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Why Does ECM/PCM Go Bad?

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Old 05-23-2008, 01:53 PM   #1
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Why Does ECM/PCM Go Bad?

Hey guys,
I cant get the thing out of my mind about the 2.5ls eating the computers. Why does it do this? My truck is fine right now with only 105,552miles on it. Im worried that my truck is going to eat the computer in my truck and im going to have to get another truck. Any ideas why?
Thanks
Old 05-23-2008, 02:52 PM   #2
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Talking Re: Why Does ECM/PCM Go Bad?

Quote: Originally Posted by ironduke2.5
Hey guys,
I cant get the thing out of my mind about the 2.5ls eating the computers. Why does it do this? My truck is fine right now with only 105,552miles on it. Im worried that my truck is going to eat the computer in my truck and im going to have to get another truck. Any ideas why?
Thanks
I've been looking at the ECU/PCM issues and even though Member k980 says that they make a pocket calculator look good, they do ALOT of "stuff"...they are made up of several components, having "drivers" for this and "drivers" for that. They have fail-safes built-in. But, they are now very old and a part of the circuits inside may fail.
There are "soft faults" and "hard faults". The hard ones allow you to begin walking, the soft ones allow you to limp home, still running the engine. They have a few "block learn" parameters where they actually remember stuff. Amazing, considering its' age..kinda like me....

But they are cheap to replace...not like me...

Last edited by Steady Eddie; 05-23-2008 at 03:04 PM.
Old 05-23-2008, 03:03 PM   #3
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Re: Why Does ECM/PCM Go Bad?

Also, I have found out, that "sometimes" the plug-in connectors get corrosion on them and cause all kinds of "mystery" running issues..then the simple act of un-plugging and re-plugging the connector(s) back in, cleans them up enough to allow it to run right...
Old 05-23-2008, 03:13 PM   #4
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Lightbulb Re: Why Does ECM/PCM Go Bad?

The idea of a brain-box failure reminds me of another issue, too. The dam clutch pedal safety switch...

What if it does stab you in the back, at a stop light maybe..?? You cannot use the starter to run the rig over to the curb side, because the clutch must be in to run the starter...how dumb is THAT!!! I will install a toggle switch
under the dash somewhere that will allow by-passing the clutch switch in an emergency....
Old 05-23-2008, 03:36 PM   #5
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Re: Why Does ECM/PCM Go Bad?

Hey guys,
I just want a reliable truck that i know that i can rely on. Do yall trust these trucks enough to rely on for the rest of your life? I want a truck that can and will last for another 20 years. Should i start looking for another truck or do yall feel confident enough to drive until yall die? I just dont like repairing a truck that will die on me one day and will have to rebuild the whole truck, thats all. Any ideas?
Thanks
Old 05-23-2008, 04:05 PM   #6
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Re: Why Does ECM/PCM Go Bad?

I know that pretty much all of the dukes have the same problem.They start running like poo and nothing you can do to fix it.Thats my case right now.Allthough,I have not replaced the computer because I dont think thats the problam,BUT,I could be wrong...
Old 05-23-2008, 05:14 PM   #7
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Re: Why Does ECM/PCM Go Bad?

Quote: Originally Posted by ironduke2.5
Hey guys,
I cant get the thing out of my mind about the 2.5ls eating the computers. Why does it do this? My truck is fine right now with only 105,552miles on it. Im worried that my truck is going to eat the computer in my truck and im going to have to get another truck. Any ideas why?
Thanks
Why does the computer go bad, let me see, how long does a normal Desktop computer last? Several things can kill a computer, #1 HEAT, #2 Shoddy Design, #3 Poor Regulation on Alternator, #4 Bad Connections, #5 Excessive Moisture, #6 Excessive Vibration, #7 AGE. I am sure I missed a few, but heat causes expansion and contraction and will allow components to pull free of their soldered in PCB state or cause a thermal breakdown of other components I.E. Capacitors are common, Electrical Spikes from power system if you jumpstart or bad regulator can damage internal IC's, Moisture can cause corrosion (primarily on connectors as PCBs have been dipped in an Ignition sealer (making the bad connections of IC's and such hard to resolder), Vibration can cause components to break away from their original locations, and just plain AGE gets everything in the end. Not to say any of these things will happen soon, it is just some possibilities, and Between you and Me these older ECMs are by far simpler than newer computer systems with multiple systems communication between each other like the PCM/ECM/BCM/VCM etc all having to talk to one another (multiple "brain boxes") for everything to work, that is why I appreciate the age of these 1st Gens.
MY 2 CENTS
Old 05-23-2008, 06:14 PM   #8
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Re: Why Does ECM/PCM Go Bad?

Thanks a lot lesterl,
What u just said made me feel a whole lot better. So its just basically everything and mostly time to wear out these trucks "computers". I feel much better about my trucks reliablitiy and if it ever takes a dump, hope not, ill probably look for another "computer". I love my truck and know almost everything that it does. thanks guys
Old 05-24-2008, 02:34 PM   #9
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Re: Why Does ECM/PCM Go Bad?

for the reliability of these things: about average. I wouldn't put above my toyota for reliability or quality of build but it's certainly at least as good as the junk chevy puts out nowadays.

lesterl pretty much hit it in the bullseye. heat, electrical, moisture, vibration are the primary causes of computer failure.

I say this things computer is primative cuz I'm used to my toyota Cressida or my friends infiniti G20. an 85 cressida has as much computing power in each of the climate control, transmission, engine, and body computer as this does total and very seldom has any trouble through 250k miles. when the G20 came out in '91 it was about 99% of full ODBII system. This thing can't even adjust mixture for intake air temp. it's not BAD... just primitive.
Old 05-25-2008, 04:39 PM   #10
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Re: Why Does ECM/PCM Go Bad?

Quote: Originally Posted by kamesama980
for the reliability of these things: about average. I wouldn't put above my toyota for reliability or quality of build but it's certainly at least as good as the junk chevy puts out nowadays.

lesterl pretty much hit it in the bullseye. heat, electrical, moisture, vibration are the primary causes of computer failure.

I say this things computer is primative cuz I'm used to my toyota Cressida or my friends infiniti G20. an 85 cressida has as much computing power in each of the climate control, transmission, engine, and body computer as this does total and very seldom has any trouble through 250k miles. when the G20 came out in '91 it was about 99% of full ODBII system. This thing can't even adjust mixture for intake air temp. it's not BAD... just primitive.
They do have an Air Intake Temperature sensor, dont know exactly what the ECM does with the data, but you gotta take ito consideration thes P/Us were built with cost in mind so they dont have a computer to run climate, computer to run door functions, etc (my 2006 Sierra did), I would much rather have a basic computer operating system such as this as they are much easier and cheaper to repair.
Old 05-26-2008, 01:00 AM   #11
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Re: Why Does ECM/PCM Go Bad?

Quote: Originally Posted by lesterl
They do have an Air Intake Temperature sensor, dont know exactly what the ECM does with the data, but you gotta take ito consideration thes P/Us were built with cost in mind so they dont have a computer to run climate, computer to run door functions, etc (my 2006 Sierra did), I would much rather have a basic computer operating system such as this as they are much easier and cheaper to repair.
I know and thats exactly why i was wiling to buy it. normally I wouldn't touch a GM (except to fix someone elses) but thats a whole other can of beans I'm not gonna open.

The only air intake temp sensor i saw operates a vacuum switch mechanically to operate the intake preheater door to maintain a constant intak temp. thats part of the reason for the coolant in the intake: rather than figure hot/cold just make it all hot
Old 05-26-2008, 01:47 AM   #12
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Re: Why Does ECM/PCM Go Bad?

k980--
Two different systems..and the one in the air cleaner, the flap door thingy, is completely independent from the S-10's "pocket calculator" brain-box. It is a stand-alone, the brain-box can't directly "see it"...
Old 05-26-2008, 08:54 PM   #13
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Re: Why Does ECM/PCM Go Bad?

Quote: Originally Posted by kamesama980
I know and thats exactly why i was wiling to buy it. normally I wouldn't touch a GM (except to fix someone elses) but thats a whole other can of beans I'm not gonna open.

The only air intake temp sensor i saw operates a vacuum switch mechanically to operate the intake preheater door to maintain a constant intak temp. thats part of the reason for the coolant in the intake: rather than figure hot/cold just make it all hot
Some have one in Intake directly beind Alternator (some have one on opposite side of intake behind TBI. They are a valid sensor as they provide a voltage drop to the ECM that is directly related to the air temp in the Intake Manifold.
Old 05-26-2008, 10:13 PM   #14
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Re: Why Does ECM/PCM Go Bad?

S10's with 2.5's don't get any respect. No one treats them as well as they do almost anything else. The stick models are very harshly treated indeed. Guess they live up to the "utility pickup" nomenclature better that any other truck ever on the market. Beat it till it drops and then blame the truck?

Couple of things come to mind with the most basic models. No sounds. have to add speakers, amps, blah blah. Instant electrical problems. lowest output alternator.

Have to run wires the easiest way, right past puter. Oops puter wont go back in right; who cares if it dangles.

I could go on, but if you read all that, then you probably realize that it's the way we, ourselves, treat the truck.

Its also quite normal for more window and door problems or tailgate breakage on all these trucks, but the fancier models of the same truck won't have the same problems for many miles more. Simple, they are not the trucks we use to take the trash to the dump or pick up the lumber at the store. We save the upgraded models for just driving around.
Old 05-27-2008, 01:30 AM   #15
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Re: Why Does ECM/PCM Go Bad?

While I agree with blazing saddle, a lot of problems do come with mis-use. But there are some trucks out there that have had a very user friendly life with the same problems as the workers.

For example, my truck was owned from new by an old man I have known since I was a child. In his words, 'I just wanted a cheap little truck with a stick' lol. Not once did that truck ever haul a load greater than 500 lbs, or did it get revved to its limits every day, nor was it driven higher than the posted speed limits. All it was used for was a driver to work (lots of highway) and get groceries. The man had the oil changed very frequently, exactly every 4 weeks no matter the mileage, I have the records to prove it. Only thing he didnt do was clean under the seat lol.

Yet I still have the same kind of issues as the work trucks such as various engine or electrical problems, sagging doors, binding and/or rattling windows, and just plain old worn out components.

I think it all boils down to the fact that a lot of these trucks are at least 14 years old, most being much older. Time takes its toll on a vehicle, especially a daily driver that sees winters. Wait and see whats wearing out on a brand new '08 Chevy fullsize after 15 years of use. Granted the list might not be as long, but its damn well going to need some maintenance.

Wow, jeez, got going off on a tangent there, sorry for the rant...
Old 05-28-2008, 05:49 AM   #16
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Re: Why Does ECM/PCM Go Bad?

Quote: Originally Posted by Steady Eddie
k980--
Two different systems..and the one in the air cleaner, the flap door thingy, is completely independent from the S-10's "pocket calculator" brain-box. It is a stand-alone, the brain-box can't directly "see it"...
yea i know how it works. I've taken my toyotas to bits and put them back again when someone mucks them up enough not to work. it uses a flapper style air flow meter. air flowing through it pushes the door open proportional to the volume of air flowing into the engine and a signal is sent to the ECU accordingly wheras the dukes flapper is a valve to bring warmer air in from the exhaust manifold controlled by the mechanical intake air temp sensor in the filter housing to maintain a constant (hot intake) so the computer doesn't have to calculate air density from temp. there's like 4 million sensors on that thing to keep it happy, they're all used by the ECU, and they discontinued that engine in '88.

I agree that many problems with the duke are neglact/abuse related. maintained and treated well, it's pretty reliable and gets you by. mines got enough power to accelerate with traffic and maintain 75 mph while at (maybe past) capacity. 2 biggest improvements: advancing the hell out of the timing (28 mpg doing 75 with windows down and 600 lbs with the 4-speed manual) and adding a rear sway bar.

Last edited by kamesama980; 05-28-2008 at 05:51 AM.
Old 05-28-2008, 09:05 AM   #17
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Lightbulb Re: Why Does ECM/PCM Go Bad?

k980---

28 MPG on the freeway was the mileage recorded by my S-10 when my son had it for a daily. I just recorded 23 MPG on the last 1/2 tank, in town. But it is a 5-speed OD manual transmission. Gas theft is running rampant in our town. The perps are now just punching a hole in the tank(s) and draining them on-the-spot...nothing quite like the fuel mileage (and expense) you get after some idiot punches your S-10's gas tank...

Locking gas caps don't even slow these guys down..BTW:
Anybody here noticed how the price of a locking gas cap has gone through the roof???
Old 05-28-2008, 11:17 AM   #18
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Re: Why Does ECM/PCM Go Bad?

Quote: Originally Posted by Steady Eddie
k980---

28 MPG on the freeway was the mileage recorded by my S-10 when my son had it for a daily. I just recorded 23 MPG on the last 1/2 tank, in town. But it is a 5-speed OD manual transmission. Gas theft is running rampant in our town. The perps are now just punching a hole in the tank(s) and draining them on-the-spot...nothing quite like the fuel mileage (and expense) you get after some idiot punches your S-10's gas tank...

Locking gas caps don't even slow these guys down..BTW:
Anybody here noticed how the price of a locking gas cap has gone through the roof???
shotgun shells are still cheap
Old 05-29-2008, 09:14 PM   #19
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Re: Why Does ECM/PCM Go Bad?

uh. about driving it till I die? My doc says that could be any day, so I guess I'll have to. I wouldnt advise anyone else owning any vehicle to trust it till you die?

Yes, and we dont even realise there is something to complain about till we get to the second rear end, the third stick shift and the second motor finally dies. So, why doesnt Chevy make one that lasts 800,000 miles. I fault the American car industry. By george, I swear my window quit working at 600,058 miles and I refuse to ever buy a Chevy again.
Old 11-22-2009, 06:44 PM   #20
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Re: Why Does ECM/PCM Go Bad?

mine is having those "weird" problems. one day it starts right up and runs great, while others it runs like crap and cuts out horribly going down the road.. and yet while the bumper is half gone, the rear main leaks, and my tail lights dont work, this thing just wont die... it has gotten me through the toughest situations and kept going when other cars wouldnt... such as the 100 miles i drove with as much as 3 cups of oil... (i didnt know it was low until oil pressure dropped.) lol. I have put my full trust into my s10 while people look at the pos rusted body and say, "how does it still work?". i just reply "its stubborn".
Old 11-22-2009, 07:01 PM   #21
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Re: Why Does ECM/PCM Go Bad?

Im having a problem with my ecm too. Keep gettin code 44 and I was told to pull the connector off and check the pins and make sure they arent corroded or just slipped back a little bit, especially pins 5 and 18.
Old 11-22-2009, 07:04 PM   #22
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Re: Why Does ECM/PCM Go Bad?

How do you add timing, i tried turning my dizzy to advance it and it wont seem to let me, mines and 87 with a complete 350 dollar tune up and im still gettin codes 44 and 24.
Old 11-22-2009, 07:50 PM   #23
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Re: Why Does ECM/PCM Go Bad?

You need to jumper pins A&B on the ALDL to adjuste the distributor, base time is 8*
Old 11-24-2009, 12:57 AM   #24
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Re: Why Does ECM/PCM Go Bad?

Im needin a complete memcal assembly for an 87 duke, if anyone has one for sale or just layin around PM me. Thanks
Old 11-24-2009, 10:34 AM   #25
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Re: Why Does ECM/PCM Go Bad?

It's all a bunch of ado over nothing. Assuming you EVER need one, a whole new ECM can be had for $125; unless your truck is missing entire body panels, they're damned good trucks, the expense is justified. I've had mine for over 15 years, has around 175k on the clock (estimated, I run oversize tires and haven't changed the speedo gear), and I trust and rely on it completely. Over the years, things have broken while out and about (most astonishing was when the fan broke a blade off!), but it's never left me stranded or been so broken I couldn't limp it home. Only time it's EVER been on a hook is when I was towing it myself on my wrecker to move it around when I needed both vehicles in a place. Eats water pumps, but it's still good.

Don't worry, you'll be just fine.
Old 11-24-2009, 11:19 AM   #26
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Re: Why Does ECM/PCM Go Bad?

I remember when I bought my 88 in 88 I went thru 2 proms within the first 3 months. THen within the second year of ownership another PCM failure, BUT the dealer decided to change the ECM and PCM , in the process they found I had a loose ground wire too. Since that repair, its been smooth sailing and no issues (knock on wood).
Old 11-24-2009, 10:00 PM   #27
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Re: Why Does ECM/PCM Go Bad?

88 only has an ECM, no PCM. PCM controlls an engine and transmission (auto) on the newer vehicles.
Old 11-25-2009, 12:34 AM   #28
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Re: Why Does ECM/PCM Go Bad?

Oh I know how to adjust the timing, i just couldnt get the dizzy to move till yesterday. It was bieng real stubborn beacuse the engine wouldnt remain at a steady idle so it was really hard to set the timing and be confident that I had it right.I just adjusted it by ear. But now I opened up a new can of worms cuz i just popped the head gasket.
Old 11-27-2009, 07:44 PM   #29
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Re: Why Does ECM/PCM Go Bad?

Ok here is one I dont think has been mentioned yet. This one was told to me by my mechanic , the guy I take it to when I am ready to give up. He's been running his own shop for about 35 years .

Wanna kill your ecm ? I mean dead , not running bad , or phantom codes , I mean melt the innards .

And I might mention that more of a few of you are on your way right now .

Just look at the condition of your spark plugs , wires , distributor cap and rotor .

Ever see a set of junk wires spark all over the place at night ? now imagine just one of them sparks hitchin a ride back to the ecm , its all it takes . Just look at how your plug wires are routed and how many fat bundles of wires are nearby leadin to the ~ ECM ~

He estimates he has replaced a couple hundred ECMs this way . People run their cars , do little to no maintenance , and are shocked when something bad happens . lol

just thought i would throw that in there
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