Computer Issue I think 93L

Also pip sensor was replaced by the dealers mechanic when they tried to get it running but distributor is origional. Also it has fender mounted ignition control module but that looks stock. Can the PCM still be bad even though I replaced the capacitors?

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93blackbeauty said:
Also pip sensor was replaced by the dealers mechanic when they tried to get it running but distributor is origional. Also it has fender mounted ignition control module but that looks stock. Can the PCM still be bad even though I replaced the capacitors?

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Yes


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Well I took a gamble on a Cardone part even though I know it's not advisable. But I've been mulling mass air conversion later on or another standalone system later so I didn't want to pay $400 for the only other reman I could find. I only need it to get it through it's last emissions test this year thank god. Hopefully it will hang on for at least six months.

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26 Mass Air Flow (MAF) or Vane Air Flow (VAF) out of range
Transmission Oil Temperature (TOT) sensor out of range

654
(O)
Transmission selector not in PARK - Transmissions

think you should remove clean and inspect your transmission connectors. and make sure the range selector is properly adjusted. Not sure about the lightning but on later models you put it in reverse and adjust till the back up ligthts come on. This is not the book way to do it Im sure but its what ive read that works.
 
Jabo04 said:
26 Mass Air Flow (MAF) or Vane Air Flow (VAF) out of range
Transmission Oil Temperature (TOT) sensor out of range

654
(O)
Transmission selector not in PARK - Transmissions

think you should remove clean and inspect your transmission connectors. and make sure the range selector is properly adjusted. Not sure about the lightning but on later models you put it in reverse and adjust till the back up ligthts come on. This is not the book way to do it Im sure but its what ive read that works.
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Yeah those seem eraneous because it's got erratic idle the 26 may have a hand in that but I doubt a trans code would cause a surging/stalling condition. I hope the PCM fixes most of it when it gets here.

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Jabo04 said:
26 Mass Air Flow (MAF) or Vane Air Flow (VAF) out of range
Transmission Oil Temperature (TOT) sensor out of range

654
(O)
Transmission selector not in PARK - Transmissions

think you should remove clean and inspect your transmission connectors. and make sure the range selector is properly adjusted. Not sure about the lightning but on later models you put it in reverse and adjust till the back up ligthts come on. This is not the book way to do it Im sure but its what ive read that works.
Click to expand...
Is vane airflow the speed density version of a MAF?

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I think vaf is like mass air but instead of using a heated wire it uses an air vane or flap that is sprung and connected to a potentiometer kind of like how a fuel sending unit works. depending on the position of the vane the voltage drop across the pot tells the computer how much air is entering the engine. No it is not part of speed density. Speed density uses MAP sensor or manifold absolute pressure. to calculate the load on the engine and supply the correct fuel based on known calculated data. They know how much air a given displacement will pump at a given rpm and how much fuel to supply based on that data and the load on the engine. That is my understanding anyway.
 
Jabo04 said:
I think vaf is like mass air but instead of using a heated wire it uses an air vane or flap that is sprung and connected to a potentiometer kind of like how a fuel sending unit works. depending on the position of the vane the voltage drop across the pot tells the computer how much air is entering the engine. No it is not part of speed density. Speed density uses MAP sensor or manifold absolute pressure. to calculate the load on the engine and supply the correct fuel based on known calculated data. They know how much air a given displacement will pump at a given rpm and how much fuel to supply based on that data and the load on the engine. That is my understanding anyway.
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Yeah just trying to figure out if the rough idle is causing computer codes or the bad computer is causing a rough idle. I hate throwing parts at anything. But I just don't know enough about the obd1 stuff haha.

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93blackbeauty said:
Yeah just trying to figure out if the rough idle is causing computer codes or the bad computer is causing a rough idle. I hate throwing parts at anything. But I just don't know enough about the obd1 stuff haha.

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I'm stumbling in on this a bit late, but keep in mind that the Speed Density logic is just a math formula that allows the ECU to record and then average data from several engine management sensors.

What I'm getting at is that a not perfectly smooth, and sometimes erratic, bordering on rough, idle is inherent in these trucks.

Thinking, feeling and hearing that you've got a somewhat lopy cam when in fact you don't is a part of owning and loving a '93-'95 351W with GT40 pieces.

Embrace it...
 
bumperquip said:
I'm stumbling in on this bit late, but keep in mind that the Speed Density logic is just a math formula that allows the ECU to record and then average data from several engine management sensors.

What I'm getting at is that a not perfectly smooth, and sometimes erratic, bordering on rough, idle is inherent in these trucks.

Thinking, feeling and hearing like you've got a somewhat lopy cam when in fact you don't is a part of owning loving a '93-'95 351W with GT40 pieces.

Embrace it...
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Oh it's much worse than that if you drop it in gear or when I could actually get it out of the driveway it would stall coming to a stop Now it won't make it to the end of the driveway without stalling .

I own a blown and cammed mustang I can handle erratic idle but swing up and down almost 1000rpm is not right haha.

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Guys: There are no 2-digit trouble codes on our trucks. They are all 3-digit codes. So no, you're not getting a 26 code - you need to go back and re-do the test. And if you are getting a 654, which is "Not in Park during KOEO self-test" then either the gear selector wasn't in park during the test, or your MLPS is bad, or your shift linkage is not adjusted properly.
 
motorhead1024 said:
Guys: There are no 2-digit trouble codes on our trucks. They are all 3-digit codes. So no, you're not getting a 26 code - you need to go back and re-do the test. And if you are getting a 654, which is "Not in Park during KOEO self-test" then either the gear selector wasn't in park during the test, or your MLPS is bad, or your shift linkage is not adjusted properly.
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I did it three times same codes over and over every time. Not sure why but it spits out a 26. I've ordered a new PCM so I will see if it continues with that one.
93blackbeauty said:
Oh it's much worse than that if you drop it in gear or when I could actually get it out of the driveway it would stall coming to a stop Now it won't make it to the end of the driveway without stalling .

I own a blown and cammed mustang I can handle erratic idle but swing up and down almost 1000rpm is not right haha.

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93blackbeauty said:
I did it three times same codes over and over every time. Not sure why but it spits out a 26. I've ordered a new PCM so I will see if it continues with that one.



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Now there was a 1 in there which I read as being a check digit in the service instructions that I have is there a 126 code?

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126 is map sensor. Check the vacume line to it and also that you dont have a major leak elsewhere. should have around 20 in at idle
 
Jabo04 said:
126 is map sensor. Check the vacume line to it and also that you dont have a major leak elsewhere. should have around 20 in at idle
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That makes more sense with bad idle. I'll check all my vacuum lines is there a vacuum diagram somewhere here? Still learning my way around this forum.

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93blackbeauty said:
That makes more sense with bad idle. I'll check all my vacuum lines is there a vacuum diagram somewhere here? Still learning my way around this forum.

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Come to think of it I have been noticing like a vibrating buzzing noise at the back of the upper intake manifold right after shutting the truck ofg for a few minutes wonder if something is leaking.

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93blackbeauty said:
Come to think of it I have been noticing like a vibrating buzzing noise at the back of the upper intake manifold right after shutting the truck ofg for a few minutes wonder if something is leaking.

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Yeah, one of your solenoids on the back side of the throttle body is allowing air to pass when it shouldn't. I just discovered this same problem with my '93, but haven't changed it yet and don't know if it will have any effect in the end.
 
needmorepower said:
Yeah, one of your solenoids on the back side of the throttle body is allowing air to pass when it shouldn't. I just discovered this same problem with my '93, but haven't changed it yet and don't know if it will have any effect in the end.
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Well I can't imagine it's all that expensive. I'll probably just redo all the vacuum lines after 24 years some are bound to be rotten.

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OK new computer is in and it starts and as soon as it warms up a bit it starts hunting for idle again. It will pretty much stay running Now though. It stalled once but I got it to run for about a half an hour solid it just fluctuated idle check engine light is back on with the new PCM though so I need to pull the codes and see if it's still the same ones. Also pulled a couple plugs and man are they black. Not sire where to go from here though. Any suggestions on trouble shooting tips is greatly appreciated.

e3a7eaead96a0361b2f609b72bc51f60.jpg


It has some oil in the threads but not crazy this was the first plug on the passenger side.

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