High Idle, hard start when hot

[system-f]

I have an 88 LXI 5spd. This car idles around 1500rpm and is very hard to start when hot. When you first start it the idle is around 1200rpm and then slowly comes up to 1500 rpm and surges downward to 1000 rpm randomly. It is almost like the Idle air control valve is trying to work but stuck open. Ideas?

[system-f]

SO I dug a little deeper and it seems the place I purchased the car from has removed the check engine light bulb. THe ECU is throwing code 6 for the coolant temp sensor which causes it to go into failsafe mode = weird idle.

The question I have now is that on my thermostat housing there are two identical looking temp. sensors but one is green and one yellowish. Which one is the coolant temp sensor? The factory service manual doesn't seem to show both of these yet in pictures of 88 and 89 LXIs I see both sensors on the thermostat housing?!?!?!

[Demon1024]

it's the one on the right looking from the front of the car.
i had that same problem a while back but it never gave me any idle issues, may have another problem keep us informed!

[system-f]

The temp sensor problem is repaired and the car runs much better, not to mention someone had the timing at + 20 degrees BTDC! The computer is now getting pissy about one or two O2 sensors, but it is time for those to be replaced as well.

[GraniteLXI]

The hard start when hot is a 99% chance that your Main Relay is shot. I had the same problem in both my 89 LXi and my 91 Civic...it didnt want to start whenever the interior got hot. The main relay tells the fuel pump to turn on and when it gets old the heat from the interior desolders it and thus it fails to turn the fuel pump on. Common issue :)

The main relay is a bit buried, you can find it by taking out your coin box and looking below the heater vent on the driver's side under the dash.

[Demon1024]

i thought the relay was my problem at first too. a clogged air filter will do the same thing too, not wanting to start hot.

[system-f]

Thanks for your help, but I solved the problem. The place I bought the car from pulled the PGMFI bulb and several sensors were unpluged. The temp sensor seems to be required in order for the car to start properly while hot.