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#1
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Transmission Problem??????
Hi guys
im driving a 1997 svx lsi with 158000 miles wxternal trans cooler installed at 115000 im driving along on freeway at 90mph or 140 kph and at exactly 3000RPM Cruise not engaged funny thing happens the rev counter just goes from 3-4 thousand rpm for no reason no throttle input maybe a slipping trans?? am i on a shift point?? how can i tell when the trans is about to fail?? any symptoms?? it does this intermittently if the revs jump and i put more throttle it just keeps putting the power on if i really put my foot down it kicks down and shifts looking for advice on how to tell when a trans is about to fail please help shimmersky@gmail.com |
#2
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Re: Transmission Problem??????
Sounds like the torque converter is locking and unlocking. This usually happens around 80kph.
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#3
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Re: Transmission Problem??????
How's the weather? Cool?
If you have an effecient external cooler the fluid may get too overcooled and the torque converter clutch releases. After a few miles the fluid heats up (above the 150F threshold) and the TCC engages again. Mine does this when the ambient temp gets below +10C. With the stock cooling setup it happens at ambients below -10C. Br, Tapani |
#4
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Re: Transmission Problem??????
Quote:
__________________
Tony 1996 Polo Green Subaru SVX LSi, 168,XXX miles, Redline D4 ATF, Redline 75W90 gear oil, K&N HP-4001 Oil Filter, Mobil 1 5W50 FS (3qt) and 5W30 High Mileage (4qt) Oil Blend, Motul RBF600 Brake Fluid, AC Delco A975C Air Filter, NGK BKR6EIX-11 plugs, Centric Rotors, Power Stop Evolution Carbon Fiber Ceramic Brake Pads 2005 Gray Acura RL, 165,XXX miles, Redline D4 ATF with Lubegard Platinum Protectant, Mobil 1 5W20 High Mileage Extended Performance Oil 2009 Red Toyota Venza, 123,XXX, Mobil 1 5W30 High Mileage Oil 1992 Red Ferrari 348 ts, 82,XXX, Redline everything |
#5
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Re: Transmission Problem??????
I don't think Las Vegas is cool at this time of year. It's 98°F there today. (43°F here today.) Unless he's driving in the mountains.
Last edited by Blacky; 09-14-2014 at 09:01 AM. |
#6
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Re: Transmission Problem??????
Im actually driving in Dubai UAE
Was in Vegas for the last few years though its hot 100F every day only happens in drive not 3rd at 3000rpm only usually only straight and level highway speed 3000 rpm = 90mph =140kph |
#7
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Re: Transmission Problem??????
Slow down. Problem solved. Next!
__________________
When I was in school I sucked in sports. Then I found out I can buy trophies and now I am great at everything. |
#8
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Re: Transmission Problem??????
At 100 F, and 140 KPH, it's also possible that the trans is unlocking the torque converter deliberately, to cool itself off ( increased flow ).
Where is the trans cooler mounted? Because to be effective in those ambient temps, it needs to be in front of the rad, or, have it's own fan for a wheel well mounting. As a side note, mine ( also a '97 ) unlocks the torque converter and then re locks about three times a minute, for a few minutes, then doesn't do it any more for a few minutes, and then does it again.... but only with the cruise on. without the cruise on, it might cycle once every couple of hundred kilometers. It could be aging electronics in the TCU, a bad line of code, or any number of reasons I know nothing about, but it definitely is related to the cruise circuit. Not even cruise being engaged, just arming the cruise control will trigger it. One day, I'll actually get around to mounting my spare one and see if that changes it's behavior. |
#9
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Re: Transmission Problem??????
Quote:
This is the reason why the TCC is engaged even in third and at low speeds when the oveheat mode is on. You may want to monitor the TCU with a lap top when all this happens. Can be done with the ECUtuner software + interface. /T |
#10
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Re: Transmission Problem??????
Your transmission is likely slipping in the extreme heat. Change the fluid and filter out and you may be able to save it.
The TC should stay locked up. The TC unlocked will generate more heat than any benefit of turning the pump quicker. |
#11
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Re: Transmission Problem??????
@ Tapani.. & 1986 Nate
I know what you mean about the heat from the TC being unlocked would seem to outweigh the benefits of the additional flow, but according to Subaru, "ATF Temperature Sensor When the ATF is hot (AWD only), the TCU shifts the transmission as if in the POWER mode. This pushes the shift points higher which allows the engine to run faster. The oil pump then circulates ATF through the oil cooler more quickly so as not to overheat the engine coolant." It would seem that the concern was engine coolant temp, perhaps the issue was localized boiling? And how to tell if it is indeed running in power mode if it's a newer one with no "power" light in the dash? Power mode would seem to exclude 3rd gear lock up. A partially plugged filter might be a contributing factor. It would also seem that not all TCUs' are created equal... Tapani's won't lock up below 150F. Both of mine will lock up from a cold start within a kilometer if it's 50F outside or warmer. But, neither of them has ever locked up in 3rd gear. Ever. Just wondering.. since mine's never done it, when the TC locks up in 3rd, does it shift into 4th locked up, or does it unlock, shift into 4th and then lock up again a bit later? an interesting read.. http://www.northursalia.com/techdocs...ssion/4eat.pdf |
#12
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Re: Transmission Problem??????
Oh yeah.... and, according to Subaru, cruise DOES affect shift points. That explains a few "idiosyncrasies"..
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