280zx AFM or throttle position sensor symptoms and diagnosis runability problems, old style maf
ฝัง
- เผยแพร่เมื่อ 29 ส.ค. 2024
- AFM is like present-day mass air flow sensors.
on the 280ZX fuel injected it will make it run extremely rich no matter how well tuned your vehicle is due to the computer telling it to do so based upon the inputs of the AFM.
throttle position sensor or should I say switch has three circuits:
wide open throttle
Cruise
idle
throttle position switch is a very simple setup and has points on it. they do wear out and is extremely important as far as the input to the computer.
for example: you're driving down the road 7 or 10 miles out no problems then all of a sudden it starts running like crap starts dying you can't keep it running..... do the check on your throttle position sensor with an OHM meter and set it on continuity and make sure that it is at the 1400 RPMs on the wide open circuit side or it is out of spec and no good... try to adjust first.
if you keep trying to adjust and you cannot get it adjusted to 1400 RPMs on the TPS at wide open throttle then your TPS is out of spec... and that is with all other circuits sensors and motor having no other issues and need to make sure it is tested.
in short, 280ZX running extremely rich all the time and you have put new plugs and everything in it no matter what and you have no vacuum leaks your AFM is suspect and needs to be changed.
also in short, 280ZX not running rich going
down the road after 7 or 10 miles and starts bucking and jumping and wants to die check your TPS and have it changed or adjusted within spec....
these are the conditions on a 280ZX out of the many others but this is what I have found
I hope this helps somebody
Also check the connector on the temperature sensor. They build up green corrosion on them and that increases resistance. Resistance should be 2.4k ohms cold and 200 ohms at normal operating temperature. On the 280z it's called water temperature sensor. On the zx it's called cylinder temperature sensor. Also clean throttle position switch, it builds corrosion too. If you 280z randomly starts huffing out black smoke, check the temperature sensor. If the black smoke (too rich) happens when you close the drivers door, it is the ECU. The printed circuit board has a hairline crack on temperature sensor circuit. Replace ECU. If your z want rev up like it has a rev limiter, it's the throttle position switch. Hope this helps.
My 83zx will not stay running when engine is cold. You gotta feather the gas to keep it running for the first minute or two after starting from cold. Just started happening a month or two ago.
After about 2 minutes of feathering the gas, it will keep it’s self idling around 800-1k rpm. It’s NA 5 speed, 2 seater (no passenger seat in car right now) base model coupe. The car hauls ass/runs great other than the cold idle issue
I have a 1983 280ZX base model. Sounds like my problem, hard start, rough idol, slight smell of gas, almost stalling at lights. On highway it fly"s, runs great. Thank you for this info!
hey brother,
I know I don't want to be the dead horse but if it start up it's burning really rich even though you tune
it up that would probably more than likely be the AFM and if it dies after 5 or 10 minutes.
the throttle position sensor or
switch which the AFM and throttle position switch coincide together feels like wide open throttle works great but idle circuit sucks at or Cruise.
if you have any other questions I'm trying to line this one out too which I think I have a line on it just waiting on the new part or should I say replacement part after this one failed and I saw the difference.
had the 81 running beautifully and then a light with a magnet fell on top of the AFM and it went back to running like crap again and that is what I'm waiting on as far as the rich and running condition.
it is like night and day difference with the AFM failing or one of the circuits failing
I've only found for the natural aspirated throttle position sensor made by Walker from stockwise Auto and you can only get them that I can see from Los Angeles California....
and what I am also finding with these cars since they're over 40 years old you may be having multiple sensors or plugs that are not having good connectivity.
the cylinder head temperature sensor or chts will cause the car to die completely if I'm unplugged, you can use a coolant temp sensor with the same style plug which are cheap online if you feel that yours is going out, but you cannot use a cylinder head temperature sensor on a coolant temp sensor where the thermostat is because it will leak
@@gerryburkhardt856 let me know what you find out my mechanic is also going to remove and clean the air flow meter but we're waiting on new hoses he doesn't want to take it apart because they are pretty crappy condition right now
@@billm83army the AFM style that is used on these vehicles are similar to the ones that are on the BMWs back and around the same time. These have five circuits and one of them is a temperature circuit. When the AFM fails to do his job it tells the computer and meters higher than normal fuel ratios due to the oncoming air and adjust the flap door with spring tension, but overall the computer makes that decision.
But that's on one side of the problem and the other side is what you were mentioning the true are going through is that intermittent cruise to full throttle and idle problems, like it's getting confused or confusing itself from the input... But we know the motor and transmission run great at full throttle it runs like a sewing machine.... It is definitely input from sensors
on the AFM they are very delicate, that's why I'm replacing again due to light hitting it from the hood falling. on the afn you can clean even adjust them but there is a circuit that I think deals with the temperature of the incoming air from that sensor and when it falls out kills the functionality of the AFM. replacement and refurbishment of that part is probably more probable and make sure you get a lifetime warranty for exchange purposes for later. the only way that you can see this or that a mechanic can see this is they got to have a stethoscope and an oscilloscope to check the wavelengths when it falls out and dies, the mechanic OR technician needs to be very familiar with the circuit and how it works. they're simple but complicated at the same time due to old school design as far as the AFM
THANK YOU FOR THIS INFO!!!!!!!!
I have a 77 280Z and when i start it up there is a popping in the rubber boot between the AFM and the intake only when i rev-up the engine. The popping only happens when i accelerate.
I'm popping in the boot would be a lean condition pre-detonation and or timing pertaining to detonation.
When you have popping in the intake versus popping out the exhaust you have two different types of conditions and each case you would have to understand what you need to attack. Both of them related to timing fuel and Air and location and where it is popping at is going to tell you what's going on with your motor.
Question for you sir. My 280zx won’t rev past 2200 and Boggs. Idle is a little rough too. Any ideas?
Hello,
Upon reading a prior comment in relation to my video, I just want to make sure that everybody is looking at the condition of their vehicle beforehand and understands that to have an open mind and look at the situation, and me not being there to see it personally is difficult but I just look at the situation and what is in front of me and ask myself questions of why or what could cause this.
Always always always, check all the basics fuel air and fire and make sure they are in spec. Your ignition timing your vacuum levels on idle your ignition components, fuel pressure before startup, does it hold pressure, fuel pressure while running and under a load what does it go to and know the specs. And make sure there are no exhaust restrictions
If I'm pushing on the accelerator and it will not go above 2,200 RPMs is it misfiring running rough or is there a restriction in the exhaust, or some other input that is not allowing the computer or the sensors themselves not allowing the computer to do his job or the motor to do its job.
Make sure that you know if you have a catalytic converter it is not plugged from running rich from overtime which they will turn cherry red, these cars are old and the sensors are old with them along with the computer...
Look at your known factors of what you have, parts you did replace and if the new ones are actually bad and the settings or setup if there are adjustments.
Ask yourself is it hard to start, easy to start, does it idle too high or too low, when you accelerate is it fighting to pick up in speed or is it easy and smooth and find out which system may not be adjusted correctly or bad.
I would want to make sure that my catalytic converter if you have one or it is coded for one is not restricted so you do not have too much back pressure.
Make sure your fuel pressure is at spec when you turn the key on before starting, that it holds the pressure and does not drop too quickly per second and that it has adequate fuel supply while it is running and under load, could be a fuel related issue.
If it is your ignition system because the fuel and ignition are tied together always have your timing checked and make sure it's not too far advanced or retarded