An interesting observation - what can be the cause of it?
10-19-2006, 09:06 PM
#1
An interesting observation - what can be the cause of it?
Tonight I was on a lonley stretch of the highway and decided to do a little spirited run... I was doing 80 in 5th gear and downshifted to 4th. I noticed the tach jumping to about 4800 RPM, staying there and then dropping to about 4200 RPM - I was mashing the gas at that time and clutch was not depressed... that sparked my curiousity. I slowed down to 60 and down****ed into 3rd gear and then mashed it. I saw the tach climb but not at an even smooth motion, it'd go up fast then slow down a but then fast again then slow down a bit more...
So I am wondering - what can be the case of that? The occurance in 4th gear made me think that perhaps my clutch is slipping in higher gears; then in the second occurance I am now thinking that perhaps my coils and plugs are just crappy, or the knock sensor... This does not happen at lower RPM and in heavy acceleration from 0 RPM to like 4.5 RPM, only after 4.5K RPM or so. When I drive normally and even slightly "fast", acceleration is fine...
So any insight?
So I am wondering - what can be the case of that? The occurance in 4th gear made me think that perhaps my clutch is slipping in higher gears; then in the second occurance I am now thinking that perhaps my coils and plugs are just crappy, or the knock sensor... This does not happen at lower RPM and in heavy acceleration from 0 RPM to like 4.5 RPM, only after 4.5K RPM or so. When I drive normally and even slightly "fast", acceleration is fine...
So any insight?
10-20-2006, 08:31 AM
#4
Originally Posted by mbandi
Did the RPM's tend to runaway or flare and then come back down?
10-20-2006, 11:51 AM
#8
Originally Posted by GodFather
Looks like a slippery clutch to me, or a toasted flywheel surface needed resurface.
-Peter-
-Peter-
But I assume that if I was gonna swap the clutch, I may as well resurface the flywheel... how much are we talking here for the components only? I get labor done at almost 1/4 price of regular shops.
10-20-2006, 08:05 PM
#10
It sounds like coils to me...you have a 99 and i had a very similar experiance with mine.
But if it's the clutch, then you most certainly have to resurface the flywheel ( same concept as rotors ). For components your looking somewhere around 250 including the resurface. This is with the 5th gen clutch, TOB, and PP. A little more for extra goodies, such as new GL-4 tranny oil, SS clutch line, rear seal since your down there...etc etc etc.
But if it's the clutch, then you most certainly have to resurface the flywheel ( same concept as rotors ). For components your looking somewhere around 250 including the resurface. This is with the 5th gen clutch, TOB, and PP. A little more for extra goodies, such as new GL-4 tranny oil, SS clutch line, rear seal since your down there...etc etc etc.
10-20-2006, 08:14 PM
#11
Originally Posted by 99se5speed
It sounds like coils to me...you have a 99 and i had a very similar experiance with mine.
But if it's the clutch, then you most certainly have to resurface the flywheel ( same concept as rotors ). For components your looking somewhere around 250 including the resurface. This is with the 5th gen clutch, TOB, and PP. A little more for extra goodies, such as new GL-4 tranny oil, SS clutch line, rear seal since your down there...etc etc etc.
But if it's the clutch, then you most certainly have to resurface the flywheel ( same concept as rotors ). For components your looking somewhere around 250 including the resurface. This is with the 5th gen clutch, TOB, and PP. A little more for extra goodies, such as new GL-4 tranny oil, SS clutch line, rear seal since your down there...etc etc etc.
10-20-2006, 08:53 PM
#12
Yeah, but all you said was that the TACH was jumping up and down. You also said the speed of the car increased. Therefore, the clutch should be fine. IF it were slipping, the ENGINE speed would increase far greater than the speed of the CAR would. SO I would say you have a faulty tach, unless when you shifted you weren't smooth. So, to make sure, the tach was doing something COMPLETELY different from what the engine was doing, right?
10-20-2006, 08:55 PM
#13
sounds like a clutch slipping problem to me. although i dont see why it wouldnt slip at lower speeds under hard acceleration. kinda like its in the beginning stages of slipping. if you replace the clutch definitly resurface the flywheel. do the 5th gen clutch setup. replace rear main seal (hope you have better luck than i did). and most definitly replace tranny fluid with only gl-4 fluid.
10-20-2006, 09:36 PM
#14
Before completely deciding that it is the clutch, I would test to see if it is slipping when you're not downshifting. Do you experience this when you are accelerating hard? You could just be seeing a failsafe system using the method that you described.
10-20-2006, 09:47 PM
#15
Originally Posted by Sounbwoy
Yeah, but all you said was that the TACH was jumping up and down. You also said the speed of the car increased. Therefore, the clutch should be fine. IF it were slipping, the ENGINE speed would increase far greater than the speed of the CAR would. SO I would say you have a faulty tach, unless when you shifted you weren't smooth. So, to make sure, the tach was doing something COMPLETELY different from what the engine was doing, right?
The tach was not going back, it kept showing higher RPM, jsut not in a very smooth motion - it was not jerking, but it was odd - maybe I will take a vid of it next time.
Originally Posted by kaneda_77
Before completely deciding that it is the clutch, I would test to see if it is slipping when you're not downshifting. Do you experience this when you are accelerating hard? You could just be seeing a failsafe system using the method that you described.
I accelerated hard today and didn't see it today (Well wasn't paying as much attention)...
10-20-2006, 10:05 PM
#16
Supporting Maxima.org Member
Join Date: Dec 2004
Location: Atlanta, GA
Posts: 1,183
Sounds like the knock sensor is torqued too hard. This was EXACTLY my problem. I would see fast acceleration, then slow, then fast, then slow ... like a roller coaster in acceleration speed. When I loosened the knock sensor ... BOOM and smooth.
Even though the knock sensor was BEYOND over-torqued, it still didn't throw a code because the sensor wasn't damaged ... just over-sensative.
Even though the knock sensor was BEYOND over-torqued, it still didn't throw a code because the sensor wasn't damaged ... just over-sensative.
10-21-2006, 11:50 AM
#17
> sounds like a clutch slipping problem to me. although i dont see why it wouldnt slip at lower speeds under hard acceleration.
The clutch slips in higher gears easier than in low gears because of the higher gear ratio -- it's harder to move the tranny. When my clutch started slipping it was at around 3500 in 5th gear (the beginning of the high torque curve). As time progressed it would slip at lower RPMs and in 4th, 3rd, etc gear.
> I accelerated hard today and didn't see it today
When my clutch was in the process of dying it'd be bad one day, and then the next it wouldn't slip at all. Then it'd slip worse.
The clutch slips in higher gears easier than in low gears because of the higher gear ratio -- it's harder to move the tranny. When my clutch started slipping it was at around 3500 in 5th gear (the beginning of the high torque curve). As time progressed it would slip at lower RPMs and in 4th, 3rd, etc gear.
> I accelerated hard today and didn't see it today
When my clutch was in the process of dying it'd be bad one day, and then the next it wouldn't slip at all. Then it'd slip worse.
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