ETXtreme99
Newbie
1999 S10 Xtreme - 5.7L Vortec Swap from a 1998 K1500 Silverado. VIN number verified from donor truck, motor has less than 100k miles, more than 60k.
This truck ran and drove flawlessly when I bought it from the previous owner up in OK in October. Drove it daily with zero issues, other than a pesky O2 sensor code causing a check engine light. Oil looked good and coolant was clean at purchase, both are still clean now.
Late March/early May I had to park the truck for a few days as I caught pneumonia, when I went to drive it to work the day after I was cleared, it made it about 15 miles then started running extremely rough going down the road. Started only under load or going up a hill. Checked codes to see a knock sensor code (don’t have it at the moment, can search back for it after I get off work and update the thread). Put a can of Berryman’s B12 through it in addition to a tank of 93 fuel to clean up any injector gunk that might have been causing the misfire. When that didn’t work, I put new plugs (AC Delco Platinum) and wires also ACD brand on the motor. Still no fix. Put two brand new Bosch Wide Band O2 Sensors on it (past where the cats would be if they were there), as well as a new Intake Plenum, Fuel Injector assembly, Fuel Pressure Regulator, Fuel Delivery Line O-rings, and a Fuel Filter. None of that worked, so I replaced the knock sensor pigtail and traced the wire to the ECU to make sure nothing was amiss. Still no luck. On to the fun part.
Truck will idle clean as a whistle when it’s cold, and even when it warms up idle is perfect. You can leave it in park and blow the mufflers off of it, no issues, no sputtering, no backfires. Motor will sing like brand new. Only when you get the truck moving will it have hiccups. Anywhere from 30mph-70mph, around 25-50% throttle, the truck shudders and spits, hesitating and missing like crazy, however if you stomp on it, it has no hesitation to absolutely shred the rear tires at any speed. Only time there is an issue with the idle is when the truck is at operating temperature, in gear and stopped, a slight roughness will kinda shake the truck (think like small RV cam level shake/drop in RPM). Timing shows dead on 0° with the only change on live data while driving is knock retard, usually about 4°. Knock sensor code has come back, but is a different code than the first. (I’m assuming one was no communication due to a bad pigtail and the new one is low voltage, again, I’ll post the codes when I get a chance to pull them again).
Definitely the engine, I’ve read a lot on here where people say look at the torque converter or what have you. This is 100% without a doubt the motor. Question is what gives? Any insight would be appreciated, I have absolutely fried my brain and destroyed my sleep schedule trying to figure out what this issue could be, and it is plaguing me still.
This truck ran and drove flawlessly when I bought it from the previous owner up in OK in October. Drove it daily with zero issues, other than a pesky O2 sensor code causing a check engine light. Oil looked good and coolant was clean at purchase, both are still clean now.
Late March/early May I had to park the truck for a few days as I caught pneumonia, when I went to drive it to work the day after I was cleared, it made it about 15 miles then started running extremely rough going down the road. Started only under load or going up a hill. Checked codes to see a knock sensor code (don’t have it at the moment, can search back for it after I get off work and update the thread). Put a can of Berryman’s B12 through it in addition to a tank of 93 fuel to clean up any injector gunk that might have been causing the misfire. When that didn’t work, I put new plugs (AC Delco Platinum) and wires also ACD brand on the motor. Still no fix. Put two brand new Bosch Wide Band O2 Sensors on it (past where the cats would be if they were there), as well as a new Intake Plenum, Fuel Injector assembly, Fuel Pressure Regulator, Fuel Delivery Line O-rings, and a Fuel Filter. None of that worked, so I replaced the knock sensor pigtail and traced the wire to the ECU to make sure nothing was amiss. Still no luck. On to the fun part.
Truck will idle clean as a whistle when it’s cold, and even when it warms up idle is perfect. You can leave it in park and blow the mufflers off of it, no issues, no sputtering, no backfires. Motor will sing like brand new. Only when you get the truck moving will it have hiccups. Anywhere from 30mph-70mph, around 25-50% throttle, the truck shudders and spits, hesitating and missing like crazy, however if you stomp on it, it has no hesitation to absolutely shred the rear tires at any speed. Only time there is an issue with the idle is when the truck is at operating temperature, in gear and stopped, a slight roughness will kinda shake the truck (think like small RV cam level shake/drop in RPM). Timing shows dead on 0° with the only change on live data while driving is knock retard, usually about 4°. Knock sensor code has come back, but is a different code than the first. (I’m assuming one was no communication due to a bad pigtail and the new one is low voltage, again, I’ll post the codes when I get a chance to pull them again).
Definitely the engine, I’ve read a lot on here where people say look at the torque converter or what have you. This is 100% without a doubt the motor. Question is what gives? Any insight would be appreciated, I have absolutely fried my brain and destroyed my sleep schedule trying to figure out what this issue could be, and it is plaguing me still.
