Stumped

So I recently installed a long block 350 in my truck. I upgraded to an Elgin 920 cam. Currently still have the stock tbi. It shows code 33 for high voltage at map. New MAP, IAC, EGR, and distributor. I have fogged the intake, tbi, and all vacuum lines with carb and choke cleaner with no change in idle.
Truck idles rough which I know is due to the stock tbi. It’s runs decent when throttling while in neutral or park, but when putting it under a load between 1500-2000 it pops back through tbi and shuts off. Any help as for which direction to look would be appreciated.

Rjudd80 said:

Truck idles rough which I know is due to the stock tbi.

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Nope. Your truck should idle fine. I have a Lunati 20080720 cam in WCJr, and my truck idled fine with the stock TBI, but as soon as you gave it more than half the gas pedal it fell on its face. Popping back through the intake sounds like a timing issue or a mechanical valvetrain issue.

Rjudd80 said:

It shows code 33 for high voltage at map

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Could download the manual for your truck, whatever that may be now with the swap.
The emmisions manuals have nice troubleshooting areas for all the DTCs.
Hopefully it's not mechanical...

Rjudd80 said:

It shows code 33 for high voltage at map. New MAP, IAC, EGR, and distributor.

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Put a scanner on it and watch what the MAP values are when idling up through WOT. If it doesn't change from ~30s up to high 90s you may have a wiring issue or a bad MAP sensor out of the box (that's been known to happen more often lately). Check your timing on the scanner too, if your MAP is pretty high at idle, try adding some timing and see if it comes down.

Rjudd80 said:

It’s runs decent when throttling while in neutral or park, but when putting it under a load between 1500-2000 it pops back through tbi and shuts off.

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That could be lean pops. What is your fuel pressure while your pops are happening? With that cam, you may need more pressure to deliver more fuel.

So I pulled the valve covers and plugs and tuned it by hand. Cylinder 3 exhaust isn’t making full travel and almost seems to “bleed off” slightly.

Rjudd80 said:

So I pulled the valve covers and plugs and tuned it by hand. Cylinder 3 exhaust isn’t making full travel and almost seems to “bleed off” slightly.

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This really isn't descriptive enough. 3 isn't making full travel? As in the rocker doesn't seem to be achieving full lift on that exhaust? You might want to look at that lobe. Did you do the springs it recommends?
That's quite a bit of cam

Hipster said:

Thi really isn't descriptive enough. 3 isn't making full travel? As in the rocker doesn't seem to be achieving full lift on that exhaust? You might want to look at that lobe. Did you do the springs it recommends?
That's quite a bit of cam

Elgin Camshaft E-920-P; Performance 2200 to 5400 0.480" 0.480" Hydraulic Flat Tappet for 1955-2002 Chevy 262-400

These camshafts offer better low-end torque, better fuel economy & improved engine efficiency. Fit's all your performance needs from oval track racing to drag racing, from street to light trucks.

www.performanceparts.com

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Hipster said:

Thi really isn't descriptive enough. 3 isn't making full travel? As in the rocker doesn't seem to be achieving full lift on that exhaust? You might want to look at that lobe. Did you do the springs it recommends?
That's quite a bit of cam

Elgin Camshaft E-920-P; Performance 2200 to 5400 0.480" 0.480" Hydraulic Flat Tappet for 1955-2002 Chevy 262-400

These camshafts offer better low-end torque, better fuel economy & improved engine efficiency. Fit's all your performance needs from oval track racing to drag racing, from street to light trucks.

www.performanceparts.com

Click to expand...

Cylinder 3 exhaust rocker doesn’t seem to be reaching full lift and seems to bleed itself back closed somewhat. I didn’t build the motor, I actually ordered a long block.

Rjudd80 said:

Cylinder 3 exhaust rocker doesn’t seem to be reaching full lift and seems to bleed itself back closed somewhat. I didn’t build the motor, I actually ordered a long block.

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The valve not achieving full lift is a different and independent issue then the tuning/computer/tbi issues. Brother I would have a look at that cam lobe before I ran it anymore. Think they got the springs right? Build sheet with part#'s? A flat lobe will definitely make one spit , sputter, and choke under load.