missfire when cold

[1992LaserRSAWD]

Ok here is my problem when it is less than 50 degrees outside and my engine is cold I am getting a really bad missfire. It will go away once the car warms up or if it is warmer outside. Have new plugs, wires, fuel filter, and air filter. Anyone know what could cause this?

 

[DSM90AWD]

Are you sure your not confusing a missfire with Fuel Cut?
Fuel cut is much easier to reach when the air/engine is cold.

 

[1992LaserRSAWD]

As you can see by my profile I have no mods and this is regular driving not racing

 

[Project ES]

Im having the same problem w/ my car. Itll start but it missfires in a few cylinders till the car is warmed up then it runs like nothing is wrong. Ive already fouled out a set of plugs because of the coolant temp sensor. Now that I fixed that it sputters till its warmed up. I know these cars arent spose to run like that. Ive done searches on this site under cold start, missfire, fouled plugs, and a few others and im not getting any answers. Why is the car running like this till it warms up?

 

[Dsm78]

Did you ever figure out what was causing your problem? I am having the exact same issue.

 

[DSM90AWD]

Things that may be the cause as change when car warms up:

- EGR System is defeated until car is warmed up via the thermo-valve. Thermo-valve is the brittle plastic/brass thinggie that screws into the thermostat housing which cracks over time and will screw up the EGRs operation a cold / warmed up car. EGR could also be stuck open / faulty. So Check/Replace both or run an EGR blockoff plate to eliminate it altogether.

- Coolant temperature sensor / wiring bad. Sensor that is also screwed into the lower thermostat housing and tells the ECU when the car is warmed up. Until this point, the car will run much richer and have lower timing.

- Boost leaks that may not be significant when car is running warm (leaner anyway), but during "richer AFR" cold operation, could put you over the threashhold of fouling plugs.