carpedevus

alright so i just bought my 1991 short bed dlx with 180 for 1200 bucks... the heat didn't work so naturally the thermo was my first guess ... turns out the thing was upside down so i flipped it right side up, flushed the system and poof i got great heat... only problem now is when it heats up and runs for a few miles it slowly gets to the point where it wont idle.

any ideas what the hell is going on here? i checked all the breathers .. nothing is disconnected

thanks for the help

jono

93toyrunner2

Engine size?
Have you pulled codes yet? Download the FSM from the link in my signature, and open the part about diagnostics. Check for codes, follow the diagnostics charts with a good ohm meter and see what you find.

carpedevus

the check engine light isnt on or anything like that .. will it still throw codes?

93toyrunner2

Yes, they can be stored without the light staying on all the time.

carpedevus

well thats the strange thing is the light never came on in the first place... also i have a code checker but couldn't find the plug for it, is this thing obdII or no?

93toyrunner2

No, it is not OBDII.
See the "MFI System diagnosis" section and it will show you how to pull codes.

carpedevus

i was looking at those but couldnt find one for my body style should i just go off the one for 4 runners with the same engine? thanks for the help man

snobdds

Pulling codes will get you nowhere, there is not a system on the truck to correlate heat and idle issues.

I do agree we need to know what you have engine wise to help you out. Until you provide that info, anything is a shot in the dark, at best.

If I had to wager a guess, and at this point it's only a guess...it's your idle air control valve. It works off the temperature of the coolant to allow more or less air to the throttle body. If it’s staying closed, your effectively choking the engine of air…