[Diy_efi] An intro and some questions - how to smooth out the idle and where

[Dave Harvey]

Hi,
My name is Dave, I've been lurking on the 2 lists for a couple of months 
now. I'm new to the world of electronic fuel injection, although I have 
been doing electronics (professionally) and working on cars (fun?) for 
over 30 years. Just never got around to putting the 2 together. Call me 
a late bloomer. Anyway, now I've jumped in with both feet. I've replaced 
the 350 in my 91 GMC pickup with an HT-383 crate engine, added an 
Edelbrock Performer multipoint conversion and an Isky 257/265 hyd roller 
cam. Drives great, idle is a little lumpy. Vacuum at idle is 15-17 in Hg 
(in neutral). The intake duration is 210 deg @ 0.050, so I don't believe 
that the cam is the culprit. So now it comes time to consider 
reprogramming the EPROM in the 747. I have read out the stock EPROM and 
the (now installed) Edelbrock 1350 EPROM. The Edelbrock cam was designed 
for a 350 running the Edelbrock performer cam & heads. I have CATS 
Tuner. There are still a few things I need to check out before I change 
the EPROM, but I figure I should stock up on 2732s just in case. What is 
reliable source of 2732s, give that DigiKey does not carry them? What is 
the best method of correcting the idle stumble? I have checked:
- coolant temp sensor
- EGR valve
- ignition timing
O2 sensor, rotor, cap, wires and plugs are all new.
I have yet to check the O2 sensor output, my DVM is on the blink, need 
to borrow one from work. I have not ruled out vacuum leaks at the intake 
manifold gasket (but I pray that I don't have to replace the gasket). I 
have read and will continue to study the GM ECM tuning tips.

Any thoughts?

Thanks,

-- Dave
94 Olds Bravada (bone stock, hers)
91 GMC Sierra 4x4 383/4L60 (ours)
89 Jaguar XJ-S V12 (mine)
81 Chevy K5 Blazer 350/4-speed stick (beater)
73 Jaguar XJ12 w/ Chevy conversion (engine & trans out for rework)
70 Harley Sportster 900cc (mine, too many mods to list)
Los Angeles, Ca.

PS. It appears that cross-posting is permitted. If not, I apologize in 
advance.



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