HELP failsafe mode activated 05 mustang gt

akpony05

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Oct 21, 2019
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Thank you in advance for suggestions. I have 05gt 4.6 SOHC, first I had codes p151a, p2004, and p2005 (codes associated with IMR). Here are some of the symptoms: idling is rough, shuts off by itself within 5-8minutes of idling and Engine Fail-Safe mode gets activated, the car seems to have issues passing 3500 rpm.

Mods: just bolt-ons nothing crazy, 4.10s, 62mm throttle body and tune(BAMA) with a little bit of suspension work

Background pertinent info - this car was involved in an accident causing minor body damage. After the repairs, there was speedometer malfunction when I dropped it off at a shop they had to bypass the speed sensor wire to fix it.

What I tried so far.
I have inspected if the carb was built upon the intake manifold runners (IMR), throttle body, MAF sensor, I also checked if power was coming to IMR motor which checked out fine so I switched the IMR motor first and did not fix it, SAME CODES WHERE STILL THERE and after changing IMR motor the car started to through p102 and p2106 codes + originals (p151a...) so I changed, MAF and TPS sensor, still didn't work. Then I started thinking can it be throttle body components causing electrical issues so I switched out throttle body with a brand new one still no luck the same issue and the symptoms were there. I don't know what else to check so I decided to install a charge motion plate (CMP) to solve the problem LOL!! So I installed CMP and tuned the car (from BAMA) hoping it will fix the problem but NO LUCK. All the codes that were associated with IMR are gone but p102 and p2106 are still there. I don't know what else I can do. Open for suggestions and thank you for your time.
 
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richiesps

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Jun 25, 2019
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Cam shaft position sensor or is it the alternator replaced sensor still have code how sure are we about the alternator?????
 
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Bullitt95

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Sounds like you still have a problem with the MAF sensor and the engine is going into failsafe mode. Make sure the wiring harness is properly connected and that the wires aren't frayed.
 
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akpony05

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Oct 21, 2019
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Sounds like you still have a problem with the MAF sensor and the engine is going into failsafe mode. Make sure the wiring harness is properly connected and that the wires aren't frayed.

So I have bought a new MAF sensor after cleaning the old one did not solve the problem. I have inspected the MAF wires they checked out fine. The signal is going to the computer and ground checked out fine.
 

don ruggles

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Jan 11, 2013
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Sounds crazy,but how old is your air filter ? Also, on some COP(coils on plug) ignitions, thr COPs can mess up the signal to the throttle. Replace cops and plugs if old.
 

akpony05

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Oct 21, 2019
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Sounds crazy,but how old is your air filter ? Also, on some COP(coils on plug) ignitions, thr COPs can mess up the signal to the throttle. Replace cops and plugs if old.
They are 2 years old with less than 10k miles, and cold air intake is clean. I clean usually clean them twice a year.

Further, update on these issues, so I have changed the whole wiring harness all the codes are gone except P151a which says that the intake runner control performance. I don't know what to do besides set this car on fire. I have eliminated, electrical issue, TPS sensor, cleaned IMR, brand new MAF, camshaft. IDK what to do next.
 

PNWRoush

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Dec 24, 2019
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Straight out of the Ford Service Manual for possible causes of DTC P151A are:
  • IMRC control circuit open
  • Mechanical concern - bind, seize, damage, or obstruction of IMRC hardware
  • IMRC control circuit short to voltage
  • IMRC VPWR circuit open
  • IMRC GND circuit open
  • Damaged IMRC actuator
DTCs provide very limited data and should only be used to help diagnose a problem. To me it sounds like you either have alternator ripple causing ghost codes to appear or you don't have a good ground to the engine block.
 

akpony05

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Oct 21, 2019
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Straight out of the Ford Service Manual for possible causes of DTC P151A are:
  • IMRC control circuit open
  • Mechanical concern - bind, seize, damage, or obstruction of IMRC hardware
  • IMRC control circuit short to voltage
  • IMRC VPWR circuit open
  • IMRC GND circuit open
  • Damaged IMRC actuator
DTCs provide very limited data and should only be used to help diagnose a problem. To me it sounds like you either have alternator ripple causing ghost codes to appear or you don't have a good ground to the engine block.

Thank you for the info, so it turned out that aftermarket 62mm throttle body(TB) mechanical mechanism needed its voltage adjusted. It's crazy because the TB has been on the car for the past 6 years and was working fine. Currently, I swapped out 62mm TB with stock TB (using all the electrical components like TPS and TB motor) the car is working fine.
 

akpony05

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Oct 21, 2019
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Thank you guys for all the help, the pony is up and running!!!
 

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