symptons of a bad AFM?

yamayuki98

New member
what are some of the symptons of a bad AFM? Does it always throw a code when the AFM goes bad. Reason i'm asking is a few months back my fuel pump died on me, and i replaced it with a Walbro 255, also replaced the Fuel Pump Relay...car won't start unless i bridge the fp/+b terminals...but when it does, it bogs a lot when cold and then dies when warmed...i thought that maybe the Walbro was pushing out to much fuel for my stock FPR, but then i just recently purchase a SARD adj. FPR and tried to adjust it...the car still acts the same...the car never acted like this before just incase anyone was wondering...if revved it keeps up rpm, but if set to idle it will die...all suggestions and advice are welcome...

PS: i'm not assuming that the AFM is the culprit at this point, its just something for me to think about...
 

RedCelicaTRD

Moderator
The stock pump has a high voltage mode and a low voltage mode. The walbaro will only run in the high mode setting. Remove the fuel pump relay and bridge the correct terminals. You can find out which ones in the tuning section of the main page and then I think its under easy mods.

On a side note, you do have an st185 right?
 

Gary

Moderator
To answer the original question, here are some symptoms of bad AFM from my own experience with few different used damaged AFMs.
- Car starts, runs for a few seconds and and shut down, code 24, 31, 32 (check AFM plug)
- Car starts, run sluggish, code 31 (check AFM using ohmmeter)
- Car does not start, no engine light when key in "ON" position (check AFM using ohmmeter)
- AFM resistance are not in spec.
 

m_haiser

New member
Gary":1e9io9vw said:
To answer the original question, here are some symptoms of bad AFM from my own experience with few different used damaged AFMs.
- Car starts, runs for a few seconds and and shut down, code 24, 31, 32 (check AFM plug)
- Car starts, run sluggish, code 31 (check AFM using ohmmeter)
- Car does not start, no engine light when key in "ON" position (check AFM using ohmmeter)
- AFM resistance are not in spec.

thats what mine was doing when the plug wasnt fully connected.
 

yamayuki98

New member
just to let you guys know the walbro was actually running for about three weeks after my pump died, it wasn't until then that the relay gave out...replacing it did not help, so as of right now the AFM is out of the quesiton, i'm going to try and bridge the relay terminal...only one problem though, the fuel pump mod is not there anymore...it only show the fuel up mod...can someone who has done this mod tell me the correct color wire to bridge and the gauge size...thanks everyone for your help, i'll keep everyone updated
 

yamayuki98

New member
okay, i tried it, still the same, try the other way still the same...i was over at the mr2 board and there was a topic that mention the open circuit relay..that i could have been burned out....could that cause the car to bogged..?
 

Conan

New member
theUNYTEDone":z5u5uzk6 said:
hey gary, how does one check for the resistance? is the the metal flap bit that does the measuring?
:twisted: The resistance is measured in ohm using a special electronic device ;)
 

theUNYTEDone

Moderator
...i knew that. :doh:

nah, but...i ALWAYS have a code 24, but wish not to tear into anything..
solveable just by getting another afm?
 

Gary

Moderator
Code 24 is the air temp sensor in the afm.
It's the white plastic thingy in front of the flap.
I'm not sure if you can swap it with another one from another AFM.
You might need a new AFM.

Here is how you check the resistance using ohmmeter.
Make sure you remove the plug first.
Then measure the resistance at the AFM, not the harness.
afmspecix5.jpg


You can also check the AFM voltage with voltmeter while it is being connected to the harness.
Use the following procedure.
It's easier to do this on the ECU side.
Test is done in three stages,

1. With ignition switch on,
VC-E2 = 4.5-5.5 V
AFM Flap fully closed, VS-E2 = 3.7-4.3 V
AFM Flap fully open, VS-E2 = 0.2-0.5 V

2. At idle,
VS-E2 = 1.6-4.1 V

3. At 3000 rpm
VS-E2 = 1.0-2.0 V

If the voltage readings are not in the range, you might have either bad AFM or ECU
 

mison

New member
Gary:

In a book I have is writen: Perform all voltage measurements with the connectors disconected.

How I may measure some volts if I unplug connectors..?
 

Gary

Moderator
mison":3siw39q3 said:
Gary:

In a book I have is writen: Perform all voltage measurements with the connectors disconected.

How I may measure some volts if I unplug connectors..?

That's weird.
Mine is opposite. :shrug:

dscn5163ko2.jpg
 

Gary

Moderator
I see. You are using troubleshooting with "voltmeter"
Basically you pull the connectors out of the ECU and measure the voltage on the connector side, not on the ECU side.
 

mison

New member
I know, but some measurements is with runing engine... how can engine idling with upluged connector?
 

Sleeka_89

New member
my guess would be to leave it connected and probe into the wire using a voltmeter if you need to check with it running :shrug:
 

Gary

Moderator
Sleeka_89":2ebeny6q said:
my guess would be to leave it connected and probe into the wire using a voltmeter if you need to check with it running :shrug:
That makes sense.
If you are measureing the resistance of a sensor, it should be disconnected from the power source (ECU)
If you are measuring the voltage, (at idling or while cranking), it should be connected to the power source (ECU).
 

mison

New member
it is not writen correct I think. "perform all voltage measurements with the connectors disconnected" and then I must measure Volts at idling or 300rpm or crank. It is not possible, because ich I will unplug any connector from ECU, engine cannot run.? Maybe your book is right..all connectors connected. I cant write in in eglish right, because I don´t know english, but I am a electrician and this is obscure for me :) I think it must be cennected and measured with thin probe?Does anbody here measure voltage on ECU?
 
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