1999 1500 service engine soon light question

[jpacha84]

Last nite I was driving home from work( 1999 silverado 1500 Z71 4wd) when my truck started acting funny and boggin down and the engine was sputtering so i pulled into a driveway and shut it off. then when i went to start it,it wouldnt start so i went got some gas put it in it the it finally started up. Now my service engine soon light is on and its the first time that light has came on since ive owned the truck. any ideas what it could be? any help would be greatly appreciated

[MrShorty]

I believe OBD-2 has about 1000+ codes that list the possibilities. Without knowing what fault the computer is seeing, I'd propose that many of those as possible ideas. Best first step is to read the trouble code(s) from the PCM and start from there. Many parts places will read trouble codes for free in the hopes of selling you parts.

[jpacha84]

thanks . i stopped in to autozone and the guy pulled a code sayin multiple cylinders misfiring. He said that often times when you run out of gas itll throw that code so after i drive it around for a day or so to let the air get out of the system i can reset the code. hopefully thats all it is.

[jpacha84]

well i went outside and unhooked the battery for 30 minutes, went back out and rehooked it and the service light is still on. I really dont want to take it to the dealer and the truck seems to be running fine so does anybody else have any suggestions?

[99silverbullit]

you need to check for codes again and see if its the same one. is it running fine now?i know that when ive ran my truck low enough on fuel that the computer goes to limp mode resulting in taking away cylinder fire to a couple cylinders or something?? anyways its suppost to let you know to get fuel quick dumba$$!!this hasent ever turned on my service light though, you may have a different problem, either way its either fuel or spark.if its running fine now and hasent acted up with the same problem it may have been a fuel issue. have you checked the simple ****? fuel filter, regulator, fuel pressure?

[kcb37]

How long has it been since it's had a tune up.
Take your spark plugs out and see what they look like. Also look at your spark plug wires, if you have a multimeter you can check the resistance.
If you run out of gas it doesnt' take days to get the air out of the system. Everytime I do a fuel filter on mine, it fires right up.

[jpacha84]

okay ill check those out. just replaced the fuel filter a couple months ago so i dont think it would be that. may change the plugs and wires, its been a while so that could be it. ill take it back and have them check the code again and see if something else comes up. thanks for the help guys

[jpacha84]

ok just got back from autozone again. its showing P0300, which says the causes could be a fault in the ignition system or high or low fuel pressure. I bought plugs and wires to try it out but im gonna put the pressure gauge on it tomorrow to test it out. Anyone know what the pressure is supposed to be?

[blackbodylift]

Im not positive but im thinking its 9-13 psi

[kcb37]

If I remeber right it should be 55-60. Something right around their.

[jpacha84]

ok ill put the pressure gauge on tomorrow after i change the plugs and wires out. Im hopin it fixes it cause id rather not change out the other stuff because those look like they could get expensive. thanks for the help

[jpacha84]

well just put the pressure gauge on and tried it a couple times. I got right around 55 each time so that doesnt look like its a problem. Im gonna change the plugs and wires out next and see if that helps

[kcb37]

Did you just check running press?
I should have told you before but,
You should check with key on engine off. Shows the prime. That should stay close. It may drop, but it shouldn't be a lot. I think 5 or 10 psi in 10 mins.
And obviously check with the engine running.
If your fuel pressure drops with the engine off, check your FPR.
If that isn't the problem then, it could be leaking injectors.

[jpacha84]

I was in a hurry the other day and check it with the key on engine off, it showed 55. When it gets above 5 degrees here sometime ill go out and check it again with the engine running lol.. too cold out for me

[jpacha84]

well i put the fuel pressure gauge on today and started it up. didnt drop too much. i changed the plugs and wires out and turned it on and the light is still on. could one of the coil packs need replaced? thats what the guy at autozone said, how would i check those to see if they are?

[jpacha84]

the only thing that gets me is the truck is running fine and not missing at all so i keep leaving the battery off to clear out the computer but each time i re-connect it the service light comes back on. maybe im overreacting but ive had the truck for 3 years and its never came on. anymore ideas?

[kcb37]

If you have coil packs on it, then you can switch packs and see which cylinder missfires.
I wouldn't doubt that they need to be grounded either. Wouldn't hurt to make sure their mounting points are clean.

[jpacha84]

switch packs? do i need to go buy one and put it on each or is there a way i can test each one without buying a new pack? ill check all the mounting points out tomorrow.

[jpacha84]

EUREKA! well driving down the road after changin my plugs the light just went off lol.. thanks for the help guys, glad i didnt have to go fixing everything to find out what was wrong

[kcb37]

That is not what I meant. Kinda like I think I said before, If you have a misfire on #1 you can switch 1 and 3 plugs, 1 and 5 wires. See what you have a missfire on. Do the same thing with the coil pack. #1 missfire. Put #1 coil on 8 and 8 on 1. If 1 still misfires after all of that you have a bad ring, or something wrong with your valves. (could be a worn cam)
If the plugs fixed it, go with it for now. See if it pulls anything up again.