9th (cold Start) injector help please
Safety Car
Joined: May 2001
Posts: 4,757
Likes: 1,647
From: Fairfax Virginia
Once again when I read about Corvettes running rich after all these parts were replaced. I go back and ask about the age of your Oxygen sensor. O2's are notorious with going rich when they break down. If you are driving around with a Older O2 sensor then That would be the very first thing I would look at. As they age their signal strength weakens and it starts to respond more slowly which causes issues for your ECM.
If your Oxygen sensor is okay then check you CTS to be sure it is reading properly. If it is telling the ECM that the engine is cooler than it really is the ECM will respond with extra gas thinking it is a cold start. This is what happened with old Carburetor engines when their choke was stuck "on".
If it fails the other way and is telling the ECM it is warmer than it really is the car will not get any cold start enrichment and will be very hard to start.
The CTS can be read with a Volt Ohm meter and there is a chart in the factory service manual that shows the temperature reading from the resistance reading you get from the sensor.
If your Oxygen sensor is okay then check you CTS to be sure it is reading properly. If it is telling the ECM that the engine is cooler than it really is the ECM will respond with extra gas thinking it is a cold start. This is what happened with old Carburetor engines when their choke was stuck "on".
If it fails the other way and is telling the ECM it is warmer than it really is the car will not get any cold start enrichment and will be very hard to start.
The CTS can be read with a Volt Ohm meter and there is a chart in the factory service manual that shows the temperature reading from the resistance reading you get from the sensor.
Safety Car
Joined: Mar 2003
Posts: 3,583
Likes: 504
From: Indianapolis IN
Finalist 2020 C4 of the Year - Unmodified
C4 of Year Finalist (stock) 2019
Once again when I read about Corvettes running rich after all these parts were replaced. I go back and ask about the age of your Oxygen sensor. O2's are notorious with going rich when they break down. If you are driving around with a Older O2 sensor then That would be the very first thing I would look at. As they age their signal strength weakens and it starts to respond more slowly which causes issues for your ECM.
If your Oxygen sensor is okay then check you CTS to be sure it is reading properly. If it is telling the ECM that the engine is cooler than it really is the ECM will respond with extra gas thinking it is a cold start. This is what happened with old Carburetor engines when their choke was stuck "on".
If it fails the other way and is telling the ECM it is warmer than it really is the car will not get any cold start enrichment and will be very hard to start.
The CTS can be read with a Volt Ohm meter and there is a chart in the factory service manual that shows the temperature reading from the resistance reading you get from the sensor.
If your Oxygen sensor is okay then check you CTS to be sure it is reading properly. If it is telling the ECM that the engine is cooler than it really is the ECM will respond with extra gas thinking it is a cold start. This is what happened with old Carburetor engines when their choke was stuck "on".
If it fails the other way and is telling the ECM it is warmer than it really is the car will not get any cold start enrichment and will be very hard to start.
The CTS can be read with a Volt Ohm meter and there is a chart in the factory service manual that shows the temperature reading from the resistance reading you get from the sensor.
Drifting
Joined: Jun 2018
Posts: 1,678
Likes: 229
From: Michigan
The CTS affects fuel, spark, and engine speed including adjusting the target AFR based off temp. So, if the engine is actually at 180*F but the CTS is saying its 50*F, you will be running rich in any condition, not just at cranking.
Last edited by KyleF; Jul 31, 2020 at 02:03 PM.
