Sick of hunting down this issue on my own - Please Help! :)

[1LowToy]

Sounds like you have corrected one issue and need to move onto the next. Is the right side running rich? Try swapping the fuel injectors left to right. See if that makes the left side run rich instead. You may be dealing with a bad injector or a spark plug wire on that bank. Cold the computer is working of a fixed setting for fuel mixture. Warmed up (operating temp) the computer is in control of the fuel mixture (richer/leaner). Check the temp sender to the computer and the wiring for it. Did you say you had exhaust leaks as well? Your truck sounded pretty loud. Is your computer operating and giving you codes?

[Evil Trailblazer SS]

Both injector spray patterns look very even. No dripping from the injector at all, but some fuel does get splashed onto the sides of the venturis at idle.

I am going to pull all the plugs this morning just to be sure I didn't crack any of the plugs when I did the manifolds but I don't think that is the issue. Since the problem clears itself up after 2,500rpm (for the most part) I think it may be electronic.

When i broght the truck home, the wiring for the coolant temp sender on the front of the block had been spliced into the factory wiring with some really ghetto 3M jelly bean locks so I corrected that immediately since the truck would not come off its cold start fast idle. After that, the idle issue was corrected so clearly it is now getting proper signal to the ECM.
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[Evil Trailblazer SS]

Okay, just kidding everyone! We got the truck on the scanner and although the ALDL is not responding when I jumper it and the light has 12v+ to the pink/black wire, the scanner connected perfectly.

The problems we found -

1. The TPS is a little out of range so I am resetting te voltage to .50v
2. The EGR system is functioning perfectly but for some reason, up at our elevation it can tend to cause a lot of issues so we are going to orafice everything down to restrict it. After we got the fuel trims corrected, we disconnected the vacuum line from the EGR and now the truck runs perfect! With the EGR connected, the trim was idling super rich and once disconnected, everything evened out.
3. The Check Engine Light had 12v at the pink/black wire so I knew the ALDL was good, it ended up being a bad ground in the ECM so my buddy had a spare laying around. I threw it in and BAM! Now the ALDL and Check Engine Light function properly!

So all's well that ends well apparently!
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[1LowToy]

I love it when a plan comes together.

[bigblok77]

Originally Posted by 1LowToy

I love it when a plan comes together.

X2 good job man

[Evil Trailblazer SS]

You guys are awesome...thanks again!

My biggest issue now is that when I toss the 454HO in, will I be able to simply run the 54mm mega bore TB from TBIParts with 80lb. injectors, fuel pressure at 25lbs. (with spring and upgraded pumps), and tune the stock ECM?

Since the system is speed density, will I have enough engine vacuum at idle to properly tune the truck? Or should I go another route?
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[1LowToy]

Leave it stock and enjoy it. The environmentalists are still looking for more rules and regs to stump you and your quests. Just ask some of the peeps in cali crying at the smog check stations. My 80 is stock to the bone and burns clean

[Evil Trailblazer SS]

I'm going to leave it for now, other than finishing the 4L80E conversion...I'm just planning for the future, that's all!

I've got so much other work to do in this project, I don't want to do the engine work just yet!

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[dmcclanahan]

Sounds like the same problem i have with my truck. I start with changing out the dist. cap and the rotor. Then moved to the spark plugs (knowing that I have already changed out my spark plug wires) as I was removing (and replacing) the old ones, I found that my number 5 spark plug/piston was where my problem was. My Piston ring is shot.