01 silverado 5.3 multiple cylinders misfire

[jlp09]

My 2001 Chevy Silverado 1500, 5.3 vortec, is misfiring on multiple cylinders while idling in drive. When I stop at a red light, some times, the misfiring is so bad that it noticeably shakes the whole truck like I'm in the middle of an earthquake. The hotter the engine temp, the worse it is. I bought a Diablo Sport Predator programmer/tuner/diagnostic tool to help find out what the problem is. The Predator has the capability of live data feed,a.k.a.- real time data. I plugged the Predator in and it says that everything runs good while driving, but when I come to a stop, idling in drive, like at a red light or stop sign, the Predator says my engine is misfiring on multiple cylinders, but as soon as I get rolling again, its fine. Also, when I give it gas to get rolling from a stop, it does the weird jumping/ hesitating/ stalling thing( I honestly don't know what to call it), but just for a second. The Check Engine light doesn't come on and the Predator shows NO trouble codes. I've replaced spark plugs and wires, throttle position sensor(TPS), BOTH knock sensors, cam sensor,and today I am going to put in a new fuel filter. Assuming the fuel filter isn't going to help, what is the problem? Please, someone help!!!

[jlp09]

I replaced the fuel filter and the IAC Valve (Idle Air Controller Valve) No improvement...

[mikel]

check valve springs.....

[Derekj]

Man, it almost sounds like you are stalling from low rpms

[Ill_Born_SS]

Ya got a EGR valve on that thing?

[gseales]

I am having the exact same problem with my 2001 Silverado 5.3. I just took it into the shop yesterday and nothing conclusive yet. The fuel pump was drawing more power than it should and gas line pressure does drop when sitting off. They did a smoke test fore vaccum leak, nothing found there. The computer had logged thousands of misfires and 1,3,5,7 but only a few on 2,4,6,8. I have only had mine chug at a stop about 6-10 times in the last year. Also I have only had the check engine light go on about 4 times in the last 6 months. They wanted to keep it for one more day to check a few more things. Not to keen on having the fuel pump replaced to the tune of $600-$700, but if that fixes the problem. Will post back what is found for solution.

[marcoengineering]

Sounds like an intake manifold leak/gasket, quite common on these truck especially of this vintage. There is a GM TSB on this exact issue, has all the symptoms you describe. Smoke test won't work, have to spray gasket area with something and see if idle improves. Hope this helps.

[JHowie315]

I have been having the same problem on my 2004 Silverado 5.3 but my misfires are mostly on cylinder 7 and sometimes #2. I currently have my injector slope set at -6. I have noticed that if I set injector slope back to -2 are higher the stalling goes away. So, maybe its just the trucks needing more fuel at lower RPM. I'm not sure if the injector slope affects low RMP or not but this is what I have found. To fix the lower RPM stalling I increased my Idle 100rpm, seems to work.