-88 not going into closed loop
Thread Starter
Instructor
Joined: Aug 2001
Posts: 217
Likes: 0
From: Finland
-88 not going into closed loop
Having somewhat high idle issue. Car starts up around 1300rpm and never goes below 1000rpm. I have done base idle adjustment to 450rpm as repair manual says, but still high idle.
I hooked up AutoXray and noticed that car never goes into closed loop. Then I remembered that one of the condition for closed loop is coolant temperature >135F. I compared the coolant temperature reading in my AutoXray scanner against corvettes own display and guess what? According to scanner my coolant never goes above 65F, but corvettes own display is showing normal 187F?! So does this mean that my coolant temperature sensor is bad or my ECM? Anyone any ideas?
I hooked up AutoXray and noticed that car never goes into closed loop. Then I remembered that one of the condition for closed loop is coolant temperature >135F. I compared the coolant temperature reading in my AutoXray scanner against corvettes own display and guess what? According to scanner my coolant never goes above 65F, but corvettes own display is showing normal 187F?! So does this mean that my coolant temperature sensor is bad or my ECM? Anyone any ideas?
Race Director
Joined: Apr 2003
Posts: 17,699
Likes: 1,667
From: moraga ca
Having somewhat high idle issue. Car starts up around 1300rpm and never goes below 1000rpm. I have done base idle adjustment to 450rpm as repair manual says, but still high idle.
I hooked up AutoXray and noticed that car never goes into closed loop. Then I remembered that one of the condition for closed loop is coolant temperature >135F. I compared the coolant temperature reading in my AutoXray scanner against corvettes own display and guess what? According to scanner my coolant never goes above 65F, but corvettes own display is showing normal 187F?! So does this mean that my coolant temperature sensor is bad or my ECM? Anyone any ideas?
I hooked up AutoXray and noticed that car never goes into closed loop. Then I remembered that one of the condition for closed loop is coolant temperature >135F. I compared the coolant temperature reading in my AutoXray scanner against corvettes own display and guess what? According to scanner my coolant never goes above 65F, but corvettes own display is showing normal 187F?! So does this mean that my coolant temperature sensor is bad or my ECM? Anyone any ideas?
Your coolant sensor for the ecm is bad. It is a different one that supplies the dash readout. I believe the ecm coolant sensor is in the front of the manifold.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Check it cold to make sure it's close to ambient. Make sure there's a good connection. Check the reference - 5 volts - yellow with the harness disconnected. Spend 12 Bucks on another one and simply plug it in. If it's now right, R & R the old one. If it's the same and the reference is good, it's the ECM.
