2005 QC Misfires????

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JPodesto

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Hello yall, I bought a 2005 QC with 73k miles recently. It was a deal that was too good to pass up on, but some things are too good to be true.

Anyways, Has a code p0351. I was hoping it was a simple coil pack replacement, but that didn't do the trick.

Had someone check the computer and they said that it needed to be fixed.

Sent the PCM to The Viper store and he checked it out and said yes it needed repair. He didn't quit tell me what was wrong with it. But..

Reinstalled computer in truck and it didnt fix the problem.

So i did a deeper dive into the harness etc... and there is no ground signal from the PCM on cylinder 6 and 1. Both have 12 volts but will not pulse. I checked continuity from the pcm injector pin to the injector on 6 and 1 and they check out OK.
I've checked the ground from the motor to the body and the body to the battery and there OK too. Checked to make sure the computer is grounding.

I'm currently changing out the camshaft sensor to eliminate that being an issue.

Does anybody have any idea why there is no signal from the PCM on 2 cylinders? Or is it still the PCM?

Thank you in advance.
 
JPodesto said:
Hello yall, I bought a 2005 QC with 73k miles recently. It was a deal that was too good to pass up on, but some things are too good to be true.

Anyways, Has a code p0351. I was hoping it was a simple coil pack replacement, but that didn't do the trick.

Had someone check the computer and they said that it needed to be fixed.

Sent the PCM to The Viper store and he checked it out and said yes it needed repair. He didn't quit tell me what was wrong with it. But..

Reinstalled computer in truck and it didnt fix the problem.

So i did a deeper dive into the harness etc... and there is no ground signal from the PCM on cylinder 6 and 1. Both have 12 volts but will not pulse. I checked continuity from the pcm injector pin to the injector on 6 and 1 and they check out OK.
I've checked the ground from the motor to the body and the body to the battery and there OK too. Checked to make sure the computer is grounding.

I'm currently changing out the camshaft sensor to eliminate that being an issue.

Does anybody have any idea why there is no signal from the PCM on 2 cylinders? Or is it still the PCM?

Thank you in advance.
Click to expand...
@rottenronnie May have suggestions maybe he will stop by
 
Spark plug maybe?


5D662D6A-F430-4A2B-8910-2296586FB3AE.jpeg
 
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Sound like you jumped into the heavey work at the start ... coil packs and plug wires routed under the intake manifold makes for a pain in the ass !
Then directly to the PCM ? Funny they didnt say what was wrong with it .. I would be raising hell .. Usually not cheap !

I had a misfire a few years ago on a long road trip ,, even sounded like a very light tappet noise ... cant remember the code from back then .. But turned out to be the back plug #10 cyl. on the passenger side . Codes can be deceptive and lead you to the wrong parts ..the codes led me to the #1 cylinder .. replced the plug and problem solved for a couple dollars ..
 
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Also read through this thread on the cam shaft position sensor installation

Camshaft sensor

Can anyone point me in the right direction to help me find a parts dealer that sells the Camshaft sensor for an 06 ram SRT 10? I've searched high and low at all my local parts stores and non of them carried the sensor. Thanks in advance.
www.vtcoa.com www.vtcoa.com
 
We’ve checked that it has spark at the plug wires.

The misfire is from injectors not firing. All of the rest of the injectors pulse correctly.

I changed the coil packs first for 2 reasons. One is the p0351 and the guy I bought the truck said that he thinks that was the problem.

And the camshaft sensor did not change anything.

Thanks guys. Keep the ideas coming please.
 
From what Ive read the crankshaft sensor and the camshaft sensor should be changed together with the same compatable brand . Factory replacements were preferred . Im not sure the Mopar sensors are avail. Any longer though !
 
JPodesto said:
We’ve checked that it has spark at the plug wires.

The misfire is from injectors not firing. All of the rest of the injectors pulse correctly.

I changed the coil packs first for 2 reasons. One is the p0351 and the guy I bought the truck said that he thinks that was the problem.

And the camshaft sensor did not change anything.

Thanks guys. Keep the ideas coming please.
Click to expand...
With changing out the coil packs and wires etc. , why not replace the Plugs ? The misfire I kentioned on mine was do to the plug gap misaligned on number ten yet still firing and only misfired at low rpm , gas mileage was down a lot but ran strong anyway ... when I pulled the plug and was hearing a slight ticking I was thinking something came in contact with the plug or worse .. after replacing that plug everything appeared normal which I came to the conclusion that many months before when I change the plugs that I bumped the electrode during the install of #10 .. MPG jumped back up , ticking gone and ran even stronger .. Something that small can cause problems which can also send info to the PCM to compensate and throw multiple codes for the ignition and fuel sensor system ..all from a couple dollar spark plug !
 
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Check the harness behind the #10 cylinder! It could have made contact with the manifold and damaged some wires. I have repaired several. Especially if the truck has higher miles.
 
Alright, still no luck. PCM is going back to The viper store, because i've exhausted all i can do.

Harness double checked for continuity and grounding. Ground wire from injector to pcm pin out checks OK.
Coils, plugs, wires all changed.
Grounds checked for engine and battery and I ran an extra ground to the pcm bolt to make sure it was grounded(just incase).
Camshaft sensor changed.

Still has no ground signal on the fuel injector to allow it to fire on cylinder 6 and cylinder 1.

All fingers point to PCM even though it was recently "refurbished" by the Viper store.

Any last ideas before I send the PCM back? Thanks guys / gals
 
JPodesto said:
Alright, still no luck. PCM is going back to The viper store, because i've exhausted all i can do.

Harness double checked for continuity and grounding. Ground wire from injector to pcm pin out checks OK.
Coils, plugs, wires all changed.
Grounds checked for engine and battery and I ran an extra ground to the pcm bolt to make sure it was grounded(just incase).
Camshaft sensor changed.

Still has no ground signal on the fuel injector to allow it to fire on cylinder 6 and cylinder 1.

All fingers point to PCM even though it was recently "refurbished" by the Viper store.

Any last ideas before I send the PCM back? Thanks guys / gals
Click to expand...
Fuses, relays ????
 
JPodesto said:
Alright, still no luck. PCM is going back to The viper store, because i've exhausted all i can do.

Harness double checked for continuity and grounding. Ground wire from injector to pcm pin out checks OK.
Coils, plugs, wires all changed.
Grounds checked for engine and battery and I ran an extra ground to the pcm bolt to make sure it was grounded(just incase).
Camshaft sensor changed.

Still has no ground signal on the fuel injector to allow it to fire on cylinder 6 and cylinder 1.

All fingers point to PCM even though it was recently "refurbished" by the Viper store.

Any last ideas before I send the PCM back? Thanks guys / gals
Click to expand...
What do #1 and #6 have in common that others may not have in conjunction with the wireing to and from the PCM .. Have you test those injectors themselves ?
 
I have checked all the fuses and I rotated the relays into different spots to see if any change, but no luck.

I didn't do a crankshaft sensor. I can try that down the line.

I have also moved injectors to other spots but the no pulse at the injector did not move. Still no signal to fire the injector at 6 and 1.

At this point the PCM has already been shipped back. We will see what happens.
 
A misfire code does not always indicate there is an issue with the ignition system. A misfire code is set when the computer detects a situation where there is an unexpected change in crankshaft speed.

With most engines, the crank sensor is the key component in determining a misfire. The PCM calculates the time between the edges of the crank reluctor wheel teeth by receiving a signal from the CKP sensor. The crankshaft rotational velocity and acceleration are compared in the event of a power loss from each cylinder.

When a power loss is less than the calibrated value, the suspected cylinder is determined to be misfiring by the PCM. The misfire detection is enabled after certain base information is received by the PCM. Typically, the engine coolant temperature, cylinder head temperature, intake air temperature and, if equipped, the mass air flow sensor (or a combination of these) are used to evaluate the condition as well as the crank and cam positions.

Misfires that turn on the check engine light and log a cylinder-specific fault code are the easiest to diagnose. The OBD II system will identify the cylinder(s) that are not contributing their normal dose of power and set a code that corresponds to the firing order. A P0303 code, for example, would tell you that the No. 3 cylinder is misfiring. To figure out which cylinder is No. 3, refer to a diagram of the engine’s firing order or look for markings on the intake manifold, spark plug wires or ignition coils (if the engine has a coil-on-plug ignition system).


When you have a misfire code for a particular cylinder, you can focus on one of three things: an ignition problem, a fuel injector problem or a compression problem.
 

WEAK FUEL INJECTOR​

A condition known as “lean misfire” can occur if there is not enough fuel in the combustion chamber. Lean misfire causes that only affect one cylinder include a dirty fuel injector, an open or shorted fuel injector, or a problem in the fuel injector driver circuit (wiring or PCM). Compression problems that may cause a misfire include a burned exhaust valve, bent intake or exhaust valve, or leaky head gasket.

LEAKING FUEL INJECTOR​

An individual cylinder with a rich fuel mixture is not as common as a lean mixture, but it can occur if the fuel injector leaks.


A more common condition would be a rich mixture in all cylinders caused by 1) a dead oxygen or coolant sensor that prevents the computer from going into a closed loop, or 2) a faulty fuel pressure regulator or plugged fuel return line that is routing too much pressure to the injectors.

Something else to look at in the spark burn line is the amount of “hash” it contains. A good cylinder will show a relatively clean line with little hash. A lot of hash, on the other hand, is a product of an ignition or lean misfire.
 
JPodesto said:
I have checked all the fuses and I rotated the relays into different spots to see if any change, but no luck.

I didn't do a crankshaft sensor. I can try that down the line.

I have also moved injectors to other spots but the no pulse at the injector did not move. Still no signal to fire the injector at 6 and 1.

At this point the PCM has already been shipped back. We will see what happens.
Click to expand...
The process of elimination does appear to be something in the circuitry from the PCM to the specific injectors 1 and 6 ... since you sent the PCM back to get checked , Yes we will see ... I would absolutley get answers as to what and why the problems are that they find ..
 
JPodesto said:
I have checked all the fuses and I rotated the relays into different spots to see if any change, but no luck.

I didn't do a crankshaft sensor. I can try that down the line.

I have also moved injectors to other spots but the no pulse at the injector did not move. Still no signal to fire the injector at 6 and 1.

At this point the PCM has already been shipped back. We will see what happens.
Click to expand...
What did they find on the PCM when you first sent it to them ? Did they do an exchange using another PCM and send it to you or just reprogram your original ?
Who did you send it to ?
 
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