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08 TrailblazerSS
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Discussion Starter #1
So, after the installation of all the mods in my signature and being tuned by the goto guy in Phoenix, the truck surges a little, mostly noticeable below 1500 RPMs. Additionally, the idle is a little erratic until the truck warms up (which happens quicker than it used to). The cam is relatively mild so I really wasn't expecting to feel much change during routine driving. The shop that did the H/C installation made it sound like this was all normal and the tuner looked at it again after the converter was installed and said it all looks good. So my question is.... am I over reacting and I should expect a little low RPM surging or should I look at having someone else check out the tune. Unfortunately there is no one else I know of around here that comes more recommended when it comes to LS tuning than the guy I am using now. I have a spare PCM that I could send out to be tuned, which is kind of where I am leaning right now. Thanks
 

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I'm not as familiar with the aftermarket upgrades you have as many on thus site will be but I will say I have seen many LS trucks with a small split in the PCV boot at the PCV orifice cause these same symptoms. Worth a check.
 

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Discussion Starter #3
I will check that in the morning
 

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'08 Silver TBSS
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I recently got my lt1z stage 2 cam with kooks headers and until the engine fully warms up I have the same surging below 2k rpms. Nothing extreme, just when I first take off from a light. I got used to it after a while. I think if everything is the tune is correct probably just the nature of the beast going with a cam.
 

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Discussion Starter #5
Mine continues to do it even once warm. Like you said it is nothing major, can mostly feel it in the seat. I just wanted to see if it is in fact normal. Thanks
 

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'08 Silver TBSS
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No problem. Is the surging mostly with light throttle? I bet if you use around 50% or more throttle the surging is not noticeable? At least that's how mine is. Mine seems to be when I'm putting around town in slow speeds.
 
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Discussion Starter #7
Yes, anything above about 15-17k i don't feel it at all.
 

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2007 TBSS AWD
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I recently got my lt1z stage 2 cam with kooks headers and until the engine fully warms up I have the same surging below 2k rpms. Nothing extreme, just when I first take off from a light. I got used to it after a while. I think if everything is the tune is correct probably just the nature of the beast going with a cam.

You can get it all out but a lot of times people get it close enough.
 

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Discussion Starter #9
You can get it all out but a lot of times people get it close enough.
I don't suppose you have plans to be in the Phoenix area anytime soon. Jk, thanks.
 

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'08 Silver TBSS
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You can get it all out but a lot of times people get it close enough.
I think that how Speedmaster tuned mine. It's close enough and I'm good with that.
 

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needs moar powa
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Do you have a wicked startup flare ?

Surging isn't normal on a mild cam, my first guess would to double check if the Fast intake is leaking .
You can either spray carb cleaner around it while idling and see if the rpms flare -

The second option will only work if your tuner adjusted the ve tables
You unplug your maf, start the truck and remove the elbow at the throttle body , if it's bouncing back and fourth a lot trying to correct you definitely have a leak
 

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Discussion Starter #13
It does have a slight rpm jump on start up. I have heard leaks on the Fast manifolds are not uncommon. I will test that. I assume they normally leak at the seam?
 

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needs moar powa
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I always use blk rtv to seal the upper to lower in the back of fast manifolds after drilling the map
^ this , I've done two installs now and after using permatex ultra gray all the way around I've had no issues .

Common leak is at Seam, often in the rear or the map sensor or vac ports - but I've heard of guys messing up a gasket as they put it in place
 

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Did you talk to Jan at xtreme motorsports in tempe?

He retuned my henny v650 and a bunch of vettes.


Sent from my iPhone using Tapatalk
 

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Discussion Starter #18
I am going to verify there are no leaks before i decide if i want to have the tune reevaluated. Like i said its barely noticeable and above 1500 rpm nonexistent.
 

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I'd be willing to bet that a lot of your light load issues are tied to your fuel injectors. Redrilled injectors have been notoriously unpredictable at low pulsewidths. Check out the article I wrote about this a while ago HERE...

If you swap your injectors for a set of stock LS3/7 injectors (also rated for about 41#/hr) and put the correct injector values in the tables, it will be MUCH easier to dial in the MAF and VE surfaces and things will start falling into place very quickly.
 

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2007 TBSS AWD
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I'd be willing to bet that a lot of your light load issues are tied to your fuel injectors. Redrilled injectors have been notoriously unpredictable at low pulsewidths. Check out the article I wrote about this a while ago HERE...

If you swap your injectors for a set of stock LS3/7 injectors (also rated for about 41#/hr) and put the correct injector values in the tables, it will be MUCH easier to dial in the MAF and VE surfaces and things will start falling into place very quickly.

While true about ls3 the 42 lb modded LS2 can be dialed in for perfect drivability just like and ID 850 or other LS9 injectors that are modded to flow 850cc/hr at 3 bar. Though easier the lower the flow rate. It is easier when GM gives you the data in proper format though.

Im also not arguing the concept but the fact is when done right the driver cant recognize an issue at any rpm.
 
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