missing when cold, posted before

[slreno1217]

i have posted this before but i have some new info on th

1996 blazer, when the blazer is cold it is hard to start and misses untill it is good and warmed up then it runs perfect.

well it has been really cold here latley and i have been useing the stock oil heater that you plug into 120 volts. i think it leeps the oil around 100 degrees. well if i use that nightly the problem goes away! never does it as long as i plug the blazer in. last night i didnt plug it in and guess what.. got the hard start and missing untill it warmed up good.

my thinking is this would surely rule out the fuel pump filter and regulator rite? because what does the oil temp have to do with any of the above.. i am thinking it is some sort of cold start sensor?

am i thinking rite here?

[mrfirebird]

my 94 does the same thing, i'll watch this post to see some comments.
i'm leaning towards the egr valve but i don't know where it is. the book doesn't show very well.
is it round and about half the size of a pop can?
did see black carbon on ground in the snow.
no smoke on start up.
i had a trans am and the egr valve would stick and cause it to miss, until it warmed up.

[ricksza]

I think you can rule out the EGR valve, it doesn't come on when the engine is cold. By the way, the EGR valve is on the front of the intake under the throttle body. There is no cold start sensor.

But here are a few ideas: If you have access to a scanner you might want to check you coolant temp sensor to see if it reads properly when cold. That can cause cold drivability concerns. You may also want to check your fuel pressure. You might find that as soon as you shut it off, the pressure drops, which floods a couple of cylinders. The heater helps because at the higher temp, the fuel will evaporate quicker.

[briantman]

Hello, just looking aruond and saw this, I would start with the things, mentioned by ricksza. I worked the service lane in a chevrolet dealer for five years, and saw alot of this. If you have access to a fuel pressure guage you can hhok it up on the back side of the intake on the drivers side, if you cycle the key (not starting) the fuel pressure should go above above 50psi. then turn of the ignition and watch the guage, some of the 4.3 W (multiport) engines had a problem with the injector or the poppet valves from the injector leaking. is the upper intake on this enigine plastic or aluminum? the ones with the aluminum tops also can have the fuel lines going to the injectors leaking. One last thing, does this engine smoke on first start? 4.3's also have been known to have valve seal problems, the colder the seal the more shrinkage.