TBI problem - no high idle

[ScottH]

I have a 87 R10 with a 305 TBI engine that has about 130k on it. When I got it the idle would stay high and it ran kinda rich. After searching on the board I replaced the CTS and thermostat. That solved the high idle problem, however since then I've noticed it does not have a high idle when cold. Also noticed that when I put the AC on there is no increase in engine speed (AC not working correctly yet, cycles on/off). Also just replaced both injectors with no change. It does run fine at idle, just no cold high idle.

Was thinking of replacing the IAC but wanted to get some opinions first.

Any suggestions or info is appreciated.

Thanks
Scott

[ScottH]

anyone?

[Krwright]

Go with the iac it's a common problem a lot of people don't notice
Posted via Mobile Device

[Desert1957]

Originally Posted by Krwright

Go with the iac it's a common problem a lot of people don't notice
Posted via Mobile Device

X2
Clean it , reset it or replace it.



If you take it out DO NOT force the plunger all the way in against the motor.

Desert

[grs]

Originally Posted by ScottH

I have a 87 R10 with a 305 TBI engine that has about 130k on it. When I got it the idle would stay high and it ran kinda rich. After searching on the board I replaced the CTS and thermostat. That solved the high idle problem, however since then I've noticed it does not have a high idle when cold. Also noticed that when I put the AC on there is no increase in engine speed (AC not working correctly yet, cycles on/off). Also just replaced both injectors with no change. It does run fine at idle, just no cold high idle.

Was thinking of replacing the IAC but wanted to get some opinions first.

Any suggestions or info is appreciated.

Thanks
Scott

What is the CTS? My 87 runs a little slow with the AC on and in gear.

[grs]

Originally Posted by Desert1957

X2
Clean it , reset it or replace it.



If you take it out DO NOT force the plunger all the way in against the motor.

Desert

How do you clean, and reset the IAC? And does it have a gasket or O ring where it mounts, and where can I get a new one if I need one?

[Desert1957]

Originally Posted by grs

What is the CTS? My 87 runs a little slow with the AC on and in gear.

Originally Posted by grs

How do you clean, and reset the IAC? And does it have a gasket or O ring where it mounts, and where can I get a new one if I need one?

CTS is the "Coolant Temperature Sensor" its job is to tell the ECM (engine Computer) when the engine is warmed up, when cold the engine runs on fixed preset parameters in the ECM or "Open loop" .

After warm up or almost warmed the idle will come down . The computer starts using inputs from the O2, map throttle position sensor,and coolant sensor to adjust timing and fuel mixture "Closed loop"

You can clean it by lightly wire brushing it after removal , spray some carb cleaner in the throttle body hole where it screws in. It does have a relearn feature , but you will need to re-install it and drive the vehicle for a few miles.

Does not take a regular o ring because of the heat from the engine. unless its cut or broken you can reuse it.

Desert

[grs]

Originally Posted by Desert1957

X2
Clean it , reset it or replace it.



If you take it out DO NOT force the plunger all the way in against the motor.

Desert

What do you mean don't force the plunger all the way in against the motor?

[Desert1957]

Originally Posted by grs

What do you mean don't force the plunger all the way in against the motor?

this part while you have it out of the throttle body is an electronic motor that is controlled by the computer. while the engine is turned off it stays fixed in the position it was in while running.

If you mishandle it, you can cause problems. Just sent you a warning in a previous post. If you must remove it, just handle it carefully. Don't panic.

Chances are it not that dirty anyway. OK?

Desert

[grs]

Originally Posted by Desert1957

this part while you have it out of the throttle body is an electronis motor that is controlled by the computer. while the engine is turned off it stays fixed in the position it was in while running.

If you mishandle it, you can cause problems. Just sent you a warning in a previous post. If you must remove it, just handle it carefully. Don't panic.

Chances are it not that dirty anyway. OK?

Desert

Thanks

[grs]

Originally Posted by Desert1957

CTS is the "Coolant Temperature Sensor" its job is to tell the ECM (engine Computer) when the engine is warmed up, when cold the engine runs on fixed preset parameters in the ECM or "Open loop" .

After warm up or almost warmed the idle will come down . The computer starts using inputs from the O2, map throttle position sensor,and coolant sensor to adjust timing and fuel mixture "Closed loop"

You can clean it by lightly wire brushing it after removal , spray some carb cleaner in the throttle body hole where it screws in. It does have a relearn feature , but you will need to re-install it and drive the vehicle for a few miles.

Does not take a regular o ring because of the heat from the engine. unless its cut or broken you can reuse it.

Desert

Is the coolant temperature sensor the same as the temperature sender unit? If not where is it located?

[Desert1957]

Coolant Temp Sensor (CTS) is on the intake manifold next to the thermostat housing. Gauge temp sender is on the left cylinder head (driver's side) between number 1 and 3 spark plug holes.

Desert