or so I swapped my TPS as it was causing a high idle problem, I also dialed it counter clockwise as much as I could to get the idle voltage to read less than 0.6 V (0.58) Well it sort of stumbled off idle and was much more noticeable in open loop. Over this past weekend I disconnected the battery to reset/clear the ECM and dialed the TPS clockwise as much as I could, did not hook the scanner up to see what actual voltage is. Anyway, I've noticed that the idle is much smoother (was hit or miss before, could be coincidental..) but also that off idle/tip in acceleration doesn't have that hesitation like before. So one of those two changes or both helped out immensely. My truck didn't exactly stumble but just didn't respond right away and then WHAM!, neck snap. It's also a stick so response is certainly different..
 

un4givn85

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My throttle does have that "neck snap" like response.
I'll test out the IAC and the TPS.
Thanks again for the help.
 

94burbk1500

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Got the new EGR in, idles much better, tho still stumbles a bit on occasion, but I'm pretty sure it did that before the really bad idle.
This stumble is almost like a miss, but very random and sporadic.
I'll see how it handles traffic tomorrow and report back.
If it's a parts store brand EGR (anything other than AC Delco), check it to make sure it functions as it should. The parts store junk can be hit or miss. If you depress the plunger on the EGR at idle, the truck should stumble if it is working correctly.
 

DerekTheGreat

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I used to fire the parts cannon a lot but now I find myself hoarding OEM parts if they're still functional. If the diaphragm holds vacuum, it's good. Clean the/any schmoo off the pintle and you'll be good to go.
 
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