1999 Civic DX hot start problem
09-21-2015
#1
Registered!!
Thread Starter
Join Date: Sep 2015
Age: 34
Posts: 3
Likes: 0
Received 0 Likes
on
0 Posts
Rep Power: 0 
1999 Civic DX hot start problem
1999 Civic DX with D16Y7 engine.
Symptoms:
No check engine light or trouble codes on scanner.
Cold starts are fine but after engine up to operating temperature then stopped for 20 to 60 minutes, restarting requires much cranking. Eventually starts at about 200 rpm and slowly comes up to 750 rpm idle and runs fine, but idle speed sometimes erratic.
Diagnosis:
Fuel pressure, spark, injectors all ok.
When hot and not starting, turned key to run position and disconnected inlet air temperature sensor. This created a data "freeze frame" which showed that the engine coolant temperature to be -21 deg. F.
This meant the Engine Coolant Temperature (ECT) sensor was defective.
Solution:
Replaced ECT sensor with used one costing $5 at local auto recycle.
An easy operation requiring a 19 mm (or 3/4-inch) deep socket wrench.
Let the engine cool and be sure there is no pressure in the cooling system. Have the replacement sensor ready to install and you will only lose a couple of ounces of coolant in the process.
Verification:
Connected an ohm-meter and put the old ECT sensor in a pot of water on the stove. The resistance decreased as it warmed until at about boiling temperature, the resistance became erratic then infinite (open circuit).
Final Result:
Running fine without any more hot start problems.
Idle speed correct and steady.
##########
Symptoms:
No check engine light or trouble codes on scanner.
Cold starts are fine but after engine up to operating temperature then stopped for 20 to 60 minutes, restarting requires much cranking. Eventually starts at about 200 rpm and slowly comes up to 750 rpm idle and runs fine, but idle speed sometimes erratic.
Diagnosis:
Fuel pressure, spark, injectors all ok.
When hot and not starting, turned key to run position and disconnected inlet air temperature sensor. This created a data "freeze frame" which showed that the engine coolant temperature to be -21 deg. F.
This meant the Engine Coolant Temperature (ECT) sensor was defective.
Solution:
Replaced ECT sensor with used one costing $5 at local auto recycle.
An easy operation requiring a 19 mm (or 3/4-inch) deep socket wrench.
Let the engine cool and be sure there is no pressure in the cooling system. Have the replacement sensor ready to install and you will only lose a couple of ounces of coolant in the process.
Verification:
Connected an ohm-meter and put the old ECT sensor in a pot of water on the stove. The resistance decreased as it warmed until at about boiling temperature, the resistance became erratic then infinite (open circuit).
Final Result:
Running fine without any more hot start problems.
Idle speed correct and steady.
##########
09-21-2015
#2
If you think a good mechanic is expensive, try hiring a bad one
Re: 1999 Civic DX hot start problem
When hot and not starting, turned key to run position and disconnected inlet air temperature sensor. This created a data "freeze frame" which showed that
Thread
Thread Starter
Honda Civic Forum
Replies
Last Post
Xuhme
Cracked block early R18 Overheating
21
08-07-2023 03:40 PM
Jonnie.
Fuel, Oil, Cleaners & Other Maintenance
3
01-13-2019 11:21 AM
gabrown2
Mechanical Problems/Vehicle Issues and Fix-it Forum
2
04-11-2015 08:22 PM
