Stupid questions!
Thread Starter
Joined: Sep 2005
Posts: 532
Likes: 1
From: Abilene, TX
Stupid questions!
What is the 20,000 mile light on the dash for in a 87 non turbo car? It's apparently turned on by the ECU.
Ok this is going to be basic I'm sure. Is the 84-85 GSL-SE transmission the same as the 86-91 13B NA transmission? Probably not I'm assuming.
Next question the S4 13B ECU requires a signal to tell it that it is in 5th gear. I am assuming for gas mileage. To let it know it's in overdrive right? So if I only have a 12A transmission then I need a 13B transmission right?
One last question has anyone ever put a 5th gear switch in the side of the 12A tranny to be able to use the 12A tranny instead of buying the more expensive 13B trannys?
The reason i ask is because I'm swapping a S4 NA engine into my 84 GSL but I want everything to work perfect. My other option is to wire up a switch that can be flipped when the car is in 5th gear. That's pretty garbage like though I'd rather have the tranny do the switching. But maybe it doesn't even need it anyways. Hell it doesn't even require a speed signal to be sent to it and that's pretty weird if you ask me.
Ok this is going to be basic I'm sure. Is the 84-85 GSL-SE transmission the same as the 86-91 13B NA transmission? Probably not I'm assuming.
Next question the S4 13B ECU requires a signal to tell it that it is in 5th gear. I am assuming for gas mileage. To let it know it's in overdrive right? So if I only have a 12A transmission then I need a 13B transmission right?
One last question has anyone ever put a 5th gear switch in the side of the 12A tranny to be able to use the 12A tranny instead of buying the more expensive 13B trannys?
The reason i ask is because I'm swapping a S4 NA engine into my 84 GSL but I want everything to work perfect. My other option is to wire up a switch that can be flipped when the car is in 5th gear. That's pretty garbage like though I'd rather have the tranny do the switching. But maybe it doesn't even need it anyways. Hell it doesn't even require a speed signal to be sent to it and that's pretty weird if you ask me.
Thread Starter
Joined: Sep 2005
Posts: 532
Likes: 1
From: Abilene, TX
FB+FC=F-ME
Joined: Jul 2004
Posts: 3,353
Likes: 5
From: Rohnert Park CA
The 5th gear switch.....or "Over the Top" switch as its called in the FSM,is to tell the ECU that you are in high gear and presumably cruising.
The ECU then turns on the split air solenoid to route secondary air to the main cat.At 5th gear speeds,secondary air can be pumped uniterrupted to the main cat,because there is plenty of cooling air flowing under the car to keep the cat from melting down.Its not entirely needed,as it only effects smog output in 5h gear.Youll still pass a dyno roller smog test and probably not have any tangible problems if you leave it unhooked.There is a speed sensor in the speedometer,but its only to tell the cruise control ECU how fast your going.
I was not aware that a 20K mile idiot light existed,but there is a 20K mile switch inside of all 2nd gens.When the odo. reaches 20K,the switch closes and tells the ECU that its OK to start pumping port air injection under certain circumstances.This is (I presume) to prevent the precat from melting down when its still new.Its likely that these precautions are not neccesary with modern catylist technology.Cats of the 1980's were still somewhat unreliable and had only evolved a little from the horrifically restrictive cats of the 70's.Add to that the high temp nature of the rotary,and its easy to see why there were so cautious.
All N/A transmissions are basically the same.There were gear ratio and syncro changes made between the generations,but they are all based on the TypeM smoothcase tranny.All the bellhousings and input shaft splines are the same.There were small changes made to the shifter and mounts,but that can be overcome easily when swapping.Although the 1st gen boxes are older,the 2nd gen boxes are often in worse shape due to the heavier and more powerful FC wearing out the unit faster.
The ECU then turns on the split air solenoid to route secondary air to the main cat.At 5th gear speeds,secondary air can be pumped uniterrupted to the main cat,because there is plenty of cooling air flowing under the car to keep the cat from melting down.Its not entirely needed,as it only effects smog output in 5h gear.Youll still pass a dyno roller smog test and probably not have any tangible problems if you leave it unhooked.There is a speed sensor in the speedometer,but its only to tell the cruise control ECU how fast your going.
I was not aware that a 20K mile idiot light existed,but there is a 20K mile switch inside of all 2nd gens.When the odo. reaches 20K,the switch closes and tells the ECU that its OK to start pumping port air injection under certain circumstances.This is (I presume) to prevent the precat from melting down when its still new.Its likely that these precautions are not neccesary with modern catylist technology.Cats of the 1980's were still somewhat unreliable and had only evolved a little from the horrifically restrictive cats of the 70's.Add to that the high temp nature of the rotary,and its easy to see why there were so cautious.
All N/A transmissions are basically the same.There were gear ratio and syncro changes made between the generations,but they are all based on the TypeM smoothcase tranny.All the bellhousings and input shaft splines are the same.There were small changes made to the shifter and mounts,but that can be overcome easily when swapping.Although the 1st gen boxes are older,the 2nd gen boxes are often in worse shape due to the heavier and more powerful FC wearing out the unit faster.
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