Hard Cold Starting 86
Thread Starter
Safety Car
Joined: Dec 1999
Posts: 4,691
Likes: 1
From: Framingham MA
Hard Cold Starting 86
My car doesn't like cold starts. It take a bunch of spins before it catches and when it does catch it sputters for a few seconds. Once started it runs fine, starts easily. I read the service manual and haven't found anything wrong with the list of items the recommend. The fuel system is fine and doesn't bleed down. The ignition is recent (coil/cap/rotor/plugs/wires) The scan tool doesn't show anythting out of the ordinary. I am only really left with grasping at idea, such as rebuild the distributor and changing coolant temp sensor (though it reads fine on diacom)
Thread Starter
Safety Car
Joined: Dec 1999
Posts: 4,691
Likes: 1
From: Framingham MA
I unplugged it and the CS injector itself is a brand new NOS part, I probably have 175 miles on it, but I don't think its been fired (I have only started the car up in warm weather)
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
You can pull the CS injector connector and connect a DMM across it to see if it is getting power on a cold start up. The Tan wire from the CS injector should be at ground potential when firing and show +12 to +13 Vdc when not. If you don't see +12 Vdc on the injector when not firing, check the CINJ/CLU fuse in the auxiliary fuse block located behind the center of the I/P on the multi-use center.
I wouldn't replace the ECM's coolant temp sensor since it is showing correct temp. You might check base timing & dist cap condition as well as that of the plugs & wires.
I wouldn't replace the ECM's coolant temp sensor since it is showing correct temp. You might check base timing & dist cap condition as well as that of the plugs & wires.
Thread Starter
Safety Car
Joined: Dec 1999
Posts: 4,691
Likes: 1
From: Framingham MA
Originally Posted by 65Z01
You can pull the CS injector connector and connect a DMM across it to see if it is getting power on a cold start up. The Tan wire from the CS injector should be at ground potential when firing and show +12 to +13 Vdc when not. If you don't see +12 Vdc on the injector when not firing, check the CINJ/CLU fuse in the auxiliary fuse block located behind the center of the I/P on the multi-use center.
I wouldn't replace the ECM's coolant temp sensor since it is showing correct temp. You might check base timing & dist cap condition as well as that of the plugs & wires.
I wouldn't replace the ECM's coolant temp sensor since it is showing correct temp. You might check base timing & dist cap condition as well as that of the plugs & wires.
Thread Starter
Safety Car
Joined: Dec 1999
Posts: 4,691
Likes: 1
From: Framingham MA
An udpate. I put a test light on one of my injectors due a cold start. The ECM isn't pulsing the injector for a 3 or 4 secs, and then it dimly lights the test light for a another couple of seconds before it becomes bright. When it become bright is when the engine satrted to catch and sputter. I have a new ECM and my previous ECM did the same thing, so I don't think that is the problem. I guess I need to figure out exactly what tells the ECM to fire the injectors (I assume the pickup or Ignition module) in the distributor.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
The injectors should show a dim light on cranking as the RPM is low and so is the duty cycle.
After the key has been on for two seconds the only source of power to the fuel pump is through the oil pressure switch.
I would think the firing rate on the injectors would depend on RPM and air flow.
Also, if the cold start injector is firing there should be enough fuel to start the engine, though it might die right out if the other injectors are not firing properly.
I wouldn't mess with the dist at this time; I don't think that is the problem source. Have you check base timing with the EST connector open? Try setting it to 8deg BTDC to see if starting improves.
After the key has been on for two seconds the only source of power to the fuel pump is through the oil pressure switch.
I would think the firing rate on the injectors would depend on RPM and air flow.
Also, if the cold start injector is firing there should be enough fuel to start the engine, though it might die right out if the other injectors are not firing properly.
I wouldn't mess with the dist at this time; I don't think that is the problem source. Have you check base timing with the EST connector open? Try setting it to 8deg BTDC to see if starting improves.
Thread Starter
Safety Car
Joined: Dec 1999
Posts: 4,691
Likes: 1
From: Framingham MA
I did some research on the CS injector and it shouldn't affect my starting right now, it triggered by thermister and suposed to work below 35-40 degrees atleast according to the service manual. With a test light on it, it doesn't fire at all.
Melting Slicks
Joined: Aug 2000
Posts: 2,925
Likes: 3
From: Dover NH
Originally Posted by dgoodhue
I did some research on the CS injector and it shouldn't affect my starting right now, it triggered by thermister and suposed to work below 35-40 degrees atleast according to the service manual. With a test light on it, it doesn't fire at all.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by 65Z01
After the key has been on for two seconds the only source of power to the fuel pump is through the oil pressure switch.
RACE ON!!!
