Posted on 06/12/2015 3:49:19 AM PDT by Cowman
I have a 2005 dodge truck with a 4.7 that has started running very rich to the point of choking out and it has a random cylinder misfire. The cruse was working intermittently and the dash lights would randomly go on and off. The mechanic changed a coil and cam sensor that did nothing but clean up a couple codes and suggested I change the ECM.
My question is: can I use a junkyard unit that I can change myself or does the new computer need to be reprogrammed for my vehicle by the dealer (I have heard both)
My father and I did the same to a ‘57 CJ5 when I was 15 years old. I’d gotten a job at 13, saved up money for a year, and bought the Jeep from a farmer when I was 14.
My dad and I stripped it down to the frame, repaired a bunch of rust, built a new wiring harness from scratch (most Dad’s work on that I must admit, but I learned a lot about electricity from assisting him), completely rebuilt the suspension and brakes, did a top end rebuild on the Chevy 283 that the farmer had crammed in the engine compartment, installed a Warn Overdrive unit (5.38:1 differentials are very highway un-friendly without one), and had it all back together by my 16th birthday.
I’ve probably owned 30-35 different vehicles since then, but that old Jeep is still on my Top 5 favorite list.
It’s not quite to that state yet.
Hi. I ‘ve had a little experience with a bad ecm but it was on a 2000 Ford mustang. They can be reprogrammed to work in your vehicle. I found a used one on eBay for 30 bucks. Mechanic charged me 75$ to reprogram. The reason I knew it was bad was that the codes said ecm not responding.
Then he said "The alternator light comes on at anything over idle, but it's dim. A couple of the mechanics thought there was a short somewhere but they couldn't find it."
We went out to the parking lot where I had him pop the hood and saw the alternator wiring had been stripped out of the harness. I pulled the connector, popped the spade lugs out of it with a pocket knife, reversed them in the connector, plugged it back in and suddenly everything worked perfectly.
If you want to change the computer, you have to ensure it is one programmed for your vehicle. Could be oxygen sensors or some other sensor, but the computer is the last resort. Go to Autozone or Pep Boys and buy/borrow a code reader, plug it in, get the codes and look them up yourself. It's a lot cheaper than starting to replace things willy nilly.
The hand held generic scan tool is a far cry from a proper laptop based system with live data. The free scan is worth what you paid.
Knowing nothing more than what you posted, I would suggest the simple and free procedure of disconnecting the negative then the positive battery cables on your battery. Clean the terminals on the battery well and also on the ends of the cables. Leave them off for about 10 minutes (the length of time needed to clean the terminals) and then reconnect the positive cable then the negative cable.
Test as necessary. It might work to reset things. It worked for me once on a Ford that was running rough and weird. And I have heard of others who have had success with this.
The downside is that you have to reprogram all your radio presets.
battery is a year old and the problem came on all at once so it sounds electrical to me. All the grounds are good and I went through the vacuum lines as well, there are no leaks.
I have had a gascap fault for some time that I didn’t pay much attention to because it was just a gascap — it’s gone now. What put me on the computer is that it is choking out AND has a random misfire AND has codes that don’t make sense (Knock sensor, evap, etc)
Now THAT’S the pistol I want. The magazine never gets emptied!
Had a '92 Jeep Cherokee XJ for a while. It would start and run intermittently. That is, it would run fine as long as it started, it just didn't always want to start. I went the computer and started reading up on causes. It boiled down to one of two things; the ECM or the Crank Position Sensor.
Well the CPS was all of $35 plus tax, and the ECM was over $100. I bought the cheaper part, and went home to replace it. I pulled the old one off, and it looked brand new (I had just bought the Jeep from my mother-in-law, and she'd had a bunch of sensors replaced trying to fix the problem). So, I put the old one back on, and took the new one back, having not installed it.
Then I ordered the ECM. Took all of five minutes to replace, and it ran great, and started every time. No issues.
On modern, fuel-injected vehicles, a loose gas cap can cause problems. Has something to due with pressure in the fuel tank and the evaporation control system (a tank that basically absorbs fuel vapor from the system to prevent it from leaking into the atmosphere). The loose cap prevents the evap system from operating correctly and sends a code. It can also cause the engine to run funny.
They have an employee, no forearms clause for in-store. He had the shotgun in his car and only entered the store with it to stop a robbery (he was returning from a break when he saw the robbery in progress). Those facts should have trumped the rule, but they seem to rather cater to criminals. If I ran the place I would have given the guy a raise and promotion.
I too only go there to purchase in a dire emergency (I avail myself of their free stuff)
I would do ^^this^^ before swag-ing out the ECM.
Winter rusted, corroded or broken electrical connections and dirty or worn out/broken sensors seem like better, cheaper guesses.
I love the thousand-yard stare that you get from the guys at Auto Zone when you ask for "breaker points".
From what I understand after paying the dealer to replace an ECM on my wife’s car some years ago...you can get a new ECM much cheaper at Autozone, Napa, etc.
This may not be your problem, but I’m posting it for the benefit of all.
We’ve had three vehicles either do odd things electrically or simply not start. All three issues were related to wood chucks chewing wires bare of insulation causing them to cross short.
I’m selling a car tomorrow where the cute little fellow chewed #2 oxygen sensor wire bare, it touched ground, and now the service engine lite stays on - the code is for the O2 sensor. Replacing the sensor & resetting the code did not make the service engine lite go off, it still codes for the sensor. Car runs great, gets over 40 mpg.
They will also get up under where gas tanks are and chew off fuel pump wires.
Another animal for my elimination list.
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The usual symptom is that the clutch in the automatic transmission will disengage and reengage every 10 or 15 seconds while cruise control is operating.
Yeah...
...No, at least not much Iately.....I buy most automotive parts/supplies online, unless I'm in a hurry. I suppose if the EMP ever does hit, I'll have a rough time buying online?
{That is, it would run fine as long as it started,}
Read the OP post again, that is not the case here. My advice is to not shotgun parts as your Mil did especially on someones DD (daily driver).
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