383 vortec running rough

99caddymess · Mar 29, 2023

Sorry if this has already been discussed, but I couldn’t find anything that pertained to my situation. So I have a 99 k2500 that I put a 383 vortec in. It is running incredibly badly. It shakes the whole truck at idle. I plugged a scanner into it and it is giving me “p0401 egr flow insufficient” “p1345 power train” “p0171 system too lean bank 1” “p0174 system too lean bank 2.” The egr code is because I blocked off both ends of the egr hose, my valve covers are too tall for it to fit. The lean bank 1 and 2 is because it has not been tuned yet I believe. The one that I believe is causing the shake and misfire is p1345 and ive been told it is due to timing. I have been messing around with the distributor for several days now and it has not helped at all. I’ve checked spark at cylinder 4 + 8, which was where the scanner said the misfire was. Both have good spark. I’m at a loss, any input would be helpful. Thank you in advance

Info about the engine:
383 eagle stroker kit balanced rotating assembly
Comp cams series xfi
Bpe muscle series 195cc sb heads

98 Nitro · Mar 29, 2023

Do you know how to set the cam retard? If not check out YouTube and get the dizzy in spec and see if it gets rid of that code.

99caddymess · Mar 29, 2023

98 Nitro said:
Do you know how to set the cam retard? If not check out YouTube and get the dizzy in spec and see if it gets rid of that code.

I do not. I will for sure check that out.

Schurkey · Mar 29, 2023

The P1345 is not likely the cause of misfire and poor performance. It should be fixed, but don't expect improvement unless it's enormously far "off" of spec, so that the spark is jumping to the wrong cylinder. The initial timing on Vortecs is NOT ADJUSTABLE, so the P1345 has NOTHING to do with timing. It's a code that relates to the synchronization of the cam sensor signal to the crank sensor signal. It allows the computer to determine which cylinder(s) are misfiring, when to (correctly) inject fuel for each cylinder, and prevents spark jumping to the wrong distributor cap terminal.

How old is the cap and rotor? Vortecs are notorious for distributor cap problems.

If you don't fix the EGR, or tune it out of the computer program, expect problems. WHY are you using "tall" valve covers? (Don't tell me it's due to "roller rockers", I've got rollers under two different SBCs, using standard-height valve covers.)

What is the fuel pressure at idle, and under load?

Poppet injectors, or the upgraded electronic injectors?

If #4 and #8 have good spark, but misfire, you may have a fuel or compression problem. What are the cranking compression pressures on #4 and #8, compared to a cylinder that doesn't misfire?

99caddymess · Mar 29, 2023

98 Nitro said:
Do you know how to set the cam retard? If not check out YouTube and get the dizzy in spec and see if it gets rid of that code.

So I checked out the cam retard and it is -16.1. I tried moving the distributor and it did not change at all, even after revving it up

99caddymess · Mar 29, 2023

Schurkey said:
The P1345 is not likely the cause of misfire and poor performance. It should be fixed, but don't expect improvement unless it's enormously far "off" of spec, so that the spark is jumping to the wrong cylinder. The initial timing on Vortecs is NOT ADJUSTABLE, so the P1345 has NOTHING to do with timing. It's a code that relates to the synchronization of the cam sensor signal to the crank sensor signal. It allows the computer to determine which cylinder(s) are misfiring, when to (correctly) inject fuel for each cylinder, and prevents spark jumping to the wrong distributor cap terminal.

How old is the cap and rotor? Vortecs are notorious for distributor cap problems.

If you don't fix the EGR, or tune it out of the computer program, expect problems. WHY are you using "tall" valve covers? (Don't tell me it's due to "roller rockers", I've got rollers under two different SBCs, using standard-height valve covers.)

What is the fuel pressure at idle, and under load?

Poppet injectors, or the upgraded electronic injectors?

If #4 and #8 have good spark, but misfire, you may have a fuel or compression problem. What are the cranking compression pressures on #4 and #8, compared to a cylinder that doesn't misfire?

Cap and rotor are the ones I got on the truck when I bought it 6 months ago. The poly lock rocker nuts are why I have to use a taller valve cover. I don’t have a fuel pressure tester or a compression tester so I wont be able to find those out. And I haven’t changed the injectors, so whatever came stock on these in 99 is what is on it. Sorry I can’t give you much information, I’m new to this.

99caddymess · Mar 29, 2023

98 Nitro said:
Do you know how to set the cam retard? If not check out YouTube and get the dizzy in spec and see if it gets rid of that code.

And what do you mean by “dizzy in spec”

xXxPARAGONxXx · Mar 29, 2023

99caddymess said:
Sorry if this has already been discussed, but I couldn’t find anything that pertained to my situation. So I have a 99 k2500 that I put a 383 vortec in. It is running incredibly badly. It shakes the whole truck at idle. I plugged a scanner into it and it is giving me “p0401 egr flow insufficient” “p1345 power train” “p0171 system too lean bank 1” “p0174 system too lean bank 2.” The egr code is because I blocked off both ends of the egr hose, my valve covers are too tall for it to fit. The lean bank 1 and 2 is because it has not been tuned yet I believe. The one that I believe is causing the shake and misfire is p1345 and ive been told it is due to timing. I have been messing around with the distributor for several days now and it has not helped at all. I’ve checked spark at cylinder 4 + 8, which was where the scanner said the misfire was. Both have good spark. I’m at a loss, any input would be helpful. Thank you in advance

To set camshaft (CMP) retard via adjusting the distributor, RPM must be around 1100 RPM. Not at idle. Of course, you will also need a scanner that can monitor CMP retard.

I need a scanner to set timing

Hey all. I searched "Vortec timing" but none of the results matched my needs. This is actually my '99 Suburban, but it has the old 5.7 Vortec. Anyway, when I got it, it didn't run. Found the gears on the distributor were worn off so the engine came out and a complete tear down/overhaul. It's a bu...

www.gm-trucks.com

98 Nitro · Mar 29, 2023

It is suppose to be +2 to -2 but does not throw a code unless it is at + - 13.
Schurkey is right about the caps though they are notoriously troublesome on these trucks.

Schurkey · Mar 30, 2023

99caddymess said:
Cap and rotor are the ones I got on the truck when I bought it 6 months ago.

Inspect them closely, or try a QUALITY replacement pair.

99caddymess said:
The poly lock rocker nuts are why I have to use a taller valve cover.

Get shorter polylocks, or modify the stock-height covers to clear the taller Polylocks. Get rid of the tall valve covers, which were invented to clear stud girdles, not Polylocks. Then the EGR can be made functional again, which reduces spark knock, minimized ignition retard, improves power and fuel economy.

99caddymess said:
I don’t have a fuel pressure tester or a compression tester so I wont be able to find those out.

Many parts stores have "loaner tools", those would be common items on the loaner-tool programs. You "buy" the tool, return it in 48 hours or less, and get ALL your money back.

The O'Reillys near me isn't even picky about the 48 hour time limit.

99caddymess said:
And I haven’t changed the injectors, so whatever came stock on these in 99 is what is on it.

The original, poppet-style injectors seem to be a high-failure item. They're generally replaced with the electric-injector upgrade kit.

Poppet-style injectors are sensitive to fuel pressure. Another reason to verify the fuel pressure at idle and at heavy load.

383 vortec running rough

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I need a scanner to set timing

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