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4.8L with FIPK/MAF question

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Old Jun 12, 2003 | 12:16 AM
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abbo7's Avatar
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Default 4.8L with FIPK/MAF question

I recently put a FIPK on the 03' 4.8L and I had a Granatelli(sp) MAF and used it also. However, the MAF was not set up for a CAI. I'm not getting any pinging with it so I am sure its not running lean. Could there be any other problems with it that I might not know about?
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Old Jun 12, 2003 | 02:17 AM
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Default Re: 4.8L with FIPK/MAF question

Welcome to the site!

You really shouldn't have any pinging unless you've used a programmer to advance your ignition timing up too much.

Probably the only thing I see happening is the maf not being calibrated for the intake will actually let unmetered air go through and that won't be caught until the 02 sensors see it and adjust your short / long term fuel trims to counteract the condition.

That's fine for part throttle driving as long as it's not way way lean, then you'd get a service light.

The thing is though since the pcm is adding extra fuel at part throttle, when you punch it the pcm automatically stops looking at the 02 sensors and goes by internal programming be it factory or hypertech etc. Then since your fuel trims were a positive number it adds in your extra shot of fuel you had at part throttle making you actually a little rich at wot. Kinda strange huh.


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Old Jun 12, 2003 | 01:56 PM
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Default Re: 4.8L with FIPK/MAF question

Wow, I never knew that. Seems like you guys know alot about this kind of thing. So what you are saying is that there will be more air coming into the engine but it will probably be running a little rich? So would taking off the MAF result in more power since its making the mixture run more rich with the MAF on? Or does the MAF ability to increase the amount of incoming air into the engine off-set its making the engine run rich?
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Old Jun 12, 2003 | 07:40 PM
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Default Re: 4.8L with FIPK/MAF question

Why don't you study OBDII and learn how fuel management works. The PCM is going to always try to adjust your A/F to 14.7:1 unless your at WOT REGARDLESS of what MAF you use. You didn't really say what your problem is. It sounds like you don't know if you have a problem or not. You need to get AutoTap or Ease to monitor your STFTs and your LTFTs to see if your running rich or lean and then you can ask a more specific question.
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Old Jun 13, 2003 | 12:48 AM
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Default Re: 4.8L with FIPK/MAF question

Welcome to the site!

You really shouldn't have any pinging unless you've used a programmer to advance your ignition timing up too much.

Probably the only thing I see happening is the maf not being calibrated for the intake will actually let unmetered air go through and that won't be caught until the 02 sensors see it and adjust your short / long term fuel trims to counteract the condition.

That's fine for part throttle driving as long as it's not way way lean, then you'd get a service light.

The thing is though since the pcm is adding extra fuel at part throttle, when you punch it the pcm automatically stops looking at the 02 sensors and goes by internal programming be it factory or hypertech etc. Then since your fuel trims were a positive number it adds in your extra shot of fuel you had at part throttle making you actually a little rich at wot. Kinda strange huh.



Ok now that I am beginning to understand this a little better tell me if I have the general jist of it. The unmetered air going into the engine will be recognized when it reaches the 02 sensors thus making the PCM read as though it was running lean ,therefore, adding more fuel to the mixture to try and reach a 14.7:1 A/F ratio? Another thing that I am wondering is how you said that under WOT the PCM stops looking at the 02 sensors...what does it do exactly (the PCM)?
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