[Fixed] 2003 Dodge Ram 1500 4.7L V8 - need help deciphering scanner data

Thanks everyone for your great forum. Lots of good stuff here so thank you all!

I apologize for the length of this post. I just want to give as much information as I can. Thank you very much for your help and time.

Vehicle: 2003 Dodge Ram 1500 4.7L V8 2WD A/T
Emissions: California Compliant Emissions
Miles: 265,000 <--- not a typo
Scanner Used: Zurich ZR8

I recently acquired the truck. When I got it it had a P0420. Since I got the truck dirt cheap I didn't even look at it. I just bought a new direct fit exhaust system from Magnaflow that contained all three cats. I took all four of the old O2 sensors out, cleaned them up, and re used them. I figured if the code returned I would replace the O2 sensors then. I also did all the normal maintenance one would do when they get a vehicle with an unknown maintenance record. When I was done the truck ran perfectly, P0420 was gone, it passed emissions and I got my license plate tags.

About 500 miles later, the passenger side cat (bank 2) was completely burned up! The driver side cat (bank 1) and the third cat before the muffler were fine. There was no signs that anything was wrong at all! I never got any service lights. No codes. No misfires. No obvious vacuum leaks. No fuel mileage drop. No engine coolant loss. Nothing at all! The truck ran perfect the entire time!

Luckily the exhaust system was warrantied so I replaced the whole system again. Within a few days the bank 2 side pipe and cat turned that purple and blue color that metal does when it gets extremely hot. The bank 1 side looked normal. My concern is probably obvious. Something is obviously getting bank 2's cat very hot again and I need to find out what it is and fix it before the same thing happens again. Still no codes, no light and nothing obvious that would cause this type of failure. Since I didn't own a scanner I checked the external temperatures using a laser thermometer and bank 2 was getting around 400 F. while bank 1 was about 290 F. (I can't recall the exact temps. Just bank 2 was significantly hotter) I went ahead now and replaced all four O2 sensors. I took the truck to a local garage and the manager hooked up a cheap looking scanner and within 1 minute told me everything looked good! It's in closed loop, fuel trims looked good, I had nothing to worry about. I wasn't very confident in this 1 minute diagnosis so I took the truck to another shop for another look.

The first thing the second shop did was check the cats temps externally with a laser like I already had done and agreed bank 2 appeared to have a problem again. They hooked up a Snap On scanner and after about 30 minutes I overhear them saying they couldn't see bank 2 in their scanner. They were only getting information about one cat. They then said they had the scanner "set right for federal emissions." I quickly let them know it was not federal emissions, it was California emissions! A few minutes later they said everything looked fine to them. They said the Intake Air Temperature looked too high for the temperature that day and suggested to replace the IAT sensor. So I did. They also said they didn't see the O2 sensors switching like normal but that was normal for Dodges. Dodges O2 sensors didn't switch like all others do. They just sit there at one level. Right then I knew I was dealing with another bone head!

Here is what I have done so far.

1. Checked external temperatures of the cats with a laser thermometer and find bank 2 much hotter than bank 1. There is a big visual difference with the two sides as well. Bank 2's pipes and cat is excessive heat colored while the bank 1 side is not.


2. Bought and Replaced all four O2 sensors. Since replacing all four O2 sensors two shops have hooked it up to a scanner said everything looks good. As I explained already though, I'm not sold on their competencies.


3. When I first got the truck I replaced all spark plugs with recommended OEM Champion Copper Plus spark plugs. The original plugs looked worn but presented nothing out of the ordinary. When the bank 2 cat burned up after only 500 miles I pulled all the plugs for inspection. All plugs had a perfect burn pattern indicating all were burning at the perfect recommended temperature. No wet plugs indicating excessive un burned fuel. No signs of coolant entering any cylinders. All looked normal. At less than $3 per plug I replaced them all again anyway.


4. Coolant level is good. None missing which indicates no coolant is entering the exhaust somewhere.


5. Injectors. I thought if I had an injector(s) bad, stuck or leaking that could cause this. So I pulled all the injectors. I couldn't afford to replace them at this point so cleaned them all up and reinstalled them. Except I flipped sides with them all. I put bank 1 injectors into bank 2 cylinders and put bank 2 injectors into bank 1 cylinders. My thinking was if one of bank 2 injectors was faulty and the culprit then I should see the problem follow to bank 1 now. I haven't noticed anything change yet.


6. Replaced the Intake Air Temperature sensor as suggested by the second shop I took it too to be put on the scanner. Nothing changed.


7. I found and fixed a minor vacuum leak but don't think it would have any bearing on this issue since it was to my speed control servo. I have searched extensively for other leaks but can not locate nor hear any other leaks.


8. Replaced the PCV valve


9. Changed the oil and did not smell any excessive gas smell.

This brings us to today. Now, it is possible that there is no remaining issue but I want to try and be sure before it burns out another cat. Since I did not received any light or codes for the first replacement cat that burned up in 500 miles I am highly concerned it will do it again. I know the service light works because I have seen it in other situations un related and can activate it myself anytime. So I bought a cheap Zurich ZR8 scanner. I took video of the scanners screen and could really use the opinion of someone that knows more than me. I did three tests. One at idle one at 1500 RPM's and one at 2500 RPM's. The temperature outside at the time of these scans was about 75 F. I am new to the scanner so I need some help. To me the O2 sensors seem to be working good and the fuel trims look OK but might be a bit high for bank 2 but I'm not sure. The truck does have 265,000 miles on it. I have read that the higher the mileage is the fuel trims will tend to be a bit higher.

Anyway, if someone could please take a look at the videos and let me know what you think. If you need me to do anything else to better server your diagnosis please let me know. I really need a piece of mind that everything is in order and another cat failure is not likely or find and fix any remaining issue to avoid another failure.

At Idle 600 rpm -

At 1500 rpm -

At 2500 rpm -

Again, I apologize for the length of this post. I just wanted to give as much information as I could. Thank you very much for your help and time.

Koda

Hey Koda,
This video has some great tips on checking the converters function with some excerpts from the book:

I've seen some Dodge Ram trucks of that age with only 2 oxygen sensors, I'm wondering if there shop who checked it for you had it identified wrong and could only view one bank, but that's just a guess.
I've also seen those aftermarket converters get some heat discoloration without any obvious problems or codes. The operative word being Some.
Judging by the data I could see, the cat function seemed fine during the time of your in the second video, although your bank 2 long term term trim is pressing the edge of acceptable in the last two videos (around -10% I think I saw).

Hello,

Lets look at data

@ idle

LTFT 1 = 4.7%
LTFT 2= 8.6%
C. LD = 4.3%
MAP = 9 inHg
IAT = 133

S1 O2's appear switching OK
S2 O2's trend rich

@2500 RPM

LTFT 1= 7.6%
LTFT 2= 10.0%
C. LD = 16.5%
MAP = 7 inHG
IAT = 135

S1 O2's appear switching OK
S2 O2's trend LEAN

---

SInce LFTS don't improve at higher RPM, I would conclude you are not chasing a Vacuum Leak.

After watching the all of the O2 voltages, I believe they are telling the truth. ( I would still try to enrich the mixture with propane, to see if LTFT's improve, and create a lean condition to see if they worsen.) This would help identify a False Lean Condition.

The PCM is currently within its limits to manage Air/Fuel.

At idle its adding a total of 13.3% more fuel, at 2500 its adding 17% more fuel( which is about 8% away from setting a P0171/74) So this problem worsens as motor accelerates.

Overall picture is that the PCM is adding more fuel in all ranges, but more so on Bank 2.

So we are looking for an overall problem and a bank specific problem I would believe.

The MAP at idle seems very low, and only drops 2 inHG at 2500RPM.( MAP should be high at idle, low at high RPM)
The MAP would lead to the very Low Engine Load Calculation, which should be higher at idle 15-20 and even higher at 2500RPM.

The overall problem would be the first I address.

I would be concerned with the MAP reading and fuel delivery for the overall problem at first glance.

Fuel Delivery (WOT test)

This can be accomplished with the scanner you have. We want to look at the voltages of B1S1 and B2S1 oxygen sensors at wide open throttle( which by the way should change your fuel control from CL Closed Loop to OL Open Loop)

Take warmed up vehicle for a test drive in a safe area, put transmission in low range, full throttle as much as you can, what we want to see is both S1 sensors pegging rich(0.8volts or better), and Open Loop. IF they do , fuel delivery is adequate.

However, if they stay pegged lean(under 0.3 volts) you have a fuel delivery problem.( Pressure, restriction, pump issues)

If you don't have a fuel delivery problem and its verified the O2 sensors aren't lying(adding propane or creating a lean condition), I would be going after the Functionality of the MAP sensor.

In general I would do the WOT test next and further diagnose from there!

Paul

Thank you very much for taking the time to read my lengthy thread and respond with such great information. I will follow your advise and do the WOT test next. We are experiencing rainy conditions this weekend in Phoenix so I will get it done as soon as I can and update this thread with the finding.

Thank you both, Noah and Weycraze for your help! I am completely at a loss when it comes to this stuff. It's awesome to have a place like here that we can come to and ask for help and get help like you gave me here! My hat is off to you guys! Thank you!

Koda

This morning I followed Weycraze's advice and warmed the truck up to normal operating temperature. I went to the mall parking lot. I put the truck in "Low 1" and floored it as long as I could. I did the WOT test twice. The videos are not viewable because I couldn't keep the scanner in frame but here are two screen shots of the results.

WOT test #1


WOT test #2


I went ahead and replaced the MAP Sensor because it was cheap enough. I re-scanned the truck again after the WOT test and installing the MAP sensor. Here are those results.

At Idle post MAP Sensor replacement:


1500 RPM Post MAP Sensor replacement:


2500 RPM Post MAP Sensor replacement:


I will wait for your advice on what steps to take next. I'm guessing here because I am still trying to learn how to diagnose using the scanner, but I think everything looks good? Except, the 1500 RMP post MAP sensor LTFT B2 still look high? The Idle and 2500 RPM look good though?

Please advise with your suggestions and as always I appreciate your help more than I can possibly express in words!

Thank You,

Koda

Good WOT Test

Good LTFT at idle.

Good LTFT at 1500 & 2500.

Watch your LTFT and STFT's at exactly 13 sec in the 2500 vid, your trim STFT & LTFT are cancelling each other!

Looks to me like a PCM RE-Learning its Fuel trims!

Confirmed Fix!

Feel free to monitor your LTFT over the next day or 2, they should balance themselves out.

Combined LTFT values less than 5% are excellent

Combined LTFT 5%-10%, PCM is compensating for an issue.

Combined LTFT 10% PLUS, your engine is having a problem, but the PCM is controlling it

Combined LTFT 20, 25%, will turn on the MIL.

I can't thank Weycraze enough for his time, expert knowledge and most of all for his dedication to this forum! I couldn't have fixed my issue without him! Being as green as I am when it comes to scanner data, I was lost without his guidance!

Once again Sir, Thank You for everything you have done for me! I truly mean that. Thank you!

Daniel

Your very welcome.

I'm no expert, I intend to be a lifelong student.

Welcome to the forum, there are some truly talented techs here with knowledge and experience far exceeding mine!

Now that you have some access to Global Scan Data, it would be good to "benchmark" while your trims are good. Write some data down in a log book under various engine loads, this way when things start not to perform well, you'll have some 'known good' data to compare to for your reference.

Paul

That is great advice that never crossed my mind. I will do that today. I just took the truck for a drive long enough to get it up to temperature then scanned it again and it all looks good still. I'm just wondering, is there a thread here to log known good data for various vehicles? If not that might be a good idea to start one. I would gladly log my data there too.

Thanks again for your help and, don't take this personally but, I hope I never have to see you again. wink, wink!