After cleaning the throttle body and MAF
02-16-08, 10:42 PM
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After cleaning the throttle body and MAF
After I clean the throttle body and MAF on my 92 LS400, the RPM start a little higher then 1000 and idle roughly. After 30 second, RPM start decrease (I can feel the car is shaking) then engine die. start it again and it die within 10 secounds. I wait for two hours and try again same thing happen (RPM start a little higher then 1000 and idle roughly. After 30 second, RPM start decrease then engine die.)
I unplug the MAF sensor nothing change.
I use CRC mass air flow sensor cleaner and CRC Throttle body & air-intake cleaner
Any one know why?
I unplug the MAF sensor nothing change.
I use CRC mass air flow sensor cleaner and CRC Throttle body & air-intake cleaner
Any one know why?
02-17-08, 01:32 AM
#3
No I don't know why for sure.. but can speculate.
Obviously it is a result of something you did. You cleaned the MAF and TB.
I don't know if the TB has any type of sensor in it or not. (Most cars I'm familiar with the TB is simply a valve), however if it does it might be the cause.
I say this because you unplugged your MAF and the problem was the same,.. I believe I recall reading where someone unplugged their MAF and the car ran fine. So if the car can ignore the MAF, then by you unplugging it , it would narrow the problem down to the TB. But, again, that is going off something I *thought* I read.. it probably isn't true.
This is what I would do.
I would take the MAF and TB out , or open them back up and inspect them. Make sure nothing looks out of place or damaged. Make sure your TB valve is in the appropriate position for the car being off. (Closed).
This is a problem that *might* clear up with time.. With heat, evaporation, and running the engine a few dozen more times. If it is a residue or some sort that is causing the sensor to act up, it might dry out or remove itself. That would be ideal.
It wouldn't hurt to reset your ECU. Just search for ECU reset if you don't know how to do it. (You can leave your negative battery terminal off for 30mins or pull a fuse.) -- Just remember when you pull the fuse, do *NOT* turn the key to ACC or ON. That will cause your Airbag light to come on permenantly. Then you have to go through the hassle of opening the Diagnostic port and grounding the Tc and AB leads. (Can be tough the first time).
If you need the car NOW, and it just won't run -- I would guess the MAF is the more sensitive of the two pieces of equipment. As such I would look in a junkyard (call around) for a used MAF for your car. Replace it, and you should be good.
I guess this is a lesson learned the hard way. Sometimes when it isn't broke, don't fix it
-- Especially with finicky sensors, cleaning them can really cause issues. Only way I would clean my MAF is via Seafoam, and that is only indirectly.. I would never spray a solution in it and rub around.
Hope things dry out, and just start working again for you.
Obviously it is a result of something you did. You cleaned the MAF and TB.
I don't know if the TB has any type of sensor in it or not. (Most cars I'm familiar with the TB is simply a valve), however if it does it might be the cause.
I say this because you unplugged your MAF and the problem was the same,.. I believe I recall reading where someone unplugged their MAF and the car ran fine. So if the car can ignore the MAF, then by you unplugging it , it would narrow the problem down to the TB. But, again, that is going off something I *thought* I read.. it probably isn't true.
This is what I would do.
I would take the MAF and TB out , or open them back up and inspect them. Make sure nothing looks out of place or damaged. Make sure your TB valve is in the appropriate position for the car being off. (Closed).
This is a problem that *might* clear up with time.. With heat, evaporation, and running the engine a few dozen more times. If it is a residue or some sort that is causing the sensor to act up, it might dry out or remove itself. That would be ideal.
It wouldn't hurt to reset your ECU. Just search for ECU reset if you don't know how to do it. (You can leave your negative battery terminal off for 30mins or pull a fuse.) -- Just remember when you pull the fuse, do *NOT* turn the key to ACC or ON. That will cause your Airbag light to come on permenantly. Then you have to go through the hassle of opening the Diagnostic port and grounding the Tc and AB leads. (Can be tough the first time).
If you need the car NOW, and it just won't run -- I would guess the MAF is the more sensitive of the two pieces of equipment. As such I would look in a junkyard (call around) for a used MAF for your car. Replace it, and you should be good.
I guess this is a lesson learned the hard way. Sometimes when it isn't broke, don't fix it
-- Especially with finicky sensors, cleaning them can really cause issues. Only way I would clean my MAF is via Seafoam, and that is only indirectly.. I would never spray a solution in it and rub around. Hope things dry out, and just start working again for you.
02-17-08, 10:03 AM
#6
Lexus Test Driver
If you unplug the MAF and it acts exactly the same then I'd assume the MAF is messed up. Those things are sensitive, you possibly may have just used too much cleaner on it?
And if I can ask a question of my own...Is there an easier way to reset the ECU than unhooking the battery?? I can't remember which fuse , or relay, to pull. I just cleaned my throttle body as well and would like to reset it. Thanks!
And if I can ask a question of my own...Is there an easier way to reset the ECU than unhooking the battery?? I can't remember which fuse , or relay, to pull. I just cleaned my throttle body as well and would like to reset it. Thanks!
02-17-08, 10:09 AM
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I clean it like this with spraying cleaner and scraping it
How do you check air leaks
How to fix it?
when I removed the parts I see the silver stuff between it, is that something to prevent air leak?
why it is fine for the first 30 sec?
It doesn't show any CEL, so I can eliminate MAF right?
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02-17-08, 10:16 AM
#8
So lets say when you start it, what if you give it some gas to keep the RPMS up, is it able to run or dies anyway?
With disconnected MAF the car should idle very roughtly, but run almost fine at high RPMs. However when the MAF is bad, the car's RPMs should jump up and down, it could stall, and usually you will get a CEL.
What you're describing sounds like an air leak. When the RPMs are high, the car will be able to run, although roughly - which is what you're describing, it starts at 1000rpms and runs rougly. As RPMs go down, it should stall. Check that all the hoses are connected correctly, check that the intake is on tight, make sure you didnt damage throttle body gasket.
With disconnected MAF the car should idle very roughtly, but run almost fine at high RPMs. However when the MAF is bad, the car's RPMs should jump up and down, it could stall, and usually you will get a CEL.
What you're describing sounds like an air leak. When the RPMs are high, the car will be able to run, although roughly - which is what you're describing, it starts at 1000rpms and runs rougly. As RPMs go down, it should stall. Check that all the hoses are connected correctly, check that the intake is on tight, make sure you didnt damage throttle body gasket.
02-17-08, 10:22 AM
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So lets say when you start it, what if you give it some gas to keep the RPMS up, is it able to run or dies anyway?
With disconnected MAF the car should idle very roughtly, but run almost fine at high RPMs. However when the MAF is bad, the car's RPMs should jump up and down, it could stall, and usually you will get a CEL.
What you're describing sounds like an air leak. When the RPMs are high, the car will be able to run, although roughly - which is what you're describing, it starts at 1000rpms and runs rougly. As RPMs go down, it should stall. Check that all the hoses are connected correctly, check that the intake is on tight, make sure you didnt damage throttle body gasket.
With disconnected MAF the car should idle very roughtly, but run almost fine at high RPMs. However when the MAF is bad, the car's RPMs should jump up and down, it could stall, and usually you will get a CEL.
What you're describing sounds like an air leak. When the RPMs are high, the car will be able to run, although roughly - which is what you're describing, it starts at 1000rpms and runs rougly. As RPMs go down, it should stall. Check that all the hoses are connected correctly, check that the intake is on tight, make sure you didnt damage throttle body gasket.
did not try to give it gas with out MAF (should I try it?)
appreciate it!
02-17-08, 08:50 PM
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If you cleaned the AFM im about 90% sure thats your problem. The AFM (notice im not calling it a MAF witch is different) Uses a small piece of reflective foil inside a vortex generator to gauge air speed. the faster the foil vibrates the more air speed or more correct signal frequency it will output to the TCCS.
Back to the AFM vs MAF thing, a MAF is a mass airflow sensor. it determines how much air is moving threw it based on temperature, density, and speed and reports a Mass Air flow reading in grams/second (or whatever the specific manufacturer uses) to the computer. Companies like GM use these in hot wire setups. they use wires almost like filaments in a light bulb. One is heated and the other is a thermistor. the thermistor measures the ambient temperature, and adjusts the heat of the other wire.
The heated wire is cooled as air passes over it, the more it get cooled the more air flow. Density (or pressure) and ambient temperature both effect the amount of heat drawn from the wire per CFM so it accurately gauges in one process the correct measure of air flow in grams/second or lbs/min, or whatever the manufacturer uses (GM uses g/sec) and relays this to the computer. BTW CFM is NOT an accurate measure of airflow.
An AFM serves the same purpose but uses a different process, the AFM uses different sensors. AFM's meter air speed, temperature and density all separately and reports all of those individually back to the computer. the computer uses the information to generate an air flow reading in g/sec or lbs/min.
The CRC mass airflow sensor cleaner is generally made for hot wire sensors such as GM uses. The AFM in the LS (definitely first gens not sure about after that) is the same as the MK3 Supra's just with a bigger housing. the problem with cleaning it is the foil inside that gauges air speed becomes damaged by the solvent and cannot report a accurate air speed reading.
The cleaner is used for hot wire sensors where dirt buildup effect the ability of the hot wire to be cooled by the airflow passing over it, almost like insulation.
Like i said im about 90% sure the AFM is the problem, ive seen it happen a lot of times on the supra boards.
/Long Post
Back to the AFM vs MAF thing, a MAF is a mass airflow sensor. it determines how much air is moving threw it based on temperature, density, and speed and reports a Mass Air flow reading in grams/second (or whatever the specific manufacturer uses) to the computer. Companies like GM use these in hot wire setups. they use wires almost like filaments in a light bulb. One is heated and the other is a thermistor. the thermistor measures the ambient temperature, and adjusts the heat of the other wire.
The heated wire is cooled as air passes over it, the more it get cooled the more air flow. Density (or pressure) and ambient temperature both effect the amount of heat drawn from the wire per CFM so it accurately gauges in one process the correct measure of air flow in grams/second or lbs/min, or whatever the manufacturer uses (GM uses g/sec) and relays this to the computer. BTW CFM is NOT an accurate measure of airflow.
An AFM serves the same purpose but uses a different process, the AFM uses different sensors. AFM's meter air speed, temperature and density all separately and reports all of those individually back to the computer. the computer uses the information to generate an air flow reading in g/sec or lbs/min.
The CRC mass airflow sensor cleaner is generally made for hot wire sensors such as GM uses. The AFM in the LS (definitely first gens not sure about after that) is the same as the MK3 Supra's just with a bigger housing. the problem with cleaning it is the foil inside that gauges air speed becomes damaged by the solvent and cannot report a accurate air speed reading.
The cleaner is used for hot wire sensors where dirt buildup effect the ability of the hot wire to be cooled by the airflow passing over it, almost like insulation.
Like i said im about 90% sure the AFM is the problem, ive seen it happen a lot of times on the supra boards.
/Long Post
02-17-08, 11:07 PM
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If you cleaned the AFM im about 90% sure thats your problem. The AFM (notice im not calling it a MAF witch is different) Uses a small piece of reflective foil inside a vortex generator to gauge air speed. the faster the foil vibrates the more air speed or more correct signal frequency it will output to the TCCS.
Back to the AFM vs MAF thing, a MAF is a mass airflow sensor. it determines how much air is moving threw it based on temperature, density, and speed and reports a Mass Air flow reading in grams/second (or whatever the specific manufacturer uses) to the computer. Companies like GM use these in hot wire setups. they use wires almost like filaments in a light bulb. One is heated and the other is a thermistor. the thermistor measures the ambient temperature, and adjusts the heat of the other wire.
The heated wire is cooled as air passes over it, the more it get cooled the more air flow. Density (or pressure) and ambient temperature both effect the amount of heat drawn from the wire per CFM so it accurately gauges in one process the correct measure of air flow in grams/second or lbs/min, or whatever the manufacturer uses (GM uses g/sec) and relays this to the computer. BTW CFM is NOT an accurate measure of airflow.
An AFM serves the same purpose but uses a different process, the AFM uses different sensors. AFM's meter air speed, temperature and density all separately and reports all of those individually back to the computer. the computer uses the information to generate an air flow reading in g/sec or lbs/min.
The CRC mass airflow sensor cleaner is generally made for hot wire sensors such as GM uses. The AFM in the LS (definitely first gens not sure about after that) is the same as the MK3 Supra's just with a bigger housing. the problem with cleaning it is the foil inside that gauges air speed becomes damaged by the solvent and cannot report a accurate air speed reading.
The cleaner is used for hot wire sensors where dirt buildup effect the ability of the hot wire to be cooled by the airflow passing over it, almost like insulation.
Like i said im about 90% sure the AFM is the problem, ive seen it happen a lot of times on the supra boards.
/Long Post
Back to the AFM vs MAF thing, a MAF is a mass airflow sensor. it determines how much air is moving threw it based on temperature, density, and speed and reports a Mass Air flow reading in grams/second (or whatever the specific manufacturer uses) to the computer. Companies like GM use these in hot wire setups. they use wires almost like filaments in a light bulb. One is heated and the other is a thermistor. the thermistor measures the ambient temperature, and adjusts the heat of the other wire.
The heated wire is cooled as air passes over it, the more it get cooled the more air flow. Density (or pressure) and ambient temperature both effect the amount of heat drawn from the wire per CFM so it accurately gauges in one process the correct measure of air flow in grams/second or lbs/min, or whatever the manufacturer uses (GM uses g/sec) and relays this to the computer. BTW CFM is NOT an accurate measure of airflow.
An AFM serves the same purpose but uses a different process, the AFM uses different sensors. AFM's meter air speed, temperature and density all separately and reports all of those individually back to the computer. the computer uses the information to generate an air flow reading in g/sec or lbs/min.
The CRC mass airflow sensor cleaner is generally made for hot wire sensors such as GM uses. The AFM in the LS (definitely first gens not sure about after that) is the same as the MK3 Supra's just with a bigger housing. the problem with cleaning it is the foil inside that gauges air speed becomes damaged by the solvent and cannot report a accurate air speed reading.
The cleaner is used for hot wire sensors where dirt buildup effect the ability of the hot wire to be cooled by the airflow passing over it, almost like insulation.
Like i said im about 90% sure the AFM is the problem, ive seen it happen a lot of times on the supra boards.
/Long Post
Thank you for your detail information
I will order a used AFM off ebay tomorrow.
BTW why check engine light is not on?
Thanks