idle rough

[92astro]

did you change out the coolant temp-. sensor that is by the thermostat/front of intake manifold? on my 1992 van there is two coolant temp. sensor one for the computer and one for the gauge. the computer one is the 2 terminal one it is by the thermostat and the one for the gauge is in the drivers side head it is 1 terminal. the one i am gonna change is the one by the thermostat.

[Cobra]

to be honest i never even saw the one by the thermostat only the single lead one on the driver side head and the hayne manual never said anything about a second one....

[92astro]

yeah there is two sensors the one you are talking about is called the coolant temp. switch which is for your gauge that is why it did not change your idle. so the computer sensor has 2 terminal and screws into the intake manifold the lower intake manifold on yous.

[Cobra]

well i'm going to leave it alone untill i find the damn vacuum leak since it seems to be reading correctly the lines i was checking out yesterday were pretty cracked i was afraid they would fall apart in my hands

[Clamster]

Cobra, Just change the CTS already and be done with the rough idle deal. You can use rubber vacuum hose to splice into whats left of the hard black plastic vacuum lines.

[Cobra]

CTS feeds the computer and the computer will send that info trough the obd port right? well it reads right on at 188 no coolant movin', at 193 coolant flowing then temp drops back down to 188 coolant flow slows.

i think i have a vacuum gauge at my house somewhere just have to find it somewhere

[92astro]

has anyone replaced the coolant temp. sensor for the computer which is located by the thermostat housing? this is on my 1992 astro 2 wd TBI vin:z if yes do you have pics? please!!

[kings-x59]

yes, but no pics, sorry.
seems to me I had to pull the upper radiator hose to get to it. I can't remember if I used a deep socket with an extension or gummed at it with a wrench, but I got it out and back in without any special tools.

[GaryDee]

Hi - New here, but found your site looking for solutions for my 2005 Astro (searched thread). Kind of the same issues you stated on this thread (mine is explained below).

Question - I believe you guys are working on 87 and 93's ??? I know that mine is NOT TBI, but I wounder if some of your trouble shooting would apply. Any idea if the 2005's had two thermostates (gauge and engine)?

2005 Chevy Astor Van - 147K (got it with 120K and runs the same)

* Plugs, wires and after-cat CO2 sensors have been changed with no difference.
* Idles very ruff, like you can feel each cylinder firing, uniformly – not really “skippy” (almost shakes the steering wheel), except when cold.
* Warms to low idle.
* Starts on first click, seem to run "ok" down the road, but it's not smooth (still feel each cylinder firing)
* Inside the exhaust pipe is black
* If you rev-it up, let the RMP's drop, then rev-it again, you get a big puff of black smoke.
* Best MPV is around 15 combined hwy / city.

The fuel injection is NOT throttle body on this year and I can't find a Chilton’s that covers the 2005's. Any ideas??? – Thanks - GaryDee

[kings-x59]

Welcome to the Board Gary!
Not two thermostats, but two temperature sensors yes.
based on the description, I think your air fuel mix is running rich.
Rather than getting lost in this epic thread, what I suggest is starting a new topic, post your model year and a description of the symptoms. Bryan and I have much older year models than your do. The fuel injection systems are much different. There's a lot of very knowledgable guys here that can offer advice.

[GaryDee]

Thanks for the welcome! Yes, I meant to say "two sensors".

I will take your advice and start a new topic.

Thanks a bunch!

[Cobra]

i'm working on a 98 in this thread but my problem is different from yours. you sound like what happened to my old mans 95 van replacing O2 sensors fixed the problem according to our mechanic

[92astro]

okay i replaced my coolant temp. sensor for the computer it did not fix my rough/low idle when warmed up. so my next step is to replace my map sensor.??

[kings-x59]

Maybe. did you unhook the battery and clear the ecm to get it reset and "re-learn" the sensor data coming in? might give it a try...

[92astro]

how long should i disconnect the batt. for?? and when i open my air cleaner lid to check my air filter it smells like raw gas. and i did replace my air filter with a k n N air filter.