Help with diagnosing trouble

Reply Subscribe

Thread Tools

Search this Thread

Nov 9, 2019 | 01:39 AM

Krzcandy

Thread Starter

New User

Joined: Nov 2019

Posts: 6

Likes: 0

Help with diagnosing trouble

Have 2003 Expedition XLT 5.3 V8 (bought used). It's been having loss of power issues. Have changed out spark plugs, coil packs. New fuel pump. The check engine light comes on after driving less than 10 miles and flashes off and on. Can't push down on gas pedal when it starts lagging or it dies. The error codes keep changing. Seems to be the ECM but was wondering
1) the fuel pump is run through a relay switch not straight into the fuse box (like that when bought). Could that be issue?
2) if it is the ECM, what would I need to look for in a used replacement?

Nov 9, 2019 | 02:02 AM

Martynka

Mountain Pass

Joined: Aug 2019

Posts: 151

Likes: 3

From: Poland

- Flashing check means misfire. If you have changed everything and there is still a problem, did you measure the compression on the cylinders ?? You could have measured it when replacing the spark plugs.
- What error codes appear (even if different)
- If you are afraid about fuel pressure, you can take a pressure gauge and connect it to fuel rail vent, and watch pressure while while driving.
- Have you checked the ECM plug ?? Traces of corrosion, moisture ??

Nov 9, 2019 | 07:05 AM

broncoholic

Laughing Gas

Joined: Jan 2003

Posts: 1,082

Likes: 40

From: Melbourne, FL

Quote:

Originally Posted by Krzcandy

1) the fuel pump is run through a relay switch not straight into the fuse box (like that when bought). Could that be issue?

Are you saying the previous owner bypassed the relay built into the ECM and it's using a different relay? Anytime there's some shade tree mechanic stuff like that you have to fully understand what they did to make sure they did it right and it's working right.

If you're getting misfire codes or lean codes, they could be because you're losing fuel pressure.

Nov 9, 2019 | 02:41 PM

Krzcandy

Thread Starter

New User

Joined: Nov 2019

Posts: 6

Likes: 0

Quote:

Originally Posted by broncoholic

Correction on fuel pump, it was wired in direct so it's constantly getting power. It's not in the relay. The ECM is retarding the timing when we give it gas, run rich on bank 1, lean on bank 2.

Nov 9, 2019 | 02:58 PM

Krzcandy

Thread Starter

New User

Joined: Nov 2019

Posts: 6

Likes: 0

Error codes: P0172, p0174, p0232, p0301,p1000

Nov 9, 2019 | 03:38 PM

broncoholic

Laughing Gas

Joined: Jan 2003

Posts: 1,082

Likes: 40

From: Melbourne, FL

Quote:

Originally Posted by Krzcandy

Correction on fuel pump, it was wired in direct so it's constantly getting power. It's not in the relay. The ECM is retarding the timing when we give it gas, run rich on bank 1, lean on bank 2.

I'd work on getting that fixed. I'm sure the PO did it because the relay on the ECM burnt. If you're handy with a soldering iron, you can do it yourself for a few bucks.

Quote:

Originally Posted by Krzcandy

Error codes: P0172, p0174, p0232, p0301,p1000

Work on getting that misfire on cylinder 1 figured out. It's probably related to the rich on bank 1 code; 1 is causing the other, or is a symptom of the other.

Jun 20, 2022 | 07:08 AM

Yorkkidinda831

6th Gear

Joined: Jun 2022

Posts: 6

Likes: 0

From: Menifee

Similar problemS!

For months I’ve had random misfire problems and engine too lean codes. I changed coils and plugs and it was better for a day before engine light came back on. Rough idle, low power, mpg loss, light will flash when trying to accelerate at higher speeds. Changed PCV valve and hoses after mechanic found small vac leak. STILL same symptoms persist. Mechanic supposedly checked MAF sensor and other easily accessible potential suspects. Idk what to do. Is it wiring to coils? Fuel injectors? Fuel filter? 2 mechanics so far have tried and failed to find solution.

2003 Navigator 2WD 160,000m 5.4L