2000 vortec 454 issue

I am at my wits end here. I have searched far and wide to find someone having my issue with no luck. I have a 2000 c3500 crew cab dually with vortec 7.4. Since I got the truck I've had the same issue. It will begin to cut up and misfire at 3k rpm and lack almost all power. Runs just fine up to that point other than slight misfire off idle. No check engine lights. I have replace plugs with delco iridium (the double platinum replacements) new delco cap and rotor, new coil, checked fuel pressure, plugged it into a computer to read all sensors and verified everything functioning as it should. I am at a loss here. Anyone had or seen this problem?

Ok, you checked the fuel pressure but what is it? Can you rig up a longer hose so you can see what the pressure is while it's under load and the problem is happening?

Unlike the Vortec small block which won't even start if the pressure is below about 55, the big block has a different injector setup and will start and run even if it's down in the 30's. It wants 58-62 psi.

You could have a pump issue, regulator issue, or even something stupid like the little vacuum line between the regulator and intake could be bad, was cracked and leaking on mine. What sucks is the intake is in the way of seeing it/replacing it.

Distributor could be worn, pretty common with some miles, you'd be amazed how bad this can get and you won't get any codes. Usually you would expect to see a P1345 cam/crank sensor correlation error but not always. Pop the cap off and try moving the rotor side to side checking for bushing wear on the shaft. If it doesn't move try turning the rotor either direction until it pops up a little then try side to side again while it's up.

If your distributor has been removed or loose ever for any reason, has the cam retard adjustment been done? Must be within +/- 2 degrees of zero while holding RPM's to at least 1000; you can be a whole lot off and not set a code but it will run like crap. And I'm not talking about timing; these can't be set with a timing light. Gotta have a scanner that is capable of showing the cam retard angle.

Richard

63 psi at idle. Reved to 3100 rpm where it breaks up at 59 psi. Load makes no difference

Also it has Bosch 5.0 injectors and was tuned for them (previous owner told me that) they are yellow injectors

Hmmm OK, fuel pressure is good, but your 2nd reply leads me to this: has the truck been like this since you got it, or this is a new problem?

If he sold it to you like that, I would start questioning if whoever tuned it had problems, if it had problems before the tune, etc.

If it developed the issues after you got it, I'd proceed on the ignition stuff I mentioned earlier.

Richard

Got it just like it is. He drove it from new Orleans to me here in Texas and said he had no issues. Now I really don't care if he was being dishonest, because I love the truck and daily driving is fine for me, its the fact I can't go over 65 mph that sucks and getting on the highway is a bit troublesome. We are going to run more tests this weekend. It has a ticking noise, but I think I've figured out it may be exhaust manifold fooling me into tearing into the valve covers and double checking all the lifters and rocker arm adjustment (or lack thereof).

Exhaust leak is a very real possibility so definitely rule that out first.

Yeah there's no adjustment on the valves; you torque 'em down (60 lb-ft if I recall but double-check that) and that's it. Once they're worn, they're worn. Comp Cams makes an adjustable kit that are some special studs 3/8" on one end, 7/16" on the other, little T-shaped spacers to slip inside the rockers to sleeve them to still fit. The locknuts included are kinda crappy and I ruined a few studs with my first kit and had to buy another, so beware on that. Kit's not bad only about $100.

Before you pull the valve covers be sure you get the gaskets first. I had hell finding a set in stock near me, really surprised me, considering I live in f'in Houston.

Richard

I pulled them last weekend and cleaned all the lifters with the carb cleaner trick, then dumped oil and poured rotella over them and put fresh 10-w40 in it, with a quart of rotella. Made no difference in the sound, but sure looked better in there. All lifters were quiet, oil flow was great before and definitely after cleaning. We cannot figure out the noise, its not coming from the timing chain. No metallic in the last 2 oil changes I've done.

did you ever figure this out? I drove the truck from new Orleans to Houston for the trade as this was my long time dually. I never had a single issue all the way to Houston driving 85-90 mph until I got gas at the shell close to your shop. just a few miles after it sputtered a little but it cleared up and didn't do it again. due to the street the shell was on, I never got over 45mph before getting to you. the ticking sound was exaust. the donut gaskets will leak and sound like lower engine. the injectors are bosch replacments from five-0 motorsports but they have been in there for years without issue. not sure really what to think on it but I know without a doubt I rolled to Houston hauling ass without a problem. shit I posted you a video on youtube of me driving it up to 95 on the interstate the Thursday before we headed to Houston. haven't been on this site in a long ass time so I missed this post..

Truck is currently parked and waiting for engine tear down. It has gotten much worse, the tick is much louder now and does not sound good at all. I will upload a video of it idling now and post.