RPM fluctuation at WOT
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RPM fluctuation at WOT Whenever I go WOT, the RPM increases with about 200 rpm fluctuations (ex. 5600-5700 then back to 5500, and so on). It does that in all gears & continues to do that until it shifts to next gear. In very few occasions, it does not shift & it continues until it hits the rev limiter. I verified this visually by looking at the gauges & via HP Tuner scan log. Speedometer looks to be working fine
Initially I thought of this to be plugs/wires issue, however I replaced those with no luck. Tuning is also not the issue here. Iam leaning to decide that it is actually a tranny/converter problem rather than an engine problem
The following is also worth mentioning
-I switched to different set of wheels/tires. However the tires height is still the same & hence no programming needed
-From comparing my current scan logs showing this problem, and other previous logs that did not have this problem, it looks like there is about 200-300 LESS WOT slippage, assuming similar RPM/Gear/Speed
Does anyone have any insight on this? Did anyone experience something similar?
Thanks!
Initially I thought of this to be plugs/wires issue, however I replaced those with no luck. Tuning is also not the issue here. Iam leaning to decide that it is actually a tranny/converter problem rather than an engine problem
The following is also worth mentioning
-I switched to different set of wheels/tires. However the tires height is still the same & hence no programming needed
-From comparing my current scan logs showing this problem, and other previous logs that did not have this problem, it looks like there is about 200-300 LESS WOT slippage, assuming similar RPM/Gear/Speed
Does anyone have any insight on this? Did anyone experience something similar?
Thanks!
Last edited by xxxhp; Jan 8, 2008 at 06:57 AM.
Its just my opinion but to me this does not sound like and transmissions slipage problem I have heard of or seen , Generally they dont slip then not slip then slip again they either hold or they dont , If I am understanding your description correctly.
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FormerVendor
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From: D-F/W
Thanks for including the recent changes with the tires / wheels.
Ordinarily the transmission will not slip then grab like mentioned. But I would not rule it out. However, I know Vinces units to be awfully strong puppies too! How old is it?
How old is the current powertrain combination? When was it last Tuned?
I know you stated it is not a Tuning issue... but it sure could be from your description. How did you rule that out?
Also, have you taken a fuel pressure reading at WOT lately? When was the last dyno pull?
g
Ordinarily the transmission will not slip then grab like mentioned. But I would not rule it out. However, I know Vinces units to be awfully strong puppies too! How old is it?
How old is the current powertrain combination? When was it last Tuned?
I know you stated it is not a Tuning issue... but it sure could be from your description. How did you rule that out?
Also, have you taken a fuel pressure reading at WOT lately? When was the last dyno pull?
g
Thread Starter
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. Fuel pressure starts at ~60psi and climbs to ~70psi due to the boost referenced regulatorI don't think it's a tuning issue because this issue started to happen while no changes were made to the tune. I initially thought it to be a spark/fuel issue, however plugs & wires change along with several tune changes did not seem to improve anything
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Here is a sample log, Iam sorry I don't know how to make more read-able
Engine RPM Vehicle Speed Throttle Position Ignition Timing Knock Retard Trans Current Gear Wide Band O2 - LM1 afr
3002 61 100 15 0 3 14.53
3368 61 100 15 0 3 11.4
3735 61 100 13.5 0 3 11.84
4012 63 100 11 0 3 11.38
4166 63 100 11 0 3 11.01
4316 64 100 11 0 3 11.03
4506 65 100 12.5 0 3 10.86
4683 66 100 12.5 0 3 10.38
4848 68 100 12.5 0 3 10.1
4739 69 100 12.5 0 3 10.64
4958 71 100 13 0 3 11.51
5158 73 100 13 0 3 11.75
5338 76 100 13.5 0 3 11.85
5219 75 100 13.5 0 3 12.5
5384 76 100 13.5 0 3 11.88
5219 78 100 13.5 0 3 12.17
5442 81 100 13.5 0 3 11.89
5312 85 100 14 0 3 11.94
5456 82 100 13.5 0 3 11.87
5296 83 100 13.5 0 3 11.76
5446 85 100 13.5 0 3 11.7
5384 86 100 14 0 3 11.75
5538 88 100 14 0 3 11.81
5430 89 99 14 0 3 11.97
5586 89 100 14 0 3 11.58
5534 91 100 14.5 0 3 12.02
5482 92 100 14.5 0 3 11.71
5638 93 100 14.5 0 3 11.53
5655 94 100 15 0 3 11.76
5536 96 100 15 0 3 12.06
5560 97 100 15 0 3 12.03
5713 98 100 15.5 0 3 11.53
5730 99 100 15.5 0 3 11.46
5632 99 100 15.5 0 3 11.78
5790 101 100 15.5 0 3 11.8
5815 102 100 15 0 3 11.84
5794 103 99 15 0 3 11.95
5670 104 100 15 0 3 11.98
5746 104 99 15.5 0 3 11.6
5851 106 100 15.5 0 3 11.46
5895 106 99 15.5 0 3 11.56
5906 108 100 15.5 0 3 11.63
5842 108 100 15.5 0 3 11.59
5865 109 67 15.5 0 3 11.31
5023 108 33 14 0 4 10.7
5126 108 12 36.5 0 4 11.36
Engine RPM Vehicle Speed Throttle Position Ignition Timing Knock Retard Trans Current Gear Wide Band O2 - LM1 afr
3002 61 100 15 0 3 14.53
3368 61 100 15 0 3 11.4
3735 61 100 13.5 0 3 11.84
4012 63 100 11 0 3 11.38
4166 63 100 11 0 3 11.01
4316 64 100 11 0 3 11.03
4506 65 100 12.5 0 3 10.86
4683 66 100 12.5 0 3 10.38
4848 68 100 12.5 0 3 10.1
4739 69 100 12.5 0 3 10.64
4958 71 100 13 0 3 11.51
5158 73 100 13 0 3 11.75
5338 76 100 13.5 0 3 11.85
5219 75 100 13.5 0 3 12.5
5384 76 100 13.5 0 3 11.88
5219 78 100 13.5 0 3 12.17
5442 81 100 13.5 0 3 11.89
5312 85 100 14 0 3 11.94
5456 82 100 13.5 0 3 11.87
5296 83 100 13.5 0 3 11.76
5446 85 100 13.5 0 3 11.7
5384 86 100 14 0 3 11.75
5538 88 100 14 0 3 11.81
5430 89 99 14 0 3 11.97
5586 89 100 14 0 3 11.58
5534 91 100 14.5 0 3 12.02
5482 92 100 14.5 0 3 11.71
5638 93 100 14.5 0 3 11.53
5655 94 100 15 0 3 11.76
5536 96 100 15 0 3 12.06
5560 97 100 15 0 3 12.03
5713 98 100 15.5 0 3 11.53
5730 99 100 15.5 0 3 11.46
5632 99 100 15.5 0 3 11.78
5790 101 100 15.5 0 3 11.8
5815 102 100 15 0 3 11.84
5794 103 99 15 0 3 11.95
5670 104 100 15 0 3 11.98
5746 104 99 15.5 0 3 11.6
5851 106 100 15.5 0 3 11.46
5895 106 99 15.5 0 3 11.56
5906 108 100 15.5 0 3 11.63
5842 108 100 15.5 0 3 11.59
5865 109 67 15.5 0 3 11.31
5023 108 33 14 0 4 10.7
5126 108 12 36.5 0 4 11.36
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I'm no expert, but I had the same issue for the last 6 months. Trans would slip above 5800-6200 then grab agian and you could see it and more over feel it grab and pull for another 500-800 rpm. The symtoms would come and go......I'm sure it was a slip...and even had a few redline slips from the shift to the rev limiter for the last 6 months, and then there were days that it never slipped.....then last week i didn't let the fluid warm up enough on a 25 degree day, and got a little heavy on the foot and the tranny revved all the way up in 2nd from shift to redline...would not hardly pull in 2nd at all until next day when everything cooled down. Now it will pull in 2nd but only up to half throttle, and then blows up 2nd.....02 4L60E with 50K, Yank 2800, 403RWHP...
Installing RPM Transmission Stage IV 4L60E next week. Good Luck.
Installing RPM Transmission Stage IV 4L60E next week. Good Luck.
On The Tree
Joined: Jan 2006
Posts: 182
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There is a test you can do since you have a tuning tool, you can be sure that is your transmission is slipping or not.
simply log you input shaft rpm and output shaft rpm, devide input/output rpm.
for each selected gear the result should be the ratio of that gear, first gear 3.06, 2nd 1.62 third 1.00 and fourth 0.76.
I might be a bit wrong with the ratios but the result should be like that.
between shifts there is some slip due to the engagment of the clutches, normal.
I hope this might help
simply log you input shaft rpm and output shaft rpm, devide input/output rpm.
for each selected gear the result should be the ratio of that gear, first gear 3.06, 2nd 1.62 third 1.00 and fourth 0.76.
I might be a bit wrong with the ratios but the result should be like that.
between shifts there is some slip due to the engagment of the clutches, normal.
I hope this might help
