Can a bad or faulty computer throw faulty codes?

[JMac101]

I have a 2001 dodge caravan 2.4 Liter 4 cylinder.
I keep getting this one code over and over even if I delete it, it returns.
Can a bad car computer or damaged computer throw faulty codes?
There are times the car runs extremely rough idle and times it runs smooth.
If I disconnect the computer for a little bit the code goes away for like 3 days and then returns.
What gives?
Could it be a faulty computer or bad wiring?

 

[willix]

A bad computer will usually set a code indicating a faulty computer. Many things can trigger specific codes that are related to a component/sensor but not the root cause of the code. Faulty wiring & connectors can be difficult to track down and more times than not the cause of specific codes in question.

 

[Texan4Life]

possible (I guess) but I would say highly unlikely

what is the code?

 

[Scienceman]

Originally Posted By: JMac101




How did you do that?

 

[Scienceman]

It dont look like a plus sign..

+

 

[bkbenjy]

Deleting the code removes it from the computers memory. As soon as the problem happens again it will store that code again. Deleting the code does not eliminate the problem.

What is the code?

 

[hounddog]

Usually bad computers set numerous codes that check out to be erroneous and or vehicle won't run or runs really bad.One code over and over means you haven't fixed the problem of that ONE code.Clear it all you want until its FIXED it will reset.

 

[willix]

You have an active reoccuring code. It is current and a fault code is stored unless you erase it again. Why don't you find out what code it is and deal with it and don't assume the ECU is faulty right off. ECU/PCM what ever you call them actually don't have many problems and are very reliable. Check engine lamps don't just indicate without a problem Do you have a Code number? Go to Advance or Autozone where they will plug you in and give you some numbers. I don't think you can read codes on a Chrysler without a code reader.

 

[mechtech2]

Why hide the code from us?
Don't you think that is important?

 

[JMac101]

P0304 code misfire cylinder 4.
Checked engine spark and have spark in all four cylinders.
Checked compression and i have 180 psi in all four cylinders.
Plugs, wires, coil pack, injectors, injector wiring harness, fuel rail, throttle position sensor and egr have all been replacement within the last six months.
I still have the P0304 code, so to answer your question I have tried all the other stuff first before automatically blaming the computer. Im at a standstill and was asking about the computer out of curiousity.

 

[JMac101]

i noticed that if i scan my codes and erase them they return. If I unplug the computer and plug it back in the code goes away for 3 days.

 

[willix]

A miss fire is a relativly simple thing. A plug, wire, distributor or coil. Does it have a distibutor or coil pack? Maybe it time for new plugs & wires.

 

[chrome]

You may have a vacuum leak that affects only cylinder #4. Check along the intake manifold runner, check the gaskets, any vacuum lines etc.

 

[Vikas]

OP has been asking this question every day for last 15 days Somebody needs to give him the answer that will make him happy. I will be that person.

YES, faulty computer will throw faulty codes; just go ahead and buy new computer. I know that is what you really want to do.

I give you my permission to buy new computer if that is what is needed for you to NOT start yet another topic asking the same question.

-

- Vikas

 

[OilNerd]

Originally Posted By: hounddog
Usually bad computers set numerous codes that check out to be erroneous and or vehicle won't run or runs really bad.


Yup, that was my experience with a my last computer failure.

 

[mechtech2]

OK.
Checking a spark when cranking only shows that something is not totally broken.
Under load, humidity, or heat, ignition components can fail.
But you did replace a bunch of parts!
Can you clear the codes, swap injectors and see if the code switches cyls?
It is possible that an injector driver n the computer is bad.
Any chance you could get a boneyard computer for cheap to test or fix it?
Having your present computer tested is expensive, and not 100% accurate.
all the best!

 

[Texan4Life]

I would bet money on an intermittent coil pack. replace the coil pack for that cylinder. I have seen it before with our 97 caravan 3.3L

you can also take of the ignition control module and have a parts store test it.

 

[JMac101]

mechtech I tried swapping injectors and no go on the misfire moving. The junk yards around here are expensive but they have refurbished and upgraded comps on ebay for around $150.

 

[dishdude]

Originally Posted By: JMac101
deleted post that got member on "vacation"


Relax, I am sure he was joking. I actually got a chuckle out of his post since I was thinking the same thing.

 

[Vikas]

Getting serious for a second.

The computer connection to individual cylinder is by the coil and injector. Crankshaft and CAM sensor allows the computer to time the spark and the injector pulse.

The computer detects misfire when it notices that a particular instance of plug firing did not increase in the momentary speed of the engine.

The computer has no other input or output to a specific cylinder. If the computer is giving you misfire code on that specific cylinder, then there is something funny about that cylinder and NOT the computer. Specifically, the computer does NOT have dedicated sensor to each cylinder to monitor misfire. Misfire is inferred by computer. In majority of the cases, computer is not sure which specific cylinder and then it throws random misfire code. But in few cases, it is sure which cylinder is not firing correctly and then it will throw the specific cylinder misfire code. Is your check engine light blinking? Did it blink before it went steady?

For example, it is possible that there is EGR blockage and because of the geometry, this cylinder is the most affected one. Also may be there is a small leak near that specific cylinder or the valves need adjustment.

I know that on Honda V6 EGR and/or valve adjustment finally fixed the misfire code after the person changed lots and lots of parts. Here is an extract from the Honda service manual, obviously it may not be directly applicable to you but should at least should give some help. Please excuse the formatting.

Random misfire only
at low RPMand
under load
Check fuel pressure (see page 11-216). Low compression.
Low quality fuel.
Correct EGR valve
function.
Random misfire only
during acceleration
Check fuel pressure (see page 11-216). Malfunction in the
VTEC system (see
page 6-12).
Random misfire at
high RPM and load,
or under random
conditions
Check fuel pressure (see page 11-216). Correct valve
clearance

Bottomline:- A bad computer will make your car undriveable; it will not give you P0305 code.

However, you should definitely try to take the computer out and put it back again. This will clear some of the connections if that is what is causing the problem.

- Vikas