my 89 N/A Z32 has been idle surging pretty bad. I went through all the basic diagnostic and fixed all vacuum leaks ( smoke tested it etc.) and check that the tps, mafs and aicv were all working which they are. i still have an idle surge. the surge is barely noticeable when cold but when it warms up it it goes from 650 revs to 1500, it bounces back and between. i pulled off the vacuum line to the fuel pressure dampener, it smelled like fuel was getting through but it wasn’t visually damp. has anyone seen something like this before ?
Setting the tps is done in volts 0.44v-0.46v the engine has to be at operating temp before you do anything, , disconnect the grey connector for 20 seconds after you set the tps to the correct dc voltage, the hard idle should now be on, leave the engine running, take the connector of the aac, adjust the idle using the screw on the end of the valve, down =clockwise, up =counterclockwise. Conzult or datascan makes things easier.
thanks for the info, i swear i seen a vid on someone adjusting it in omhs. oh well at least i know now
Good advice mate. And for the listeners-in : The other thing to consider with a TPS - It's just a potentiometer, the same Tech as a volume control on an old skool radio or guitar amp. The internal graphite surface will wear out. The area of the potentiometer in the TPS which aligns with 60 kph, 80 kph, 100 kph etc will get worn out sooner. Because your foot is constantly making micro adjustments at those speeds, friction causes more wear on those areas of the graphite. Hah, lately it will be the 40 & 50 kph areas that will wear out too! The point is, setting the TPS for idle is a good start. But you might have weird shit happen at other speeds. The MAF will take over once you get moving and sucking serious air into the engine but the worn spots on the TPS can cause silly things to happen sometimes. Maybe moreso with auto transmissions. Correct me if I'm wrong but I think the ATCU ( Auto Transmission Control Unit ) reads the the TPS output voltage to decide when to change gears, along with ECU and other readings? Such as air flow, revs etc. If the ATCU gets erratic data from the TPS at certain throttle settings because the graphite track is worn, it will have issues with deciding when to shift gears? Might cause clunking & notchy shifts maybe? I'm good, replaced my TPS during the re-build. Twice. Because the first one I bought was faulty... Any TT auto owners, pease add your thoughts.
Maybe an issue with the coolant temperature sensor or its connector? A bad signal to the ECU might confuse it as to what temperature the engine is up to. The ECU might get confused, trying to decide if the engine is cold or not? As things warm up, they can change. Check for a bad connection on the coolant temp sensor. Connector good? Replace the sensor and cross your fingers. Sorry, that's the best I can think of without being there.
