ECM just controlling Lock up Converter
Thread Starter
Instructor
Joined: Jun 2019
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ECM just controlling Lock up Converter
Carb and dist delete. HEI and non ECM carb. If I don't unplug, or disable ECM, will the ECM still control the lock up on the transmission and will the lock up converter work as it is supposed to work?
Le Mans Master
Joined: Jul 2000
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From: columbia city in
We will have to assume that you have a 1981 or a 1982 corvette.You can drive the car and see how it performs.It should work ,But I am not positive.The only imput that I know of for the computer to the tranny is the speed sensor, from the speedo cable on the back of the speedometer.[vss]
Drifting
Joined: Aug 2009
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From: new iberia la
Race Director
Joined: Jul 2004
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From: Scottsdale Arizona
Though I’m not certain, I really doubt the lockup will work with the Check Engine light on. Also, I don’t think the CCC got any input from the speedo but it did from the distributor. Since lockup only works in third gear, my guess is that it was RPM based.
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Drifting
Joined: Aug 2019
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The converter won't be engaged unless it's in closed loop mode. That being said, do you still have an O2 sensor.? Closed loop is based on O2 and coolant temp. are the main controllers as well as vehicle speed. Also your converter locks up in 2nd and 3rd gear. if the conditions are right.
2026 Loser of the Year
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From: New Or-leens Loo-z-anna
The converter won't be engaged unless it's in closed loop mode. That being said, do you still have an O2 sensor.? Closed loop is based on O2 and coolant temp. are the main controllers as well as vehicle speed. Also your converter locks up in 2nd and 3rd gear. if the conditions are right.
Drifting
Joined: Aug 2019
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The only reason why lockup wouldn’t work on a 700R4 is if the brake light switch or TPS sensor was bad or faulty providing internal transmission electronics and ECM is good . Lockup controls Cooler flow on the 700 and it doesn’t flow until lockup so GM wants it to lockup just so it doesn’t burn up . For those that don’t want lockup Sonnax does sell a tcc valve that corrects cooler flow without lockup
if your 81 has a 3 speed T350C then no harm done if lockup doesn’t work but no lockup on a 700R4 will burn it up on 1982 Vettes . I did enjoy the lockup on my T350C in my 1980 but have since converted to 700R4 , the best single item change I’ve made to the car so far
if your 81 has a 3 speed T350C then no harm done if lockup doesn’t work but no lockup on a 700R4 will burn it up on 1982 Vettes . I did enjoy the lockup on my T350C in my 1980 but have since converted to 700R4 , the best single item change I’ve made to the car so far
Team Owner
Joined: Jan 2006
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From: Crossville TN
Lockup is not anything like an overdrive gear. It merely eliminates the hydraulic 'linking' of the converter pump and turbine. At best, the rpm change when it goes into lockup mode is 200-300 rpm. There is a noticeable change is speed, but nothing like a major gear change.
Burning Brakes
Joined: Feb 2020
Posts: 904
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From: Central NJ
I have an 82 with a crate 355, only thing the ECM does is the fuel pump, you can verify that by turning the ignition on but not starting. The pump will cycle for 2 seconds and then turn off if no demand. It will not lock up the TC and the only ways I know to do that is the B&M kit or what I have which is a pressure switch inside the trans that goes to ground when it hits forth and initiates the lock. The trouble is that it will lock it at slower speeds than I want especially when the engine is not fully warmed and possibly lug. two ways around that, keep it in 3rd when driving around town or putting another switch on the wire coming out of the trans and turning off the lock when not needed, I plan to add the switch and put it near the shifter. From what I was told by a good trans guy, not locking the TC will cause the temps to go up at highway speeds and might shorten the life of the trans. The RPM difference ,locked/unlocked, is 3-400 from what I see on my tach. I heard from a few trusted mechanics the the B&M kits are a bit of trouble but I have not experience with them. Good luck,
60
60
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From: New Or-leens Loo-z-anna
Lockup is not anything like an overdrive gear. It merely eliminates the hydraulic 'linking' of the converter pump and turbine. At best, the rpm change when it goes into lockup mode is 200-300 rpm. There is a noticeable change is speed, but nothing like a major gear change.
Every little bit helps: 200 rpm x 60 min x 5 hr. road trip = 60,000 rpm (un-used @ 60mph)
60,000 rpm / 3000 rpm @ 60mph = 20 minutes of wear you saved on your engine (@ 60 mph)
(did I do that correctly?)
Last edited by doorgunner; Apr 17, 2021 at 10:32 AM.