Hello and welcome to Just Answer!
Is the check engine light on and if yes, did you get the codes checked?
Has the fuel pressure been checked while the problem happens?
Do you notice a problem with it when accelerating or at any other speed? Thanks!
Was the problem there before replacing the ignition parts and that is why you replaced them?
So does it run ok when you are driving lets say 70 mph in o/d?
No, the truck ran pretty good. I just new it was time for the parts to be replaced and I wanted to improve the gas mileage if I could (4x4) LOL. Once it reaches around 65 or 70 it will run just a little rough but it does not chug or backfire. If I reach a hill and it puts strain on the engine the RPM's go down quickly and it wants to backfire and resist acceleration. Hence, punching it in to passing gear.
Have you double checked to make sure you have the spark plug wires on in the correct order? #5 & #7 are easy to mix up. The firing order is 1-8-4-3-6-5-7-2. #1 being on the drivers side front followed by 3, 5, & 7. The pass side is #2 in the front followed by 4, 6 & 8. I would check this again to make sure. The distributor turns clockwise and #1 should be on the pass front on the distributor and is usually marked. Let me know, thanks!
I will check it out in the morning. It is already 11:03 pm here in Fl. Would a bad Oxy sensor affect this situation?
If you had an O2 sensor that was locked on rich it would tell the computer to lean it out and it can cause lean misfires. If you had an O2 sensor that was locked lean it would give it more fuel and would not cause misfires. You could very well have a faulty O2 sensor, but I would double check the wires etc first and let me know. I will try to help you figure this out! Just let me know after you have checked. Thanks!
I'll let you know in the morning. Thanks for your help!
Sure no problem! Just reply back to this thread and I will try to get back to you asap!
Good night and we'll chat tomorrow!
I confirmed the firing order and there were no mix ups. What do you think?
I would suspect there has to be something wrong with the ignition system if it only started after the tune up. It could be a coincidence but we need to check a few things before we know. Is it possible that maybe the spark plugs aren't gapped to the proper gap, or the rotor metal piece got bent during cap installation? These distributors are hard to get at and it could be possible??
An ignition system problem will always seem to be worse at the 40-60mph range in o/d. That is when it needs more voltage to jump the spark plug. When you have a rich mixture like when you accel into passing gear it does not require as much voltage to jump the spark plug gap.
Let me know, thanks!
I gaped the plugs at 0.40 which is the correct gap as far as I know. Since the truck ran for quite a will after I did the changes I would assume that there may be part that has died or is working intermittently. I'm with you, with my limited knowledge of this old girl, I had figured a firing problem or a signal problem to the CPM. I will check the plugs and see if there is any sign of problems. I did go to Discount Auto and had them check the read out of the check engine signal that has come on since I talked to you. The read out says that I have an intermittant firing on cylinder number 5 and a failed oxygene sensor in bank number 1. I new wires on the engine so I will replace the plug in number 5. I am going to also replace that sensor. If you can think of anything else I would really appreciate it. Thank you for your patience and cooperation.
Do you know what the P codes were, was it P0305 for a misfire code on #5 cyl?
There is only 2 O2 sensors an upstream and a downstream do you know what the code number was for it?
No, they did not give me the codes only the explanation. They said it was an intermittent firing of the number five cylinder and the O2 sensor on the number one bank. I'll go back and see if they can print the codes for me and let you know.