Question about A/F vs. KR vs rwHP

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02-09-2003, 03:00 AM

EuG

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Question about A/F vs. KR vs rwHP

Saw kind of a weird thing today…

Made a pull: A/F was ~12.8:1 autotap registered 5-6.5 deg of KR
Fatted it up, another pull: A/F ~12.2-12.4:1, 2.5-3 deg of KR, made ~10 more rwHP
Fatted it up just a bit more, another pull: A/F ~11.8-11.9, 0.5-1 KR, roughly same HP (1.5 less)

I don’t understand why this is happening. <img src="http://www.agrnet.com:8888/Pictures/Images/Smilies/Dunno.gif" alt=" - " />
11.8:1 seems awfully rich, but the car would have KR if any leaner and would make less HP.
What does it mean? <img src="http://www.agrnet.com:8888/Pictures/Images/Smilies/Dunno.gif" alt=" - " />
Any ideas?

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02-09-2003, 08:44 AM

niphilli

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Re: Question about A/F vs. KR vs rwHP

I wish I knew but I dont so TTT for ya.

My guess is that your KR is coming from somewhere else other than A/F. You should be able to run 12.5-12.8 with no KR. But it is weird that the more you richen it up the less KR you have??

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02-09-2003, 02:03 PM

John B

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Re: Question about A/F vs. KR vs rwHP

Without much to go on here is my take:

Your whole issue surrounding the power loss is directly related to your KR</li>
The reason you are seeing more power by making it richer is because this is causing the KR to go away and it is more timing making the power, not the richer fuel (the richer fuel is merely reducing KR)</li>
You either have the infamous LS1 PCV sucking oil into your intake tract and this is causing KR. You will see this more over time because when you first put your motor together or slap on ported heads, etc everything is clean. A quick verification check here is to yank of the TB and shine a flashlight inside of the intake manifold. If it's oily....not good!</li>
Another problem could be that you are running oxygenated gasoline. This time of year a lot of places offer only gas with 10% caca added which will wreak havoc with your A/F ratio because the additives make your motor run leaner for emissions which can cause KR</li>
You may just have bad gasoline</li>

Let's get this fixed! I want to see 500RWHP out of your beast!

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02-09-2003, 02:03 PM

EuG

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Re: Question about A/F vs. KR vs rwHP

dupe <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" />

[ February 09, 2003, 02:15 PM: Message edited by: EuG ]

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02-09-2003, 02:13 PM

EuG

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Re: Question about A/F vs. KR vs rwHP

niphilli,
<blockquote>quote:<hr />But it is weird that the more you richen it up the less KR you have??
<hr /></blockquote>Well usually that is the case, but what I don’t understand is why such rich A/F is required to get rid of KR <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

I’m thinking it can’t be false knock, because then KR wouldn’t go away no matter how much fuel you add…

Colonel,
Yep, wideband, no cats, 10.9:1 CR, 94 octane gas too.

John B,

<blockquote>quote:<hr />The reason you are seeing more power by making it richer is because this is causing the KR to go away and it is more timing making the power, not the richer fuel (the richer fuel is merely reducing KR)
<hr /></blockquote>Undrestood and agreed. The thing that I don’t understand is why would it require such a rich A/F <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> to get rid of KR.

<blockquote>quote:<hr />You either have the infamous LS1 PCV sucking oil into your intake tract and this is causing KR.
<hr /></blockquote>I have “PCV oil catch can mod”, so I dunno about this one…. I think this is not the case here.

Interesting idea about gas. Not sure. <img src="http://www.agrnet.com:8888/Pictures/Images/Smilies/Dunno.gif" alt=" - " /> It’s Sunoco 94…..

Any other ideas?
Thanks. <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

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02-09-2003, 02:41 PM

NoGo

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Re: Question about A/F vs. KR vs rwHP

I would look at

Your actual timing that you are running.

The octane of the gas you are running.

Any oil possibly getting into the combustion

Your compression

The viability of the O2 sensor. Make sure their equipment is clean, and all of the filters are clean (if they are using a draw through).

Spark plug heat range.

Good Luck,
Kevin

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02-10-2003, 12:50 AM

Colonel

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Re: Question about A/F vs. KR vs rwHP

I assume this was measured on a wideband.

Do you have cats? What C/R are you running?

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02-10-2003, 01:06 PM

EuG

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Re: Question about A/F vs. KR vs rwHP

Kevin ,

<blockquote>quote:<hr />I would look at

Your actual timing that you are running.<hr /></blockquote>I’m seeing ~24deg by TQ peak (where the KR usually starts), then going up to ~26 by redline

<blockquote>quote:<hr />The octane of the gas you are running.<hr /></blockquote>Sunoco 94

<blockquote>quote:<hr />Any oil possibly getting into the combustion<hr /></blockquote>Well not 100% sure, but like I said I have PCV catch can mod, so

<blockquote>quote:<hr />Your compression<hr /></blockquote>10.9:1

<blockquote>quote:<hr />The viability of the O2 sensor. Make sure their equipment is clean, and all of the filters are clean (if they are using a draw through).<hr /></blockquote>Ok, not sure about that, but it’s too late anyway.
Although, autotap O2 reading kinda correspond to wideband reading

<blockquote>quote:<hr />Spark plug heat range.<hr /></blockquote>Not sure <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

Thanks for your help. <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

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