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Old 01-17-2006, 11:10 PM   #1
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Default More on the custom cammed L36

I determined shortly after the heads/cam were done that I have a bad fuel injector. I just ordered a set of flowmatched, used 25# injectors from Michael Peck to replace my stockers. I will then reinstall my Intense Standard PCM and tune my AFC accordingly for a trip to the dyno.

We might remove my LIM and do some further porting on it before then, because I have a mysterious whistling sound that occurs at mid throttle. We're guessing that it might be from irregularities and ridges in the LIM ports, but I'll take any suggestions on other things I should examine. If I remove the UIM and LIM, is it okay to reuse the gaskets since they're fairly new?
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Old 01-17-2006, 11:15 PM   #2
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Default Re: More on the custom cammed L36

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Originally Posted by big_news_1
We might remove my LIM and do some further porting on it before then, because I have a mysterious whistling sound that occurs at mid throttle. We're guessing that it might be from irregularities and ridges in the LIM ports, but I'll take any suggestions on other things I should examine. If I remove the UIM and LIM, is it okay to reuse the gaskets since they're fairly new?
this may be stupid, but are you sure that its not ur cai. i know mine makes a whistlin noise under mid throttle. it sounds like a turbo spoolin.
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Old 01-17-2006, 11:28 PM   #3
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99% sure it'* not the CAI. It never made the noise before, and we didn't change anything with the filter/rice pipe setup. I'm thinking it'* either an irregularity in the LIM/heads or a vacuum leak.
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Old 01-17-2006, 11:34 PM   #4
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Default Re: More on the custom cammed L36

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Originally Posted by big_news_1
We might remove my LIM and do some further porting on it before then, because I have a mysterious whistling sound that occurs at mid throttle. We're guessing that it might be from irregularities and ridges in the LIM ports, but I'll take any suggestions on other things I should examine. If I remove the UIM and LIM, is it okay to reuse the gaskets since they're fairly new?
this may be stupid, but are you sure that its not ur cai. i know mine makes a whistlin noise under mid throttle. it sounds like a turbo spoolin.
interesting note also, both CC and VigCS'* car (l36'*) have the whistle sound when you get on the throttle
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Old 01-17-2006, 11:51 PM   #5
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I was wondering about you. lol.
before you take your LIM off I would spray all around it with carb cleaner while it'* running. You may be able to find your vac leak like that. If you do have a leak, your idle should stumble a bit when the carb cleaner gets in.
IMO the LIM gaskets are a big enough job to where you should just replace them for good measure. Get the newest metal gm ones while your at it. and don't be timid when rtving those corners.
Just thought of this.. Did you keep your EGR system? If not you may want to check your block off plate.
And with the LIM make sure all your ports are identical... If they aren't then each cylinder will be pulling in a different amount of air, throwing your exhaust O2'* off.
Good luck and hope that helps.
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Old 01-18-2006, 01:44 AM   #6
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Ah, I forgot about the EGR system.... it could potentially be the source of the whistling. We just disconnected the tube that ran to the rear exhaust manifold and put a small air filter on it. So it still sucks air and charges the intake, but it won't get hot and warp the UIM. It should never leak coolant again. The whistling could be the sound of air being sucked into the EGR tube.

Is there a brand new update to the GM gaskets? I got a GM LIM set back at Thanksgiving when we did all the work... it has the nice metal inserts for longer life. I assume I could reuse it if I pull the LIM in March.

Also, I'll do a little more spraying with the carb cleaner. I already sprayed my vac lines, and they aren't currently leaking. I'll spray around the UIM/LIM and see if I can get any stumbling. However, I have to wonder if it'* EGR related, because if I recall VigCS also disconnected his EGR in the way I did. We'll see, I guess.

BTW, I think I'll soon be in the same boat as you, Mike. I need a built tranny :(
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Old 01-18-2006, 02:11 AM   #7
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Ben, you should really un hook the egr system from the LIM.
Not having the egr at all will raise cruise temps since the computer thinks that exhaust gas is coing in and reall isn't. The exhaust gas allows for more timing since it displaces air and less air is being burnt. Now whenever your egr valve opens, your sucking in un metered air. This alone will lean out your engine and raise temps (KR). So right now you have 2 extra reasons to have KR. #1 your computer raising timing at cruise thinking exhaust gas is being taken in and #2 Un metered air is coming in an leaning you out
So, I'd really suggest that you plug up that hole in the LIM. If you want you can leave the electrical hooked up and it won't throw a code.
And yeah there is a brand new revision of the LIM gaskets, there metal with rubber embossed into them. Kinda reversed from the ones you and I have.
Sucks about your trans. Mine'* hanging tough after I changed the fluid & filter. Shifted WOT the couple times I tired it and no gear hunting.
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Old 01-18-2006, 02:28 AM   #8
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Hmmmm..... never thought of it that way.

There are multiple guys running their EGR the same as mine, though..... I can think of 2000SilverBullet in particular.

So you're saying I can just unhook the other end from the LIM and leave it all plugged in, and it will still be happy?
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Old 01-18-2006, 02:32 AM   #9
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Ditch that AFC. It'* a crutch, or at best, maybe a tuning tool. It'* not truly logarithmic, but maybe 'multi-linear'. Once you get some LT and ST numbers, get a PCM burned to compensate and sell the thing.

Let'* get that car burning some horsies.
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Old 01-18-2006, 09:16 AM   #10
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You guys wanna know what I think your whistling sounds are....

PCV.. check it and ensure it'* in there and sealed properly. Upon initial install mine would make some noise.
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