Yellow Bullet Forums banner
1 - 20 of 27 Posts

·
Titanium Member
Joined
·
12,293 Posts
Discussion Starter · #1 ·
My truck(1996k2500,5.7,160K miles)has just started idling slighty higher than normal when coming to a stop,in gear or in neutral.
It's only about 200rpms,guessing.Its not much.
Then returns to normal lazily,about 10 seconds later.
Is this a sign of a failing sensor?
Just replaced a few ignition parts a few weeks ago,it shut off on me.Was either cam sensor,coil,or ignition control module.Replaced all three and it fired back up and runs good,except for this new rpm thing creeping in.
 

·
Titanium Member
Joined
·
12,293 Posts
Discussion Starter · #5 ·
has it surged while driving? could be throttle position .i would pull the IAC and clean that could be carboned up do you have scanner to view live data
No scanner.No surging.Just staying a little high on the idle when coming to a stop,then normal a couple seconds later.
 

·
I kill parts
Joined
·
11,362 Posts
did you do the crank sensor relearn/verify cam sensor offset after swapping the cam sensor? - It will run outside of range but has to be within a couple degrees to run properly
 

·
Titanium Member
Joined
·
12,293 Posts
Discussion Starter · #7 ·
I didnt replace the crank sensor,and just bolted in the new cam sensor.This idle thing came up some time after,but not within two weeks
 

·
Titanium Member
Joined
·
12,293 Posts
Discussion Starter · #15 ·
So this little bug when coming to a stop would most likke be a vaccuum leak then?I wouldve thought it would surge and run rough with a constant vac leak.I immediatly went to a sensor,lol.Everything is original to the truck though,except distributor,and the assorted ignition parts to get it back running.
I'll check that vac hose to the booster.
 

·
Registered
Joined
·
341 Posts
So this little bug when coming to a stop would most likke be a vaccuum leak then?I wouldve thought it would surge and run rough with a constant vac leak.I immediatly went to a sensor,lol.Everything is original to the truck though,except distributor,and the assorted ignition parts to get it back running.
I'll check that vac hose to the booster.
CRANK/CAM CORRELATION! OR AT LEAST CHECK THE BASE TIMING WITH A SCANNER! IF IT'S NOT WITHIN SPEC, YOU WILL ONLY BE FIRING PARTS AT IT AND WASTING MONEY.
 

·
Registered
Joined
·
3,942 Posts
So this little bug when coming to a stop would most likke be a vaccuum leak then?I wouldve thought it would surge and run rough with a constant vac leak.I immediatly went to a sensor,lol.Everything is original to the truck though,except distributor,and the assorted ignition parts to get it back running.
I'll check that vac hose to the booster.
It most likely is NOT the brake booster or hose. That large of a leak will cause more than just hanging idle on decel. Easy test to see if the booster is leaking is while the truck is running at idle pinch the booster hose closed with a pair of needle nose pliers and see if the idle changes. If it does you have a leak.

Since you replaced the skibidder it is possible the timing is too far advanced and causing it. Need to check and set the timing to specs.

A small vac leak won't necessarily make it run rough but it will cause exactly what you're describing. Easiest way to tell from your scan data is if the IAC is abnormally low or closed at idle. It's going to try to make up for the unmetered air at idle by closing more than normal. On decel it will have a cruise control effect or hanging idle, until you stop and it goes into idle mode and the IAC closes up to try to get it to target idle.

Easiest thing to do is smoke it with a smoke machine.
 
1 - 20 of 27 Posts
Top