I'll start off by saying this is my first post (other than an intro in that section) and I've fixed the problems, so the intent of this is to be a guide and/or warning to others with similar issues.
Short version: truck had jumpy idle when in drive with a warm engine freshly started (not a cold engine start), and poor fuel econ. Solution was to change plugs & wires and clean throttle body and MAF sensor.
Detailed Version:
Here's the symptoms:
Fuel economy got really bad, used to get 20+ mpg easily on highway. On a trip from FL to AZ, I got about 14.8 (with a strong headwind), which was unsat. So I changed my spark plugs and wires (used denso for both, got from rockauto.com), hadn't done this ever, so I knew it needed to be done. They were very worn, gap was way off. This bumped my fuel mileage up about 1 mpg highway, as shown on a trip from Phoenix to Las Vegas. So now I was at about 15.8 mpg highway, still not good, that's what I used to get city.
Next part of the equation: when I would start the car, with a already warm engine (didn't do this cold, I'll explain my theory as to why further down), then put it into Drive or Reverse, the RPM needle would bounce between about 400 rpm and 550. As soon as I started driving, it was fine. Hot engine that had been running for a while had no idle problems, same with cold just started.
After doing some research, I decided to clean my throttle body and MAF sensor. Hadn't done that since I bought it (had 80k then, has 160k now, so 80k at least having never been cleaned). It was nasty, so I scrubbed it out, sprayed some contact cleaner on the MAF sensor (didn't want to mess with taking it out). Now my idle is back where it should be: about 750 in neutral, 650ish in Drive/Reverse. The truck 'feels' happier, and seems to have more power like it used to.
Don't have a new MPG measurement yet, will post back when I do.
-Luke
Short version: truck had jumpy idle when in drive with a warm engine freshly started (not a cold engine start), and poor fuel econ. Solution was to change plugs & wires and clean throttle body and MAF sensor.
Detailed Version:
Here's the symptoms:
Fuel economy got really bad, used to get 20+ mpg easily on highway. On a trip from FL to AZ, I got about 14.8 (with a strong headwind), which was unsat. So I changed my spark plugs and wires (used denso for both, got from rockauto.com), hadn't done this ever, so I knew it needed to be done. They were very worn, gap was way off. This bumped my fuel mileage up about 1 mpg highway, as shown on a trip from Phoenix to Las Vegas. So now I was at about 15.8 mpg highway, still not good, that's what I used to get city.
Next part of the equation: when I would start the car, with a already warm engine (didn't do this cold, I'll explain my theory as to why further down), then put it into Drive or Reverse, the RPM needle would bounce between about 400 rpm and 550. As soon as I started driving, it was fine. Hot engine that had been running for a while had no idle problems, same with cold just started.
After doing some research, I decided to clean my throttle body and MAF sensor. Hadn't done that since I bought it (had 80k then, has 160k now, so 80k at least having never been cleaned). It was nasty, so I scrubbed it out, sprayed some contact cleaner on the MAF sensor (didn't want to mess with taking it out). Now my idle is back where it should be: about 750 in neutral, 650ish in Drive/Reverse. The truck 'feels' happier, and seems to have more power like it used to.
Don't have a new MPG measurement yet, will post back when I do.
-Luke
