I need help explaining the mysterious misfire

[Fawazalsabay]

I have RAM 2019 DT 5.7 with CAI, Lt headers catless, ATI dumber pulley, h pipe dual exhaust

The truck was a true dual 2.5 inches runs great

Recently I changed to a 3-inch H pipe

Currently, I'm struggling with the misfire engine only at part throttle the check engine light blinking four times. When I scan the PCM, no codes show up! Afr 15.5 to 16.7 ��It happens at part throttle

I checked the vacuum and exhaust leak?all good.
However, I disconnect the negative battery; the AFR goes normal without a misfire. Finally, the truck runs normal I think the fuel trim has been reseted


Four days later, the problem comes again where the AFR goes lean and misfires.

Where should i start looking o2 sensors?


Below video run at part throttle where the problem happen AFR goes lean and misfires
https://youtube.com/shorts/5gnh1APClfc?feature=share

At wot no misfire runs perfect !!

https://youtube.com/shorts/nOZYJrvyoDs?feature=share

[f.creek-ranch]

you should check the fuel delivery.

[rays04gtx]

Are you running 3in true Duals Now ?

[Fawazalsabay]

Are you running 3in true Duals Now ?

The previous set up was 2.5 inch true dual no cross over

now H pipe 3in

[Fawazalsabay]

Also i updated the thread with afr reading

[N2speed]

you should post a data log with the tune file,

[rays04gtx]

The previous set up was 2.5 inch true dual no cross over

now H pipe 3in

Might be my old age here, but if I understand you .

it's 3in true duals with an H-pipe ,header to tail pipes , was 2.5 duals no cross headers to tail pipes?

From my experience , your leaning it out and causing a Misfire....... How are the Knock sensors reacting when it flashes CEL light flashes 4 times ? My kids 02ram(with wiring PCM,and dash from a 2014)ran great with headers LT headers to 2.25in(w/Stock cats) to X pipe, 2.5 out to tail pipes. swapped it over to Headers to 3 in, Hiflow cats x-pipe 3 inch out. truck ran lean AFR would climb to mid15 till the SRV valve kicked in around 3400rpm, we lowered the "Charge motion device" Medium RPM disable to 2200 and added 1.15 Fuel from 1920 -3744 RPM air Charge(MG) 675 to 900 block, truck would still hit 14.1-14.5 in the same rpm area, we dumped more fuel in the same spot, no change, pulled some PT timing, didn't help any. finally went back to a 2.5in system front to back.

Engine was a 5.7 Eagle, SRT392manual cam, some port work 2.08 intake valve/1.625exh valve.5.7 truck intake.

[SultanHassanMasTuning]

always log the car and post the tune

running leak will cause misfiring, poor grounds could cause it as well

a datalog will show

[luciddeath]

Sounds to me like you need to delete your p0420/p0430 ... seems to me anyhow..