Tranny problems?

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jibbby

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Santa Monica, California
While running the Nitrous on my 1992 SC400, I experience a delayed shift between 2nd and 3rd gear at times...It did this before my recent tranny build up and it still does it now...When I hit the 3rd gear shift mark it either bogs or gets hung up sometimes. I have to ease the gas pedal quickly and then it shifts into third... Without the Nitrous under full throttle this does not happen...

Can anyone tell me what this problem is and how it can be corrected? Is it the tranny codes from the ECU or tranny valves sticking or something that is causing this to happen? I have no clue as to what causes this delayed shift at times but it pisses me off and I would like it fixed...
 
Have you looked into using a standalone tranny controller? A few people are using them to control their autos since they run aftermarket ECU's. It sounds like some freak computer behavior from overloading the engine during shifts. Some factory ECU's cut or modify spark inbetween shifts to prolong the life of the transmission.
 
Yeah Smithers...The stand alone is an option but I am not so sure it is the ECU codes that is causing the problem because it does not occure when not using the Nitrous.... It seems that with the additional 100WHP it fouls the shifting from second to third at times...With the ECT button pushed I seem to experience that problem more then when it is off also...

Just a weird problem...Though I have heard of others with 150hp shots experiencing foul shifting on their SC4's......I was thinking maybe a shift kit would help?
 
3rd gear

Yeah Smithers...The stand alone is an option but I am not so sure it is the ECU codes that is causing the problem because it does not occure when not using the Nitrous.... It seems that with the additional 100WHP it fouls the shifting from second to third at times...With the ECT button pushed I seem to experience that problem more then when it is off also...

Just a weird problem...Though I have heard of others with 150hp shots experiencing foul shifting on their SC4's......I was thinking maybe a shift kit would help?

TRY RUNNING A SEPERATE GROUND FOR TRANS, ARE YOU USING RELAYS TO ENGAGE NITROS; MAKE SURE THEY ARE NOT INTEFERE WITH TRANS CIRCUIT.
POPS
 
POPS, I will look into that....Thanks... There are no relays that would interfere with trans circuit from my Nitrous system...I will look into running a new seperate ground for the trans and see what happens.....
 
trans

POPS, I will look into that....Thanks... There are no relays that would interfere with trans circuit from my Nitrous system...I will look into running a new seperate ground for the trans and see what happens.....
Also run a ground for trans computer
 
Pops, have you worked on alot on these transmissions?

Thanks, again for the heads up... Curious, could a bad ground really be the cause for bad shifting in just one gear? I was thinking Tranny valve adjustment or something funny going on with those internals may be the culprit...Or maybe a bad ECU as this has been an ongoing problem for 3 years or so regardless of the tranny rebuild.......
 
trans

Pops, have you worked on alot on these transmissions?

Thanks, again for the heads up... Curious, could a bad ground really be the cause for bad shifting in just one gear? I was thinking Tranny valve adjustment or something funny going on with those internals may be the culprit...Or maybe a bad ECU as this has been an ongoing problem for 3 years or so regardless of the tranny rebuild.......

Trans is almost identical to 340e used in a supra i had;i had it rebuilt by Hypster in German town, Wisc. I am familiar yes' very knowledgable no !
Same trans ! Trans can run hooked up wrong. meaning wire loom was cut! But you will notice it in first gear no power.I ran a 396hp 7mgte with 150 Nos for 7 years.Trans rebuild was necessary because radiator portion used for trans cooler leaked water into trans. The ECT portion of your trans is related to shiftpoints of 3rd gear. Grounds are everything on Toy products and easiest to try, Just run a second temporary grnd to see if it works. Most of the problems we refuse to let be simple.Did you try trans without energizing nitros for this problem. Check body grounds on both computers make sure they are hooking up; Plugs that go on trans good connect no cuts; Trans ground to chassis tight and clean.
May everything in your life be as tight as a good ground.
pops
 
the ecu retards timing between gear changes

does it feel like its still in retard mode and already selected gear then after a second or 2 it comes out of retardation mode and you get full power

i have experienced this when i played with the speed signals to the ecu
so i can adjust at what revs to change gears at full throttle

but there is a limited range you can adjust cause the ecu knows exactly
what speed difference and how long it takes to change gears

bit hard to explain but with the nitrous maybe the extra power accelerates car much faster than what the ecu is programmed for so your gbox has chnaged gears but the ecu still thinks its goin thru the shift so you still have the retarded ignition timing untill the ecu thinks enough time has gone past it then brings the ignition timing back up to what it needs

not sure of this is your prob but i use special signal adjusters to play with when to change gears so if you lied to ecu and said it was goin a tiny bit faster then it might fix yr problem

this problem usually happens to me when i slow the speed signal to the ecu to much
 
Sideshow, Well yes, the first to second gear change is perfect then when in second gear the rpms do climb very rapidly and then the car bogs or hesitates to shift into third. If I quickly ease up on the throttle the car shifts normally into third...Then I lose the race.... Happens alot of the time... No nos I do not experience this problem under full throttle ever...

The ECU maybe slow as the shifts do come quickly...I will look into that..Thanks for replies...
 
You dont have a trans problem; no nos no problem! Nos is either a dry or wet system, if wet you could be robbing fuel needed for injectors. And there is possibility you are blowing flame off pistons.Your letting up would allow fuel and or spark to return to decent paremeters. Pinch plugs down 5k and try.Check fuel pump out voltage when under boost as i have seen many lex and toy that drop to 8.5 volts and anything under 13 volts wont cut it.(fuel relay) Could also be as simple as throttle and trans cable adjustments.
 
Pops, I have thought about that...However, for 1 year when I first had my Nos dry system I did not experience this problem..It came on over time...I actually use to have a bog problem when at full throttle at launch...That was when I installed the headers...Ecu learned and the car adjusted... Tranny I have tried a few things and am still working on it...I also did 5 full throttle runs with out nos and on the fifth try it did bog, but that is very rare.....So this does happen even without out the use of NOS as I just found this out yesterday... The problem persists and am still looking into this fix...Electronic issue I am sure, maybe fuel cut but I dought it... The bog/delay in shift seems to not happen as much with the ECT button OFF under the nos...When the ECT button is on it happens every time...Just a weird deal...
 
when the ect button is on is that power mode or economy mode

cause if its in power mode this makes ecu change gears later

maybe making hte problem more visible
 


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