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problems again with my 99 crew

twoslo4five0

twoslo4five0

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so i took a trip down to clarkjw24s house this weekend and on the way home i stopped about 30 mins from him and got 8 gallons of 87 to top off to come home..when pulling out the gas station my truck started to stuble and run bad when u were just barley on the gas..wide open it runs fine but it idles oll over the place like 300 to 1000 rpm and its spitting and sputtering all the time under low accleration...here is the truck

99 chevy
5.7 vortec

its had in the last 4 months

new dist
new fuel filter
plugs and wires
and air filter..

any ideas where to even start??clarkjw24 pulled the fuel ressure and said it was right around 50 to 55 psi iirc
 
Was the check engine light on?

Sounds like the egr is sticking open.
 
Pull of the egr it may have a big chunk of carbon chit sticking it open. It could just be a bad egr as well. Quick to check.
 
cool.where is it located on that motor?is this a comon problem?truck has 160k on it so id imagine so.the codes havint been pulled yet as well
 
In front of the thermostat on the intake. Two ten mm bolts and the connector. If you are careful you can reuse the gasket.
 
Let me try a pic.

22072.gif
 
i dont think with the little i got mixed with the good it would have acted THAT bad...


i forgot to add when i limped back to clarkjw24s house it cut off on me and would not start again...he told me when it was cold it would crank just fine
 
Ok checked a few things, still no go.

At idle no problem. Put it in gear and under a slight load and it will damn near cut off. Its like the "fire" is going away. Then put it back in neutral or park and in seconds its idling fine. I can really smell the exhaust once it starts acting up. Don't know if it matters but the day before it started messing up a heater hose blew and sprayed on the engine.

I've checked:

fuel filter OK
fuel pressure OK, 60 at ignition, then drops 8psi while running (within spec)
crankshaft sensor OK (working anyway)
egr OK sealed and clean
 
The vortecs have a spider injection system under the top half of the manifold that gives problems.

Vortec 4.3L 5.0L and 5.7L engines from 1996-2002 have been found to be very sensitive to fuel deposits in the fuel injectors. The Vortec Central Sequential Fuel Injection system utilizes a unique fuel injector for each cylinder. The injector coil is located in the central 'spider' with a tube sending the injected fuel to a poppet nozzle in the port of each cylinder. These poppet nozzles require >45psi fuel pressure to open when working properly. If the poppet becomes contaminated or the fuel pressure is lower than specifications, the injector will not fire.​
 
Pull the codes and I and many others on here will tell you exactly what your problem is.
 
I know its a longshot, but I had nearly the identical thing happen to me on an 01 Dodge Ram 5.9l. Turned out to be a broken valve spring. It was running great, stopped and gassed up, when I started it back up - bang, it was running like ****. Took me a while, and setting it on fire (dont ask, lol) till I figured it out.

Have you checked compression on any of your cylinders?
 
I had a 00 crew with the 5.7. Mine was doing the same thing. I had a hairline crack in the dist cap. GM used cheap plastic caps in those years. Hope this helps.
 
I know you just tuned it up but look inside the dist. Also make sure the coil wire is not rubbing on the trans dipstick tube. Also pulling any codes will help.
 
check your catalytic converter if your running one,when they take a crap it can block off your exhaust, will run fine at idle, but not flow above idle
 
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