76Datsun280z Posted February 7, 2007 Share Posted February 7, 2007 I was curious if you guys could explain to me exactly what the TPS does. I think I heard somewhere that if you disconnect it, it will en rich the mixture. Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted February 7, 2007 Share Posted February 7, 2007 It tells the ECU where the throttle is at (kinda). It closes 2 pins at idle, opens on part throttle, and then closes the two other pins at WOT. On the turbo ECU, it only tells the computer when it is closed, the computer then handles closed loop part throttle and WOT using other sensors. The ECU then actually changes the way it manages fuel. Mario Quote Link to comment Share on other sites More sharing options...
naviathan Posted February 7, 2007 Share Posted February 7, 2007 So what you heard is partially true. Disconnecting it will make it run rich at idle, but not at speed. It will also make it run lean at WOT for a non turbo. Quote Link to comment Share on other sites More sharing options...
olie05 Posted February 7, 2007 Share Posted February 7, 2007 According to the efi bible, (on non-turbo pre zx models) it says that the TP switch is used to let the engine know when to cut fuel on decel. Conversly it richens the mixture at full throttle. It doesn't mention to what extent it richens the mixture though. also, the efi bible says it adds fuel at idle to keep the engine from dying "If the engine is idling, then the control unit can richen the mixture ratio slightly, just as the idle circuit in a carburetor supplies a slightly richer mixture than does the high-speed circuit." Quote Link to comment Share on other sites More sharing options...
76Datsun280z Posted February 7, 2007 Author Share Posted February 7, 2007 Thanks guys, I just got my new one in the mail today my old one started to the thing where it would shut the injectors off and do the whiplash thing so and was also told that I need to get a new one. So I've been driving with it un plugged for a while and just today plugged the new one in, it did do the whiplash thing a couple of times right after I installed it when I took it down the street. Took it back home and adjusted it and took it for a long drive and it didn't do it once, so I'm hoping all is well. Quote Link to comment Share on other sites More sharing options...
GrayZee Posted February 7, 2007 Share Posted February 7, 2007 It depends on the type of tps switch you are talking about. I assume you mean the stock 3 pin one? Basically the center pin is like a common. When the engine is at idle the top pin forms a loop with the center. This basically tells the ecu that the engine is idling and goes into a mode that is very basic and just runs on temp/rpm. Trying to drive it like this will prove quite useless as you won't be able to get it to increase rpms with the accelerator at all. Once the tps sees a slight throttle movement it allows the ecu to access the fuel/timing maps and drive normally. The lower pin also connects to the center pin, but only at full throttle. Alot of times it is not used, but uses for this could be things like turning off the A/C so the engine can have maximum power under full throttle. This is rather a primitave setup, most cars.. (newer ones) use a variable resistor (potentiometer) style. These can be made to do much more precise tasks when used with the ecu. The 240sx TB that alot of people upgrade to actually have both style TPS switches. Quote Link to comment Share on other sites More sharing options...
GrayZee Posted February 7, 2007 Share Posted February 7, 2007 Thanks guys, I just got my new one in the mail today my old one started to the thing where it would shut the injectors off and do the whiplash thing so and was also told that I need to get a new one. So I've been driving with it un plugged for a while and just today plugged the new one in, it did do the whiplash thing a couple of times right after I installed it when I took it down the street. Took it back home and adjusted it and took it for a long drive and it didn't do it once, so I'm hoping all is well. Wow, you must have posted right as I was writing mine.. did you do any re-wiring at all? I had a similar problem with my Pathfinder tps (I tried to put a 240sx one on) Anyway they rotate in opposite directions so the outer pins ended up being hooked up backward for that tps. Everytime I would hit full throttle, it would KILL all power, but never stall. I ended up switching the outer wires and then it was fine. Quote Link to comment Share on other sites More sharing options...
76Datsun280z Posted February 7, 2007 Author Share Posted February 7, 2007 Thanks for the explanation, but no, we haven't done any re-wiring at all. Quote Link to comment Share on other sites More sharing options...
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