L67 EGR Blockoff? good idea? bad idea? - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 04-28-2006, 01:40 AM   #11
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Paul, blocking off the EGR will actually INCREASE your combustion temps. Regardless of the effect on intake charge temps.
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Old 04-28-2006, 01:49 AM   #12
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I have removed mine too. Doing before and after scans I didn't notice a difference in KR. I do know that my intake track is cleaner then ever.
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Old 04-28-2006, 01:51 AM   #13
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Yes I know the theory but... meh.. it has worked for me for 30 years so why should I stop now.

Call it old fart stubborness.
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Old 04-28-2006, 01:52 AM   #14
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Quote:
Originally Posted by llBlazin_llLo
I have removed mine too. Doing before and after scans I didn't notice a difference in KR. I do know that my intake track is cleaner then ever.
I run an EGR and a PCV. Try porting your LIM to prevent reversion. My LIM and SC are spotless. Ask driverjohn2005 and chadow427. They saw the supercharger that ran on my engine for 6 months with the ported LIM. I didn't clean anything on it, and the rotors were absolutely pristine. The supercharger is now running on John'* car. In all it'* clean, spotless, ported and polished glory.
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Old 04-28-2006, 01:58 AM   #15
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Bill the EGR closes when you are WOT and you are there most times so of course it would be clean.

Seriously though, before I disconnected mine there was black soot in the intake with only 20 K on the engine. I cleaned it and now at twice that mileage it'* still clean...and cool. I just don't like pumping 600 F air into my intake, no matter how little, when I go to great pains to bring down my intake temp by 60 F.
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Old 04-28-2006, 02:25 AM   #16
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Quote:
Originally Posted by willwren
Quote:
Originally Posted by llBlazin_llLo
I have removed mine too. Doing before and after scans I didn't notice a difference in KR. I do know that my intake track is cleaner then ever.
I run an EGR and a PCV. Try porting your LIM to prevent reversion. My LIM and SC are spotless. Ask driverjohn2005 and chadow427. They saw the supercharger that ran on my engine for 6 months with the ported LIM. I didn't clean anything on it, and the rotors were absolutely pristine. The supercharger is now running on John'* car. In all it'* clean, spotless, ported and polished glory.
So your saying that it is the LIM'* falt that everything gums up?

How many miles was put on in 6 months? I'm not going to do the LIM porting until good solid data comes out that it works well on more then one or two cars. Then maybe I'll think about doing it.

I can tell you that my intake track on my car is perfectly clean with over 10K on it and will be perfectly clean after 100K
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Old 04-28-2006, 02:37 AM   #17
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We've had the EGR blocked off on the GTP for a few years now. It didn't seem to make a noticable difference in gas mileage. There was no noticable change in KR (the car never has any so no difference) after removing it. But with it removed the supercharger and intercooler are both spotless.
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Old 04-28-2006, 08:53 AM   #18
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Ok, previous to the LIM porting, my last SC swap stayed on the car for a year and about 10k miles. The LIM was filthy. But if you were to really 'sniff' it, it would smell somewhat like FUEL as well. All of them do to one extent or another. Odd.

After the ported LIM went on (in August), the car was driven every day (only put 2k on the SLE in this period of time) including two trips to CA. Probably 5-6k miles easily in 6 months. The SC came off in March for the Gen3 swap. When it came off, any one of you boost heads would have thought I just took it apart, cleaned it and rebuilt it. That clean. The LIM as well.

There are flow restrictions in the LIM that cause reversion or 'back flow' preventing SOME of the fuel, pcv, and EGR goop from simply flowing through and getting burned like it'* supposed to. If you can get the flow optimized, you won't have it circulating in the LIM leaving deposits.

ssei1995 can actually explain the effect a bit better than I can.
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Old 04-28-2006, 10:28 AM   #19
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After all I went through disconnecting and reconnecting my EGR system, I feel confident in saying that you CAN disconnect it, but you should supplement its removal with a custom PCM tune.

Running an EGR valve with a filter on it to draw in outside air is effectively introducing a vacuum leak to your system under part throttle conditions. The EGR is designed to circulate inert exhaust gases in order to effectively reduce the size of the combustion chamber. When you replace those inert gases with regular air, the car would theoretically be running lean because you're letting air into the cylinders that the MAF sensor is not reading. Only with custom PCM modification could you effectively counteract this condition.

Aside from that, I'm not sure what to think of Bill'* statements regarding reversion. I'm inclined to believe that dirty intakes are the fault of the EGR itself, not necessarily an intake that isn't flowing efficiently. But I have no flow data or mechanical background to support that statement. All I can say is at this point, I think eliminating your EGR will make for a much cleaner intake system.

On a side note, I just realized that the function of an EGR system is effectively the same as "displacement on demand." It limits the effective volume of your cylinders by using inert gas, and then lets that volume grow larger when you press the gas and need more power. Instead of cutting off a few cylinders, it simply makes all your existing cylinders "smaller" when you don't need the power.
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Old 04-28-2006, 11:55 PM   #20
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Quote:
Running an EGR valve with a filter on it to draw in outside air is effectively introducing a vacuum leak to your system under part throttle conditions. The EGR is designed to circulate inert exhaust gases in order to effectively reduce the size of the combustion chamber. When you replace those inert gases with regular air, the car would theoretically be running lean because you're letting air into the cylinders that the MAF sensor is not reading. Only with custom PCM modification could you effectively counteract this condition.

Aside from that, I'm not sure what to think of Bill'* statements regarding reversion. I'm inclined to believe that dirty intakes are the fault of the EGR itself, not necessarily an intake that isn't flowing efficiently. But I have no flow data or mechanical background to support that statement. All I can say is at this point, I think eliminating your EGR will make for a much cleaner intake system.

On a side note, I just realized that the function of an EGR system is effectively the same as "displacement on demand." It limits the effective volume of your cylinders by using inert gas, and then lets that volume grow larger when you press the gas and need more power. Instead of cutting off a few cylinders, it simply makes all your existing cylinders "smaller" when you don't need the power.
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You are a wise man Ben.

I know I am not running lean and the black soot in my tail pipes and residue on the spark plugs confirm it.
I have compensated by increasing fuel pressure. ......more tricks given away.
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