Still chasing problem of car not doing a burnout+shifting 1000 earlier than it should
#1
Still chasing problem of car not doing a burnout+shifting 1000 earlier than it should
The car has been to the shop a couple of times and small problems were found each time but the main issue still exists. The car will not do a burnout in the burnout box at the track or anywhere for that matter. Car starts, drives and seems to do fine until you put the motor in a bind low in the RPM band with your foot on the brake. Car idling, shifter in 1st gear (or any gear for that matter) everything seems normal. You start to depress the accelerator with brake still applied and the RPM's go up to around 1200-1300 like it should and then the car surges forward and the motor nearly stalls out. It seems like the converter is locking up. Trying to go through the gears it's really sluggish off the line as the RPM's don't flash up like they should with a Yank PY3600 stall. Going through the gears I swear the converter is locked up. RPM's drop a couple thousand on the shifts and it used to drop just a few hundred. Related to this also is that the transmission shifts at 5800 RPM and the ECU is calling for the shift at 6600. Three possibilities I guess could be causing the problem. Converter bad, transmission bad, or tuning bad. Yank says it cannot be the converter. RPM says it cannot be the transmission. Tuner says it is not in the tune and that it has to be in the transmission or converter. Now honestly, did you expect anything different from the players involved? Transmission and converter are brand new. Now, the car did make a couple of decent initial passes right out of the shop but gremlins crept in and have been keeping the car from running anything at all since then. Initial pass right out of the shop rolling the car out of the gate to maintain traction netted a 1.36 60' and 6.18 @ 110. Now because of how badly it takes off it runs between 1.98 60', 7.47 @ 98 and a worst of 2.18 60' 8.09 @ 96. The car is just plain dead like it is. It's back at the shop one more time but they're telling me they've never seen anything like this and have no idea what's going on. I'm reaching out to anyone that might have experienced anything like this or have any ideas of where to turn to next. Traction control and ABS have been eliminated. It's not shifting into 2nd gear as soon as it moves as it does this when the shifter is in 1st gear and taking off the transmission stays in 1st gear the whole time. This was one of the things suggested. New bypass valve installed as it was suggested that the car might not be making boost at first because the bypass valve might be blowing off all the pressure until the RPM's built up. That actually helped some but he car is still off almost 2 seconds and 20 MPH at the track from what I'm expecting it to run. I'm just looking for any suggestions I can call the shop with to hopefully point them in a direction that they can effect repairs on car. I've got all sorts of mods in the works to supposedly put the car solidly in the 5's but cannot move forward with these until this current issue is resolved. ANY thoughts or ideas will certainly be appreciated. Thanks in advance.
#2
Intermediate
My car did the same thing to me. First two passes it was fine then 3rd pass no burn out. Car just shuttered and acted like it wanted to die. For mine this is when the abs lights came on. But the funny thing is on a normal road it will do a burn out. I just assumed it was the abs and traction control screwing up on mine. You mentioned yours have been elimited, did you take it out of the car or just turn it off in the computer? I haven't figured mine out yet, as the torque tube bearings took a crap on me. I have mine all apart now getting ready for new converter and rebuilt trans and new torque tube.
I'll be looking at this thread to see if anyone else chimes in and figures it out. Just thought I'd post to say your not the only one with the problem.
I'll be looking at this thread to see if anyone else chimes in and figures it out. Just thought I'd post to say your not the only one with the problem.
#3
My car did the same thing to me. First two passes it was fine then 3rd pass no burn out. Car just shuttered and acted like it wanted to die. For mine this is when the abs lights came on. But the funny thing is on a normal road it will do a burn out. I just assumed it was the abs and traction control screwing up on mine. You mentioned yours have been elimited, did you take it out of the car or just turn it off in the computer? I haven't figured mine out yet, as the torque tube bearings took a crap on me. I have mine all apart now getting ready for new converter and rebuilt trans and new torque tube.
I'll be looking at this thread to see if anyone else chimes in and figures it out. Just thought I'd post to say your not the only one with the problem.
I'll be looking at this thread to see if anyone else chimes in and figures it out. Just thought I'd post to say your not the only one with the problem.
#4
Intermediate
I have tried pulling the fuses in mine when it was running and it didn't help. I believe the abs affects the torque management system in the ecm. If this is the case then simply pulling the fuses won't do the job. Need to go into the ecm and delete the abs and traction control. I could be wrong but that's my understanding of it so far.
#5
I have tried pulling the fuses in mine when it was running and it didn't help. I believe the abs affects the torque management system in the ecm. If this is the case then simply pulling the fuses won't do the job. Need to go into the ecm and delete the abs and traction control. I could be wrong but that's my understanding of it so far.
#6
Intermediate
I just wanted to let you know what I found out about mine. I had the transmission out so I went ahead and had it rebuilt. When he pulled it apart he found the sunshell was in two pieces, the sprag was also broke and the spacer between the valve body was badly damaged. He was surprised I was even driving the car.
#7
I just wanted to let you know what I found out about mine. I had the transmission out so I went ahead and had it rebuilt. When he pulled it apart he found the sunshell was in two pieces, the sprag was also broke and the spacer between the valve body was badly damaged. He was surprised I was even driving the car.
#8
Update:
RPM took the transmission apart and says they found torrington bearing material all in the input shaft of the transmission. They say this came from the torque converter. Dave @ Yank is highly suspect of this diagnosis to put it kindly (actual words much more damning) and wants the converter back to confirm what RPM says has any basis in fact. Dave @ Yank suspects the bearing material came from inside the transmission?? Both are pointing the finger at the other right now with no help in sight. Looks like I'm going to end up spending close to double (thousandsssssss) what the cost should have been for an upgraded transmission and converter as I'm not getting a good vibe from either as far as admitting that anything that's happened could be their fault and not the other guy's. I'll follow up once all the chips fall. They're all still up in the air right now but it looks like it's not going to be pretty in the end. And that's the best case scenario. Remember, this was an initial failure or as close to it as possible. Beware of using products together from feuding companies.
RPM took the transmission apart and says they found torrington bearing material all in the input shaft of the transmission. They say this came from the torque converter. Dave @ Yank is highly suspect of this diagnosis to put it kindly (actual words much more damning) and wants the converter back to confirm what RPM says has any basis in fact. Dave @ Yank suspects the bearing material came from inside the transmission?? Both are pointing the finger at the other right now with no help in sight. Looks like I'm going to end up spending close to double (thousandsssssss) what the cost should have been for an upgraded transmission and converter as I'm not getting a good vibe from either as far as admitting that anything that's happened could be their fault and not the other guy's. I'll follow up once all the chips fall. They're all still up in the air right now but it looks like it's not going to be pretty in the end. And that's the best case scenario. Remember, this was an initial failure or as close to it as possible. Beware of using products together from feuding companies.
#9
Dave @ Yank took a vid of him cutting the converter apart and examining the bearings. Torque converter was not the problem. The owner of RPM transmissions called me today and talked with me 30 minutes or more trying to get to the bottom of this issue. He's willing to work with me in whatever way possible after he saw the video showing it was not the torque converter as his guys had said it was. My concern is that RPM did not fix the problem with the transmission as they said it wasn't anything the transmission did to cause this but it had to be the converter so they didn't even look into the possibility of it being the transmission. Rodney said he'd never bash another vendor but his "guys" had something well beyond hate and rage towards Dave @ Yank. He says he's going to put a stop to this now as it's customers like me that end up paying for this blood feud. He said he's going to refund me a bunch of money but I haven't seen it yet. I also don't know if I have a transmission that works yet. Neither does Rodney. He told me so today. Man, this sucks bad when vendors don't get along with one another. I can only hope Yank and RPM can finally bury the hatchet and no one else will have to put up with the crap I've had to put up with over the past 4 months. This stuff should have ended on a Grammar School playground years ago but these grudges, however started, have continued on through adulthood. Come on guys, you're better than this.
#11
Rodney called Jay @ Mayhem Motorsports, the shop that does my work, and had a long talk with him about my car and the steps to insure I don't have any more problems like this. I just got an email from Jay and hopefully there is a plan in place now so that I don't have months more down time and don't have to sell the farm just to pay for something else that I never should have had to pay for in the first place. I'll certainly report back with the outcome of this whole thing. Dave @ Yank charged me 150 dollars to prove his innocence and told me he was giving me a big break as he normally charges 250 when his product is accused of being faulty and he proves them wrong. On the bright side, I've gone all Summer without blowing up the motor.
#12
Le Mans Master
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St. Jude Donor '13-'14-'15
Not sure about your year model but newer Corvettes have a table in the tune that LOWERS the RPM shift point based on the acceleration rate ---If the engine revs up too quickly it can reduce the shift RPM 's as much as 400 RPM---Most tuners will delete this table to stop the early shifting on heavily modded engines
#13
Not sure about your year model but newer Corvettes have a table in the tune that LOWERS the RPM shift point based on the acceleration rate ---If the engine revs up too quickly it can reduce the shift RPM 's as much as 400 RPM---Most tuners will delete this table to stop the early shifting on heavily modded engines
#14
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CI 6,7,8,9,11 Vet
St. Jude Donor '08
Tuned in for the RESULTS! Good luck brother!
BC
BC
#15
Thanks, Bill. Once Rodney from RPM called me and spoke for about 30 minutes on the exact history of the car from back when it had the Level V installed in 2008 to now in order to make sure we had no more issues going forward I feel pretty good about everything this time. He called Jay @ Mayhem and spoke with him for a good, long bit as well. He said he was going to call Dave @ Yank also. I know I'm pushing things to the extreme but honestly, 800 RWHP is the new 500 RWHP and pretty much everything I read about someone with a really fast Corvette now lends truth to this statement. Mine isn't outside of the norm anymore. I doubt if I'll reach my goal of an 8 second timeslip this year but if I don't reach my immediate goal of a 5 second 1/8th mile timeslip, I'm going to be really disappointed. I'm just so impressed with how these later model Vettes can run so well, be so well mannered when driven on the street getting great gas mileage and look like every other Vette you see. I've always been a fan and always will be 'til the day I die.
On another note, Dave, Rodney and Jay finally talked me out of trying to lock the converter up during the last part of the run. Dave and Rodney said that in order to lock the converter up without damaging it during the pass, it had to have things done to it that would compromise the ET to the 60', 330', and 660'. It might run more MPH out the end but it'd be playing catch-up to what it would run unlocked and it just wasn't worth it as the ET would be roughly the same at one MPH or so more. So, we're not going to lock up the converter during the pass now. I've got to seek my 150 MPH trap speed some other way. More horsepower and less weight.
On another note, Dave, Rodney and Jay finally talked me out of trying to lock the converter up during the last part of the run. Dave and Rodney said that in order to lock the converter up without damaging it during the pass, it had to have things done to it that would compromise the ET to the 60', 330', and 660'. It might run more MPH out the end but it'd be playing catch-up to what it would run unlocked and it just wasn't worth it as the ET would be roughly the same at one MPH or so more. So, we're not going to lock up the converter during the pass now. I've got to seek my 150 MPH trap speed some other way. More horsepower and less weight.
#17
No, unfortunately. We even completely disabled it along with the anti-lock brakes and the stability control trying to eliminate potential possibilities. This problem had much more sinister roots but I'm pretty sure we've gotten to the bottom of it now. I just hope and pray the transmission will shift where I want it to this time instead of the 5800 RPM it wanted to shift at last time. Even RPM transmissions had no explanation for this or cure for it if it continues to shift there. We're leaving ~100 horsepower average on the table if it continues to shift there. I'm convinced that's why the car trapped 4-5 MPH less in the 1/8th mile on its maiden pass down the track than I calculated it should. It did make a few passes successfully before the converter lockup issues reared its ugly head. After the first pass trapping a little over 110 it never trapped over 108 after that. I'm hoping to be up around 117-118 this time if everything works like it's supposed to even though we're going to be running bias ply slicks which typically kill MPH. 3500 pound raceweight. ~800 RWHP if anyone wants to do their own calculations as to what I should expect it to run.
#18
The torque converter arrived back from Yank today. All the parts are now in place to put the car back together. Jay assured me that the issue with the transmission shifting early is a non-issue and that he's absolutely sure he can make the transmission execute the shift wherever it needs to occur. We just need to get everything running again and go to the track for some real TNT with datalogging. They go to the track every Thursday night for TNT so we'll be tagging along probably not this Thursday night but the following one if all goes according to plan. Results from everything to follow.
#19
Got a call from Jay @ Mayhem right before they closed this afternoon and the car is back together and the transmission/converter are playing nice together once again. They still have to put on the new supercharger pulley and do the most aggressive tune possible on straight 110 race fuel plus as much meth as the dual nozzle Alky Control kit will spray. I want it loaded for bear and don't want to leave any power on the table. Everyone is running too fast for us to be conservative and try to compete. I've been looking around at the fast guys and we're still going to be several hundred horsepower down vs the average guy and several hundred pounds too heavy. But at least it's a start and it's going to be such a relief to actually have the car back home and running again. Having it gone for several months and not coming up with a solution as to why it's doing stupid stuff will age one way beyond reason. Trust me. Especially when you're too old to be messing with this kind of thing anyhow like I am. And my partner in crime, Sam, is actually a couple of years older than me so it's been tough on the "Too Old Guys" race team this year. At least I got some good news today so I thought I'd share. I'm not sure if we're heading over there tomorrow for the dyno tune or wait until the car is ready for track testing. It's a 4+ hour drive one way for me from the OBX over to Raleigh so I can't just pick up and go on a whim. More results to follow as we get them. I'm anxious to report what we come up with on the dyno. We're pushing our itty bitty P1SC-1 well beyond its limits but we're going to switch to an F1something this Winter anyhow. Then it'll make power like the masses.
Last edited by smokinstorm; 08-17-2016 at 07:21 PM.