North American Turbocoupe Organization



CODES 72 & 81
87TurboBird2.3 Offline
Junior Member
#1
Hey guys, I need help figuring out why I’m getting these two codes (72 & 81). But first let me explain what I’ve done to my 87 Turbo Coupe, which might help you guys with advice.
 
When I bought this car it ran good, idled good, etc….with the exception that if I spun the turbo too high (built too much boost), I would get an alarm and was told by the previous owner that if I didn’t back off the throttle when I heard this alarm, I could blow the engine. So after doing some troubleshooting of the wastegate and wastegate actuator (which checked out fine) I determined that the boost control solenoid (BCS) was bad. So I purchased a Gillis Boost Control Valve and installed it. When I installed the Gillis valve, I unplugged the two vacuum hoses from the factory BCS per the instructions (didn’t cap or plug them), but I left the electrical connector plugged in. Then I fired up the car and now it does not want to idle whatsoever!! It runs rough for a couple seconds and then dies. So I put my code reader on the computer and I got a code 41, which told me the O2 sensor was “lean or out range”. This was the only code I got. So I replaced the O2 sensor tonight. After getting it installed, I fired up the car again and it still won’t idle. So I plugged the code reader in again and now I get these two codes; 72 & 81 (I no longer have the code 41).
 
According to my code reader book, code 72 tells me: “MAP, MAF, or BP sensor out of range during dynamic response test”. That was listed under: Key On Engine Running. There is another 72 code listed under: Continuous Memory which states, “system power circuit fault; message center control assembly (MCCA) circuit failure.
 
Code 81 tells me: “air diverter solenoid fault; intake air control circuit fault / air injection diverter”.
 
Regarding code 72; I’m assuming this issue has to do with the MAF sensor, which I assume to be the Vane Airflow Meter between the air filter and the intercooler????? How do I know if this is bad or not? Is there a way to test it? Do these have a tendency to go bad? How do I fix this? If it is bad, can I replace it with a traditional Mass Airflow Sensor like my 92 Mustang has? What options do I have?

Regarding code 81: What is the air diverter solenoid or intake air control circuit? I have no idea what this is or where it’s located. Would this have anything to do with unplugging the factory BCS vacuum lines? I did not plug them. Should they be capped off or plugged?
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JT Online
Posting Freak
#2
(05-26-2021, 02:31 AM)87TurboBird2.3 Wrote: Hey guys, I need help figuring out why I’m getting these two codes (72 & 81). But first let me explain what I’ve done to my 87 Turbo Coupe, which might help you guys with advice.
 
When I bought this car it ran good, idled good, etc….with the exception that if I spun the turbo too high (built too much boost), I would get an alarm and was told by the previous owner that if I didn’t back off the throttle when I heard this alarm, I could blow the engine. So after doing some troubleshooting of the wastegate and wastegate actuator (which checked out fine) I determined that the boost control solenoid (BCS) was bad. So I purchased a Gillis Boost Control Valve and installed it. When I installed the Gillis valve, I unplugged the two vacuum hoses from the factory BCS per the instructions (didn’t cap or plug them), but I left the electrical connector plugged in. Then I fired up the car and now it does not want to idle whatsoever!! It runs rough for a couple seconds and then dies. So I put my code reader on the computer and I got a code 41, which told me the O2 sensor was “lean or out range”. This was the only code I got. So I replaced the O2 sensor tonight. After getting it installed, I fired up the car again and it still won’t idle. So I plugged the code reader in again and now I get these two codes; 72 & 81 (I no longer have the code 41).
 
According to my code reader book, code 72 tells me: “MAP, MAF, or BP sensor out of range during dynamic response test”. That was listed under: Key On Engine Running. There is another 72 code listed under: Continuous Memory which states, “system power circuit fault; message center control assembly (MCCA) circuit failure.
 
Code 81 tells me: “air diverter solenoid fault; intake air control circuit fault / air injection diverter”.
 
Regarding code 72; I’m assuming this issue has to do with the MAF sensor, which I assume to be the Vane Airflow Meter between the air filter and the intercooler????? How do I know if this is bad or not? Is there a way to test it? Do these have a tendency to go bad? How do I fix this? If it is bad, can I replace it with a traditional Mass Airflow Sensor like my 92 Mustang has? What options do I have?

Regarding code 81: What is the air diverter solenoid or intake air control circuit? I have no idea what this is or where it’s located. Would this have anything to do with unplugging the factory BCS vacuum lines? I did not plug them. Should they be capped off or plugged?

Code 81 is the Boost Solenoid Control circuit. These Turbo Coupes did not use a smog air pump. This code will set if the solenoid is disconnected, as you have stated you have done so. So ignore the code. You could put a resistor inline to fool the circuit, if really wanted, to bypass seeing that code again.

Code 72 is related to the ECM. It means the EEC believes there was a brief interrupt in the power supply and could be a bad EEC power relay, bad grounds, bad connections or electrical noise.

It's important that when you're looking up codes to make sure you're also looking up the code that applies for your application. The codes can have different meaning for the different engines as well as different phases (KOER, CM, KOEO).
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87TurboBird2.3 Offline
Junior Member
#3
(05-26-2021, 03:46 AM)I need to clarify something. Initially I had the BCS electrical connector unplugged when I first started the car. Then when the car wouldn't idle or stay running, I plugged the connector back into the BCS and started the car again, but it made no difference; it still wouldn't idle. So maybe it's possible I got the 81 code because I had the BCS disconnected on my first startup? Regarding the code 72 (interruption in power supply)....would this code show up because I had the BCS unplugged? I have an Innova Code Reader for OBD 1 ECU's (1981-1995 Ford Vehicles). The codes I described came from the book that came with the code reader. Are you saying the code description in the book may not be accurate for what I'm experiencing? Should I just erase the codes and start over since I now have the BCS plugged in? Do I need to cap the vacuum lines from the BCS? Wrote:
(05-26-2021, 02:31 AM)87TurboBird2.3 Wrote: Hey guys, I need help figuring out why I’m getting these two codes (72 & 81). But first let me explain what I’ve done to my 87 Turbo Coupe, which might help you guys with advice.
 
When I bought this car it ran good, idled good, etc….with the exception that if I spun the turbo too high (built too much boost), I would get an alarm and was told by the previous owner that if I didn’t back off the throttle when I heard this alarm, I could blow the engine. So after doing some troubleshooting of the wastegate and wastegate actuator (which checked out fine) I determined that the boost control solenoid (BCS) was bad. So I purchased a Gillis Boost Control Valve and installed it. When I installed the Gillis valve, I unplugged the two vacuum hoses from the factory BCS per the instructions (didn’t cap or plug them), but I left the electrical connector plugged in. Then I fired up the car and now it does not want to idle whatsoever!! It runs rough for a couple seconds and then dies. So I put my code reader on the computer and I got a code 41, which told me the O2 sensor was “lean or out range”. This was the only code I got. So I replaced the O2 sensor tonight. After getting it installed, I fired up the car again and it still won’t idle. So I plugged the code reader in again and now I get these two codes; 72 & 81 (I no longer have the code 41).
 
According to my code reader book, code 72 tells me: “MAP, MAF, or BP sensor out of range during dynamic response test”. That was listed under: Key On Engine Running. There is another 72 code listed under: Continuous Memory which states, “system power circuit fault; message center control assembly (MCCA) circuit failure.
 
Code 81 tells me: “air diverter solenoid fault; intake air control circuit fault / air injection diverter”.
 
Regarding code 72; I’m assuming this issue has to do with the MAF sensor, which I assume to be the Vane Airflow Meter between the air filter and the intercooler????? How do I know if this is bad or not? Is there a way to test it? Do these have a tendency to go bad? How do I fix this? If it is bad, can I replace it with a traditional Mass Airflow Sensor like my 92 Mustang has? What options do I have?

Regarding code 81: What is the air diverter solenoid or intake air control circuit? I have no idea what this is or where it’s located. Would this have anything to do with unplugging the factory BCS vacuum lines? I did not plug them. Should they be capped off or plugged?

Code 81 is the Boost Solenoid Control circuit. These Turbo Coupes did not use a smog air pump. This code will set if the solenoid is disconnected, as you have stated you have done so. So ignore the code. You could put a resistor inline to fool the circuit, if really wanted, to bypass seeing that code again.

Code 72 is related to the ECM. It means the EEC believes there was a brief interrupt in the power supply and could be a bad EEC power relay, bad grounds, bad connections or electrical noise.

It's important that when you're looking up codes to make sure you're also looking up the code that applies for your application. The codes can have different meaning for the different engines as well as different phases (KOER, CM, KOEO).
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JT Online
Posting Freak
#4
Code 72 is not set from Code 81 (Boost Solenoid circuit). They are unrelated.

Ford defines the codes, not the tool. Some codes are shared between different engines despite they are not the same. This is one of those examples. The Turbo Coupe engine has a few codes that are not related to other Ford engines. Unfortunately, it sounds like your tool is using a "generic" set of code definitions. So, yes, your book is not 100% correct for your application.

Also, Code 41 can exist in different forms (such as KOER or CM) and knowing what form is important. Also, an o2 code does not mean the sensor is faulty. The code is reporting the o2 sensor is out of range. While a faulty sensor could be the cause, so could be a poorly running engine.
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87TurboBird2.3 Offline
Junior Member
#5
Ok guys, I have an update. So today after work I pulled the VAM & MAP sensor connectors off and inspected them and plugged them back in. Took the intercooler off and looked around for anything that looked out of the ordinary, looked at vacuum lines, etc...Found nothing wrong. So then I cleared the codes on the computer and then fired up the car. The car ran like shit at idle. It tried to idle, although extremely rough, but would eventually die. However, when I revved the engine up a little, it stayed running, but you can hear it missing. So I put the code reader back on the computer and this time I got a code 14, but I didn't get the 72 or 81 codes. So according to my book and also a trouble code website I looked up to verify my book was accurate, a code 14 in my book states: "Ignition Profile Pickup (PIP) Circuit Failure". Code 14 on the website states: "Ignition Pickup (PIP) was erratic". So I assume this has to do with the distributor and/or ignition components. 

So let me mention what I've done to the ignition system. I replaced the cap, rotor, plugs and wires. While I was at it, I did unplug the SPOUT and inspected it and plugged it back in. Another thing I did was get rid of the TEVES brake system and replaced it with a vacuum brake booster system (did the 93 Cobra Mustang conversion). The only reason I mention this is because now that I no longer have the old factory TEVES brake system, the wiring that was used for that system is now unplugged. I'm not sure if all of these plugs being unplugged would cause any electrical interference with the PIP system, but I thought it was worth mentioning to help rule it out. 

So would this code 14 have anything to do with the new spark plug wires I'm using? They are from Autozone (Duralast p/n 4112).The wires have this printed on them: Bosch Ultra-Premium 8mm Opti-Layer Mag Core. I'm not sure how much resistance they have or if they're interfering with each other (they do cross each other in a couple places), but I do have wire separators on them to help keep them organized. Here are the wires: https://www.autozone.com/ignition-tune-u...2/2788_0_0 

Not sure if this has anything to do with it, but I thought I'd mention the spark plugs. The old plugs had a huge gap. I didn't measure them, but you could see it was a lot bigger gap than what I set it at. 

So any idea what might be causing my issue with the Code 14?
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JT Online
Posting Freak
#6
I don't know about today's Bosch but it was a known issue running Bosch ignition parts causing misfires and a PIP (Code 14) error on these systems. You can still buy Motorcraft spark plug wires and that has been recommended for years. Besides that, it could be a bad PIP, TFI or connection issue. There's a bigger chance the secondary ignition wires you're using are causing the interference and misfire than a disconnected ABS system.
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87TurboBird2.3 Offline
Junior Member
#7
I’m thinking the same thing as you regarding the wires being the problem. After thinking about everything I’ve done, the only changes I made to the ignition system was new plugs, wires, cap & rotor. The car ran really good before I changed this stuff, so I’m guessing it’s got to be the wires. I’ll see if I can find some Motorcraft wires and see if it resolves the problem.
 
Question…..is there a certain spark plug wire that works better to prevent electrical interference? I know EFI systems are very sensitive to electrical interference whereas carbureted engines are not. What features should I be looking for when deciding which wires to buy?
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JT Online
Posting Freak
#8
(05-27-2021, 04:09 PM)87TurboBird2.3 Wrote: I’m thinking the same thing as you regarding the wires being the problem. After thinking about everything I’ve done, the only changes I made to the ignition system was new plugs, wires, cap & rotor. The car ran really good before I changed this stuff, so I’m guessing it’s got to be the wires. I’ll see if I can find some Motorcraft wires and see if it resolves the problem.
 
Question…..is there a certain spark plug wire that works better to prevent electrical interference? I know EFI systems are very sensitive to electrical interference whereas carbureted engines are not. What features should I be looking for when deciding which wires to buy?

The Motorcraft wires have been recommended within the community for years and they're still available for $30 at Rock Auto.
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Jeff K Offline
Administrator
#9
As JT mentioned, you can get rid of the BCS code 81 with a resistor. Simply put a 100 ohm 1 Watt resistor across the BSC connector plug and you will never see the code 81 again.

I saw a code 72 about 10 years ago. Checked connectors to IRCM, PCM, harness, etc and found no issues. The 72 has never returned.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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87TurboBird2.3 Offline
Junior Member
#10
JT--I just bought some Motorcraft wires (p/n WR-4011-C) at Autozone for $22. They will be in tomorrow. I looked at the specs on these wires and they say they have a spiral core and provide RFI suppression, but of course the Bosch wires also said they provided RFI suppression. But they didn't say anything about being a spiral core. Maybe that's the difference??? Who knows. I'll put them on tomorrow afternoon and pray it resolves the problem. 

Jeff--I plugged the wire connector back into the BCS, cleared the codes and then fired up the car and so far the codes haven't come back...yet. But that's not to say they won't come back once I get the car running right. But since it's still running like crap, I'm assuming the 72 & 81 codes were just a coincidence because now I have a code 14. But it confuses me why the code 14 didn't show up in the first place with the 72 & 81 codes, but only showed up after I cleared them. Weird...

Question....so if I'm not using the BCS (using a Gillis boost valve), is it ok to keep the BCS plugged into the wiring harness or do I need to unplug it? If it's plugged in but not detecting any vacuum (vacuum lines disconnected), will the ECM think it's not working and throw a trouble code?
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