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51 Posts
Discussion Starter #1
OK boys,

I have a mk3 with 1991 5.0 set up.
Ron Francis engine harness
A9l computer manual
No smog equipment
EGR delete

so some symptoms are:
very hard to start up if it does that day(very moody)
en even rev
wont start back up " ignition module again?"
codes:
22 MAP/BP sensor out of self test range.
35 PFE or EVP circuit has intermittently failed above the maximum limit of 4.81 volts.
51 ECT sensor signal is greater than the Self-Test maximum of 4.6 volts.
53 TPS circuit above maximum 4.5 volts.
54 ACT sensor signal is greater than the Self-Test maximum of 4.6 volts.
81 Air management 2 circuit failure (AM2/TAD).
82 Air management 1 circuit failure (AM1/TAB) .
84 EGR Vacuum Solenoid circuit failure.
85 Canister Purge Solenoid circuit failure.

Any help would be greatly appreciated!
 

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Official OLD GUY
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codes

Sounds like you're in "Limp mode".

For the 81,82,84 & 85, did you put the required resistors in the circuit to fool the EEC into thinking that the activation coils are still there?

For all the others, check your "reference voltage" and "return path" wires for correct voltages. Most of the sensors use a 5 volt source and the sensor(s) drops that down to somewhere just above zero (depending on the sensor) as return signal to the EEC.

HTH

Doc :beerchug:
 

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OK boys,

I have a mk3 with 1991 5.0 set up.
Ron Francis engine harness
A9l computer manual
No smog equipment
EGR delete

so some symptoms are:
very hard to start up if it does that day(very moody)
en even rev
wont start back up " ignition module again?"
codes:
22 MAP/BP sensor out of self test range.
35 PFE or EVP circuit has intermittently failed above the maximum limit of 4.81 volts.
51 ECT sensor signal is greater than the Self-Test maximum of 4.6 volts.
53 TPS circuit above maximum 4.5 volts.
54 ACT sensor signal is greater than the Self-Test maximum of 4.6 volts.
81 Air management 2 circuit failure (AM2/TAD).
82 Air management 1 circuit failure (AM1/TAB) .
84 EGR Vacuum Solenoid circuit failure.
85 Canister Purge Solenoid circuit failure.

Any help would be greatly appreciated!
Yeah, it would definately run like poop. The emissions stuff is fine. Sounds like a wiring issue to have that many sensors out of range. Probably a missing ground???
 

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You definately need to fix these, others are debatable:

OK boys,
22 MAP/BP sensor out of self test range.
51 ECT sensor signal is greater than the Self-Test maximum of 4.6 volts.
53 TPS circuit above maximum 4.5 volts.
54 ACT sensor signal is greater than the Self-Test maximum of 4.6 volts.
I think you must have a bigger problem than the sensors, as I find it highly unlikely that all these sensors have failed. Grounding to the computer maybe?

Pete
 

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section 8
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5,135 Posts
obviously you wrote the down . Now clear them and see what comes back. Sometimes an "open " sensor will cause all to read wrong. The map code was 1st , test it or swap it out. Test voltage at tps sensor , while meter is connected disconnect map sensor and see if voltage returns to normal. The codes are listed in priority order. Disconnect / reconnect sensors 1 at a time and see if voltage returns to normal when you test tps disconnect it and probe from harness connector.. Good luck , does it run at all??
 

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Discussion Starter #8
Ok, I'm gonna try to test the interlinked sensors and look over my grounds.

The car does run but, it runs very poorly and has a very hard time starting up and restarting. I'll keep every one posted on what I find.

thanks!!
 

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Discussion Starter #9
so, I cleared the memory and re-grounded the computer so that it is for sure getting a solid ground(as well grounded it directly to frame, which had the same results). so the car basically wont start unless it has starting fluid. but it is getting gas. we purged the line and shot fluid out.

for the codes the priority it is

51
22
23
54
35
67
81
82
85
84

I'm gonna try to check the sensors by priority to see if that changes anything
 

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I had very similar codes and results when my error check harness (where the code scanner plugs in) was pinched/cut/broke/mangled/etc.
 

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Discussion Starter #11
I had very similar codes and results when my error check harness (where the code scanner plugs in) was pinched/cut/broke/mangled/etc.
Yeah all everything is in very good condition as far as the harness. its brand spanking new. so I dont think that that is the problem.

Also, I regrounded everything No way any of its not getting a decent ground, and had the same results. Is there a way to check the sensors by via its resistance using a multimeter?
 

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Just very odd all the sensor faults you are getting, as I would expect something else not the sensors. How is the ECU ? Have you done a swap to test that out or and bent pins on the 60 pin connector?
 

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Official OLD GUY
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Nss

All of the sensors you listed have a common return path to the EEC on pin 46 (SG RTN). The only other item connected to this return path is your neutral start switch/clutch switch. Any chance you have power going to those switches and it's returning the 12 volts on the 46 leg? Your codes all indicate an over voltage on the return leg:

22 MAP/BP sensor out of self test range.
35 PFE or EVP circuit has intermittently failed above the maximum limit of 4.81 volts.
51 ECT sensor signal is greater than the Self-Test maximum of 4.6 volts.
53 TPS circuit above maximum 4.5 volts.
54 ACT sensor signal is greater than the Self-Test maximum of 4.6 volts.

Check your "VREF" line ( I think pin 26) to see if you're getting 5.0 volts or 12 volts. It can be checked at the TPS, EGR valve position sensor or the MAP sensor - White/Orange wire.

HTH

Doc :beerchug:
 

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FFCobra Captain
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Seems like the first thing to do is check one of the sensors to see if the power feed is greater than 5 volts. Just pick the easiest one to test and report back.

You should be able to grab the connector that runs to the TPS and test that one pretty easily.
 

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Discussion Starter #16
Seems like the first thing to do is check one of the sensors to see if the power feed is greater than 5 volts. Just pick the easiest one to test and report back.

You should be able to grab the connector that runs to the TPS and test that one pretty easily.
Yup every sensor that i have tested so far has been at 5.03 volts.

also with the neutral safety switch i don't run one so the wires are joined together. Ill have to check those after I get home. Answer to this mystery? It shouldn't affect the computer if its just signalling that the clutch is down?
 

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Discussion Starter #17
Just very odd all the sensor faults you are getting, as I would expect something else not the sensors. How is the ECU ? Have you done a swap to test that out or and bent pins on the 60 pin connector?
Hey my man,

so pulled the computer this morning and the connectors looked awesome no bent or damaged pins that i could see.
Is there a way to check if the computer its self has gone bad?
I might go to a ford dealership with the whole computer and see if they can run a diagnostic.
 

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Any resolution ?
 

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Hey my man,

so pulled the computer this morning and the connectors looked awesome no bent or damaged pins that i could see.
Is there a way to check if the computer its self has gone bad?
I might go to a ford dealership with the whole computer and see if they can run a diagnostic.
Usually if the computer is bad, it won't run the self test at all.

Pete
 

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Discussion Starter #20
Pin 30?

Ok, so ill post some pictures of what i found on my computer in a little bit. but it looks like i had the pin thirty problem where there was a fried circuit that connects the Neutral safety switch to the rest of my sensor circuit. I'm gonna try to repair it tonight. As well gonna get more research time in to figure out how to avoid having this problem again. if ya know any thing about this problem let me know please!!!!
 
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