RPM hovering / Converter locking up under WOT, not down shifting
02-09-2010, 03:44 PM
#1
RPM hovering / Converter locking up under WOT, not down shifting I have a built 4L60E(not bullet proof but it has good parts in it) and Yank SS3800 in my '01 SS. I just put a new motor in the car and with the help of FROST have been doing some street tuning to get everything in order. once I got to WOT tuning I immediately noticed an issue.
from either a dead stop or from a roll when I go WOT the converter flashes up to around 5K rpm and it bogs/hovers there not raising in RPM, but MPH increases. If I stay in it for more then a few seconds then it seems that the converter tries to fully lock-up and the engine bogs further. From a stop it will spin the tires for a second as the RPM's raise to 5K and bog, from a roll it doesn't down shift and pretty much flashes up and bogs immediately at 5K. I don't know if "bogs" is the right term for a motor spinning at 5K rpm but once its up there thats what it reminds me of, like it has a heavy load on it. in Park/neutral it revs clean and fast.
For some reason I decided to try and shift it manually. I put it in 1st went WOT and it will now do a brake stand and freely revs up the RPM range in gear pulling from Idle to redline, I shifted to 2nd and it pulled all the way back to redline(7K).
It's good that it pulls and shifts manually but what could be causing the other issues? I'vegot close to 200 miles on this new motor and 750ish on the Yank. It drives and shifts fine otherwise, just as long as im only under light to moderate throttle.
We cant find anything in the tune that might be causing it. For the record the transmission part of the tune is the same as it was with the old motor and I don't think thats it. I went back and looked at the logs from the day that the stock shortblock blew up at the track. I made seven passes all logged and all reving/shifting fine EXCEPT the 7th and last pass. on that pass it came out of the hole soft and held RPM hovering at 5K like its still doing now. I threw a rod half track and that was the last time I messed with it until trying to tune it now. At that time I didn't realize it was something trans related causing it to bog.
If anyone has any ideas or has experienced something like this please speak up.
from either a dead stop or from a roll when I go WOT the converter flashes up to around 5K rpm and it bogs/hovers there not raising in RPM, but MPH increases. If I stay in it for more then a few seconds then it seems that the converter tries to fully lock-up and the engine bogs further. From a stop it will spin the tires for a second as the RPM's raise to 5K and bog, from a roll it doesn't down shift and pretty much flashes up and bogs immediately at 5K. I don't know if "bogs" is the right term for a motor spinning at 5K rpm but once its up there thats what it reminds me of, like it has a heavy load on it. in Park/neutral it revs clean and fast.
For some reason I decided to try and shift it manually. I put it in 1st went WOT and it will now do a brake stand and freely revs up the RPM range in gear pulling from Idle to redline, I shifted to 2nd and it pulled all the way back to redline(7K).
It's good that it pulls and shifts manually but what could be causing the other issues? I'vegot close to 200 miles on this new motor and 750ish on the Yank. It drives and shifts fine otherwise, just as long as im only under light to moderate throttle.
We cant find anything in the tune that might be causing it. For the record the transmission part of the tune is the same as it was with the old motor and I don't think thats it. I went back and looked at the logs from the day that the stock shortblock blew up at the track. I made seven passes all logged and all reving/shifting fine EXCEPT the 7th and last pass. on that pass it came out of the hole soft and held RPM hovering at 5K like its still doing now. I threw a rod half track and that was the last time I messed with it until trying to tune it now. At that time I didn't realize it was something trans related causing it to bog.
If anyone has any ideas or has experienced something like this please speak up.
02-11-2010, 12:12 PM
#3
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Looking at your comment below would make it seem the trans or converter is the problem considering the tune was fine below. However, it's really hard to diagnose automatic transmission issues over the internet because it can be so many things.
- Does the problem happen in both D3 and D4?
- You have a new motor, but was the trans rebuilt after the motor let go? If not, how many miles and track runs are on it?
- Is it the same converter that was on the old motor?
- That's not that unusual from a roll with a big converter, but it depends how much the mph increases by. If I hit WOT from a 50-60 mph roll (D4), the converter will flash to about 5200 rpms and stay around the same, but the mph will increase to 93 plus mph in a matter of a few seconds. I've had 3 different converters in this setup and they all acted similar (some better than others).
- Do you have datalogs to compare before and after under similar load conditions?
A video would help. I would also contact some sponsors here like FLT and see if they can offer additional input.
I made seven passes all logged and all reving/shifting fine EXCEPT the 7th and last pass. on that pass it came out of the hole soft and held RPM hovering at 5K like its still doing now.
- You have a new motor, but was the trans rebuilt after the motor let go? If not, how many miles and track runs are on it?
- Is it the same converter that was on the old motor?
from either a dead stop or from a roll when I go WOT the converter flashes up to around 5K rpm and it bogs/hovers there not raising in RPM, but MPH increases
- Do you have datalogs to compare before and after under similar load conditions?
A video would help. I would also contact some sponsors here like FLT and see if they can offer additional input.
02-11-2010, 08:53 PM
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Hey Stuart,
Hows it going bro, sucks to hear your having troubles with the tranny. Have you gave Yank a call yet?
It sounds like a converter issue to me?... There was a shop in Albuquerque who built my 4L60e and the converter for it, I believe it was called "gear 1" but I'm not exactly sure its been quite awhile but if you could find them, they were real helpful and knew what they were doing. They might be able to help you figure it out.
Worst case give one of the sponsors who specialize in the 4L60e's and see if they could help.
Hope you get it sorted out bud!
Hows it going bro, sucks to hear your having troubles with the tranny. Have you gave Yank a call yet?
It sounds like a converter issue to me?... There was a shop in Albuquerque who built my 4L60e and the converter for it, I believe it was called "gear 1" but I'm not exactly sure its been quite awhile but if you could find them, they were real helpful and knew what they were doing. They might be able to help you figure it out.
Worst case give one of the sponsors who specialize in the 4L60e's and see if they could help.
Hope you get it sorted out bud!
