Engine/Transmission (1998.5 - 2002) Back again with surging / bucking issues...

[kevhype0825]

My dad's 02 is once again experiencing surging / bucking after the truck goes into overdrive while driving normally with no load. The truck isn't showing any codes, has a new VP44 and has a new output shaft speed sensor. It also has a fairly new fuel filter. He doesn't notice this at any other time. Any ideas?

 

[JLandry]

Does it seem like maybe the torque converter is locking and unlocking, or does it seem different?



Is it rapid or slow?



I ask because before the VP44 was replaced in your dad's truck, at one point you described the surging / bucking problem as seeming like the engine was shutting off and on. Is it pretty much the same now or milder?



John L.

 

[kevhype0825]

Does it seem like maybe the torque converter is locking and unlocking, or does it seem different?



Is it rapid or slow?



I ask because before the VP44 was replaced in your dad's truck, at one point you described the surging / bucking problem as seeming like the engine was shutting off and on. Is it pretty much the same now or milder?



John L.

He said it doesn't feel like converter lock-up but it is a rapid jerking accompanied by surging RPM's. The way he is describing this occurrence it doesn’t sound similar to what he experienced when the VP44 was dying. This happens just after the truck shifts into overdrive. The strange thing is that no codes are displayed.

 

[JMetzger]

It is cooler now & I wonder if it could be the MAP sensor or IAT sensor.

 

[bromano676]

If any of you guys read through a lot of these threads, you might think that I am crazy, I almost always say the same thing.

I think it's the APPS. I had the same thing happen, two shops, lift pump, injectors, and still the problem persisted.



I recommend the TIMBO APPS

 

[JLandry]

If any of you guys read through a lot of these threads, you might think that I am crazy, I almost always say the same thing.

I think it's the APPS.

I don't think you're crazy at all, but I do think it's important to try and narrow down the problem a little before throwing expensive parts at it. It could very well indeed be the APPS, but then it may not, and it could be a true transmission problem.



Either way, admittedly it's exceedingly difficult trying to diagnose a problem simply by reading about it third hand.



John L.

 

[JLandry]

He said it doesn't feel like converter lock-up but it is a rapid jerking accompanied by surging RPM's. The way he is describing this occurrence it doesn’t sound similar to what he experienced when the VP44 was dying. This happens just after the truck shifts into overdrive. The strange thing is that no codes are displayed.

And it ONLY does this once the transmission shifts into 4th gear? Never in any other gear... even if much less noticeable?



Does it stop and stay gone if he turns the OD switch off?



When in 4th gear, can he make it stop by changing the throttle position?



Has the transmission been serviced recently (fluid and filter changed, and the bands properly adjusted)?



John L.

 

[BDaugherty]

What does the fuel pressure do when the truck bucks/jerks?

 

[hcole]

I just replaced my APPs because of surging with NO codes set. I got one of Timbo's and all is well. I think 2002 trucks all came with electronic cruise control. If so, and he has cruise on his, then will it surge in cruise? If it doesn't, then its not the APPS because its out of the circuit in cruise.

 

[kevhype0825]

And it ONLY does this once the transmission shifts into 4th gear? Never in any other gear... even if much less noticeable?



Does it stop and stay gone if he turns the OD switch off?



When in 4th gear, can he make it stop by changing the throttle position?



Has the transmission been serviced recently (fluid and filter changed, and the bands properly adjusted)?



John L.

He is now saying that it happened twice today just after the truck shifted into 4th gear (O/D). Which makes me think the truck is gear hunting (3 to 4). He serviced the transmission recently but has never adjusted the bands. I think I am going to drive the truck tomorrow morning and see if I can determine what is happening.



One thing I can say is that you 2ND Gen guys are really helpful and contribute a lot of useful information! Thanks! I will update after I drive the truck tomorrow.

 

[kevhype0825]

I just replaced my APPs because of surging with NO codes set. I got one of Timbo's and all is well. I think 2002 trucks all came with electronic cruise control. If so, and he has cruise on his, then will it surge in cruise? If it doesn't, then its not the APPS because its out of the circuit in cruise.

I am not sure if it happens with cruise on but i will test that tomorrow also.

 

[kevhype0825]

What does the fuel pressure do when the truck bucks/jerks?

We do not have a fuel pressure gauge on this truck but we do have a low fuel pressure warning light from Blue Chip which has never indicated a low fuel pressure condition.

 

[PC12Driver]

I think 2002 trucks all came with electronic cruise control.

The automatics still used the vacuum setup. The PCM needs the APPS information to shift/lockup properly.

 

[kevhype0825]

I drove the truck yesterday with my dad in the passenger seat and I figured out what he is describing seems to be the transmission gear hunting between 3rd and 4th gears. Every time the truck shifted into overdrive it began to buck slightly. This usually happened under moderate acceleration. During full acceleration it seems to shift fine. He mentioned that the bucking was more violent at times but it was definitely what he experienced. How are you guys addressing this issue in the 2nd generation trucks?

 

[bromano676]

I still think that its the APPS. And I don't think that it's a lot of money. The factory APPS is junk too, so putting in TIMBO's APPS is money well spent in my opinion. The factory APPS will get you one day, change it now before you're stranded, and may be it'll fix this problem too. Win Win.

 

[Darrenf]

This is exactly like what I've got going on right now too, and have been fighting for awhile. I don't notice it so much with the cruise on, and it seems more pronounced with with a load in tow. I changed out the Apps (Timbo) and still have it, Unless it needs a re-cal again. ???



I've read suggestions about shorting a couple wires to eliminate the shift hunt and that wasn't it. Wrapped the alternator wire with foil, I think that was supposed to shield surrounding wires from a noisy alternator and causing transmission lock/unlock(I think), still no help.



I might have to try the IAT or MAP sensors idea. Beginning to wonder if this isn't a outside air temp related issue. KevHype, Does your dad's do this during the heat of the summer? I'm kinda thinking i didn't have so much of an issue this summer and thinking the cooler air brought this on again. ???



Keep those ideas coming!

 

[kevhype0825]

This is exactly like what I've got going on right now too, and have been fighting for awhile. I don't notice it so much with the cruise on, and it seems more pronounced with with a load in tow. I changed out the Apps (Timbo) and still have it, Unless it needs a re-cal again. ???



I've read suggestions about shorting a couple wires to eliminate the shift hunt and that wasn't it. Wrapped the alternator wire with foil, I think that was supposed to shield surrounding wires from a noisy alternator and causing transmission lock/unlock(I think), still no help.



I might have to try the IAT or MAP sensors idea. Beginning to wonder if this isn't a outside air temp related issue. KevHype, Does your dad's do this during the heat of the summer? I'm kinda thinking i didn't have so much of an issue this summer and thinking the cooler air brought this on again. ???



Keep those ideas coming!

Darrenf, according to my dad this issue has gotten worst in recent times. Since we live in an area that is mostly warm year round I do not think this is related to temperature.

My 06 exhibited this same issue but since loading the Smarty it has completely disappeared. I know there is a big difference between the ECM's of Gen 2 and Gen 3 trucks but I wonder if a Smarty would have the same positive affect on a Gen 2 truck?



What is the best way to contact Timbo about his replacement APPS?

 

[Darrenf]

I found this email for him in another thread ... Timbom1976@aol.com

 

[Floyd4runner]

me too

I have this same problem. Mine is not hunting I have already fixed that. I just firgured it was the adrenaline. Level 1 I drive in all the time because it does not do it as bad. But level 2 and up. If you are on the highway and say let off of it to keep a certain speed it bucks and if you keep the throttle in the same spot it gets worse. But if you push the foot feet down it takes without any problems and clears right up. I have 185k on it and have not adjusted the valves yet. I figure that would probably fix my problem.

 

[Darrenf]

Yup that's it... I've got 125k on mine, I'm not inclined to think it would be valves, but dunno. I forgot that I already replaced the IAT sensor last year. I've got a newer VP44 with Glacier fuel pump, I did run it out of of fuel a time or two(stupid fuel sending unit) so hopefully I've not damaged the VP as a result. No codes indicating the VP so crossing fingers. Guess I'll try a Map sensor next and/or try another recal of the APPS.