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Feb 4, 2004 | 03:40 PM

plapczynski

Thread Starter

Senior User

Joined: Nov 2003

Posts: 107

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From: Chillicothe OH

Code Help

93 F150 - 4.9 I6 - 5 Speed - Dual Tanks - XL 99,500 Miles

My check engine light started coming on yesterday. It won't happen until the truck warms up for about 5 minutes at road speeds. It won't stay on all the time and will turn off with some accelleration or de-accelleration.

I pulled the codes when I got home today with the engine off/key on and got the following:

173 - HEGO shows system always rich
181 - Fuel at rich adaptive limit at part throttle; system lean
327 - EVP or DPFE circuit below minimum voltage
542 - Fuel pump secondary circuit failure: EEC to ground
556 - Fuel pump primary circuit failure

When running in the driveway I get:
538 - Insufficient RPM change during KOER dynamic response test

Any help on these codes?

Is it ok to leave the code scanner hooked up on my drive to work tommorrow to see when if I can get some codes at operating speeds?

Thanks,

Paul

Feb 4, 2004 | 03:50 PM

EPNCSU2006

Lead Driver

Joined: Nov 2002

Posts: 9,556

Likes: 43

From: Concord, NC

Check fuel pressure and the fuel pressure regulator. It sounds like the computer is leaning it out as far as it can get it, and it still is rich. If you have not replaced the O2 sensor since the truck was new, it might be time to replace it. Get a Haynes manual and go through the EGR system checks to pinpoint the problem with that system. The KOER test, you didn't goose the throttle. Read the test procedure again, you have to floor the throttle to make the engine go up to at least 2000 rpm. This lets the computer check to see if EGR, Canister purge, etc, work like they are supposed to when the engine is off idle. I can't remember exactly when the "goose" code is, but it should be very soon after initiating the test.