Just curious

I have a 90 mm throttlebody 4 inch intake then at maf tapers down to a 3 inch for the maf.

i've googled it and searched it and I'm not getting that question answered.

Whats the thoughts? My velocity might be off?



Truck is rough to start- when cold jumps rpm then falls on its face over and over - I have to hold throttle at 15-20% then 10 seconds later it's like a miracle Rpms run up quick then I left of throttle slowly

when end warm it sometimes catches and stays idling

then I started thinking my crank case venting- my pcv is to the back of the blower and my other valve cover is tied into my intake. So my crankcase is on a negative vacuum at all times!?! Any help to clear this up would be cool

 

it shouldn't be an issue like that. has it done this since you originally built the intake tube?

 

Ever since I put this mp122 blower on it- Nelson told me to check for vacuum leaks like 2 years ago.

It runs good but start up sucks ***

 

did you check for vacuum leaks?

 

lol sorry yes- that's why it's making me think of my crankcase venting

when I first got it going I couldn't pull the cap of the oil fill and when I did it would almost stall -

at that time I only had the pcv hooked up no valve cover vent (pluged)

 

vent the crank case to atmosphere and see if it still does it.

 

i think that I will- are you vented to atmosphere?

 

My hotrod is through a catch can. The silverado is running a stock pcv setup

 

Here's a clip that finally uploaded- this is just after it started so it's still a cold motor. I'm trying to upload the first one still

http://s15.photobucket.com/user/trxmxzx/media/Truck%20sierra%20and%20parts/D4EC7366-BE59-4BB6-B829-532CFE875962.mp4.html
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What are your fuel trims doing when it smooths out? When you first start an engine, the O2 sensors don't correct fueling until they have time to warm up.