Backfire and then all good

Sam Odajima · Jul 15, 2018

I've recently purchased a 2004 4.6l and I've been working on getting repairing the years of neglect and abuse. Here is my issue. When I 1st place the expectations in drive it idles rough like it's gonna die until it backfires and then drives like a champ. I've replaced spark plugs, cop, egr, egr sensor, vacuum lines. No check engine light comes on. Help and suggestions would be great.

1997SCEBFEX · Jul 15, 2018

welcome aboard.

How many miles on her?
Have you pulled the codes? Also suggest changing fuel filter, Air filter, IAC, throttle position sensor, PCV & PCV line....
report back.

sure others will chime in.

BRIANGEE · Jul 15, 2018

Whaa?

Talk about parts shotgunning...

1955moose · Jul 15, 2018

I'm with 97, pull up any codes through data port. Backfiring can be something as simple as spark not advancing, all the way up to a bad exaust/intake valve. Let's eliminate the easy stuff first. Ford Expectations, that name says it all!

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Sam Odajima · Jul 15, 2018

Codes are as follows:
P0443 Evap Emmission system purge control valve circuit
P0446 Evap Emmission system vent control circuit
P0135 O2 Bank 1 Senor 1
P0155 O2 Bank 2 Sensor 1
P2195 O2 lean Banking 1 sensor 1
P0403 Exhaust Gas Recirculation Control Circuit

Sam Odajima · Jul 15, 2018

124750 miles btw

Ed_Strong · Jul 15, 2018

I would start by checking for vacuum leaks especially around the EVAP system. Then check that the intake throttle body and EGR are functioning properly before throwing parts at it! It seems that you may have EGR orifices plugged and in need of cleaning. There's a few videos posted on YouTube showing the process and tools needed. Its a fairly quick and easy job.

A quick and easy test to perform is to unplug the vacuum line to the EGR and apply vacuum at Idle, if the engine dies, the EGR is functioning correctly.

BRIANGEE · Jul 15, 2018

All of your codes point to something as potentially easy to fix as replacing a fuse. Your evap system components as well as your EGR vacuum solenoid AND your O2 Heater circuits all share a power feed (yellow w/ red tracer) from a 10amp fuse #33. Id' start by checking that fuse then follow up w/ checking powers and grounds at those locations.

DontBeJeff · Jul 16, 2018

BRIANGEE said:
Whaa?

Talk about parts shotgunning...

Yeah, don't shotgun parts. Unless you can see it needs replacing, you may just be replacing a good part otherwise.

I second checking the fuse, could be an easy fix.

1955moose · Jul 16, 2018

It's unfortunate, but too many of our members won't take the time to do simple diagnostic. We've had some in the past that changed out damn near every part under the hood, just to find it was a corroded wire or something simple. Sadly in this day and age most people and shops too don't know or care, and start shotgunning parts at these SUV's.

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Backfire and then all good

Sam Odajima

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