hi all, i have a problem that i need help with. i have a 5.3 truck engine that i put a ls1 intake on, ran fine with truck intake ,but with ls1 intake i have a high idle that i cant get rid of? i checked for vacuum leak but found none? do i need computer re tuned ?

 

Yes it need to be retuned... Did you also change the steam vent cross over?

 

How did you check for a vacuum leak? Which throttle body are you using?

 

While its idling, spray the gasket area with carb cleaner. If it idles up then its leaking in that spot

 

For some reason doing it that way doesn't work nearly as well with plastic intakes. Why I don't know. If you have a scanner or data logger watch the STFT's or 02 sensors while spraying.

Also make sure the throttle cable is releasing all the way and that the cruise control cable has slack in it.

Are you using an LS1 throttle body or the one off the 5.3?

 

Yes I changed steam vent. Using ls1 tb .sprayed all over can't find a leak ? No cables on it rt. Now.

 

How did you hook up your pcv system? Also, did you use the truck injectors? If so, what kind were they, standard or flex fuel?
Btw, running an LS1 intake on my 05 5.3, no retune needed.

 

Pluged pvc . Running ls1 injectors and rails

 

does the ls1 tb you're using have an oversize drilled hole in the blade or a set screw which can be adjusted? either one could have been altered by previous owners

 

Take the throttle cable off and see if this solves your problem, ask me how i know?

 

No over sized hole or set screw. No cable on it. Put truck tb on it but didn't change it .still high idle. No tack rt now but would guess it's idle is about 1700

 

is your map sensor installed? you have two lines up front and one air line on the back near the passenger side. are all these plugged in? Since you said LS1 Intake, do you have the EGR of EGR delete plate hooked up?

 

Map sensor in . All plugs in. Egr plate not leaking ? Is it possible to spray brake cleaner under foam on bottom of intake to see if maybe I have a leak on the low side of intake ports?

 

Codes? Is your IAC working correctly? Where is the MAF relative to the TB?

 

hi guys , i figured it out! combination of slight leak at egr, and something going on with ls1 tb ? fixed leak at egr, and put on truck tb and it idles great! any ideas why ls1 tb would cause high idle? thanks for all your help!

 

only reason a TB would be the cause of a high idle would be a larger drilled hole or set screw.. I can't see why else.

 

What's your TPS voltage, throttle % and IAC duty cycle with the LS1 T/B?