Misfire Mystery...

[ricofrancois]

Hi,

I posted about an intermittent rough idle on my 07 Expedition but wanted to start a new thread as the issue disappeared and I suspect it may be unrelated.

I was using a Vyncs OBD2 Tracker and Engine Health reader in the last couple of days. I received 2 messages saying that:
1) Fuel mixture is lean and consumption may be high.
2) O2 Sensor reading out of range

On a trip on the freeway uphill, I got a blinking engine light and some misfire under load. Letting go of the gas a bit made the misfire stop and the flashing light disappear. I finish my journey driving slower and using the Overdrive uphill which seems to help. I only got misfires another couple of times with flashing light which again was fix when slowing down.

This morning I took the car to the mechanic who read misfire code on cylinder 5 and 4. With misfire still occurring. Mechanics removed plugs and check them. they were fine. Checked injectors and coils, all good.

He started the car and no misfire. He told me to just drive the car to see what happens but he couldn't locate any issue. His guess is maybe a bad wiring somewhere but he couldn't verify...

Any comments?

 

[Steeple_Jack]

Subscribed...my 2010 did this once but not again since...now I a bit paranoid. Interested to see what comes up.

 

[ricofrancois]

When I picked up the car, I could hear a ticking noise. hard to tell where it comes form but seems to be from the exhaust near the driver's side. The engine seems to not running great at idle but the car runs okay in the city with no engine light...
I connected my blue drive scanner and got a P1000 code:

VIN: DECODED:

P1000 Repair Report

2007 Ford Expedition (XLT)

P1000 CODE DEFINITION:

• On-Board Diagnostic OBD Systems Readiness Test Not Complete

4 POSSIBLE CAUSES:

• Battery keep alive power (KAPWR) circuit to the PCM has been opened
• One or more OBD II Monitors did not complete during an OBD II Drive Cycle • PCM Reset step was performed with an OBD II capable Scan Tool
• PTO circuit is shorted to voltage (VPWR or B+), or PTO "on" during testing

TOP REPORTED FIX:

• Performed Emission Monitor Drive Cycle(s)

FREQUENTLY REPORTED FIX:

• Performed Powertrain Control Module (PCM) Programming w/P0122, P0223, P0607...

7 OTHER REPORTED FIXES:

• Repaired Fuel Pump Driver Module (FPDM) Connector • Replaced Automatic Transmission
• Replaced Coil On Plug(s) (COP)

7 OTHER REPORTED FIXES: (Continued)

• Replaced Engine Oil Temperature (EOT) Sensor
• Replaced Powertrain Control Module (PCM) w/P0122, P0223, P0607... • Replaced Spark Plug(s)
• Reset Emission Monitor Drive Cycle(s)

 

[ricofrancois]

Something else I noticed when accelerating on park, the engine will not go over 3000 rpm...

 

[ricofrancois]

After driving today, I noticed that misfires occurs under load over 3000 / 3500 rpm but no codes

 

[stamp11127]

Possible vacuum leak causing a lean misfire. If the mechanic can smoke test the lines and intake manifold that would be a good test.

When was the last tune up?

Are the cops & boots original?

 

[ricofrancois]

Ford did a tune up at 40k ago at 100k. 1 COP was replaced. I replaced 2 more COP since and all plugs again 3000 miles ago.
Recently I had a rough idle and Ford replace COP and injector on #8. They did a stress test on the block and couldn't see any isssue.
Now the misfire is constant, it is going in today. I will update on what they say

 

[ricofrancois]

Quick question. Are there more issues on the 07 triton or is it just a myth?

 

[ricofrancois]

Ford called me and reported a bad coil on #4. That will proceed with replacing COP and plug... I am surprised that this is such a straightforward fix but I guess I will see when I pick up the car tomorrow. I wish I had an engine light or some kind of code.
Ford quoted $498... Annoying but having said that #4 is probably a pain

 

[docraymund]

You have to check fuel pressure at the aforementioned rpm range.