misfire 2000 gmc 5.3

[joakwin]

the truck has about 82k miles on it now, i have had the truck since 74k miles, i have ext warrenty on the truck
i just took the truck on a long road trip, from new mexico to san diego to seattle and then it was put on a boat and is now in anchorage ak

the truck didn't start to misfire to when i was in seattle, but the 1st time it did it was when i was passing the san fan area

at 1st i was thinking it was a tranny problem because it only happened at freeway speeds
but when i got it up here in alaska with me, it started to miss at idle also
so then i knew it was something else besides the tranny

it missfires at idle and when im driving, doesn't matter what speed im at

ive been looking around online at different sites trying to figure out what could be the problem but nothing really yet but lots of different ideas

this morning i noticed a sound coming from my exhaust, not the reg sound but like metal on metal hitting sound
witch could be the cats
i heard their is a 80k mile warrenty on the cats from the dealer, wicth would suck for me in my case having 82k miles

theirs no computer codes right now, and even when it missfires nothing comes up for the few secs that it missfires

i work in vehicle maints so if their is any problems i can take care of them myself for the most part

anyhelp i'll can give me

thanks

ps im gonna take it to the dealer saturday and have them take a look at it

peace

[Z71sierra7787]

i had the same problem and was worried with the misfiring but alls it was was a loose sparkplug wire that i didnt get hooked back up good after working on some stuff, it looked ok but wasnt getting a connectection so check that, im also dealing with the broken cat issue and if its rattling under load then thats prob it. hope you get it worked out

[RedHeartbeat]

broken cat problem is usually due to something else being screwed up.

[joakwin]

i called the dealer the other day and i have it set up to take it in tuesday at 7:30am,
tonight the truck started to miss like crazy, when i step on the gas pedal it won't do anything and it started to back fire alot and was idleing at 400rpm and wouldn't do anything when steping on the gas

and its running rich like crazy and a check engine light came on tonight,
so when i take it to the dealer they should be able to find out whats wrong with it faster,
i don't own a code reader so i don't know what code its showing right now but i'll find out


the exhaust sounds like i have a really high lift cam in the engine but its stock, to give u guys somewut of a idea on how bad its missing

peace

[RedHeartbeat]

Check you engine oil level and transmission fluid levels first. Check all your fuses. Check the water temperature lead at the engine block for bare or shorted wires. It sounds like the truck has gone into limp mode and is dumping raw fuel into the cylinders to cool the engine. Most auto parts store will have a code reader that they will scan your vehicle with for free.

[joakwin]

yeah i do need to do a oil change, im right at 3k miles since the last change, im running mobile 1 oil in the truck

its got new plugs and wires and i made sure they were gapped at .60 like what the trucks says it should be at


the fuel filter has 3k miles on it also, changed it the same time as the oil

thanks for the help

today the truck died a few times on me when i would come to a stop light

i already checked the tranny oil a few days ago and it was red and the level was good, im gonna go and check the fuses and engine oil levels right now

peace

[RedHeartbeat]

Usually the biggest problem is a dead or dying fuel pump. The pressure gets low and then the fuel injectors no longer spray the fuel in, it streams in and won't vaporize. That will cause the rich condition and running rough as a cob. If you have access to a fuel pressure guage I'd definitely check that out.

[joakwin]

i had the fuel pump changed when i was in San Diego by one of the dealers their, beg of nov sometime be4 the 8th

when i made the drive from new mexico to yuma az, the fuel pump started to make a buzzing sound, and the next day when i was leaving it stopped but when i got into san diego it was their again and after that everytime i started the truck it was their, so driving the truck up to seattle i didn't want it to go out so i had the fuel pump changed out be4 leaving san diego

the truck didn't start to missfire to i was in seattle so i put it on the boat to ship it up to alaska and when i got it up here the truck wasn't missing and then it just started alittle bit at idle and now its missing all the time

im taken the truck to the dealer tomorrow morning,

i also changed out my parkbrake pads when i was in seattle at my grandparents house,

the coolant levels are fine and they are good to -60, just tested that a few mins ago

didn't see any bad wires off the coolant sensor and the oil level is good

thanks

[RedHeartbeat]

They'll test the sensors for you while diagnosing it. Could be a bad MAP or TPS sensor or the new fuel pump was crap.

[joakwin]

if it was a bad map sensor could i disconnect the wire that goes to it, shouldn't that make a differents and tell if the map sensor is good or not?

anyways its going to the dealer tomorrow morning and they'll let me know whats wrong with it and let me know if its covered under warrenty or not befor ethey do anywork

i don't know what the problems is but i bet that its something dumb and probably ez to fixes,
my wife wants me to get a obd2 code reader to be able to troubleshoot this thing myself next time

if its the map sensors or tps sensor then i'll change it out myself

peace