89 Corolla SR5 acts like throttle is sticking - Toyota Nation Forum : Toyota Car and Truck Forums

tojones · 05-10-2011, 07:19 PM

I have an 89 SR5 and the car suddenly acts like the throttle is sticking. The car started fine and idled normally and drove fine for the first mile or so, then it reved to 3K to 4K and held steady at that RPMs. I can accelerate beyond that speed but the car doesn't drop down to normal idle speed. I've checked the throttle cable and pedal and found nothing wrong there. I also sprayed all the linkages on the carb with WD40. I don't know if it's related to this problem but lately the car diesels when I cut it off. I've replace the AAP diaphram so I don't think that's the problem. Any advice or good places to start troubleshooting would be greatly appreciated.

Donald · 05-10-2011, 08:10 PM

Look for a broken vacuum line. Maybe bad brake booster.

tojones · 05-10-2011, 08:20 PM

A bad brake booster would cause the high idle? The brake pedal felt normal even after the car started the idling issue. How can I check and see if the booster is bad? I've taken a quick look at my vac. lines and I didn't see anything wrong. I'll have to take a closer look at them.

eberbs1 · 05-11-2011, 12:52 AM

take the air filter off and look down the carb and see if the secondary's are stuck open.
happend to me while i was driving and pulled upto a light and the car sat at 2k. Turns out it was a metering gasket in the carb that blew out and was jamming the secondary open.

90 GP · 05-11-2011, 06:05 AM

Check the throttle positioner on side of carb. It has two vac lines attached and is designed for two speed settings. One for a lower speed when accessories get turned on and a second setting designed to hold throttle open slightly on deceleration. Sounds like the second setting is getting engaged probbly due to a vac leak. Also check to make sure choke is fully releasing. Look at carb when warmed up to make sure butterfly is open all the way. Look at fig 1 in link for throttle positioner location on carb.

http://toyotadiesel.com/photopost/da...l_overhaul.pdf

tojones · 05-11-2011, 02:01 PM

Thanks for the advice, I started the car today without touching the throttle and the car immediately started revving to 3K RPM. This made me go back to the linkage. I checked the linkage one more time and found it was stuck open about a 1/16 of an inch. I lubed all the linkage again and cycled it close to wide open several times. Started the car and it runs fine. Now I know where to go when these little grimlins creep up with the old Corolla y'all are Toyota experts.

Donald · 05-11-2011, 04:22 PM

Quote:

Originally Posted by tojones

A bad brake booster would cause the high idle? The brake pedal felt normal even after the car started the idling issue.

The brake booster works with vacuum, so a torn/leaking diaphram or rusted through case could be a source of a vacuum leak.

The fact that the brakes feel good is a good sign that it is not the booster, but not a guarantee.
To be sure, pull the booster vacuum line and plug it. If no change, then that is not it.