2004 Dodge Ram Hemi 5.7- p0172 and p0175

[Johnny Appleseed]

I got a 2004 Dodge Ram Hemi 5.7 from my brother. It has 250k miles on it. He said the motor had been rebuilt but it still wasn't running. I fixed a few bad sensor codes. I decided to change the fuel injectors on it with some OEM ebay ones. Now that I think back on it I shouldn't have done this. I am left with these two codes- p0175 and p0172. Running rich on both banks. I am a broke college student and I'm trying to figure this out if I can to get the truck running. I have been reading up on this forum on other similar cases. I have carried out a compression test and got around 150-160 on all cylinders. I also plugged in a Vacuum gauge and had a constant 19 inHg reading. Plugging in a simple harbor freight scanner I see that I am running -15 through -25 STFT and eventually -32 LTFT. I don't want to take anything apart that I don't have to if I can diagnose it before breaking it open. Does anyone have any suggestion for this?

 

[Bloody_Knuckles]

https://www.engine-light-help.com/oxygen-sensor-codes.html

 

[Fast69Mopar]

I got a 2004 Dodge Ram Hemi 5.7 from my brother. It has 250k miles on it. He said the motor had been rebuilt but it still wasn't running. I fixed a few bad sensor codes. I decided to change the fuel injectors on it with some OEM ebay ones. Now that I think back on it I shouldn't have done this. I am left with these two codes- p0175 and p0172. Running rich on both banks. I am a broke college student and I'm trying to figure this out if I can to get the truck running. I have been reading up on this forum on other similar cases. I have carried out a compression test and got around 150-160 on all cylinders. I also plugged in a Vacuum gauge and had a constant 19 inHg reading. Plugging in a simple harbor freight scanner I see that I am running -15 through -25 STFT and eventually -32 LTFT. I don't want to take anything apart that I don't have to if I can diagnose it before breaking it open. Does anyone have any suggestion for this?

Since you installed the eBay fuel injectors, have you looked at the injector pulse width?

Also, you can OHM check the fuel injectors and compare them to the old ones you pulled out.

If you can see the STFT & LTFT with the cheap scan tool, can you see what the MAP Sensor shows for engine vacuum?

Does it match what the mechanical vacuum gauge shows?

If your MAP Sensor readings are low at idle then the PCM thinks the engine is under a load and is adding more fuel causing the rich condition.

What does the scan tool show for Barometric Pressure?

Have you determined that you do not have a large vacuum leak?

Check the intake manifold o-rings (gaskets), throttle body o-ring, brake booster vacuum hose, cracked intake manifold, EGR o-ring torn or missing or EGR tube not pressed into the intake manifold all the way, etc...

 

[HemiLonestar]

Which injectors did you put in? Did you just do a general search for 5.7 hemi and get the cheapest ones that came up (can you post a link to the auction)? Sounds to me like you ended up with 5.7 injectors, but for an eagle 5.7 (uses the same injector as a 6.1). Your stock tune isn't setup for this injector and it would give you the exact codes you're getting.

 

[Johnny Appleseed]

As far a vacuum leaks, I performed a smoke test similar to this one . I didn't find any smoke leaking out any where. The MAP presure was set at 11 inHg and gauge read 19 inHg. I read that this was a good reading to have since the MAP reading is the atmospheric pressure (around 29 inHg) minus the vacuum being created (19inHg read in the gauge). Not being to smart I lost track of the old injectors. I will go ahead and take an OHM reading of the injectors later today when I get home.

How can I get the injector pulse width? I've googled this but found no clear answer.
.

This is the link to the ebay injectors I bought:
https://www.ebay.com/itm/SIEMENS-OE...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

What do you guys think? Thanks for all your help!

 

[Fast69Mopar]

If your MAP Sensor shoes 11"hg that is a problem. That is why it is pouring the fuel to the motor. The 02 sensors are normally not the cause of a rich condition. The oxygen sensors are the story tellers.

Disconnect the MAP Sensor and see how it runs. I suspect that your MAP Sensor has failed.

If the MAP Sensor is showing a lower data reading than the mechanical gauge then we need to look at it.

 

[HemiLonestar]

This is the link to the ebay injectors I bought:
https://www.ebay.com/itm/SIEMENS-OEM-FUEL-INJECTORS-8X-for-2004-09-Dodge-Ram-1500-2500-3500-Durango-5-7L/173627282610?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

Good, that rules that out

 

[Johnny Appleseed]

I thought I read somewhere that the MAP reading was only the difference between atmospheric pressure and the gauge pressure. If so then that means my MAP sensor reading is within working conditions? Or is this completely wrong?

 

[Fast69Mopar]

That is completely wrong. With Chrysler's programming and the speed density system, our PCM shows acutal MAP vacuum. If your MAP Sensor shows 11" hg then there are one or two different things happening. The sensor has failed and is stuck at one voltage or shorted internally and providing the wrong signal to the PCM. The MAP vacuum should match your external vacuum gauge.

When the engine is running MAP vacuum is high assuming the engine is in normal running order I.E. no mechanical issues. When the engine is under a load like during acceleration the MAP vacuum is low. The PCM sees this and starts adding the proper amount of fuel. The oxygen sensors are just the story tellers here, not the problem.

What is the MAP voltage with the key on, engine off?

What is the MAP reading on the scan tool with the key on, engine off?

On my 2004 Dodge Ram 1500 QC 5.7/545RFE truck, my MAP vacuum with the key on, engine off is 0.0" hg. It is a 3-wire sensor that has a 5V supply, signal and ground.

The 5V supply is tied into the Intake Air Temp sensor, A/C Pressure Transducer, Engine Coolant Temp Sensor, EGR Solenoid, Camshaft Position Sensor etc.

The 5V Supply for the MAP Sensor is shared from a splice with the Camshaft Position Sensor at Splice S154.

If you do not have 5 volts on the circuit then I would unplug all of the engine sensors and monitor the 5V supply from the PCM. Start by plugging in the MAP sensor and watch the voltage. Does it drop?

Next, continue plugging in each sensor and monitor the 5V supply and see if it falls after plugging in a particular sensor. This will at least let us know the PCM's 5V supply is stable and that another sensor is not pulling the 5V supply down.

 

[Johnny Appleseed]

At Key on Engine Off the map sensor signal is 30 inHg. At idle it is 12inHg. I will upload a video of this. Is this maybe a bad or wrong sensor?

 

[Johnny Appleseed]

This is the screen with key on engine off, on my code reader scanner.

 

[Johnny Appleseed]

Is there any information I can learn from this? Thank you.

 

[Fast69Mopar]

At Key on Engine Off the map sensor signal is 30 inHg. At idle it is 12inHg. I will upload a video of this. Is this maybe a bad or wrong sensor?

I was unable to watch the video. YouTube says its a private video. No worries.

If the mechanical vacuum gauge shows 19"hg with the engine at idle and the MAP Sensor shows 12"hg at idle then the sensor is providing the wrong data and it will cause the engine to run really rich. If you have a solid, stable 5V supply and a good ground at the MAP Sensor then I would consider the MAP Sensor to be suspect. Its a cheap part. Grab a new MAP Sensor from your local parts house and be done.

Mopar 56041018AC average price around $65.00

Oreilly Auto Parts $30.99
Standard Ignition
Part #:AS217
Line:STD

 

[Johnny Appleseed]

Hey Fast69Mopar. I went ahead and bought that specific map sensor at oreilly's. However the readings were the same. It might be my scanner that reads these values. Thanks for the idea though.

 

[Fast69Mopar]

Hey Fast69Mopar. I went ahead and bought that specific map sensor at oreilly's. However the readings were the same. It might be my scanner that reads these values. Thanks for the idea though.

If the scan tool shows the same vacuum, let's do an OHM check on both sensors to see if they give the exact reading.

Also, can you measure the signal voltage with the engine running? I have a chart that I can compare volts/vacuum to. That way I can see if the voltage matches the actual vacuum reading.

 

[Johnny Appleseed]

Hey sorry for the late reply. I’ve been busy with work and haven’t had much time to check it out.
I checked the voltage going to the sensor, it’s 5 volts.
At key on engine off the sensor signal is 4.5 volts. At idle the signal is 1.7 v. How does this sound?

 

[Johnny Appleseed]

I also took ohm readings of my current injectors. They vary from 12.9 ohm to 13.8 ohm. Is this ok?