Will bad Afm cause no spark?
#26
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ok Tried starting it without the afm...nothing, fired a couple times but no start, then it flooded.
De-flooded and tried again, did this 4 times an no start.
I am completely confused at this point
If my trailing plugs were junk would that cause my car not to start? they looked fine so I re-used them along with a new set of leading plugs
De-flooded and tried again, did this 4 times an no start.
I am completely confused at this point
If my trailing plugs were junk would that cause my car not to start? they looked fine so I re-used them along with a new set of leading plugs
#27
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So I just went and started the car, It half assed started then stalled, felt like it was running on one rotor then flooded.
I just put in new leading plugs, spark plug wires, a set of trailing plugs that looked good, injector grommets, cleaned the ecu and coil grounds after the problem started.
what on earth is the deal?
should I swap out the trailing plugs with new ones, or is that just water under the bridge?
I really need to figure this out guys, my car has been sitting on the side of the road for almost two weeks and is at risk of being towed if a neighbor complains
I just put in new leading plugs, spark plug wires, a set of trailing plugs that looked good, injector grommets, cleaned the ecu and coil grounds after the problem started.
what on earth is the deal?
should I swap out the trailing plugs with new ones, or is that just water under the bridge?
I really need to figure this out guys, my car has been sitting on the side of the road for almost two weeks and is at risk of being towed if a neighbor complains
#30
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i just wanted to post my results of the same problem so that the original poster of this thread could get some ideas from my car problems, thats all.
#32
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i dont know. my car would fire right up for 3 secconds and then die. im 150% sure of this as i did it on other peoples cars, and it would do this exact same procedure.
rev up to 3k rpms, then back down and dead.
just out of sheer curiosity, try it.
does the tach needle bounce? this was also a symptom. if it does not bounce, then there are no coils firing. remove it the afm, and see if the tach bounces.
rev up to 3k rpms, then back down and dead.
just out of sheer curiosity, try it.
does the tach needle bounce? this was also a symptom. if it does not bounce, then there are no coils firing. remove it the afm, and see if the tach bounces.
#33
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i dont know. my car would fire right up for 3 secconds and then die. im 150% sure of this as i did it on other peoples cars, and it would do this exact same procedure.
rev up to 3k rpms, then back down and dead.
just out of sheer curiosity, try it.
does the tach needle bounce? this was also a symptom. if it does not bounce, then there are no coils firing. remove it the afm, and see if the tach bounces.
rev up to 3k rpms, then back down and dead.
just out of sheer curiosity, try it.
does the tach needle bounce? this was also a symptom. if it does not bounce, then there are no coils firing. remove it the afm, and see if the tach bounces.
#35
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I may as well try that too haha, although I didn't disconnect it
Got a volt meter today so I am going to start checking voltages
Can anyone tell me where ecu pin 2a is? haha
Thanks again for all your help guys!
Got a volt meter today so I am going to start checking voltages
Can anyone tell me where ecu pin 2a is? haha
Thanks again for all your help guys!
#36
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http://www.teamfc3s.org/main/factory...SYSTEMS_NA.pdf
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You should look at the "Fuel and Emissions Control Section" of the FSM (link below) and it lists all the pin locations, their description as well as their values (volts). Pin 2A would be the middle plug, top right position (top row and farthest right). Should read about 5 volts w/key to on. This pin wire goes to 5 different engine sensors and you could read the value at any of these sensors which is much easier to do then going to the ECU. Depending on the year of your car, the Vref will be the Brown based wire and the TPS having 3 wires will have one of these wires so it could be measured there (w/key to on).
http://www.teamfc3s.org/main/factory...SYSTEMS_NA.pdf
http://www.teamfc3s.org/main/factory...SYSTEMS_NA.pdf
also I feel kind of dumb for asking, but if I were to test the voltage at the ecu, I stick the positive probe of the multimeter into the back of the plug correct?
#39
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Is there any other places I can check voltages for the sensors? Instead of pulling my interior apart again? haha
If there is, what are they and which order do you recommend I test them in?
Thanks!
If there is, what are they and which order do you recommend I test them in?
Thanks!
#43
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well, i was told this: make sure that these three things are working before going into anymore detail...........fuel, air, spark.
if you are getting fuel, you would know it. the engine would be flooded when you take out your plugs to check it.
and you already know that you are getting airflow even if the maf if bad, it will still start but run crappy.
now for the spark: you know your trailing coil is working as long as your rpm needle is bouncing. also, if the needle bounces, you know that the main relay works as well. the coil might not be strong, but it is working enough to spark the fuel.
check the leading coil again.........i switched out mine and the car fired up. try the coil, try the coil, try the coil
oh yeah, and try the coil, lol.
if you are getting fuel, you would know it. the engine would be flooded when you take out your plugs to check it.
and you already know that you are getting airflow even if the maf if bad, it will still start but run crappy.
now for the spark: you know your trailing coil is working as long as your rpm needle is bouncing. also, if the needle bounces, you know that the main relay works as well. the coil might not be strong, but it is working enough to spark the fuel.
check the leading coil again.........i switched out mine and the car fired up. try the coil, try the coil, try the coil
oh yeah, and try the coil, lol.
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ok so I tested, the brown and white wire at the tps read 4.9 volts
then at the pressure sensor it was also 4.9
I checked the resistances on my AFM and they were all in spec.
What now?
then at the pressure sensor it was also 4.9
I checked the resistances on my AFM and they were all in spec.
What now?
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ok I checked voltages per the FSM at the plug that goes into the ecu. I checked the leading coil, trailing coil and the CAS. The voltage readings for each coil were in spec, but the CAS was not.
In the FSM it says the voltage (CAS) is supposed to be >1v mine was at about 1.9v.
my internet crapped out last night so I had no access to the section of the fsm I needed, and now I have to work, so I will have to wait until tomorrow to check resistances on the plugs like you said in that other thread.
Thanks again for all the help guys! I don't know where I would be without you!
In the FSM it says the voltage (CAS) is supposed to be >1v mine was at about 1.9v.
Thanks again for all the help guys! I don't know where I would be without you!
#49
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ok I checked voltages per the FSM at the plug that goes into the ecu. I checked the leading coil, trailing coil and the CAS. The voltage readings for each coil were in spec, but the CAS was not.
In the FSM it says the voltage (CAS) is supposed to be >1v mine was at about 1.9v.
my internet crapped out last night so I had no access to the section of the fsm I needed, and now I have to work, so I will have to wait until tomorrow to check resistances on the plugs like you said in that other thread.
Thanks again for all the help guys! I don't know where I would be without you!
In the FSM it says the voltage (CAS) is supposed to be >1v mine was at about 1.9v.
my internet crapped out last night so I had no access to the section of the fsm I needed, and now I have to work, so I will have to wait until tomorrow to check resistances on the plugs like you said in that other thread.
Thanks again for all the help guys! I don't know where I would be without you!
#50
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A bad afm can absolutely lead to no spark! It's not saying it always will as there is more than one thing that can go wrong with it but it most certainly can. I've actually had that particular failure. The afm may measure air but it still talks to the ecu which tells the coils to fire. This is not a thread jack. It is a relevant topic to this thread as I had a failed afm cause a no spark situation.
Back when that problem occurred about 15 years ago, I took the car to a Mazda dealership after a couple of weeks of nearly pulling my hair out. They told me that my coils must be bad. Both of them at the same time? I don't think so! They surmised that the cas burned them up. Um, not going to happen. Even a bad cas although not impossible, it highly improbable. Then they told me the ecu fried taking the cas and coils with it. They said repairs would be $2,000. Not satisfied with their answer I took my car back home. I replaced the ecu. Nothing happened. The coils, plugs,and plug wires had all been swapped out and wiring to the ecu was verified to be good. The only thing left to check was the afm. People insisted to me that the afm can not cause the coils not to fire. After staring at the schematic, I felt otherwise. I swapped out the afm and the car ran great. When I put a new intake on that car I pulled the connector too hard when trying to disconnect it and it severed a connection to the ecu. The ecu no longer sent the signal to the coils to fire.
I was going to check it first since I had just installed an intake but I was being told that it couldn't happen. They were wrong!
Back when that problem occurred about 15 years ago, I took the car to a Mazda dealership after a couple of weeks of nearly pulling my hair out. They told me that my coils must be bad. Both of them at the same time? I don't think so! They surmised that the cas burned them up. Um, not going to happen. Even a bad cas although not impossible, it highly improbable. Then they told me the ecu fried taking the cas and coils with it. They said repairs would be $2,000. Not satisfied with their answer I took my car back home. I replaced the ecu. Nothing happened. The coils, plugs,and plug wires had all been swapped out and wiring to the ecu was verified to be good. The only thing left to check was the afm. People insisted to me that the afm can not cause the coils not to fire. After staring at the schematic, I felt otherwise. I swapped out the afm and the car ran great. When I put a new intake on that car I pulled the connector too hard when trying to disconnect it and it severed a connection to the ecu. The ecu no longer sent the signal to the coils to fire.
I was going to check it first since I had just installed an intake but I was being told that it couldn't happen. They were wrong!