5.7 vortec troubleshooting

shelby27604 said:
You said the dizzy looked great, have you pulled it out and checked the gear? I seem to remember there being some bad dizzy (soft gears) out there a few years back. Might also be a worn gear on the cam side.....I can't remember if it was overly hard gears eating cams, or overly soft gears.
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Dizzy gears looked new we pulled it when timing it to make sure! It’s billet dizzying new cap and rotor
 
rodney eppes said:
Don't mis-understand. The Autozone pump was fine, & no power problems. It was the china tank pressure sensor, on top of the pump, that had the wrong Ohms. The sensor is separate & interchangeable. Just plugs into a hole. After I put the AC Delco sensor on, it stopped throwing emission codes.
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I’m going on the guess these china pumps don’t have enough volume, I need to do a volume test to double check this for this pump not positive on if fuel regulator was replaced when spiders were upgraded but I’d sssune so and fuel pressure held for awhile after new pump went in if I recall!
 
Sorry, I haven't read through everything, but have you checked spark quality? Are you 100% on the plug wire order?
I use a short piece of rubber hose between boot and plug, and a test probe connected to the negative terminal on the battery, a good spark will jump the gap made by the hose, when you touch the test probe to the hose, the spark will arc. through the hose. This is a good way to check the quality of each cylinder....if you jump the spark (shut down the cylinder) and the idle doesn't change, you have found a cyl. with an issue.
 
fyi, I only test 2 cylinders at a time, shut the truck off, move tubes, repeat.

Yes, you can pull the plug wires, but this is a real time test AND....most importantly, if the energy isn't discharged (grounded) it can damage the ICM....as an added bonus, no worries of spark grounding through you, I know we have all taken 50k volts a time or two, it's never fun.
 
I’ll check spark next picked up a fuel pressure gauge and key on engine off pops to 60psi then to 54-55 when I start the truck pressure sits at 50psi... I got the Bosch tester with pressure relief can that be used to measure volume of the pump by chance?? I’m guessing not but figured I’d ask lol
 
shelby27604 said:
Sorry, I haven't read through everything, but have you checked spark quality? Are you 100% on the plug wire order?
I use a short piece of rubber hose between boot and plug, and a test probe connected to the negative terminal on the battery, a good spark will jump the gap made by the hose, when you touch the test probe to the hose, the spark will arc. through the hose. This is a good way to check the quality of each cylinder....if you jump the spark (shut down the cylinder) and the idle doesn't change, you have found a cyl. with an issue.
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Def 100% on plug wire order 18436572 has been numbers I’ve known since a young age but timing on these vortecs are electronic, I hate i can’t tune without a computer.
 
Check fuel pressure don't just change the pump!!

Diagnose . Repair . Verify .

You're throwing money and time away doing it any other way.

Did you do a power balance test? What is the fuel pressure under load and at idle and under load WOT? I've been around vortec 350s.. grew up working on them, for ten plus years. The dizzy caps can fall internally with no visible failure. Check rotor button under the tab that contacts the center pin for black marks, also look underneath for black arc marks. Have the ignition module tested, if you change the module, change the coil or you'll have repeat failures.
 
a_kelley said:
Check fuel pressure don't just change the pump!!

Diagnose . Repair . Verify .

You're throwing money and time away doing it any other way.

Did you do a power balance test? What is the fuel pressure under load and at idle and under load WOT? I've been around vortec 350s.. grew up working on them, for ten plus years. The dizzy caps can fall internally with no visible failure. Check rotor button under the tab that contacts the center pin for black marks, also look underneath for black arc marks. Have the ignition module tested, if you change the module, change the coil or you'll have repeat failures.
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Ok haven’t done a power balance test cap was replaced when I had it timed end of last year I’ll pop cap to check rotor tho! Throwing exhaust back together and going to drive it while watching fuel pressure my pressure at axle is 50 psi tho haven’t changed the coil either or module so they could be culprits!
 
Power balance is best done with a digital tech 2 or even tool. You can get a knock off DT2 for about $250. Not sure if it includes can-di module for 07+ though. Still a good deal without it.
 
This is what I seen in my cat so it looked great imo...
DB051AC1-0517-45A9-A4E1-0AE59C3D1258.jpeg
This is actually what was happening...
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so that def fixed my slow ass acceleration through 1,2 gears and on hills it now down shifts and I’m not passin over 2500rpm to run 55/60 on big inclines. It’s still not got that 350 push ya back feeling unless I’m past 2nd gear tho but 4.10 gears makes diff, in 4th and it drops to 3rd to pass and throws ya back a little but the trucks driving better than ever. Now to order two new cats and a muffler bc I can’t do this loud exhaust crap lol fuel pressure still alarming that I’m under 60 psi driving but I’ll work in that now since my main issue is solved!
 
You could always reuse the "resonators" you made with new mufflers & be g2g. There is a simple fix for p0420/0430 codes. If it's got any real high miles on it, the engine may consume oil and cause the same issue down the road.. also if it's running pig rich will cause premature failure as well.
 
a_kelley said:
You could always reuse the "resonators" you made with new mufflers & be g2g. There is a simple fix for p0420/0430 codes. If it's got any real high miles on it, the engine may consume oil and cause the same issue down the road.. also if it's running pig rich will cause premature failure as well.
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No codes on it from gutting cats this far, has 189k on it also gonna look into just using mufflers but I’m not big on the super loud exhaust any more 10 years ago I’d run straight headers and love it lol pulling up on job sites sounding like a top fuel dragster isn’t cool at 35... haha
 
C.Berry said:
No codes on it from gutting cats this far, has 189k on it also gonna look into just using mufflers but I’m not big on the super loud exhaust any more 10 years ago I’d run straight headers and love it lol pulling up on job sites sounding like a top fuel dragster isn’t cool at 35... haha
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I'm a quiet exhaust guy as well. Quieter the better. If you get a decent on grade muffler, it won't be much louder than stock. And yes the motors do like to have just a little bit of back pressure, which an oe style muffler will provide.. plus if you install a tail pipe, even if you ran a glass pack, the sound would be directed out & away any how.
 
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