MAF / P1102
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Junior User
Joined: Dec 2005
Posts: 79
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From: Flint, MI
MAF / P1102
Yesterday I got a MIL, pulled a code using an ELM327 WiFi and EngineLink iPhone App. Code came back P1102. Cleared it but it came right back.
Got out my service manual and ran the easy tests they call out.
1. Power to sensor (VPWR to PWRGND) at 12.06 volts - good.
2. MAF RTN to PWRGND at 5.7 volts - good.
3. MAF to GND - inf ohms, thus no short - good.
Stopped here. Didn't try the 'open circuit' check for the MAF signal line from sensort back to PCM. Also didn't check the signal itself as I haven't yet figured how to query custom PIDs with the EngineLink App. Not sure I have have a reference to which PID that is anyway.
In reading the manual section on the MAF, there is a curious sentence: 'The MAF signal is used to calculate the EGR flow rate and for concern detection'.
I deleted the EGR in this truck, but left the actuator in place to get around EGR actuator codes. Do I really have reason to worry about MAF plausibility issues if it's only used for an EGR system which isn't really there?
Got out my service manual and ran the easy tests they call out.
1. Power to sensor (VPWR to PWRGND) at 12.06 volts - good.
2. MAF RTN to PWRGND at 5.7 volts - good.
3. MAF to GND - inf ohms, thus no short - good.
Stopped here. Didn't try the 'open circuit' check for the MAF signal line from sensort back to PCM. Also didn't check the signal itself as I haven't yet figured how to query custom PIDs with the EngineLink App. Not sure I have have a reference to which PID that is anyway.
In reading the manual section on the MAF, there is a curious sentence: 'The MAF signal is used to calculate the EGR flow rate and for concern detection'.
I deleted the EGR in this truck, but left the actuator in place to get around EGR actuator codes. Do I really have reason to worry about MAF plausibility issues if it's only used for an EGR system which isn't really there?
Lead Driver
Joined: Feb 2011
Posts: 8,241
Likes: 155
From: L.A. (Lower Alabama)
MAF return voltage should be 0.0 Key On Engine Off, around 1.44v at idle, and 2.65v at 2,500rpm. Operating range is 0.5-4.75v.
I think MAF is used to calculate injector timing and duration. Maybe you can watch the return value with the app?
I think MAF is used to calculate injector timing and duration. Maybe you can watch the return value with the app?
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Junior User
Joined: Dec 2005
Posts: 79
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From: Flint, MI
The app goes give back MAF, but it's in Engineering Units [grams / sec], not volts. I'll post those numbers for off, idle and 2500 RPM unloaded this afternoon.
I can tap the wires and get real voltages later this week.
I can tap the wires and get real voltages later this week.
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Junior User
Joined: Dec 2005
Posts: 79
Likes: 1
From: Flint, MI
App is coming back with zero for MAF during cruising. Something wrong here as it had--as recently as last week--averaged 133 g/sec during cruise with readings above 200 g/sec during throttle on while cruising.
Will look at measured voltage across MAF and MAF RTN pins next.
Will look at measured voltage across MAF and MAF RTN pins next.
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penman39
1983 - 2012 Ranger & B-Series
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Apr 28, 2006 01:47 PM
