Hellllpppp!!!!!!!!

[CoupeDevilln]

I have a 03 5.3 ext cab LS with 109k. Today i was on the highway had to pumch it to get around traffic, at high rpm I lost power and the engine light started flashing. Later that day I was driving and got on it again same thing happened. Then on my way back it just started missing out like crazy on normal throttle and the engine light was flashing again, at stop lights it was trying to die. I went to a parts store and ran codes, got MAS code and random misfiring code. So in the parking lot I replaced the $80 MAS. Didn't change a thing, cleared the codes and let it run till the light came back on. This time it was only random misfiring code.

So I limp it home, then check plugs and wires. They were original and had planned on changing them any way, but now only had plug money. New plugs ddn't help.

Well I continued to investigate, Noticed a noise that kinda sounded like a diesal engine from the center of the engine, used to only make this noise when it was cold. I sprayed carb cleaner all over the intake looking for leaks. No luck there. Please help! Need my truck for work.

PS I recently replaced the door speakers, not a bose system so I don't think ths maters but I don't know. Anyway yesterday got in my truck and the radio wasn't working. Could change stations but no other buttons worked and no volume. Later it was back and working fine, but the clock reset. No probs since.

[George C]

throw it in gutter go buy another. if a motor seems like its down on power you dont floor it to see if it goes away. this only creates more issue. its like if you have a knife in your leg, would you really keep pushing it in deeper?

[CoupeDevilln]

throw it in gutter go buy another. if a motor seems like its down on power you dont floor it to see if it goes away. this only creates more issue. its like if you have a knife in your leg, would you really keep pushing it in deeper?

Thanks Captain Obvious! The I didn't get on it again to see if the problem was still there. I had to get over a lane on the highway and needed to get around someone. When it started missing I let off right away.

[NITROUS]

Cold start the engine and see if ant of the plastic intake runners are hotter than the others. If so, pull the valve covers and see if a spring is broke or possible valve stuck. Do you have any engine mods like a cam swap?

[Madd Maxx]

The flashing CEL means the PCM thinks the misfire is severe enough to cause damage to the cat. For starters, check your fuel pressure and the coil pack connectors. Can you measure the plug wire resistance? The factory wires should be between 400 and 500 ohms. Were any misfire codes set for individual cylinders? IOW, can the misfires be isolated to one bank? What was the MAF code?

[GasGuzzler]

+1 ^^^

Need codes. My wires ohmed at 900+!! New ones 40 or so. My vote is fuel pressure but that would not explain the noise.

[JHART]

Had a buddy that just recently had a problem that sounds just like this. His wife drove his truck out of gas. Next day he went and got the truck filled it up and it ran like s***. Idles fine but when you get into the peddle it sounds like its missing and sluggish.

Changed the fuel filter and all was well. When she ran it out of gas she picked up all the sediment on the bottom of the tank and clogged the filter.

Good Luck!

[AFSP1211]

I don't know about the Diesel sound, but I'd say fuel pressure regulator. That's going to be my answer for everything from now on. Seriously though. Mine did the exact same thing when mine went out. (exept for the diesel sound). That might explain the misfire codes that I was getting along with the flicker at high RPM and wanting to die out at a stop. Mine was difficult to start when my FPR was actually toast. And when it did it ran like a pile of elephant poo

[NITROUS]

I don't know about the Diesel sound, but I'd say fuel pressure regulator.

The diesel sound is the only reason I mentioned checking the runners for heat. Mine made the same sound, misfire code and I had broke springs. I drove it home easy and was lucky enough the retainer didn't come off. It could be almost anything so an easy start would be to feel the runners, check fuel pressure and see the misfore codes which would bep1314, P1314, P1315, P1380 or P1381 if you say misfire detected.

[GasGuzzler]

What codes are those Lance?