Seafoam is hard on plugs, if those were the original plugs, I would suspect they might be the problem. According to some GM engineers, when you descreen a MAF on a high horse engine like the C5-LS6 you gain almost 2.4 hp...with proper tuning. On a standard truck engine you might gain 1-2 hp at most. A screened MAF will flow enough cfm for most 5.3 and 6.0L engines, unless highly modified. FWIW.

 

I want to saw it was in GMHTP they said on one of their cars when they descreened the MAF it gained something like 5hp or so and they said that was caused by the added timing. Something about the velocity over the contacts tricking the computer and making it add some timing. They showed before and after dyno pulls on a F body. There was a good write up on the free mods. Like bypassing the coolant lines, trimming the EGR tube, and descreening the MAF. The rest of the mods were LS1 F body specific and they gained like 20 or so over the stock baseline. I have done so many on these with never an issue...I guess I will see tonight when I swap them.

 

Since your scanner said you have an idle control valve problem, I'd look at the throttle body and make sure you've got the plugs properly attached. Do you have another 99-02 TB that you could swap on there for testing?

I doubt that the MAF is causing your problems, but I also doubt that you gained any power from removing the screen on a stock vehicle.

 

Since you have a code for the idle circuit, I'd be looking at the throttle body and the wiring to it. One of the wires on one of the connectors may have become damaged upon removal. I wonder if it's also possible that a chunk of carbon worked it's way into the IAC (Idle Air Control) valve...I've actually seen that once or twice before. Both things that I mentioned are easy enough to check, especially since that's the area that was disturbed.

Also, when I do Seafoam, if I'm also doing a tune up and replacing plugs, I do that after the Seafoam treatment, just in case. I plug may have gotten fouled but I don't think that's the problem here.

I too have horror stories about descreening the MAF, that it usually hurts more than it helps or does nothing at all. The screen helps to straighten the air so that the MAF sensor can get a more correct reading. I don't think that the descreened MAF is your current problem though...I'd go after the "idle circuit or idle control valve problem" first...

 

LOL, Big Tex and I are on the same page...I must have taken too long to type

 

That's a teeny tiny gain. I know adding HP isn't easy, but I also don't like seeing a given mod on a hypothetical 700 HP engine. Test on a typical stock motor would be the way to help the average consumer. But I rarely see it done that way.

I also was wondering if a chunk of carbon worked its way into somewhere it shouldn't have. I didn't post that earlier cause I figured someone would say Seaform breaks all that down. But, in saying that, I didn't think in the IAC valve, as Billy said. Makes sense tho.

 

Ok, I said nothing about the test being done by GMHTP was done on a 700 hp motor it was a stock car, they were showing the "hidden hp" in the LS based platforms. Where would I find the idle control valve and is it something I can clean or does it need to be replaced.

 

Hypothetical... means it could've been 500, 600, or 700 or whatever. I wasn't necessarily citing your example. Point I was driving at, is beyond what the Joe Average normally is runnin.

 

From what i have been told, when you descreen the MAF you need to add ~5% to your entire MAF table...



What are you trims doing at idle????

 

The Idle Air Control motor is the brassy colored module toward the top of the TB. It has one of the two wire harness plugs (the other is the throttle position sensor and it connects at the center of the TB).