No doubt this has to do with some computer issue. I have the above described Chevy. I posted something earlier on about how it has a "missing" problem. Since that post, I now only drive it around town. (To afraid to go much further with it...) Here's what bugs the bejezers out of me. Sometimes I can start it up and drive it to the store or my folk's house and it will run perfectly. Other times, I start it up and it runs like crap from start to finish. The one thing I have noticed is if I punch it, it will get up and go without any problems. If I start off from a stop like I'm supposed to, it will spit and sputter right along. I paid a station here to find and fix what ailed it. The machine, of course, only shows "random misfires". DUHH! They checked this and that and put new wires, plugs, cap, etc. and charged $350.00 for that tuneup. I came and drove it home and then to a store and low-and-behold, you'd have thought they hadn't even touched it. It ran just as crappy as ever. One day, I had a daddy-daughter-date-day. We were going to go to a town about 35 miles away. I took the Blazer (for some reason) and the dang thing drove _perfect_ all the way there, around town, and back again! So~ tuneup, lots of gas treatment, new fuel filter, other things "checked", and I'm still left wondering, Thanks for your previous responses, any other ideas would be greatly appreciated!
Maybe... Zig - I had an '89 olds with a V6 and my brother used to be a GM Mr Goodwrench mechanic. Whenever the battery was disconnected (computer shut down) it would act up. He recommended that I set the parking brake, chock the wheels, start the car, put it into drive and not touch anything electrical, brakes, radio, etc. just let it idle in gear for 10 minutes in order to reset the computer. I remember it taking care of the issues it had. It wasn't a Vortec engine, but it might be worth burning the fuel to see if it heals your problem.
Thanks, Larry. With this computer cr@p that they implant all over the place, -anything- is possible. One thing I forgot to mention is the main wiring harness had a meltdown inside the dash. It was repair by a genuine GM service tech for a mere $750.00. I've been wondering if maybe one of the wires he spliced might be causing this?
Try cleaning your maf sensor. I had a the same symptoms you have on acceleration. The dealer did a "cleaning" of my throttle body and told me the maf sensor was bad. They wanted 499 for a new one but got an aftermarket one. I cleaned the old one first and I noticed a difference. When I got the new one iT was night and day. This was on my camaro but your symptoms seem similar good luck to you.
Thanks, abg. I will check into this! Today, it has hit both ends of the spectrum. One trip this morning it actually seemed like it might just not make it. Later, coming home from my mom and dad's, it ran just like a Chevy is supposed to... Anyway, thanks again.
Cool site, Larry! Well, my Vortec doesn't have a MAF sensor, but what a great bunch of visual clips at that site! Great how to videos! I think I will replace my TPS and see what that gets me. I say this only because of the "If you punch it, it goes~ if you keep it at the low end of throttle it screws up..." (Mostly) To me, it is seeming like the sensor has lost it's sense for the minute variations of normal driving, but once you open it up past that point it is like, "OH, YEAH BABY!!! LET'S GO!!!!" Connection? Contact(s)? Electrical input problems at the worn out low end? We shall see. But thank you for the wealth of info the site links show! Great stuff!
1995 I put a new TPS on it today. No effect. Stomp on it~ it gets up and goes. Drive like you're supposed to~ phagidaboudit!
Have you checked the fuel pump? My sister's '98 C2500 was acting the same way about a year ago; sometimes driving fine, other times felt like it was about to stall when you tried to accelerate. Fuel pump was bad (for the 3rd time).
Sorry to hear you went through three! Actually, when I try to accelerate (like you would under normal driving conditions) it "randomly misfires" just like it does once you get to in-town cruising speed. If I stick my foot in it from a stand still, it will take off without any problem~ it's even burnt a little rubber... This _stuff_ has been going on for a long time now. It hasn't really worsened, and there are still those times when it drives oh-so-smooooth. Two things I know it DIDN'T need to cure it's ailment was a tuneup and a TPS. Thanks for the thought. Who knows? I've often wondered if there might be crap in the tank that screws with fuel delivery, but wouldn't punching it be a thing that really wouldn't work?
I would recommend doing a fuel pressure check to make sure it is not the fuel system. If the MAAP, TSP sensors are good then the next thing to check would be the O2 sensors. Along with all these tune-ups did you happen to replace the fuel filter? Lastly make sure you don't have any vacuum leaks.
hey buddy have you checked your purge solenoid. these are a common problem and can cause a lot of head scratching... it should be on your vacuum diagram.
