Computer Code 334 and 411

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Jan 3, 2004 | 09:59 AM

sdnorden

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Computer Code 334 and 411

I am hoping someone may have an answer to my problem. So, here goes.....

I have a 95 F150 with the 300 I6. Recently, I installed a new upper intake to lower intake gasket, throttle body gasket, and EGR valve gasket. Replacing these gaskets made the truck run much smoother and seemed to correct the annoying bucking at part throttle. Funny, the gaskets ford used on assembly seemed to be of low quality and poor sealing ability....i.e. very thin. The new gaskets were at least twice as thick and were reenforced (FelPro).

Anyway, after clearing the computer and running the truck for awhile I recorded the following computer codes (Check engine light not on).

Continuous code - 334 (My repair book does not have a listing for this code)

Running Code - 411 (Unable to control high idle)...I called the dealer they indicated a possible vacuum leak or IAC valve. Since I have replaced the intake gaskets and any suspect vaccum hoses. Does anyone have any ideas on how to test the IAC valve or where to look for the problem.

The engine does idle high when warm.....about 1200 rpm.....

I have done all the other stuff such as wires, plugs, timing, pcv, injectors........

Thanks,

Jan 3, 2004 | 02:32 PM

95BlackF150

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i was using chiltons online but something is farked over i know it would have your code in it
according to F150.net the 334 is electronic vacum regulator but dunno if i put full trust in that is correct.

Jan 3, 2004 | 05:44 PM

95BlackF150

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check here as well https://www.ford-trucks.com/framered...tech/codes.htm

Jan 4, 2004 | 08:54 AM

sdnorden

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Hmmmm, thanks for the link. According to the site the code 334 is the EGR sensor above closed limit and 411 is unable to control RPM during low RPM test.

I will check the manual on how to test these. I wonder why the manual says something different for the 411 code. The low rpm control makes sense because it idles high. The hayes book seems to be incorrect.

What would cause the egr to set code 334. Not sealing completely or intermitant sealing? I noticed the egr while the truck is running does make a strange vibration noise.

Is the egr valve spring loaded? If so then would higher than normal backpressure cause the valve to be forced open and not seat all the way? Or would this be caused by a bad valve that is not sealing correctly.

I may have to get a vaccum gauge and test for system backpressure.

Thanks for your help.

Jan 4, 2004 | 09:30 AM

95BlackF150

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could be vacum leake or the sensor on it i have a 332 code on mine which means its not opening

Jan 4, 2004 | 05:04 PM

95BlackF150

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just fixed mine bout half hour ago had a broken vacum line which i was pretty sure it was that or i cracked the vacum soleniod when i was changing plugs spliced the line and now no lite w00t