Brandon45
Member
Hello all!
To start off, I have a 2000 Silverado 1500 with a 4.8l and it is also 4x4. Has 365,000 miles on it and bought it as somewhat of a project truck to restore. The engine has been replaced with a junkyard engine with ~145,000 miles on it currently and the transmission has ~100,000 miles on it. I have installed a transgo shift kit and some other valvebody stuff but it was doing this stuff before that too. I have just replaced the output shaft bushing in the transfer case due to ~1/8" of up and down play in it, and I replaced the transmission mount while I was at it.
Now that that's out of the way, lets get on to my problems:
1. When I let off the gas and get back on (lower speeds mainly) I can hear and feel an obvious clunk that sounds like its coming from the rear of the truck. The diff has around 1/8 of a turn of play, with no up and down or side to side play. It is a G80 that as far as I know is the original diff. Does this almost every time when I slow down for taking a turn then getting back on the gas when exiting the turn.
2. Sometimes when I start the truck I will hear a clunk but can't really identify where it is coming from. Does it far less often since the bushing was replaced in the transfer case.
3. If I quickly jab the throttle to more than about 25% from a stop I will feel a sort of double lurch. They are not sharp but it will start accelerating somewhat slow then will lurch into a faster acceleration. Does this whether or not the gas tank is full or empty. I'm thinking this could be related to the torque converter as when I'm on the highway and I get the transmission to unlock the TCC in 4th, when it locks up again I have to get off the gas and then back on to make sure the TCC fully engages (if I don't do this it will slip anywhere between 10-200 RPM depending on throttle position). I have installed a Fitzall TCC valve, which made the problem way better than it was (would slip ~50% of the time and had to get off and back on the gas multiple times in order for it to lock up).
4. The engines idles somewhat rough. The felt vibrations got worse after replacing the transmission mount. The RPM only jumps around 10-15 RPM (I have an ultra gauge hooked up to monitor transmission temps) but it feels like a misfire. I have a scanner that does show it is misfiring occasionally (randomly on all cylinders) when it is idling but not all the time when it is idling rough. Fuel pressure checked out good and all the injectors were within tolerance for pressure drop when using the method from the charm.li diagnostic guides. Long term fuel trims normally stay between -2% and +2%. Sometimes when I come to a stop they will be at -10% but will quickly recover to somewhere in the previous mentioned range. The engine has been sounding more "whiny" and high pitched around 1500-1800 RPM recently. Never misfires when driving, only when idling or giving throttle in park/neutral (ONLY at idle in drive). Feels better with the AC on also.
Sorry for the rambling! This is pretty much everything that I'm having trouble with. If you have any questions just let me know I'll try my best to answer. Thanks!
To start off, I have a 2000 Silverado 1500 with a 4.8l and it is also 4x4. Has 365,000 miles on it and bought it as somewhat of a project truck to restore. The engine has been replaced with a junkyard engine with ~145,000 miles on it currently and the transmission has ~100,000 miles on it. I have installed a transgo shift kit and some other valvebody stuff but it was doing this stuff before that too. I have just replaced the output shaft bushing in the transfer case due to ~1/8" of up and down play in it, and I replaced the transmission mount while I was at it.
Now that that's out of the way, lets get on to my problems:
1. When I let off the gas and get back on (lower speeds mainly) I can hear and feel an obvious clunk that sounds like its coming from the rear of the truck. The diff has around 1/8 of a turn of play, with no up and down or side to side play. It is a G80 that as far as I know is the original diff. Does this almost every time when I slow down for taking a turn then getting back on the gas when exiting the turn.
2. Sometimes when I start the truck I will hear a clunk but can't really identify where it is coming from. Does it far less often since the bushing was replaced in the transfer case.
3. If I quickly jab the throttle to more than about 25% from a stop I will feel a sort of double lurch. They are not sharp but it will start accelerating somewhat slow then will lurch into a faster acceleration. Does this whether or not the gas tank is full or empty. I'm thinking this could be related to the torque converter as when I'm on the highway and I get the transmission to unlock the TCC in 4th, when it locks up again I have to get off the gas and then back on to make sure the TCC fully engages (if I don't do this it will slip anywhere between 10-200 RPM depending on throttle position). I have installed a Fitzall TCC valve, which made the problem way better than it was (would slip ~50% of the time and had to get off and back on the gas multiple times in order for it to lock up).
4. The engines idles somewhat rough. The felt vibrations got worse after replacing the transmission mount. The RPM only jumps around 10-15 RPM (I have an ultra gauge hooked up to monitor transmission temps) but it feels like a misfire. I have a scanner that does show it is misfiring occasionally (randomly on all cylinders) when it is idling but not all the time when it is idling rough. Fuel pressure checked out good and all the injectors were within tolerance for pressure drop when using the method from the charm.li diagnostic guides. Long term fuel trims normally stay between -2% and +2%. Sometimes when I come to a stop they will be at -10% but will quickly recover to somewhere in the previous mentioned range. The engine has been sounding more "whiny" and high pitched around 1500-1800 RPM recently. Never misfires when driving, only when idling or giving throttle in park/neutral (ONLY at idle in drive). Feels better with the AC on also.
Sorry for the rambling! This is pretty much everything that I'm having trouble with. If you have any questions just let me know I'll try my best to answer. Thanks!
