No WOT downshift...
No WOT downshift... I installed the GM hotcam over a weekend a couple of weeks ago. Install went well. Installed the new Predator tune from James at RWTD. Ever since that weekend, I have a couple of issues that I can not come up with an answer on. (99 SS a4)
#1. From a stop, 1/4 accel, vehicle shifts rapidly 1,2,3 before 30mph, then If i go WOT, vehicle stays in 3rd for about 3 seconds Then it will jump into 2nd. After doing some logging of this event,
The only thing i saw was 4.3 volts at tps, 26mph in 4th gear at 1350 rpms. Stays this way for about 9 frames, then finally goes into second gear. No getting any slippage, feels like a M6 in 6th gear at 40 mph when you go WOT, just boggs down.
#2. Since cam install, my gauges now sweep like a corvette 3 out of 4 times when starting, also my trip odometer resets every start.
Have tried 2 different tunes and even stock tune, still does it. Related to #1???
I have checked all of the connection i messed with during install, all ok there. also has new TPS.
Any help would be great!!!
#1. From a stop, 1/4 accel, vehicle shifts rapidly 1,2,3 before 30mph, then If i go WOT, vehicle stays in 3rd for about 3 seconds Then it will jump into 2nd. After doing some logging of this event,
The only thing i saw was 4.3 volts at tps, 26mph in 4th gear at 1350 rpms. Stays this way for about 9 frames, then finally goes into second gear. No getting any slippage, feels like a M6 in 6th gear at 40 mph when you go WOT, just boggs down.
#2. Since cam install, my gauges now sweep like a corvette 3 out of 4 times when starting, also my trip odometer resets every start.
Have tried 2 different tunes and even stock tune, still does it. Related to #1???
I have checked all of the connection i messed with during install, all ok there. also has new TPS.
Any help would be great!!!
4.3V is kinda low for WOT. What does that make your
throttle % read as? Check for cable slack, throttle stop,
bunched carpet, anything that prevents full opening
(physical). If the blade opens to 90 degrees then see
about slotting the TPS and adjusting it to get the max
sensible TPS voltage (=?) at 90 degree blade.
Check your shift MPH settings, maybe these got munged
(reset) by the tune? They affect downshift as well as
upshift (a real high shift MPH will make the kickdown
nice like it shoulda been, but you'll hit the rev limiter).
Predator next revision is supposed to include kickdown
adjust, so I figure that means they know how to do it
on an individual tune basis. If none of the suggestions
pan out, I'd go back to them with your beef and get the
trans params looked at & revised.
throttle % read as? Check for cable slack, throttle stop,
bunched carpet, anything that prevents full opening
(physical). If the blade opens to 90 degrees then see
about slotting the TPS and adjusting it to get the max
sensible TPS voltage (=?) at 90 degree blade.
Check your shift MPH settings, maybe these got munged
(reset) by the tune? They affect downshift as well as
upshift (a real high shift MPH will make the kickdown
nice like it shoulda been, but you'll hit the rev limiter).
Predator next revision is supposed to include kickdown
adjust, so I figure that means they know how to do it
on an individual tune basis. If none of the suggestions
pan out, I'd go back to them with your beef and get the
trans params looked at & revised.
Originally Posted by jimmyblue
4.3V is kinda low for WOT. What does that make your
throttle % read as? Check for cable slack, throttle stop,
bunched carpet, anything that prevents full opening
(physical). If the blade opens to 90 degrees then see
about slotting the TPS and adjusting it to get the max
sensible TPS voltage (=?) at 90 degree blade.
Check your shift MPH settings, maybe these got munged
(reset) by the tune? They affect downshift as well as
upshift (a real high shift MPH will make the kickdown
nice like it shoulda been, but you'll hit the rev limiter).
Predator next revision is supposed to include kickdown
adjust, so I figure that means they know how to do it
on an individual tune basis. If none of the suggestions
pan out, I'd go back to them with your beef and get the
trans params looked at & revised.
throttle % read as? Check for cable slack, throttle stop,
bunched carpet, anything that prevents full opening
(physical). If the blade opens to 90 degrees then see
about slotting the TPS and adjusting it to get the max
sensible TPS voltage (=?) at 90 degree blade.
Check your shift MPH settings, maybe these got munged
(reset) by the tune? They affect downshift as well as
upshift (a real high shift MPH will make the kickdown
nice like it shoulda been, but you'll hit the rev limiter).
Predator next revision is supposed to include kickdown
adjust, so I figure that means they know how to do it
on an individual tune basis. If none of the suggestions
pan out, I'd go back to them with your beef and get the
trans params looked at & revised.
no the shifting problem is related to the cam in some way. in the internal section theres a thread about the TSP 231/237 cam giving similar results, like me. Anyway, keep this one going and check that one, if I find an answer i will post up and let you know as well.
Charlie
Charlie
Joined: Nov 2001
Posts: 34,611
Likes: 2,525
From: Schiller Park, ILL Member: #317
4.3v TPS is not the issue. 4.3 is plenty at WOT to get the proper downshifts so long as you're in the high 9X% range on angle and the blade is phsyically open all the way.
I have had a minor downshifting issue since my cam as well. I know it's not my trans (done the same thing with 2 trans' now) and I know it's not my tune.
About 90-95% of the time my downshifts are exactly as they should be according to my personal Edit tune. But, once in a while, when I'm going 31-34mph, I will not get a downshift to first when going WOT. I have set it to go back to 1st up to 37mph with Edit. The issue only happens between 31-34mph, it's NOT traction related, and when I log the issue it shows that the PCM is not even commanding the shift to 1st, but rather 2nd. Again, this issue only happens about 5-10% of the time.
So with my issue, if the PCM commands 1st, it will always go to 1st. But sometimes the PCM is not commanding a downshift to 1st at WOT when it should be; instead it commands 2nd, and the trans follows that direction.
I would say to log your commanded gear and see if your issue is like mine. Not sure what it means (still haven't figured out mine) but at least you'll know it's not the trans then. The trans should be doing whatever the PCM commands.
I have had a minor downshifting issue since my cam as well. I know it's not my trans (done the same thing with 2 trans' now) and I know it's not my tune.
About 90-95% of the time my downshifts are exactly as they should be according to my personal Edit tune. But, once in a while, when I'm going 31-34mph, I will not get a downshift to first when going WOT. I have set it to go back to 1st up to 37mph with Edit. The issue only happens between 31-34mph, it's NOT traction related, and when I log the issue it shows that the PCM is not even commanding the shift to 1st, but rather 2nd. Again, this issue only happens about 5-10% of the time.
So with my issue, if the PCM commands 1st, it will always go to 1st. But sometimes the PCM is not commanding a downshift to 1st at WOT when it should be; instead it commands 2nd, and the trans follows that direction.
I would say to log your commanded gear and see if your issue is like mine. Not sure what it means (still haven't figured out mine) but at least you'll know it's not the trans then. The trans should be doing whatever the PCM commands.
Joined: Nov 2001
Posts: 34,611
Likes: 2,525
From: Schiller Park, ILL Member: #317
Originally Posted by strokedls1
Have you changed both the normal shift and the hot shift tables. Set them to the same values and see if it still happens.
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Originally Posted by RPM WS6
I did this. I changed the WOT boxes and the tables in normal and hot and it made no difference. However SS891s issue seems to be far more drastic than mine though, and might be due to totally different reasons. This adjustment might help his issue....
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Originally Posted by SS891
I am still lost and having the problem. I have talked with James at RWTD this morning, he said to take the shift mph and raise them about 30 mph to take them out of play. I will try this and see what happens.. I hope this solves it!
Joined: Nov 2001
Posts: 34,611
Likes: 2,525
From: Schiller Park, ILL Member: #317
Here are some questions in random order to review that might shed some light on the issue. Maybe it will give you some new ideas to check:
- Is the trans opperating correctly in other areas of normal driving? (i.e. TC lock-up occuring as normal?)
- If you launch from a dead stop (WOT), does it upshift properly?
- At any point before or after the cam install, have you had any DTCs stored or SES lights flash?
- Are you seeing large misfires at any rpm? Have you logged this yet?
- When you replaced the PCM, what flash did you use? A stock file from the dealer or a custom tune?
- Have you checked all the trans cooler lines for any kinks or blockages in fluid flow?
- Did this issue begin the VERY FIRST time you went WOT after the cam install? Or did it take a short while to appear?
- Have you taken a vacuum reading since the cam install? If so, what was it? Are you noticing any sure signs of too low of vacuum like some loss of power brakes, etc.?
- Obvious things that might be overlooked like loose plug wires, cracked/seriously mis-gapped plug(s), issue with throttle cable hanging/sticking/etc.?
- Anything you might have done to damage the VSS?
- Is the trans opperating correctly in other areas of normal driving? (i.e. TC lock-up occuring as normal?)
- If you launch from a dead stop (WOT), does it upshift properly?
- At any point before or after the cam install, have you had any DTCs stored or SES lights flash?
- Are you seeing large misfires at any rpm? Have you logged this yet?
- When you replaced the PCM, what flash did you use? A stock file from the dealer or a custom tune?
- Have you checked all the trans cooler lines for any kinks or blockages in fluid flow?
- Did this issue begin the VERY FIRST time you went WOT after the cam install? Or did it take a short while to appear?
- Have you taken a vacuum reading since the cam install? If so, what was it? Are you noticing any sure signs of too low of vacuum like some loss of power brakes, etc.?
- Obvious things that might be overlooked like loose plug wires, cracked/seriously mis-gapped plug(s), issue with throttle cable hanging/sticking/etc.?
- Anything you might have done to damage the VSS?
My replies are in CAPS.
DIDNT GO NEAR THE VSS AS FAR AS I KNOW. CAM SWAP WAS DONE WITH ENGINE IN CAR.
I dont know what could have happened. im so lost.. lol
Originally Posted by RPM WS6
Here are some questions in random order to review that might shed some light on the issue. Maybe it will give you some new ideas to check:
- Is the trans opperating correctly in other areas of normal driving? (i.e. TC lock-up occuring as normal?)
YES... ALL SEEMS NORMAL WITH THIS.
- If you launch from a dead stop (WOT), does it upshift properly?
YES IT DOES, AND PULLS LIKE MAD!!
- At any point before or after the cam install, have you had any DTCs stored or SES lights flash?
NO, OTHER THAN P0300 RANDOM MISSFIRE. NO FLASHING
- Are you seeing large misfires at any rpm? Have you logged this yet?
NO MISSFIRES AND LITTLE TO NO KNOCK AT WOT.
- When you replaced the PCM, what flash did you use? A stock file from the dealer or a custom tune?
THIS IS A FRESH PCM NO TUNE WHAT SO EVER.
- Have you checked all the trans cooler lines for any kinks or blockages in fluid flow?
I DONT SEE ANY KINKS, FLUID LOOKS/SMELLS OK, FILLED CORRECTLY
- Did this issue begin the VERY FIRST time you went WOT after the cam install? Or did it take a short while to appear?
NOTICED IT 3 DAYS LATER. PROBABLY WHEN WOT 20 TIMES BEFORE I SAW IT
- Have you taken a vacuum reading since the cam install? If so, what was it? Are you noticing any sure signs of too low of vacuum like some loss of power brakes, etc.?
HAVE NOT TAKEN A READING, BRAKES FEEL FINE.
- Obvious things that might be overlooked like loose plug wires, cracked/seriously mis-gapped plug(s), issue with throttle cable hanging/sticking/etc.?
I HAVE CHECKED WIRES, PLUGS WERE CHECKED AND RECHECKED DUE TO THE PAIN TO INSTALL. THROTTLE CABLE MOVES WITH NO EFFORT.
- Anything you might have done to damage the VSS?
- Is the trans opperating correctly in other areas of normal driving? (i.e. TC lock-up occuring as normal?)
YES... ALL SEEMS NORMAL WITH THIS.
- If you launch from a dead stop (WOT), does it upshift properly?
YES IT DOES, AND PULLS LIKE MAD!!
- At any point before or after the cam install, have you had any DTCs stored or SES lights flash?
NO, OTHER THAN P0300 RANDOM MISSFIRE. NO FLASHING
- Are you seeing large misfires at any rpm? Have you logged this yet?
NO MISSFIRES AND LITTLE TO NO KNOCK AT WOT.
- When you replaced the PCM, what flash did you use? A stock file from the dealer or a custom tune?
THIS IS A FRESH PCM NO TUNE WHAT SO EVER.
- Have you checked all the trans cooler lines for any kinks or blockages in fluid flow?
I DONT SEE ANY KINKS, FLUID LOOKS/SMELLS OK, FILLED CORRECTLY
- Did this issue begin the VERY FIRST time you went WOT after the cam install? Or did it take a short while to appear?
NOTICED IT 3 DAYS LATER. PROBABLY WHEN WOT 20 TIMES BEFORE I SAW IT
- Have you taken a vacuum reading since the cam install? If so, what was it? Are you noticing any sure signs of too low of vacuum like some loss of power brakes, etc.?
HAVE NOT TAKEN A READING, BRAKES FEEL FINE.
- Obvious things that might be overlooked like loose plug wires, cracked/seriously mis-gapped plug(s), issue with throttle cable hanging/sticking/etc.?
I HAVE CHECKED WIRES, PLUGS WERE CHECKED AND RECHECKED DUE TO THE PAIN TO INSTALL.
THROTTLE CABLE MOVES WITH NO EFFORT.- Anything you might have done to damage the VSS?
I dont know what could have happened. im so lost.. lol
On The Tree
Joined: Jul 2002
Posts: 113
Likes: 0
From: Someplace high in the Himalayas
Is it possible that with the new cam your making so much torque that the computer doesn't think the load on the engine is great enough to warrant a downshift? I noticed mine would not downshift as easily just after installing a LM on a stock car....honest...
Joined: Nov 2001
Posts: 34,611
Likes: 2,525
From: Schiller Park, ILL Member: #317
Originally Posted by PurplePiss
Is it possible that with the new cam your making so much torque that the computer doesn't think the load on the engine is great enough to warrant a downshift? I noticed mine would not downshift as easily just after installing a LM on a stock car....honest...
SS891, you mentioned that you probably went WOT 20 times before the issue happened with the first tune/PCM, but what about when you tried the new PCM? Did it take 20 or so times to start up again, or was it instantly? If it again took about 10-20 times with the new PCM as well, then I would guess that the PCM is "learing" something after a few occurances that is causing the issue. If this is the case you could confirm this further by resetting the PCM and trying some more....
If instantly, I would tend to think something yet unfound is/has broken/damaged/etc, hence the reason it was ok for 20 times with the first PCM but not the fresh tune/PCM.
Last edited by RPM WS6; Dec 30, 2003 at 06:30 PM.
