100 RPM spikes, trying to shift?
#1
100 RPM spikes, trying to shift?
I have a 1999 3500 4x4 QuadCab Dually Auto, with ~230k miles, bought earlier this year. It had a bad APPS when I bought it, and I got a new one at Autozone and installed and adjusted it with an analog multimeter following instructions I found online. This fixed the intermittent dead pedal instantly. It also has slightly-larger-than-stock tires, 235/85R16, as opposed to the stock 215/85R16, speedometer doesn't appear to be adjusted for this. It also has all new clean battery terminals, along with one brand new battery and an old one it came with. I mention these things having no idea if they have anything to do with the problem.
Now sometimes when I am driving it, *usually* when it's under a slight load, like starting to head up a hill, after keeping a steady speed, it will act like it is going to shift, and the tach will jump 100 or so RPMs. It does this repeatedly though, in quick succession. Kind of hard to explain with typing, but even my wife can hear the resulting vr-vr-vr-vr sound. It only stops if I let off the gas some, or press it down harder, changing my speed a bit. It seems to be happening more often now that it is getting colder outside, though I don't know if it's related to the cold or if it's just getting worse as time goes on.
It isn't just a problem with overdrive, because if I turn overdrive off, the problem will still happen. The transmission fluid is full (dipstick says ATF+4 or Dexron/Mercron III, dealership(s) said ATF+4 only, so that's what I used, who knows what other people put in?), but I don't know anything else about the truck. What can I do to troubleshoot this and hopefully fix the problem?
Now sometimes when I am driving it, *usually* when it's under a slight load, like starting to head up a hill, after keeping a steady speed, it will act like it is going to shift, and the tach will jump 100 or so RPMs. It does this repeatedly though, in quick succession. Kind of hard to explain with typing, but even my wife can hear the resulting vr-vr-vr-vr sound. It only stops if I let off the gas some, or press it down harder, changing my speed a bit. It seems to be happening more often now that it is getting colder outside, though I don't know if it's related to the cold or if it's just getting worse as time goes on.
It isn't just a problem with overdrive, because if I turn overdrive off, the problem will still happen. The transmission fluid is full (dipstick says ATF+4 or Dexron/Mercron III, dealership(s) said ATF+4 only, so that's what I used, who knows what other people put in?), but I don't know anything else about the truck. What can I do to troubleshoot this and hopefully fix the problem?
Last edited by moparisthebest; 11-10-2013 at 02:36 PM. Reason: battery info
#2
kind of sounds like torque converter locking and unlocking. heres a good link on it.
Torque Converter Lock / Unlock Issues
Torque Converter Lock / Unlock Issues
#4
I appreciate the pointers, after reading a few other threads on torque converter locking/unlocking that seems like exactly what is happening.
They also all seem to point to the alternator, however, I disconnected the alternator by removing that fusible link, and it didn't change the behavior. Does this rule out the alternator? Or are there more things to disconnect?
Also I asked autozone about testing the alternator and they said all they test is whether it puts out power or not, which it is doing, since my batteries stay charged. They said they couldn't test whether it was going bad or whether some diodes were out. Any pointers on where I CAN get this tested?
They also all seem to point to the alternator, however, I disconnected the alternator by removing that fusible link, and it didn't change the behavior. Does this rule out the alternator? Or are there more things to disconnect?
Also I asked autozone about testing the alternator and they said all they test is whether it puts out power or not, which it is doing, since my batteries stay charged. They said they couldn't test whether it was going bad or whether some diodes were out. Any pointers on where I CAN get this tested?
#5
I appreciate the pointers, after reading a few other threads on torque converter locking/unlocking that seems like exactly what is happening.
They also all seem to point to the alternator, however, I disconnected the alternator by removing that fusible link, and it didn't change the behavior. Does this rule out the alternator? Or are there more things to disconnect?
Also I asked autozone about testing the alternator and they said all they test is whether it puts out power or not, which it is doing, since my batteries stay charged. They said they couldn't test whether it was going bad or whether some diodes were out. Any pointers on where I CAN get this tested?
They also all seem to point to the alternator, however, I disconnected the alternator by removing that fusible link, and it didn't change the behavior. Does this rule out the alternator? Or are there more things to disconnect?
Also I asked autozone about testing the alternator and they said all they test is whether it puts out power or not, which it is doing, since my batteries stay charged. They said they couldn't test whether it was going bad or whether some diodes were out. Any pointers on where I CAN get this tested?
#6
#8
Hmm, and with a serpentine belt that's not really an option to drive it. So is there any way to tell if the alternator is bad in that way? :/
#10