Throttle Surging in 4th Gear (1 Viewer)

[AppleTech]

I am having an odd issue. Replaced oxygen sensors on bank 1 recently due to being stuck lean. Truck running normally for about 2 weeks now but just noticed a new issue. In 4th gear, when accelerating at around 2200 RPM, there is a noticeable surge - power drops about 100RPM repeatedly up-down-up-down - you can feel it and see it on the RPM gauge. It doesn't do this in all gears and it doesn't seem to do it anywhere else in the power band. Going to pick up MAF cleaner today since that hasn't been done just to see if it helps. I'm thinking its more ECU/TPS related though based on what's happening. Any ideas? No current CEL and TechStream says all clear other than TPMS issues.

Thanks!
-Phil

 

[AppleTech]

OK so I cleaned the MAF with CRC MAF cleaner. Let it dry for an hour or so then reinstalled and reconnected battery and ran the truck around town. Now I have a P0101 error. MAF was really clean - could cleaning it make it worse? Some other research indicates possibly a dirty throttle body? What next steps would yall take?

 

[D0g]

I had an issue like that on my 99 do the cheap stuff first
1.delete your check engine light and see if it comes back
2.Clean throttle body
3.if 1-2 don't work suspect the TPS and APPS = Accelerator Pedal Position Sensor worst case scenario is your throttle body motor is on its way out ,which ended up being my issue,however mine wouldn't get out of lmp mode so that probably isn't your issue.

 

[AppleTech]

So between writing this and now, the MIL has cleared on its own. I've cleared the code memory and we'll see what happens. Surge still present after an ECU reset unfortunately.

 

[D0g]

So between writing this and now, the MIL has cleared on its own. I've cleared the code and we'll see what happens. Surge still present after an ECU reset unfortunately.

Its going to be one of those 2 sensors you can throw money at it guessing which one like i did or have someone diagnose it with a fancy $5,000 scan tool, I replaced both before finally replacing my throttle body
PS. If you change out the TPS make a note of the angle its in before you take it off i think mine had some issues afterwards because it wasn't in the right position

 

[AppleTech]

OK so it turns out that surging is a symptom of the torque converter lockup slipping, which is due to old trans fluid. Replaced and the issue appears to have gone away!

 

[D0g]

Nice job man