Codes 334, 311, 538s
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Joined: Sep 2005
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From: Houston, Texas
Codes 334, 311, 538s
The truck's power just dropped, it felt like it did when the last of the two fuel pumps died, but floored, it keept running.
The first time it happened I was running down the freeway, and hadda floor it so it would stay running, and got a huge, puffy cloud of grayish-white smoke in cab. Thing backfired, power way down--in the good ol' days, and in a C$%^&y, it woulda been jumped time from a sloppy timing chain.
Quits if I let it drop below 1,500 RPM. If I didn't know better, I'd say it's running out of gas. Runs fine, then intermittently does its run-outta-gas trick.
Fresh in-tank pump, 65 psig fuel pressure (specs).
Fresh fuel filter.
Truck: '91 F-150
Engine: 4.9L
Codes Read:
(Key On, Engine Off)
334--EGR Valve Closed, Voltage High
(Key On, Engine Running)
311--Thermactor or Air System Fault
538--Insufficient RPM change during KOER Dynamic Response Test
538--(Trucks ONLY): invalid cylinder balance test due to throttle movement during test
Yesterday, after sitting for 3 weeks, it fired right up and drove fine, after which I got those readings--and never showed any sign of the power drop.
WTF?
The first time it happened I was running down the freeway, and hadda floor it so it would stay running, and got a huge, puffy cloud of grayish-white smoke in cab. Thing backfired, power way down--in the good ol' days, and in a C$%^&y, it woulda been jumped time from a sloppy timing chain.
Quits if I let it drop below 1,500 RPM. If I didn't know better, I'd say it's running out of gas. Runs fine, then intermittently does its run-outta-gas trick.
Fresh in-tank pump, 65 psig fuel pressure (specs).
Fresh fuel filter.
Truck: '91 F-150
Engine: 4.9L
Codes Read:
(Key On, Engine Off)
334--EGR Valve Closed, Voltage High
(Key On, Engine Running)
311--Thermactor or Air System Fault
538--Insufficient RPM change during KOER Dynamic Response Test
538--(Trucks ONLY): invalid cylinder balance test due to throttle movement during test
Yesterday, after sitting for 3 weeks, it fired right up and drove fine, after which I got those readings--and never showed any sign of the power drop.
WTF?
