2018 ram 1500 5.7 stalling and bucking rich

[erick_2018ram]

With the scan tool connected, how much vacuum is the motor making at idle I.E. what is the MAP Vacuum?

I'll pull the live data for that tomorrow as I cant recal what I actual had of the top of my head

 

[erick_2018ram]

It sounds like you have already picked all of the low hanging fruit.

Do you have access to an oscilloscope?

If you can get a waveform @ idle, from several injectors and compare them to a known good idle waveform from another truck.

See if the PCM is firing the injectors correctly.

Since you say you have headers, safe to assume the truck is tuned? It's possible something happened with the PCM.

Yeah I've already picked all the stuff you would normally think it usually is. My has had 3 of my best friends saying they dont know anymore

And I dont not have an oscilloscope but I should be able to pull all the injectors pulse width on my live data

And yes truck is tuned but 99% of the time its in stock with mds deactivated that's the route I've been thinking is something had happened to the pcm because even with removal all all tunes and back to stock nothing clears so dont know if it just fried something

 

[Ken226]

Yeah I've already picked all the stuff you would normally think it usually is. My has had 3 of my best friends saying they dont know anymore

And I dont not have an oscilloscope but I should be able to pull all the injectors pulse width on my live data

And yes truck is tuned but 99% of the time its in stock with mds deactivated that's the route I've been thinking is something had happened to the pcm because even with removal all all tunes and back to stock nothing clears so dont know if it just fried something

Live data MAY tell you what the PCM thinks it's doing, but not necessarily what it IS doing.

If the mosfets that control the injectors got really overheated, the PCM commanded pulse width, which is what live data will show you, won't reflect the actual open/close time at the injector. A scope will.

If you decided to invest in one, I use the Launch 02-2 scope box. It is plug & play with Launch, Topdon and ThinkCar scan tools, and they have software so you can use it with a Windows laptop as well.

But, for what you are doing here, you can probably get by with a cheap 2 channel from eBay or something.

 

[erick_2018ram]

Very odd situation check the fuel pressure but i would also check for exhaust restrictions

Fuel pressure is In range going from 56-58psi and the exhaust has no restrictions goes from 1.75 in primary tube long tube headers 2.5 In true duals into 10in mufflers to 5in big tips strong exhaust at exit of tip

 

[Fast69Mopar]

I'll pull the live data for that tomorrow as I cant recal what I actual had of the top of my head

No worries. I'm curious what the MAP sensor says along with the injector pulse width at idle.

Do you have a mechanical gauge you can connect to the intake manifold to verify engine vacuum?

 

[erick_2018ram]

No worries. I'm curious what the MAP sensor says along with the injector pulse width at idle.

Do you have a mechanical gauge you can connect to the intake manifold to verify engine vacuum?

So map sensor is showing 1.3to 1.5 v at idle which would indicate high vacuum and manual gauge on vacuum at idle is 20psi about attaches is the injectors live data at idle and map volts, vacuum, and intake pressure which all looks good to me

 

[Ken226]

So map sensor is showing 1.3to 1.5 v at idle which would indicate high vacuum and manual gauge on vacuum at idle is 20psi about attaches is the injectors live data at idle and map volts, vacuum, and intake pressure which all looks good to me

You said earlier that the injectors are OEM.

Are you certain that they are OEM for that specific engine? Not from a 6.4? Verify the part#?

 

[Fast69Mopar]

So map sensor is showing 1.3to 1.5 v at idle which would indicate high vacuum and manual gauge on vacuum at idle is 20psi about attaches is the injectors live data at idle and map volts, vacuum, and intake pressure which all looks good to me

I always check MAP Vacuum when I have a HEMI running rich. It can tell you a lot about the motor.

Is this thing switching between open loop and closed loop operation at idle?

I would start the truck with the upstream oxygen sensors disconnected and monitor the data to see what is happening. With the oxygen sensors disconnected the PCM uses a different map for fuel control to try and stay in emissions compliance. See how it runs with them unplugged. I'm curious of the outcome.

 

[Tominator223]

You check the air filter? And air box inlet. Maybe you sucked up a plastic bag ?

 

[erick_2018ram]

I always check MAP Vacuum when I have a HEMI running rich. It can tell you a lot about the motor.

Is this thing switching between open loop and closed loop operation at idle?

I would start the truck with the upstream oxygen sensors disconnected and monitor the data to see what is happening. With the oxygen sensors disconnected the PCM uses a different map for fuel control to try and stay in emissions compliance. See how it runs with them unplugged. I'm curious of the outcome.

It is not coming out of open loop and as soon as the temp gets 160 degrees it kills its self and as soon as I pull the o2 upstreams and now my omhs and my pcm ground are going erratic as well are going crazy and my grounds look great idk if im missing a ground that hidden but everything looks great or if my coolant sensor is going bad keeping it in open loop but I dont think so because my fans ain't running no stop . And if I pull the sensor fans come on immediately im starting to think its an electrical issue because this is blowing my mind

 

[Wild one]

It is not coming out of open loop and as soon as the temp gets 160 degrees it kills its self and as soon as I pull the o2 upstreams and now my omhs and my pcm ground are going erratic as well are going crazy and my grounds look great idk if im missing a ground that hidden but everything looks great or if my coolant sensor is going bad keeping it in open loop but I dont think so because my fans ain't running no stop . And if I pull the sensor fans come on immediately im starting to think its an electrical issue because this is blowing my mind

If you think it's a bad or missing ground,just build yourself some new ones.There's a stud by the battery that makes a good starting point,then run one over to a bolt on the engine,and another one down to the frame,that should cover any missing or bad engine grounds.

 

[Bob Horowski]

Going out on a limb here, but I had similar performance issues with a jeep that at times would buck and shift abnormally, especially when not completely at operating temperature. Turned out to be a bad throttle position sensor that did not throw any codes.

 

[Fast69Mopar]

If you think it's a bad or missing ground,just build yourself some new ones.There's a stud by the battery that makes a good starting point,then run one over to a bolt on the engine,and another one down to the frame,that should cover any missing or bad engine grounds.

I agree here. Make yourself some new grounds to eliminate that as an issue.

With the motor running as poorly as it is, something will stand out in the scan tool or HP Tuners when monitoring live data. If you have graphing capabilities that can really help when monitoring voltages and percentages.

 

[erick_2018ram]

If you think it's a bad or missing ground,just build yourself some new ones.There's a stud by the battery that makes a good starting point,then run one over to a bolt on the engine,and another one down to the frame,that should cover any missing or bad engine grounds.

I plan on making new grounds sometime this weekend. And I've been looking at live graph data and every sensor I've been looking at the voltage is in range nothing really jumps out

 

[erick_2018ram]

Going out on a limb here, but I had similar performance issues with a jeep that at times would buck and shift abnormally, especially when not completely at operating temperature. Turned out to be a bad throttle position sensor that did not throw any codes.

And I've already changed out with the stock throttle body with low miles i have it on the shelf at the shop to the stock one and relearned with no difference so I know my ported one is good they both operate the same percentages

 

[erick_2018ram]

I agree here. Make yourself some new grounds to eliminate that as an issue.

With the motor running as poorly as it is, something will stand out in the scan tool or HP Tuners when monitoring live data. If you have graphing capabilities that can really help when monitoring voltages and percentages.

Well I did new grounds and no joy , so im lost for words on this one. Im starting to think something is wrong with this pcm

 

[erick_2018ram]

Well I took the truck to the dealership and and told the guy what's going on and he flashed the pcm and it didn't hold so he did more tests guy was thinking possible cam phaser knowing what all has been replaced and done already and he has come to the conclusion that the pcm has an internal fault so new pcm is being ordered so hopefully this solves the issue

 

[EdGs]

I hope that solves your issue.

This a shot in the dark, but here goes:

Have you checked your coolant temp sensor?

I had a little 2001 Saturn SL 5 speed that all of a sudden, my MPG went way down and I could smell raw fuel, big time.

I called up the dealership and spoke to a tech, explained that I didn't have alot of money, asked if there was a cheap way to see what was wrong, before I brought it in for service.

He said my coolant temp sensor was likely shot, when they go, the computer thinks it's below zero, so it dumps more fuel.

Funny thing was I had noticed my coolant temp gauge would only read 25% when it normally would read right near 50% at operating temp.

Sensor was $15 then (20+ years ago). Worked like a champ.

Not sure if its the same way in our Rams, but something to chew on and easy to check. I just replaced the CTS on my '15 and it ran me $68. Part # 5149077AB.

Dealer told me the oil temp sensor is the same part number not sure if that has anything to do with the fuel parameters, though.

 

[erick_2018ram]

I have already tested that sensor it reads fine and the electric. Fans dont run non stop so I know it hasn't failed and once I unplug it they come on like the should

I hope that solves your issue.

This a shot in the dark, but here goes:

Have you checked your coolant temp sensor?

I had a little 2001 Saturn SL 5 speed that all of a sudden, my MPG went way down and I could smell raw fuel, big time.

I called up the dealership and spoke to a tech, explained that I didn't have alot of money, asked if there was a cheap way to see what was wrong, before I brought it in for service.

He said my coolant temp sensor was likely shot, when they go, the computer thinks it's below zero, so it dumps more fuel.

Funny thing was I had noticed my coolant temp gauge would only read 25% when it normally would read right near 50% at operating temp.

Sensor was $15 then (20+ years ago). Worked like a champ.

Not sure if its the same way in our Rams, but something to chew on and easy to check. I just replaced the CTS on my '15 and it ran me $68. Part # 5149077AB.

Dealer told me the oil temp sensor is the same part number not sure if that has anything to do with the fuel parameters, though.

 

[EdGs]

I have already tested that sensor it reads fine and the electric. Fans dont run non stop so I know it hasn't failed and once I unplug it they come on like the should

Bummer.

Swing and a miss.