Hey everyone, well, I replaced the rotor and the distributor cap yesterday, and that fixed my rough running problem, I drove it around for over 1oo miles and it seemed great......at least for the time being. Well, this morning I go and crank up my car, and it is running like crap again, I didn't have time to look at it, and drove it to work, but it ran like crap, when I was at highway speeds, it seems to be lacking in power, but it runs smooth, but idling in another story, it is almost dieseling, feels like it is going to quit on me, etc... well, i pulled the alternator and got it tested at advanced auto and it is fine, it should be since it is less than a year old....i called my brother who has a blazer, and he told me to check the vacuum lines going out of the back of the intake manifold, which i did. Well, the hoses were on, but leaking.....the rubber is hard, and not like rubber anymore, and the hose keeps popping off...well, I pulled the hose off the little vacuum T-like thingy and it started running better....any ideas on what my problem is? My 4 wheel drive doesn't seem to be working either, so i think maybe vacuum is the problem. would that cause my vehicle to run like crap??? i know that is probably the reason my 4 wheel isn't working......thanks ahead of time.

Ryan

 

Check to make sure that the plug wires are still firmly attached to the cap. They have a tendancy to air lock and push off. This will cause intermittent misfires. I always use a small screw driver or ice pick slid into the boot while I push the boot over the terminal on the cap. This will allow the air to escape and lock the boot onto the cap nice and tight.

 

I have checked the spark plugs, but I will go out and do it again....I am going to pull them out individually and re-attach them and see if it helps....brb

 

plugs are fine, all the wires are tight and are brand new,......I still think it has something to do with the vacuum...maybe my EGR valve is stuck, or blocked some way....although it seams that the vacuum is working fine coming from the manifold....when i pull the vacuum hose off the back of the intake right there by the distributor, thing actually runs better...maybe one of the hoses is plugged or there is a major leak somewhere else. I will go through all of the hoses on Sat when i have a day off...."I just don't know enough about the vacuum system to diagnose the problem....I guess some research is in order.....thanks for the help, and any other suggestions are greatly appreciated!!

 

Make sure to check the wires where they attach to the terminals on the cap.

*EDIT* - didn't see your most recent reply. If pulling off a vacuum hose helps, then it is possible that you have a fuel leak into the intake... Is this a TBI (round air cleaner) or CPI (large aluminum intake)?

 

sorry i forgot to mention engine, 4.3 Vortec Vin"W" w/big aluminum intake, could it possibly be the EGR? maybe it is gummed up or something...

 

It is possible, especially with how prone these are for sticking open.

 

i was reading another post about EGR Cleaning, and someone said they had their GM Mechanic drive it, he said that the brake pedal was hard to press because the pintle in the EGR gets stuck, and doesn't give adequate vacuum....I am having that same problem...when the truck is slowing down, i apply the brakes and they don't work right some of the time...mostly when it is acting up the most. I will definately clean out the EGR, and post how is all goes...I am going to take lots of pics and post them on Photobucket Thanks for the help!
Ryan

 

Well, I got done with work today, started the truck and it was still idling rough, well, I drove home, about 10 miles, and now the truck is running like a champ....I am still going to pull the EGR and clean it out while i am changing the oil, and hopefully it is still working when I am done with it....wish me luck!
Ryan

 

Hey everyone,
Well, I got the oil changed, cleaned the EGR valve out, throttle body out...i even went and pulled the battery tray out and looked at the actuator...well, for some reason the actuator vacuum line was disconnected...I cleaned the end out cause there was dirt in it, reattached it and now my 4 wheel drive works!! The truck is running better than it has since I bought it, but it still has a slight stumble when it idles...not very noticable to anyone else, but I can tell.....the vehicle has now plugs and wires, new air cleaner, new cap and rotor, so now I guess it is the coil, or maybe a worn lobe on the cam or something to that effect...I may still take it in to get it checked out, I have GM extended warranty on it so they will fix it if is someting like that. thanks for the help.
ryan