grouning the afm signal? need info.
05-09-06, 11:52 AM
#1
grouning the afm signal? need info.
Hi
I have an 87 t2 and I have great compression on both rotors. I did the fuel pump rewire and im geting spark. And i cant get the car to start unless i keep my foot on the gass pedal and even than it will not stay running for more than a few seconds and than it floods out. And i have eliminated the vaccum rack so its not a vaccume leak Im 99.9% sure. However i was going over the wiring diagram and i found the pin at the ecu where the afm (air flow meter) puts its signal in and i grounded it and the car will start run and idle just fine but it will not rev over 4k rpms so the 2enday injectors are not coming on. and if i shut the car off cold it floods out. what do you guys think
I have an 87 t2 and I have great compression on both rotors. I did the fuel pump rewire and im geting spark. And i cant get the car to start unless i keep my foot on the gass pedal and even than it will not stay running for more than a few seconds and than it floods out. And i have eliminated the vaccum rack so its not a vaccume leak Im 99.9% sure. However i was going over the wiring diagram and i found the pin at the ecu where the afm (air flow meter) puts its signal in and i grounded it and the car will start run and idle just fine but it will not rev over 4k rpms so the 2enday injectors are not coming on. and if i shut the car off cold it floods out. what do you guys think
05-13-06, 03:46 PM
#2
HAILERS
Join Date: May 2001
Location: FORT WORTH, TEXAS,USA
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I think the secondary injectors can be unplugged and the engine will rev to six grand or miore. The primarys stay online all the time but their duty cycle drops in half when and IF the scondarys come on line. The secondarys only come on line under Load sensed by the boost/pressure sensor.
Number two, the fuel delivery during the START cycle is pre programmed by the ECU. The ECU uses rpm/waterthermo sensor input and the START SIGNAL on pin 3B during the STARTcycle. The AFM is not a player until the key is put to ON.
The ground wire for the AFM is a brown/black wire on a 87 turboII and 87 non turboII. That ground wire is spliced to the same ground wire as the other sensors in the engine bay and terminates inside the ECU at pin 2C.
If you grounded a wire other than the one at 2C.............you made a big mistake.
I'd make sure the fuel pump is running, first of all. Running all the time, not just when you hold the key to START.
You might make sure the water thermo sensor is plugged in and functional. If the sensor is disconnected, the ECU defaults to 176 degrees which in turn makes the fuel delivery during START, very difficult because the ECU cuts the duty cycle of the injectors quite a bit at higher temps vs stone cold.
Number two, the fuel delivery during the START cycle is pre programmed by the ECU. The ECU uses rpm/waterthermo sensor input and the START SIGNAL on pin 3B during the STARTcycle. The AFM is not a player until the key is put to ON.
The ground wire for the AFM is a brown/black wire on a 87 turboII and 87 non turboII. That ground wire is spliced to the same ground wire as the other sensors in the engine bay and terminates inside the ECU at pin 2C.
If you grounded a wire other than the one at 2C.............you made a big mistake.
I'd make sure the fuel pump is running, first of all. Running all the time, not just when you hold the key to START.
You might make sure the water thermo sensor is plugged in and functional. If the sensor is disconnected, the ECU defaults to 176 degrees which in turn makes the fuel delivery during START, very difficult because the ECU cuts the duty cycle of the injectors quite a bit at higher temps vs stone cold.
Last edited by HAILERS; 05-13-06 at 03:49 PM.
