HELP! Huge Mystery backfires and cuts out on acceleration after warming up.

[JT1USA]

I say fuel pump or ignition coils. When you say you're getting 45psi where in the chain is that? At the fuel rail or the pump? I have seen weak ignition coils and weak fuel pumps create similar symptoms with no CEL. If you're getting the spec'd fuel pressure at the fuel rail then I am thinking ignition coil. Maybe even the fuel filter if not changed in a long time It may provide the right flow at idle but not be able to keep up with more demand.

 

[deep994rnr]

Hopefully you saved all those 'old' parts, just in case.

Your symptoms sounds like very bad misfiring while things are running poorly. Since it runs well most of the time, I'd assume most of the components are working well that you replaced...

Get an OBD-II reader that can display live data. Have it show short term and long term fuel trims along with open/closed loop.

When it is running poorly, check if it is open or closed loop.

When it is running well, check to make sure fuel trims are within a range of +/-5%

You need DATA to figure out the problem - firing the parts cannon is either really expensive (OEM parts) or problematic (most aftermarket parts).

-Charlie

Thanks for pointing me in the right direction. Your mention of LTFT and STFT caused me to research these items where I noted that they are mainly affected by a vacuum hose leak. After using a mirror to look on the backside of every hose I noticed where a rat had eaten away a tiny hole into the 17343B Hose NO. 3 coming out of the Air Resonator box. Replacing this hose seems to have taken care of the problem. If only I had thought of this simple check before I started firing the parts cannon ......