Smooth transition on throughout the throttle positions?

 

recheck all the piping and everything for leaks after the mass air flow sensor. i know on my friends 96 the plastic hat on the throttle body wasnt seating right and it was allowing additional air in that the mass air flow sensor wasnt detecting. and it was the same with him that it wasnt throwing up any codes either.

 

My '99 is doing the exact same thing. So maybe this thread will help me to.

 

Yes, it should be a smooth increase from ~0.5V at idle position to ~4.5V at WOT. It should also be a smooth decrease back the other way.

 

yea the piping sounds like a good idea. i know i have probs with the connector right after the maf sensor always falls off. but most of the time when it does it that piece is still connected pretty good. the seating of the hat might be messed up, it was such a pain to do because it kept falling off of the throttle body. oh well im gonna clean the maf so i mind as well check that too. and try the old airbox setup

 

Wait, so you have problems with the intake duct work between the MAF and the TB staying on?? That can cause a whole host of problems as the engine is getting air that is not being seen by the MAF sensor...

I failed to connect the crankcase vent line (between the passenger valve cover and the hat on top of the TB) one time and thought I had blown the motor in my truck it ran so horribly.

 

its your vacuum lines u got a leek some were no matter wat any one say the told me it wasnt the i tor into my rig and found my leek in the vacuum lines and fixed it my was duin sammee thing goes norm but wen u punch it it chokes puts and studers

check ur vacum lines i had same prob check vacuum resevoir and lines for leeks

 

yes the rubber connector every once in awhile it will suck into the hat pipe. i'll check for vac leaks too.

 

ok well drove around today after fixing the rubber connector a little better. while having a computer hooked up to it this time, and yea everytime i would mash on the pedal i would get that nasty hesitation/jerk/bog. while studying the cylinders and sure enough i was getting misfires most of which came up as cylinder 4, and they were so sudden that they would not set codes. so im not sure what the hell is going on.

 

Well now you have a good start. If most misfires are number 4, and you have others you did not list...when was the last time you had a tune up, plugs, wires, cap, and rotor?

Pay attention to what the plugs look like, be very wary of any clean ones or wet black plugs. The plugs are usually good for 100,000 miles on a maintained engine. Mine lasted 80k and were good still replaced them anyway. But a cracked cap or rotor will cause all kinds of problems arcing to other cylinders or to the closest ground. Start it up at night and look under the hood for sparks. If it is really bad you will see them, but removing the cap and look for carbon tracks or cracks in the cap. Same with the rotor. It is also possible multiple wires are failling, (mine are 11 years old, 80k miles and original, checked with ohm meter and they are to spec), you will know that it's if you don't come up with a smoking gun on the cap and rotor.

I also recall a service bulletin that a small screen on the bottom of the distributor can plug and not let moisture out causing misfires.