Hello I'm hoping someone can help me with this issue.

I was driving my 1999 Ram 1500 5.9L to work a week ago and the idle got super rough.

The first code I got was P0308 Cylinder 8 Misfire so I replaced:
-Spark Plugs
-Spark Plug Wires
-Distributor Cap and Rotor

And still got the P0308 Code so a friend of mine said replace the fuel injector and so I did and that code went away.

Then I got a P0203 Code and I replaced that injector but the code wouldn't go away so I:
-Check the voltage when the truck was running and it was over 13v (Injector Harness)
-Tested the fuel pressure and it was 45 PSI during idle (Good pressure is 49 or 50 but can be as low as 44)
-Replaced the ECM

And still got the P0203 Code and so after reading many threads I found a person who had that code and replaced the IAC and his P0203 went away. That seemed odd at first but when I looked at the wiring harness I notice that the IAC wiring passed through that area. So I replaced the IAC and there was significant improvement but the truck is still running really rough and can barely go 30 MPH and dies a lot.

After replacing the IAC it took a LONG TIME to get another error code and when I got one it was P0500 for Faulty Speed Sensor for the ABS.

After doing some reading it was suggested that you take the truck for a test drive before determining that it is really a P0500 issue. So I took the truck for a test drive and it stalled many times and I could only go 30 MPH max and pissed off a lot of people behind me

Then I got another code on top of the P0500 ... the new code was P0206!!!!

My engine is running like total crap and I'm getting a lot of Codes so I'm wondering what could cause this problem? Do I have a MAJOR short somewhere? Thank you for taking the time to read my problem.

 

Check all the grounds on the engine, also make sure battery connections are clean, and tight. Check/clean all connections from the Alternator, to the PDC. Verify fuses for ECM. Reseat ASD, and Fuel pump relays.

If you still have issues, unplug the front O2 sensor, go for a drive. If it runs better, replace the sensor.

If it doesn't, physically remove the O2 sensor from the exhaust. (front O2) Go for a drive. See how it acts.

For the P0206, just swap injectors on 6 and 8, see if the code moves.

 

I have been tracking down all the ground wires and found a bad ground from the alternator to the fuse box and replaced it. The ground terminal bolt was stripping out and the ground wires connecting to the Negative part of the battery were corroding so I cut and stripped the wires and made them like new. There are a few more ground wires I can check still near the firewall.

I replaced the ASD and Fuel Pump relays.

The truck is now giving the code P0203 again.

I will test the O2 sensors tomorrow.

Anything else I should try? The truck is still running so bad. Could this be an exhaust problem? The truck doesn't die during idle but has a REALLY rough idle.

 

Find a mouse nest by any chance? That is sure what it acts like, with random electrical issues.......

Try the O2 sensors tests. See what happens.

 

It is funny that you talk about a mouse nest because that happened to my wife ... a mouse got into her air intake and made a nest in the air filter. That happened last year sometime

OK so I swapped out the fuel injector with another one thinking maybe I was given a bad injector. I got the same code P0203 and did not expect that to happen.

At that point I thought there is definitely a problem with the wiring. So I started digging into the wiring harness and I found a really bad rig job with the wiring someone took all 4 injector wires and spliced them together.

The question is how in the hell did this go unnoticed by the computer for 2 years and then give me the trouble code? I got that code before I changed the computer out.

 

Probably, as far as the computer was concerned, things were working as advertised, if it ran a little rich, the computer would shorten injector pulse, which would end up making the other bank run lean.... it would all average out, but, not really good for the motor.

Get that straightened out, and see what happens.

 

OK here is the update:

After tearing apart the wiring I'm more confused than ever.

One side of the fuel injectors are spliced together and then a wire goes to the other side of the engine and combines with a splice that includes all 4 wires on the other side. Then the other wire goes to the fuse box. After all the wires are spliced for the fuel injectors there is one wire going to the computer.

OK so if you are confused ... one wire comes from the fuse box and one wire comes from the computer and those two wires are spliced together with ALL the fuel injector wires.

All the wires that I'm talking about are green with an orange stripe. Is it possible that they all act like the ground wires?

Are the black, white and yellow wires the power wires? So each injector has two wires all injectors have a green wire and then another wire (2 wires per injector) but the colors of the second wire very.

 

The wire with the same colors that shows up at each injector is the power feed, that should be coming from the PDC, the individually colored wires, should go to individual cavities in the PCM connectors. PCM controls the ground side of the circuit, so, they have a common power source, but, individual grounds.

So, green with orange stripe should be power feed TO the injectors.

 

The truck had zero compression in two cylinders and I need the heads redone. One of the cylinders is #3 so that is why I was getting the P0203 code.

 

Don't bother doing anything with the stock heads, just replace them. They were poor castings when they were new, and there are better alternatives available for not too much money.