bad safc or map sensor??
05-01-11, 09:42 PM
#1
Driver
Thread Starter
Join Date: Feb 2008
Location: Florida
Posts: 179
Likes: 0
Received 0 Likes
on
0 Posts
bad safc or map sensor??
I was doing some street tuning and a couple pulls, car just shut off on me when I did a pull. Car won't start now, the safc reads the pressure reading at -760mmhg when it's not started, I'm pressure sure it's suppose to read -21mmhg normally. Is this the safc or Map sensor that went bad??
05-02-11, 05:34 AM
#2
Lead Lap
iTrader: (2)
Join Date: Apr 2008
Location: Colorado
Posts: 665
Likes: 0
Received 0 Likes
on
0 Posts
will it even try to start? " my car still would try and start with no map hookedup.
Check your Battery Connections those dang things have cause many headaches.
check the wiring for the SAFC and im sure oyu knew to keep that one wire splice about an inch away from the ECU.
Check your Battery Connections those dang things have cause many headaches.
check the wiring for the SAFC and im sure oyu knew to keep that one wire splice about an inch away from the ECU.
05-02-11, 07:54 AM
#3
Driver
Thread Starter
Join Date: Feb 2008
Location: Florida
Posts: 179
Likes: 0
Received 0 Likes
on
0 Posts
Yeah it cranks and what not, just doesnt start. The car ran perfectly before i rebuilt the motor, i was thinking the safc because it was in hot florida weather for 3 months in the car with windows up.
05-02-11, 08:14 AM
#4
Lead Lap
iTrader: (2)
Join Date: Apr 2008
Location: Colorado
Posts: 665
Likes: 0
Received 0 Likes
on
0 Posts
what is your setup? It could be the map but that only has 3 wires 1 power 1 ground and another Signal wire.
How Much boost? Maybe you broke the map if you went over 20? (this just dosnt even sound right saying it out loud. The map sensor is pressure based and would just max out)
What does your AFR say and do you have one?
Fuel Pressure?
and are you running stock injectors?
I have only delt with one bad SAFC and it wouldnt start either. it could be a bad SAFC but the best way to check that, is to use someones else's and seee if it works or ship it to Apexi and let them fix it.
How Much boost? Maybe you broke the map if you went over 20? (this just dosnt even sound right saying it out loud. The map sensor is pressure based and would just max out)
What does your AFR say and do you have one?
Fuel Pressure?
and are you running stock injectors?
I have only delt with one bad SAFC and it wouldnt start either. it could be a bad SAFC but the best way to check that, is to use someones else's and seee if it works or ship it to Apexi and let them fix it.
05-03-11, 11:48 AM
#5
Driver
Thread Starter
Join Date: Feb 2008
Location: Florida
Posts: 179
Likes: 0
Received 0 Likes
on
0 Posts
Well im running mkiv injectors, so i think bypassing afc it prob still wont start the car. Are there certain voltage at ambient pressure that i can check if the map sensor is good? My afr was good, i dont have a fp gauge.
Always throwin that out there first because it happened to me!
05-03-11, 12:28 PM
#7
Lead Lap
iTrader: (2)
Join Date: Apr 2008
Location: Colorado
Posts: 665
Likes: 0
Received 0 Likes
on
0 Posts
What was your AFR when it ran because i thought you said 7 and that is toooooooo rich. Maybe your Flooding the motor with Fuel.
Pull out the Spark Plugs and see whats up.
I only know how to Check fuel pressure if it runs. YOu can actually just start it let it run and grab the Rubber fuel line with a pair of Channel locks( Gently no freakin tuff guy stuff) pinch it and see if the car bogs and bingo you can tell if you have fuel pressure.
Coil packs have also been know to cause a headache so dont forget about them.
Map sensor - i think Ambient Air is based of the Voltage when the car is on but not runing. Do some research on finding out the info. i know i saw it on some forum lately when i swapped mine out for the GM 3Bar.
Make sure all these work!
Fuel
Air
Spark
Timing
Last edited by Triple C; 05-03-11 at 12:38 PM.
Trending Topics
05-03-11, 01:15 PM
#9
Driver
Thread Starter
Join Date: Feb 2008
Location: Florida
Posts: 179
Likes: 0
Received 0 Likes
on
0 Posts
Its a 1.5jz, 550 injectors. Afrs are fine, i also hear the fuel pressure going through the rail. On the safc it reads -760mmhg when the car is off, which i know is wrong. Ill check the crank pickup tommorow, pull the plugs and what not. Ima try to look up the map sensor voltage for ambient pressure. Thanks for the suggestions.
05-04-11, 09:33 AM
#10
Driver
Thread Starter
Join Date: Feb 2008
Location: Florida
Posts: 179
Likes: 0
Received 0 Likes
on
0 Posts
Well I think its a bad safc, I tried a GM 3 Bar map sensor, scaled it down but the output voltage map sensor out of the safc is the same and it still says im in -760mmhg. I plugged in the old map sensor and bypassed the safc and it started for 2 seconds and died. I'm assuming the ecu can't run 550 injectors by itself. So Ima try to borrow an safc and see what happens
05-04-11, 03:00 PM
#12
Driver
Thread Starter
Join Date: Feb 2008
Location: Florida
Posts: 179
Likes: 0
Received 0 Likes
on
0 Posts
Nope didn't puke the timing belt, and swaped with a working safc and it didn't work. the pressure still reads -760mmhg on the safc. Must be a short in the safc harness or map sensor or something, will look in to that.
05-07-11, 11:37 AM
#14
Driver
Thread Starter
Join Date: Feb 2008
Location: Florida
Posts: 179
Likes: 0
Received 0 Likes
on
0 Posts
Hey guys I found something wierd, I think my map sensor input to the ecu is giving out a 5v when it's not suppose to. Is that mean the ecu is bad?? It's the teal wire with black stripe on the 22P plug (well the pictures show its yellow because its the wiring from the safc)
05-07-11, 11:39 AM
#15
Driver
Join Date: Jan 2011
Location: tx
Posts: 128
Likes: 0
Received 0 Likes
on
0 Posts
the ecu will often drive a small 5v to the sensors via a pull-up resistor in order to sense current from the sensor, the sensor is supposed to drive this down. sounds like an open circuit. If you have the connector disconnected, this seems normal.
-bug
-bug