is it true that a CAI will lean out the engine?

941 Views 6 Replies 5 Participants Last post by .boB, May 14, 2008

le012wf

Discussion Starter · May 13, 2008

when i installed my kn flpk cai, my high flow cat mid pipe and cat back. I started to get knock or pre-ingnition under load. do you guys think these new mods might have caused this?
oh, i also have a hypertech power programmer tune on it, if that helps...

thanks

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fobra559

· #2 · May 13, 2008

Could be a possibility. Check the A/F with your programmer.

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steve_stang2003

· #3 · May 14, 2008

le012wf said:
when i installed my kn flpk cai, my high flow cat mid pipe and cat back. I started to get knock or pre-ingnition under load. do you guys think these new mods might have caused this?
oh, i also have a hypertech power programmer tune on it, if that helps...

thanks

Personally I would lose the 165 Thermo.....

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le012wf

Discussion Starter · #4 · May 14, 2008

I agree about the thermostat.

That was a rookie mistake when I put it in... I just haven't had the time to replace it and that wasn't on the top of my list, if you know what i mean.

I do you really think that could be part of the problem? What are your thoughts?

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· #5 · May 14, 2008

steve_stang2003 said:
Personally I would lose the 165 Thermo.....

agreed, anything under a 180* thermostat can and will cause excessive engine wear, esp on a Modular....if you're having detonation problems, it could be whats in your tune, return it back to "stock" settings and sea if the "pinging" continues.....

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Yellow03

· #6 · May 14, 2008

Something cheap and easy to try. Just unplug the battery so it clears the engine pcm, and let it learn it's fuel trim over. It could be a simple as you may have forgotten to do it while installing your parts.

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.boB

· #7 · May 14, 2008

le012wf said:
when i installed my kn flpk cai, my high flow cat mid pipe and cat back. I started to get knock or pre-ingnition under load. do you guys think these new mods might have caused this?
oh, i also have a hypertech power programmer tune on it, if that helps...

thanks

Absolutly. The goal of the CAI and exhaust is to move more air in and out. That makes more power, and increases efficiency. Along with all that extra air, you also need extra fuel. If the engine is running lean, it will knock until it destroys itself.

Which Hypertech tune did you use? In my limited expriance, the 91 octane tune advances the timing a significant amount, but doesn't increase performance all that much. Try the next tune down the list (89 octane) and see if it runs better.

If that doesn't work, I'd suggest a custom tune from somebody like Brenspeed.

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