1996 LGT Accelerates by itself, starts and idles hard.

[SteelFlounder]

Hey everyone, new to the forum here. First post.

 

I've got about 139k on the motor, and it was kept in pretty good condition when I got it, and I've kept it well maintained since. It's an automatic (unfortunately). The problem I am having now occurred to me about a week ago when I started my car, put it into drive, and immediately had to slam as hard as I could on the brakes as my car tried to ram my boss's car which was parked in the spot in front of me.

 

When I started my car it took a couple more rotations than usual. I let it idle for about 5 seconds before shifting out of park. Sometimes it does it, sometimes there's just a little extra pulling forward.

 

From what I can tell, something is causing my engine to randomly/unstably rev for a few minutes after startup. No significant temperature changes between days when it runs almost fine and days when I have to sit for 10 minutes so that I can drive without fear of scooting into an intersection before I can press my brakes hard enough to stop.

 

TL;DR

 

After startup engine sometimes:

-Stalls

-Goes between revving to 3-4k or almost stalling at 300-400 rpm

 

Can take up to ten seconds turning to starter over to start. A couple of times I had to pump the gas pedal (even though it's fuel injected, I know) to start.

 

My first instinct is a vacuum leak on a hose or the gasket, but I've heard of "older subarus randomly accelerating" almost like it's a common problem. I wanted to check if anyone knew what to look for first before I spend my entire day off searching for a leak, when it's actually a MAP sensor.

 

Thanks in advance! =)

 

PS- Searches on google and this forum yielded no results, but I did look for about 30 minutes first. =\

[Osei]

Check the throttle cable. first.

 

O.

[Stang70Fastback]

My RPMs would literally jump all over the place from idle to 4k while driving, and it turned out to be a bad thermostat, so that's something you might want to look into as well.

[SteelFlounder]

The thermostat thing is odd. Thanks for the suggestions guys, I will check those two things first. =)

[SteelFlounder]

I filled the gas tank up and it didn't do it. Is it possible that crap inside the bottom of my fuel tank could've caused it? That's what my father suggested when I visited him today... It ran smoother and didn't jerk around the rpms as much. I couldn't find any loose vacuum hoses and my intake wasn't cracked. I used a can of starter fluid to look for vacuum leaks as well with no luck.

[ultrasonic]

Random ideas:

 

- could be a weak and/or flaky fuel pump

- IAC- idle air control could be sticky or failing

- coolant temp sensor could be intermittent

 

Is the Check Engine Light on? If so, pull the codes and report back.

[SteelFlounder]

Can't believe I didn't update you all. Thanks for the help ultrasonic. I replaced the ECT (just picked on up at advance auto) and the problem was fixed immediately.

 

I cannot remember if it threw an OBD-II code or not.

 

If you have this problem expect 30 minutes to replace it. Also, do yourself a favor. Remove the airbox and air hoses. It will save you a big headache. I just loosened the hose clamp on the throttle body and rotated the intake duct straight up and out of the way. Don't forget to re-tighten it though!