Won't engage in 4th or 5th gear?
#1
11-09-2017, 01:36 PM
Join Date: Nov 2017
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Won't engage in 4th or 5th gear?
Hey guys I have a 2008 g35x (5AT) with 126xxx miles on it. Over the past 2 hours driving I've run into some troubling issues with my car's gear selection.
The issue started when my car,very randomly, decided not to shift into the higher gears when speeding up. Around 40-50 mph, the car is revving from 4-6.5k rpm. When this happened, I would shift my car into tiptronic, put it into a higher gear, and all was well. I slowed down and sped up, having to do this probably 5-6 times before the problem worsened. When I tried to put my car into a higher gear in tiptronic mode: the dash would display my car is in 3rd immediately after putting it into tiptronic, then after attempting to upshift to 4th the rpm's would redline with no power to the wheels (think neutral). The car would even let me upshift to 5th, still with no engagement of power to the wheels. If I try to downshift back to third and release the accelerator, the rpm's go down to about 1k before I hear a big 'clunk', and I can then continue moving in 3rd. I don't want to put any strain on the transmission in continuing to try to figure this issue out.
I'm assuming and praying that the issue is electronic, not mechanical or having to do with my transmission. So far I have only tried resetting the ECU however the problem persists. Transmission fluid is not in need of replacement either. I think it might be a pressure sensor in the transmission or something but I don't know how I could diagnose that specifically.
I've searched this forum and many other places but cannot seem to find any one who has had an issue where the car seems to go to neutral in the higher gears... If you have any insight please let me know!
The issue started when my car,very randomly, decided not to shift into the higher gears when speeding up. Around 40-50 mph, the car is revving from 4-6.5k rpm. When this happened, I would shift my car into tiptronic, put it into a higher gear, and all was well. I slowed down and sped up, having to do this probably 5-6 times before the problem worsened. When I tried to put my car into a higher gear in tiptronic mode: the dash would display my car is in 3rd immediately after putting it into tiptronic, then after attempting to upshift to 4th the rpm's would redline with no power to the wheels (think neutral). The car would even let me upshift to 5th, still with no engagement of power to the wheels. If I try to downshift back to third and release the accelerator, the rpm's go down to about 1k before I hear a big 'clunk', and I can then continue moving in 3rd. I don't want to put any strain on the transmission in continuing to try to figure this issue out.
I'm assuming and praying that the issue is electronic, not mechanical or having to do with my transmission. So far I have only tried resetting the ECU however the problem persists. Transmission fluid is not in need of replacement either. I think it might be a pressure sensor in the transmission or something but I don't know how I could diagnose that specifically.
I've searched this forum and many other places but cannot seem to find any one who has had an issue where the car seems to go to neutral in the higher gears... If you have any insight please let me know!
#2
11-09-2017, 03:23 PM
Join Date: May 2017
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What was the fluid last changed? It's only good for 30k miles. I would inspect/clean the transmission ground wire located at the front of the ENGINE, it's bolted to the top of the timing chain cover and there are two grounds, one is the transmission, clean it with a wire brush and apply anti-oxidation grease. You didn't specifically mention that you checked for proper fluid level either, those symptoms you described are exactly what happens when the fluid level is low.