OldGlory91
Newbie
First off guys, I'm at a loss with this issue. I bought this truck a little over a year and a half ago from the original owner. The guy was meticulous with maintenance and overall care of this truck. I have a complete record of EVERY oil change, part replacement and service. All done by recommended time and/or mileage. It's a 91' K1500 350 TBI with 245k on it. Top half was rebuilt at 216k. I bought it in the summer and it ran great until last winter. Our winters are mild so the problem was intermittent. By the end of the cold season is when I put it together that it was only happening when it's cold outside. By then it had warmed up (60+ degrees) and no more issues. This winter it started back up stumbling. So I've been on a mission to try and fix it and I'm stumped as could be.
The issue:
Only when its cold outside (temp below 55 degrees) does it stumble at idle. While driving under a load it hesitates/surges also. However, if I mash the gas, it roars to life and no issues. After doing this and letting off at cruising speed it goes back to hesitating/missing. After running for 20 minutes to 1/2 hour it doesn't do it as bad but still does it. I cant for the life of me think of how the outside temperature has this effect on my truck. I thought it might be the fuel pump acting up but over the summer I didn't have a single issue with it and it's been a year so I figured it would have crapped out on me by now. Over the course of the last 2 months I've replaced a few things in hopes to resolve this problem. They are:
ignition pick up
ignition module
cap/rotor
plugs/wires
map sensor
fuel filter
2009 at 216k when the upper 1/2 of engine rebuild, these items where replaced:
rebuilt injectors
tps
iac
egr
pressure regulator
pcv
coolant temp sensor&sender
thermostat
2011 at 225k these were replaced:
knock sensor and connector
oxygen sensor
fuel injectors
pressure regulator
I've checked all of my vaccum lines to find no issues. My ignition coil ohms out. My ignition wires are separated and not touching each other or manifolds. No codes stored. Sprayed intake cleaner around intake gasket and tbi gaskets to check for vacuum leak. No leaks. My guess are possible bad pcm, or intermittent ignition coil issue or maybe something related to the timing advance system. Any and ALL help is appreciated guys.
The issue:
Only when its cold outside (temp below 55 degrees) does it stumble at idle. While driving under a load it hesitates/surges also. However, if I mash the gas, it roars to life and no issues. After doing this and letting off at cruising speed it goes back to hesitating/missing. After running for 20 minutes to 1/2 hour it doesn't do it as bad but still does it. I cant for the life of me think of how the outside temperature has this effect on my truck. I thought it might be the fuel pump acting up but over the summer I didn't have a single issue with it and it's been a year so I figured it would have crapped out on me by now. Over the course of the last 2 months I've replaced a few things in hopes to resolve this problem. They are:
ignition pick up
ignition module
cap/rotor
plugs/wires
map sensor
fuel filter
2009 at 216k when the upper 1/2 of engine rebuild, these items where replaced:
rebuilt injectors
tps
iac
egr
pressure regulator
pcv
coolant temp sensor&sender
thermostat
2011 at 225k these were replaced:
knock sensor and connector
oxygen sensor
fuel injectors
pressure regulator
I've checked all of my vaccum lines to find no issues. My ignition coil ohms out. My ignition wires are separated and not touching each other or manifolds. No codes stored. Sprayed intake cleaner around intake gasket and tbi gaskets to check for vacuum leak. No leaks. My guess are possible bad pcm, or intermittent ignition coil issue or maybe something related to the timing advance system. Any and ALL help is appreciated guys.
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