Drivability problem when cold

[opfor2]

My 1990 stock Blazer started acting funny when the engine is cold. When cold the engine starts and idles fine and it will drive fine but when at a traffic lite and the light turns green and I give lite throttle she seems to hesitate and stumble. press the throttle harder she moves along. Sometimes as I'm accessing the freeway on ramp she seems to totally cut out but when I press the throttle more the truck runs ok. I replaced the fuel filter a while ago, new MSD plug wires, rotor, and cap. I have noticed that this problem only occurs when the truck is cold. It runs fine when hot any ideas? BTW there are no codes in the ECM, code reader shows nothing unusual that I can see. Any help would be appreciated.

Dan..

 

[broncoman6524]

id like to know, too...ive got the same problem. lol, i put a little water down my ports on my carb and it seemed to help. idk though

 

[dyeager535]

Whats the coolant temp sensor saying?

In good tune otherwise? (plugs, wires, visual inspection-all good?)

 

[opfor2]

Whats the coolant temp sensor saying?

In good tune otherwise? (plugs, wires, visual inspection-all good?)

Ya I was thinking coolant temp sensor also. When I put my code reader on the ECM the temp was normal but that was when the Eng. was hot. Maybe the sensor is wacky when it's cold. I have an extra coolant sensor that I bought from NAPA that I'll switch with and see what happens. Like I said in my original post the problem only seems to appear when the truck is in "Open loop" mode and it seems to go away when hot and in "closed loop"

Dan..

 

[dyeager535]

Temp is one of the things that contributes to open/cold and a host of other things, it's possible for them to be "dead" at one end or the other of the spectrum.

 

[broc944]

Have you checked the coil? I just finished a friends car that had the same problem. one bank of coils tested bad (this was on a Mercury V6) on the bench, but when the car revved up they worked, at idle and slight acceleration they did not.

 

[opfor2]

Temp is one of the things that contributes to open/cold and a host of other things, it's possible for them to be "dead" at one end or the other of the spectrum.

I just replaced the ECM temp sensor and we'll see what happens in the morning.

BTW, thanks for all the help.

 

[opfor2]

Well after replacing the ECM coolant sensor with a new NAPA Echelon one the problem seems worse now than ever. This morning with the Eng cold from sitting overnight she sputters and stumbles when accelerating from a stop. It starts, idles, and drives OK just when coming to a stop and then starting to drive under light acceleration is were I have this problem. When the truck is in closed loop it doesn't have a problem at all. I'm lost were and what to check next. HELP !!!

 

[opfor2]

ttt

 

[opfor2]

No one has any other ideas ??

 

[broncoman6524]

check your plugs maybe? like i said mine is doing the same thing, octane booster, carb cleaner, and spritzing water into my carb helped but it didnt go away. now i think i have a misfire sooo ill be getting new plugs tomorrow.