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Sep 1, 2007 | 10:55 PM

drakul20us

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Please help

I have installed a K&N cold air intake and Powerdyne throttle body spacer in my truck and ever since then I am getting a DTC of air/fuel mixture is too lean in both banks. Also my truck does no want to accelerate as fast as it used to, having a hard time getting to 3+RPM, and MPG went down the toilet to about 9. Now, when the truck is idling, my RPM go wildly up and down, and the truck is starting to take off by itself with my foot on the brake. I have replaced the MAF sensor and the IAC valve, didn't change a thing. I have narrowed the problem down to the electrical signal being sent to my MAF sensor. I have probed the wiring harness of a MAF sensor and it is at 14volts, in the manual it is specified that the voltage should be 2.0v at open throttle. My question is what would cause such a huge differential and how would I go about fixing it.

2000 F-150
4.6L v8
142,000

Sep 1, 2007 | 11:47 PM

khadma

Carpenter Local 745

Joined: Apr 2006

Posts: 5,794

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From: on da beach

It has been stated here on FTE, some F150s do not like mods to the spacer and the K&N system robs MPG - the computer senses that there is more air and adds fuel to the mix.
I was going to use K&N products and changed my mind when I heard about conditions like the one that you have.
Did you ever consider replacing the mods back to stock?
K&N filters may place oil on the sensors, but you changed your already, and it maybe dirty again.
AEM has dry filters, maybe better for F150s.

Sep 2, 2007 | 12:18 AM

LxMan1

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From: Louisville,Ky.

No vacuum leaks anywhere?

Sep 2, 2007 | 10:00 AM

drakul20us

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I don't think there are any leaks anywhere, I haven't heard any, but I'm going to try some soap solution tommmorow to see if I can find anything. I'm probably going to take off the spacer see if that does anything for me. thanx guys.

Sep 2, 2007 | 10:15 AM

screwy

Cargo Master

Joined: Aug 2002

Posts: 2,117

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From: Over Yonder, MN

Here's your first thread.
https://www.ford-trucks.com/forums/6...l-problem.html

Sep 2, 2007 | 10:48 AM

screwy

Cargo Master

Joined: Aug 2002

Posts: 2,117

Likes: 8

From: Over Yonder, MN

I suspect your measuring the wrong wire. There is a power supply wire that should run between 12v and 14v. I'd check for air getting in around your spacer. The 2v would be the signal return to the computer while the engine was running around 1800 rpm.

Last edited by screwy; Sep 2, 2007 at 10:51 AM.

Sep 2, 2007 | 02:32 PM

Club Wagon

Posting Guru

Joined: Feb 2007

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Vacuum leaks might not be so easy to find, especially using soapy water.

Quote:

Originally Posted by drakul20us

I'm going to try some soap solution tommmorow to see if I can find anything.

Save the "soap solution" for for hard to find pressure leaks in tires. The latest trick to search for vacuum leaks is to use the unlit flow of raw gas from a propane plumber's torch to probe the areas where you suspect vacuum leaks with motor idling. Any gas sucked in will increase revs.