bcrooms

Providing an update. Since my last post, I replaced the cap, rotor, and plug wires. No CHANGE. Misfire is still present under the higher load/throttle and incline scenario, and it is more noticeable (truck shaking, loss of power & speed, etc). I've done extensive research on other forums and YouTube videos of similar issues, as well as on different vehicles with a similar problem and have seen several mentions of faulty sensors such as the Knock Sensor, TPS, etc. With as much $$$ I've previously put into MPFI repairs (3 MPFI kits so far in 8 years) this issue creeps back until it becomes so bad that I can't drive the truck. I did take the truck to a local shop in TN (recently moved here) and from the minor diagnostics they have done so far (planning to do more) they believe its the MPFI nozzles again OR the cam shaft is worn enough to cause misfiring on Cyl 3, 4, 5 & 7 where I see the counters go crazy when it does it. The shop is going to give me an estimate to diagnose deeper into the engine. I know its gonna be $$$$. What are the chances, that its something super simply like the Knock Sensor throwing everything off? I'm tired of the problem being "fixed" by a shop for about a year or so and then returning with a vengeance.

Well after driving my truck awhile without being able to replicate the misfires, it returned yesterday. Not as rough of a misfire as before but same scenario and symptoms

Does anyone know the correct size of the factory rear speaker bolts? I have replaced my factory speakers with aftermarket speakers that required an adapter for proper fit, and the adapter obviously has added material between the bolt washer and the body panel. The factory bolts are too short to use with the aftermarket speaker + adapter. I tried using the screws and such included with the new speakers but those screws aren't the right size for the factory holes.... I've checked a few hardware stores in my area but I can't find anything that is close to the factory bolts. I just need the same type but slightly longer.

Another update that could be relevant: I changed the spark plugs on my truck. The 4 plugs closest to the rear on both sides have oil on the ends. Not a ton, but its enough to immediately notice and be concerned. My truck tends to "use" oil between changes, and I change the oil every 3500 to 4000 miles. My truck does have the oil filter adapter kit installed. I replaced all 8 plugs. I didn't do the wires or anything else as I was short on time over the weekend. I have noticed some improvement in the smoothness of the engine. I still believe the O2 sensor change helped the most so far for my truck. I found a reputable shop in the area I am in now and I am planning to have them check it. They have confirmed they have more advanced tools and skilled techs that can do a deeper inspection and diagnosis.

Not yet, but I can give that a try

I can see and feel the rear of the truck bouncing up and down at times when I apply the brakes.

I can tell that cold & warm idle is smoother. I have driven the truck as I normally would and tested it on the same inclined highway where it usually wanted to misfire. I haven't been able to reproduce the misfire since the O2 swap. Will keep posting updates as I have time.

Sensor #2 IMG_1114.HEIC IMG_1115.HEIC IMG_1116.HEIC

So I decided to replace the two upstream O2 sensors to see if anything changed. Here are pictures of the (I believe original) O2 sensors that were replaced. Sensor #1 IMG_1110.HEIC IMG_1111.HEIC IMG_1112.HEIC

I would say the rear is the cause for the hop. The fronts only have a grab/release pattern.

It hasn't been smooth for quite a while. I thought the last guy would be able to resolve it...but no different.

It's always had this intermittent brake bounce.... the last guy that changed the front rotors/pads and rear drums said it was as good as its gonna get for my truck...which I dont believe is true. I should have smooth braking if all the brake components are operating as they should, right?

Could this be an issue with worn out wheel cylinders on the rear?

I can also feel the heat in the cab get much warmer if I have it on while this is happening. I can also feel it cool down.

Yesterday I noticed my truck's water temp gauge has started to give an inconsistent reading. While I'm driving the temp gauge shows below 210, closer to the mark between 100 and 210. When I come to a stop for a few minutes (red light, etc) the temp seems to increase back to 210 and at times goes above 210, but not by much. When I resume driving the temp drops again. I know it's been colder than normal lately in our area but the last few days it has been in the mid 40s to low 50s. Could this be relative to the water pump not operating as it should or temp sensor / sending unit?