2002 Dodge Dakota:Confessions of a analogue guy in a digital world parts changer

Hello ALL. I am at my wits end. Fortunately I have had the pleasure of attending the DIY on line school of Scannerdanner videos for about nine months now.
I have a 2002 Dodge Dakota Four Door 2 wheel drive with the 4.7 liter single overhead cam engine. Direct Fuel Injection DFI with coil on plug COP and The Power Control Module PCM . It has 195,926 miles. Until this all started, I have enjoyed flawless performance and really enjoyed the ride, performance and silent comfort of this truck. The problems began with no warning oddly after a refueling stop while on the road. The engine developed a misfire and my troubles began. Codes included P0203, P0306, P0308 and these varied with time. Then P1391 cam crank crk code. So here is what I have changed so far not in sequential order.
Had the computer checked and re programmed as per VIN# because it indicated it had a checksum problem.
OEM: Plugs, Cam Sensor, Crank sensor,
Cam and Crank connectors, Soldered in.
Rebuilt Fuel Injectors 8 each.
Coil on Plugs 8 each
Crank Sensor CkS
Map Sensor MAP
Idle Air Control IAC
Cleaned port and flap of intake on the throttle body.
Checked compression from 130 psi on 2 cylinders separate banks and 150 average on other.
Fuel pressure 145
Some improved the performance, but still had the minute misfire.
Finally decide that the computer was trying to compensate for loose cam counts.
Installed new cam kit:
New gears, new chains, new nylon guides and tensioners.
new gasket set including new valve cover gaskets. Noted on issues with any of the valve lifters etc.
Installed new thermostat and water pump
installed new spring loaded belt tensioner.
Now I no longer have any of the codes related to the cam sync.

This engine has never had any issue with long starts. It starts instantly and idles at 600 rpm unless the ac is on and increases properly then.
On initial start up after install for the gear sets, the vehicle idled perfectly for about an hour. Then it began to have just a minor glitch in the rpm. The glitch is now regular when idling. There are misses on an irregular basis, The engine runs quite strong at road speed, but as soon as there is decrease in RPM the miss is obvious. It is as though for just an instant the ignition key has been ever so quickly turn of and the fuel is about to stop. I have scanned with a Creader VIII+ and get these codes. P0203, P0206, injector open circuit P0302 coil misfire. It began with the P0203 initially and my last run it added the ignition.

I desperately need to have a more complex scan tool to look at the system with the square wave graphics, and freeze frame. In my town of Lavonia, Georgia there are a couple of mechanics who have the tool, but do not have the expertise to know how to decode the problem one sees on the screen.

My last try to trouble shoot the #3 injector included the Danner technique of using the test light connected to the positive lead on the battery and probing the # 3 injector lead. I have a pulsating light, but it varies in brightness. When I reattached the lead, I could feel the injector pulsating.

So now I have another injector on P0206. And the plug on P0302 cylinder.

Question: How much drop in the fuel pump pressure would create any of these codes, if any. The fuel pump is about the only thing I have not replaced.

I know this is quite involved, but would appreciate any suggestion you may be able to offer.
Buoyantly Professor Bob

Mask ON! Spock 'Live Long and Prosper'..High Sign! UP

You said the issue started after a fuel up.
Was this a station you regularly use?
Could you have filled with E85?
We don't have ethanol where I live, I'm not sure if you do or not.
This video shows how to check for alcohol in gasoline:


The misfires at idle but not under load could indicate a valve sealing issue. A vacuum gauge on the intake manifold should hold steady at idle. A dipping needle on the gauge that coincides with the "glitch" you describe would point to a mechanical issue.
It's a cheap, simple test that can save you a bunch of wasted time and money.

While the p0203 and p0206 codes indicate a circuit fault with the number 3 and 6 injectors, the p0302 is just reporting a misfire on the number 2 cylinder. It doesn't necessarily mean there's an ignition fault on the number 2 cylinder. Anything that can cause a misfire on that cylinder can set that code.

You stated that 2 cylinders had sightly lower compression than the others. Knowing which ones were low could help determine what direction to go.
To answer your question, I wouldn't expect low fuel pressure to set injector circuit codes.

After the vacuum test, I would focus my efforts on the fuel system for the time being based on the recurring p020x codes.
Key on engine off fuel pressure should hold fairly steady. (You said 145 psi???)
A drop in pressure over time is normal, but a rapid drop in pressure could point to an injector hanging open.
That is another quick, cheap test.

The power feed to the injectors is shared and comes from the ASD relay.
To rule out a power feed problem, I would clear the codes and monitor voltage on the power feed of the number 6 injector (since that's the one that seems to code most repeatedly) with the engine running.
A scope or graphing meter would be ideal, but a meter would be better than nothing.
Using the min/max function might be helpful to catch an intermittent drop in voltage.
This is very good video showing how to check the injector circuit with just basic tools


If the p0206 comes back while you're testing but there is not a noticable loss of voltage, you can try to Ohm the injector right after the fault sets.
Injectors can fail when hot and come back to life when cooled down.


Hope that some of this helps you out.

Noah, These are great suggestions. I do notice that on cold start up the engine seem to be quite smooth and these glitches seem to increase as the engine warms up and the longer it runs.

Thanks for your rapid reply. I will report back as soon as I can make these tests.
Now on to. s.
Have an issue with a sudden stoppage of my RV 1992 Ford E350 with 7L gas engine. Will post separately to avoid mixed messges
Buoyantly
Professor Bob.

Just a follow up on your questions: No E85 fuel added.
The vehicle has had non ethanol fuel added then the last tank was regular 10 % ethanol plus I added B12 fuel treatment.
Have just received a bio scope for my cell phone and plan on removing all the spark plugs and the injector and have a look inside the cylinders. Also plan on following Danner's case study of checking for the open circuit back to the computer. I would like to locate a pin out diagram of the dodge JTEC computer It is the one with three harness plugs. This would make sure that I backprobe the proper pin out for the #3 and the #6 injectors.

All the injectors will have 2 wires. One will be the same wire common to all of them. That's the power feed.
The other wire will be unique to each injector.
That's the control wire.
No diagram required

Have been away working on my 460 FORD Cuttaway RV.

Have the Dakota back together. Still have misfired codes.. P0302 on cylinder 2. And P0203, P0206. wnen the truck is first started it has no issues and responds very smmothly.

After several minutes, as it reaches operating temperature, the glitch will come at random moment. Especially when transitioning from road speed into the idle range. The truck has a very slight momentary skip. However, while in park at idle, there are moments, it is as though the vehicle key has been turn of as the truck for a split second acts as though it is about to stop, but continues.
I am wondering if contamination in the fuel could cause these symptoms. IF debris is in the bottom of the tank and were pulled up to the fuel rail as when going over rough road, what decrease in fuel pressure would cause the injector to miss fire? The bottle of B-12 fuel treatment seems to improve the condition. If I use a test light to trace out the codes provided and know that each injector has two wires. Signal and positive feed. What voltage should the signal wire from the computer provide. Also, , how can I also check the spark plug coil. with the test light.

My first thought here, is the cam/crank code. If you’re not in time... well, nothing else matters until your in time. Also, if the misfire happens to be from a reluctor wheel problem such as a bent or missing tooth the codes could be related though I’d expect a random misfire and not

Professorbob wrote: The vehicle has had non ethanol fuel added then the last tank was regular 10 % ethanol

Since you were running E0 water could have been building up in the tank without you noticing. Then add the E10 and the ethanol combines with the water. And if there was enough water the ethanol/water blend will drop out of the gas and settle at the bottom of the tank, just like it does in a jar when you do an ethanol content test.

For more info on this scroll down to "Problems with the transition to E10 fuel" at the link.

www.westmarine.com/WestAdvisor/Busting-Ethanol-Fuel-Myths

My suspicion immediately went to compeditive contaminated fuel at the start of the thread when a fuel stop was mentioned, if it is free water problem rather than an alcohol content issue you could try adding a dry fuel additive I have used with success in diesels but it works with gasoline just as well.