Reprise: EGR Codes again!

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Dec 20, 2003 | 08:50 AM

banjopicker66

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From: Coal country

Reprise: EGR Codes again!

I replaced the EGR valve, the control valve (solenoid) and the DPFE, cleaned the EGR hoses and metal tube, and after driving about 75 miles, I get the CEL/MIL on again.
Code this time is P0401, Insufficient EGR Flow.
I have read where cleaning the upstream EGR ports in the throttle body will help; this makes sense to me.
Any advice on what components to remove to get to the ports? how to do this? I have a Haynes, but it isn't very clear to me.
Thanks.

Dec 20, 2003 | 08:55 AM

banjopicker66

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From: Coal country

Also, I am getting only 12 MPG, about 1/3 city and 2/3 highway - is this normal? I thought it should be higher than that with the 4.6 and overdrive.
Will fixing the EGR codes (and any others which may show up) increase it significantly?
My experience is mostly with my '66 F-100 and my son's '72, and they get about 15 MPG!

Dec 20, 2003 | 02:23 PM

50th ann

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From: Royal Palm Beach, Fl

I suffered through the same problem with code P0401. You did not say what year or engine I changed the ERG Valve and the DEPF swich and it did not fix it. Same as you the light came back on in a few miles, but I finally fixed my 98 4.6L F150 with 112,000 miles by cleaning the ERG ports. The ports I'm skeaking of can only be accessed my removing the throtal body off the top of the intake manifold. It's an elbow that connects most of the vacumn lines including the ERG Valve. I got alot of carbon out of there and that fixed it. There is a simple test to tell you if the ports are clear.

Remove the vacumn line from the ERG Valve and cap the hose. Start the engine and let it idle. Then apply vacumn (outside source) to the ERG Valve. The engine will stumble or stall if the ports are clean. If the engine continues to idle without change the ports are blocked and need to be cleaned. I cleaned mine in about an hour it's not that big of a deal on the 4.6L

Good Luck

Dec 20, 2003 | 02:38 PM

50th ann

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From: Royal Palm Beach, Fl

Adding to my previous post.

The ports are in an Elbow that is nothing more than a 90 degree elbow between the throttle body and the intake manifold. A few hoses and four bolts on each end will remove it.

I changed the plugs and wires at the same time and my mileage returned to 16 MPG in town (same as when new) Haven't checked Highway yet but it runs much smoother with more power now.

Dec 20, 2003 | 04:57 PM

banjopicker66

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From: Coal country

Well, another update: The EGR ports in the throttle body WERE badly clogged. I cleaned them out easily enough. I did NOT clear the pending codes this time using the ODBII tool. (Note that the light isn't on)
I haven't driven the truck yet, so I don't know if the codes will clear itself yet.
If I understand it right, the truck will clear the penidng code whn it runs for awhile with the error corrected.
Hopefully, this is fixed.

Dec 21, 2003 | 01:13 AM

geoaigel

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From: LA

Yup. The "upper intake" portion needs to come off. Brake parts / carburetor cleaner and a small bottle brush will get you there. One test to do is pull a vacuum on your EGR valve. If it doesn't almost stall the engine at idle, it means that there is insufficient flow and your channels are likely clogged.

Cheers, George

Dec 21, 2003 | 02:22 AM

50th ann

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From: Royal Palm Beach, Fl

There is something known as a drive cycle. I'm not sure but I have read that if you go through I think two or three drive cycles without the fault the code will clear itself and the light will go off. I have had my light turn itself off while I was drivivg along after a repair.