trxmxzx

iTrader: (7)

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

TXsilverado

iTrader: (19)

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

trxmxzx

iTrader: (7)

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 ***

TXsilverado

iTrader: (19)

did you check for vacuum leaks?

trxmxzx

iTrader: (7)

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)

TXsilverado

iTrader: (19)

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

trxmxzx

iTrader: (7)

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

TXsilverado

iTrader: (19)

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

trxmxzx

iTrader: (7)

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
​​​​​​

​​​​​​​

Gadgetized

iTrader: (9)

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.