I have a 1996 gmc truck 4.3 v6 I replace my spakplugs and wires the coolant temp sensor. check engine light went off ran good for a couple of days now light is back on and truck doesn't want to start than when it does it runs really ruff till it is warmed up. any help would be welcomed

I have got the computer read at autozone and im getting to codes p0300 and p0420

Changing plugs and wires go hand in hand;not sure where the temp sensor fit in there. Were you running hot and you still are running hot ? Plugs,wires,and sensor ain't gonna cool it down.

truck doesn't run hot at all.. I replaced the sensor cause the read out I got before said it was bad/

so you had a scan and you have 2 numbers, did you ask the auto zone guy where the #s pointed to?

i got the print out saying it could be multiple things for each read out.. just trying to get some help from someone who might have had the same problem or have more knowledge. I cant afford to got to a garage cause im poor. so i have to do work myself

no they didn't help at all they just said what the print out says.. no help from them at all

@timvk - that fix you did a week ago wasn't quite it then. Not very helpful to you if all they do is give you a print-out you don't understand.Should have pointed you towards a misfire in cylinder 1 and a cat problem.

read out p0300 says ignition system fault-plugs wires or coil; vacuum leak injector fault or high or low fuel pressure..p0420 says catalytic converter defective failure possible due to number 2 3 or 4 engine misfire or running condidtion large vacuum leak seals, piston rings

p0300 definition says cylinder misfire detected random cylinders p0420 definition says catalytic efficiency low bank 1

where can i find a diagram of the vacuum hoses

Maybe in the engine compartment ( not in mine though) but I have seen some vehicles with it printed. That's where shop manuals are really nice to have. There is another poster on the site that always seems to have a handy web site address for all kinds of stuff (I'm new at this typing stuff ,I never had a Email address until a month ago when I was looking for some info on my car - I'm too tight to pay big bucks for a book;no matter how much I want one) ...Anyway I'll see if he can help with hose locations. In the mean time you might try google for a picture.

I've asked him and I'll get back or he might ( he gets around this computer pretty fast)

Here's what I was told to pass on; but no guarantees because shop manual info is nearly impossible to find for free ..........https://www.alldatadiy.com/

I have a book but its down at my parents 2 hours away. going to have to wait till Saturday to mess with anymore. I will comment back when I get it and figure something out thanks for your help so far

good hunting and you should find those codes & related procedures in there too. Just think how much time you could have saved if you kept the shop manual in the vehicle.

ok vacuum lines are all good no spark at plug wires could it be the ignition coil or mudule

update.. have not fixed anything yet.. I left my battery un hooked for about an hour hooked it up turned the key and it fired up on first try.. so I don't know what that means.. don't know if I checked spark wrong is why thought it had no spark or if the reset fixed that... does this mean my mass air flow sensor is bad

Any help?????

soo it would not start this morning went out just now and it started but it took awhile it would start to turn ove than stop.. than it would start than putter down and die finally got it to stat .. I need help don't have money to take to mechanic so I got to do it myself but don't wanna keep buy parts I don't need

easy way to get your manual for repair find the real name of the book at the store... then search for it with the word torrent after it... use yandex.com to search for that cause google censors.. check out YouTube for cleaning the cat or muffler... much easier when you see someone do the repair then attempt it too. trade secrets not so much a problem in mechanic-in these days, now i just gotta find a good techie that can teach me how to make cell phones work on other provider networks