Hesitation/missing

[Cooz]

Ok, I have a 94 Grand Am 4cyl, SOHC, 5spd with 210K miles. I have some questions and a couple of problems. First question, the black box that sits in front and to the side near the power steering pump, does it need to be changed periodically? I beleive it has to do with crankcase ventilation, correct? Second, is there anything other than a leak that would cause the water pump to be bad? Third, is the valve that connects the two heater hoses necessary?

The problems. Over the past year the car has developed a hesitation/miss under acceleration and has been running hotter than in the past. It's slowly developed and I've been changing parts along the way. Each time I change a part it gets better, but doesn't go away.

The list of parts:
New O2 sensor
new coils
new boots
new plugs
new coil housing
new fuel pump (because it actually crapped out)
new fuel filter
new heater hose (got a hole, straight hose no valve)
New vacuum hoses and belts.

I've never gotten a check engine light, ever!
It still gets great gas milage. Plugs look good.
I just found one of the injectors has a cracked housing. I was told it would still work though.


I would appreciate any help any could give me.

[Chameleon-kat]

I hope you get an answer for thr hesitation/miss. I have a 96 2.4l 5sp with 209k that does the same thing under load (heavy acceleration or long steep hill). Maybe somethings carboned up or something like that

[Cooz]

Have you changed your clutch yet?

[Chameleon-kat]

no need to change clutch yet, may be getting a little tired though

[Cooz]

I don't know if it means anything but its cold and rainy and the car runs better. I was told all engines run better with moisture but could it be a clue as to what the problem is?

[jayspot]

I had a similar problem with my '93 and it was a dirty MAF sensor (mass air flow). My engine is a 3.3 V6 so I don't know if yours has one (or if it does, where it would be locate). Mine is located right at the inlet of the throttle body. It senses the amount of air flowing into the intake. When it gets dirty, it can affect the engine performance. On mine, I can take out the sensor and spray it liberally with brake parts cleaner, allow to dry, and reinstall. It made a big difference on mine. Might be something to check into. I originally found out that was the problem by taking it to a dealership. Since then, I clean it regularly myself.

Jason

[jayspot]

Also, check out this link.... (read from the bottom to the top)

http://www.automotivehelper.com/topic126422.htm

[Markgase2000]

When its rainy or wet it runs better. Condensation helps remove carbon buildup , use a safe throttle body cleaner or go to a shop and do a moto vac , this will remove carbon and your car will have more power and run nicer than before. If you cant afford that try using a fuel system additive , I use penzoil octane booster and drive it hard for that tank of gas , works good. I took a look at my intake and exhaust ports and they are clean as a whistle. Another trick i use , take your pvc valve off the crank case cover while the cars running and dip it into a glass of water real quick , this blows carbon out too.

[Markgase2000]

If your coolent to water ratio is greater to water , the lubricant in the coolant will not do its job in lubing the water pump , that could be the problem there.

[pontta]

not sure if this will help but it could be a egr valve possibly. that would cause it to run roiugh and it would get rough er and possibly even stall if bad enough when under hard exeleration. also the info about the ingection cleaner m.a.f. sensor and changing plugs at least once every 60 -70,000 miles is good the injector cleaner is good to do at least once a month or every time you get oil changed
and the running better when it is cold moist that is due to a higher oxygen desity it is just geting better o2 supply so it will have better fuel burn. the moistur it's self dosn't do anything pos. for the engine really it just increases the o2 density . as does the colder temp.