Live data p0172 p0175

Jhkj04 · Mar 10, 2023

Almost got my 04 back on The road after a lift and lots or updated maintenance. Tons of help on this site getting the right lift and in the end pulling the motor to do head gaskets and a TQ. I’ve swapped about ever sensor which all started with the back two 02’s having cut up wires prob shorted out at some point. Now with new sensors, map, iac, mass air, etc I’m running again and good until the cel hits 172 and 175. Thought it was the intake gaskets swapped those again and checked vac hoses still lost. Checked data and trim but not sure how to read that and now I own a live data scanner. Stft and Lyft at idle is -32.8 across all. Anyone know what I’m looking for to test 02’s or the PC itself?

Ksat · Mar 10, 2023

What engine do you have? -32% means the PCM thinks things are too rich and it's trying to remove fuel to compensate. There's a number of things that can cause a rich condition that you can google. The O2 sensors may also be faulty making the PCM think there's a problem when there really isn't one. When's the last time you replaced the upstream O2s?

Jhkj04 · Mar 10, 2023

Fronts changed last week rears in Jan. While driving its allot of neg fuel trim for sure. Also I did injectors and coil packs and plugs. Ngk plugs and 02’s and mopar coils. Rear 02’s had rough wiring could the pcm be bad if they grounded it out? Pics of the driving trim video. Thx for checking it out.

Jhkj04 · Mar 10, 2023

It’s a 3.7. New- injectors, head gaskets, timing chains etc, iac/mopar , Mass air and map not mopar, 02- Ngk, plus Ngk/ntk, coils mopar, pcv, coolant temp sensor, cam sensors, intake gaskets, valve cover gaskets, fuel rail new o rings, took out cruise and blocked the vacuum line. Before it was running on 5 cylinders as one had a stuck open intake valve with a thrown rocker pass side number 6 and a bad gasket and coolant leak into the exhaust on driver number 5.

DadOSix · Mar 10, 2023

Jhkj04 said:
Fronts changed last week rears in Jan. While driving its allot of neg fuel trim for sure. Also I did injectors and coil packs and plugs. Ngk plugs and 02’s and mopar coils. Rear 02’s had rough wiring could the pcm be bad if they grounded it out? Pics of the driving trim video. Thx for checking it out.

Being as you had issues at the rear o2 sensors, i think i would start there. Rough wiring could be your culprit as you mention. I think the only way forward at this point is to find the wiring diagram and trace each wire from the rear o2 sensor forward. Something akin to the ‘green crusties’ as Eric O. from South Main Auto finds when the insulation integrity has been disturbed. Corrosion along any one ( or a common wire, such as a ground) could throw the readings to the PCM off. I’d be looking hard and long at wiring before condemning the PCM.

Jhkj04 · Mar 10, 2023

I did see brittle wire loom up over the transmission from the 02’s but I’m also getting readings on the scan tool of .840-.860-9.40. Did a cold start reading. Coolant 60-70-80-113 went cold to warmed up seamed normal. Both Front 02’s danced .124-.345-.764 as it warmed up and the tears started at .840 which is near what I see when it’s hot warmed up. That’s also the only time I’ve seen any 02 read .1or anything below .8 and .9. Once it’s warmed up all 4 are in the high V range .8-.9 .Could this be cats holding exhaust at the front 02 showing rich? It does have 187k on it.

Jhkj04 · Mar 10, 2023

New data- cold start coolant temp does read on the scanner at 60 steadily runs up to 79-80-113 seamed normal. Front 02’s randomly ran .100-.324-.845-.730 etc on warm up. Rear 02’s .840 .860 which is similar to what they run when it’s all warmed up. Could this be bad cats? Holding exhaust before the cat showing rich conditions?
I’ll search for wiring diagram and try to test from the pcm to the 02. Maybe Google knows the pin locations.

derekj · Mar 11, 2023

When you stand behind it when it is running does it smell like raw fuel coming out? If you had bad cats you would see the rear O2 sensor voltages switch like the front ones do. It's a bit of a hard one to diagnose over a computer unfortunately.

Jhkj04 · Mar 11, 2023

Lots of data, I went back and started from point A. If I unplug the mass air meter/air temp shouldn’t something happen? It didn’t react and the new sensor has no resistance. The harness shows volts 3-4-5-6v when running. The sensor is dead.

Jhkj04 · Mar 11, 2023

Mass air ended up good under heat test just 0 at cold. Pulled the plus and not overly fuel smell at the tail pipe.

Jhkj04 · Mar 11, 2023

New plugs with 300 miles

derekj · Mar 11, 2023

Looking back at your data you said the -30 fuel trims were at idle and the -20 on the long term was at cruising speeds - if so what that is telling me is that you have more unburnt fuel at idle then as you add more air it starts to lean out a bit. by the looks of your spark plugs it looks like you have 3 cyl's running more rich than the other 3 (the darker plugs getting more fuel) - i'm wondering if you have a couple bad fuel injectors. Does your scan tool data give you an actual temp reading for the intake air temp sensor and what is the map sensor reading with ignition on and engine not running?

Jhkj04 · Mar 11, 2023

It does map I’ll check. Also I just tested the coil voltage while running from the Pc to the plug. Odd numbers all around. Most show 4-8 volts the cleanest white plugs show 0-1-2-3-0-2 a range of low voltage. The only one showing 8-10-12-9 etc was the left front plug and that was first checked right at start up upon rechecking it last it was 4-7-8-3-6 etc. if they need 12v to work the coil and plug I’m for sure not seeing it.

derekj · Mar 11, 2023

Are you checking the voltages with the vehicle running or with just the ignition on and the coil and injectors unplugged?

Jhkj04 · Mar 11, 2023

Tested each coil plug as it was running one at a time. That’s voltage from the pcm to coil.

Ksat · Mar 15, 2023

Upstreams need to be NTK brand, in the NTK box in a sealed bag with NTK logos on it. Many sellers, especially on ebay, Amazon claim to be selling you NTKs but are substituting cheaper ones.

Rear O2s usually only check for cat efficiency and have no other function, so I wouldn't be concerned with them for now. To answer your question, I doubt the cats have anything to do with the trims being the way they are.

Since the rich condition is on both banks, it would help to try and think of something that would collectively affect both sides together. Excessive fuel pressure is one thing I can think of. Bad coolant temp sensor might cause that, but sounds like yours' is okay. A bad MAP could do that,, I don't know offhand what a good MAP reading is at idle or when engine is off, but maybe someone else can chime in on that. I guess it's also possible the injectors collectively could be allowing too much fuel through them per injector pulse. If you had a scope, wouldn't be a bad idea to check the waveform going to them from the PCM, either,

Jhkj04 · Mar 15, 2023

So I’ve been tracking. Before swapping the pcm I found I have a ground out or bad Parasitic draw. Meter between neg post and cable I’m getting voltage on the fuse 3-7-9-15 JB power lines. Tracked 15 to a bad wire behind the radio I believe it’s fixed. Tracked 7-9 to the BCM and it seams it’s bad. If I pull it the voltage drops out. Number 3 is still not located.
Hoping a new BCM and no grounded out 12v might help the PCM??? Not sure that the bcm can affect the volts going to the coil but hope it helps. Now how do I get a BCM to swap???

Ksat · Mar 18, 2023

If you don't know already, once you key off, it's normal for there to be a draw on the battery until all the modules go to sleep. This could take up to a half hour.

Replacing the BCM may require proper the programming in order for it to function with the other systems.

Jhkj04 · Mar 18, 2023

I had forgotten that but it was unplugged awhile. I’ll retest and give it 45 min doors shut lights off meter neg term to cable. I’m getting mixed reviews on programming or not on the bcm. I called a couple PCM places and they don’t do BCMs at all which is odd. The 3rd I found wanted 400 for a bcm claimed programmed and sounded like a scammer. Gonna try the bcm and fuse panel it’s a base Liberty so holding it functions. If I had to go to the pcm as the next step is it better to order online or do a junk one with the skim and key?

Jhkj04 · Mar 18, 2023

And I don’t have a skim in my 04

Live data p0172 p0175

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