Question-------------------------
Followup To
update....
I changed the plugs and found the #4 exhaust plug was somewhat loose, meaning it didn't take anything to unseat it....so it's possible that I was having maybe a small amount of compression loss there, not positive, however after replacing the plugs that small percieved hesitation seems to have gone away....but then again.....time will tell. I also had cleaned out the throttle body as you suggested, and in fact before I even read your last reply....but honestly it was not bad at all...I only did it because I was already in there (heck you gotta get there to get to the intake plugs anyway). I did encounter a wierd start, meaning it turned over, seemed to to quit, then suddenly started.....does that bring up any clues of any other problems?
Question -
Okay, here is what I found. The sensor is clean, in fact looks brand new honestly. However the rotor was looking poor, the contacts were all rusty and corroded. I replaced that along with the O2 sensor as that looked pretty fouled as well. The truck ran much better, in fact no bucking but still a very small percieved hesitation. I checked the timing and had to adjust the dist. back to full retard posistion (which is how it came from the factory) to get it back to 10 deg btdc, I'm still confused about the vacuum advance since there is none on this distributer so I hope my checking is correct. I'll be replacing the plugs as well, can't hurt I guess and will get back if I find more things.
----------------------
Followup To
Question -
Okay, I'll check that tomorrow, but I would like to ask you a few more questions....one, is it possible that the oxygen sensor would be causing this? I don't believe it's ever been changed btw. Second, I'll want to check the timing as well, however I'm confused on when it says to remove and plug the vacuum advance tube....I don't find one on the distributer, I assume the computer controls this....so how do I check the timing in this situation?
-------------------------
Followup To
Question -
I have an 89 nissan pickup with the z24 engine manual trans, it is bucking, hesitating and has power loss but that seems to go away when the rpm's hit 3K. Any ideas of what is causing this?
Answer -
William,
Check the distributor for oil on the optical pickup. it is located under the rotor. You have to take the rotor off and then the rotor post and then the cover. All you need is a phillips screwdriver.
Answer -
William,
No, the oxygen sensor would not cause the bucking problem. But, with the age and the miles you would be ahead changing it. You see, the oxygen sensor feeds information to the computer and with age it gets coated and lazy. So, it reads lean and your mileage goes down. But, for my thoughts the distributor is causing your problem.
Answer -
William.
Sounds good on all fronts. Some books still say to plug the vacuum advance when they do not have it on the vehicle. The computer does that for you. You will know if it is too far advanced if it pings. When the car is running if you advance the timing the engine speeds up at first then the computer slows the engine down. So, set it at the factory spec and then advance one degree at a time to see if you get more power and mileage without pinging. If it pings retard it back one degree at a time until the pinging goes away. This is called power timing. But, one bad load of gas and it pings. So, time it with the gas you will use on a regular basis. On the slight hesitation I would clean the throttle body and try it again. This should clear it up. Also, make sure that the throttle cable is adjusted where there is little slack in the cable. I have seen some where you press on the gas for an inch or more before the throttle plates even move.
AnswerWilliam,
Yes, the plug being loose would do it. Be sure not to overtighten as the head is aluminum and the next time you change the plugs you might have the threads come out with the plug. Also use antiseize on the threads of the plugs to keep them from sticking.
