Powertrain jolting at highway speeds

[Liam Oswald]

Started by checking distributor/wires which all look good..I’ve been having this ongoing issue with my 1997 Tahoe with 5.7 and 4l60e where at light to mid throttle especially at aprox 50-60 mph where something is causing a intermittent aggressive clunk/jolt. Just wondering if anybody had encountered this as I have ran out of ideas other than maybe something such as a solenoid etc has failed in the transmission it self.. transmission will still shift through all of the gears normally so I’m stumped as to what it could be since I have no codes. Any help would be greatly appreciated since this is my only running vehicle

 

[Liam Oswald]

Clunk/jolt will occur in final gear once I let off throttle usually every time

 

[Supercharged111]

Sounds like a misfire, any codes?

 

[Liam Oswald]

All I have for a code is a p0340 circuit a for a long time that I’ve never been able to figure out.. all of the readings I took for the 3 wire sensor circuit were okay and the sensor is new. Truck had this code and ran normal until recently, checked the wiring now about 5-6 times looking for anything wrong. Starting to wonder if somethings wrong with the pcm itself. Really unsure as to what could be causing this at this point and if this particular code/issue could be the cause. It only does this in the 50-65 mph range probably going to re check cam position sensor circuit and crank position sensor circuit again cause somethings obviously wrong somewhere I’m thinking.. transmission is fairly new and has been taken care of so it shouldn’t be having issues

 

[skylark]

Try pulling it down into drive and see if it changes.

 

[Liam Oswald]

Do you mean shift it down into third gear rather than drive? It happens in drive only from what I’ve seen..I Tryed putting it into third and drove for a little bit and it did not continue to clunk/jerk intermittently from what I remember.. that’s why I figured it was something with the transmission.could try driving again in third for a longer time and confirm

 

[Liam Oswald]

Does it in third also must be a misfire

 

[Jared Jackson]

Does it in third also must be a misfire

I have had a misfire where I would notice it in a high gear pulling up a hill... but not as aggressive as you make it sound!

Have you checked the transmission fluid level?

 

[Supercharged111]

Mine bucks and farts pretty bad with very light throttle in OD and also misses at an idle. If it's not the distributor it must be mechanical.

 

[Liam Oswald]

I have had a misfire where I would notice it in a high gear pulling up a hill... but not as aggressive as you make it sound!

Yeah it’s not good

Have you checked the transmission fluid level?

Mine bucks and farts pretty bad with very light throttle in OD and also misses at an idle. If it's not the distributor it must be mechanical.

Trans fluid is perfect and filter is fairly new.. probably gonna pull the distributor and look it over since they are known to cause issues if I don’t find anything when I check cam/crank sensors+circuits again