Transmission / Differential Slip, or Misfire?

The Tacoma is a 5 speed, 2.7 4 Cylinder, 4x4

Symptoms include:

- Hard to shift into first and second gears periodically, mostly when cold.
- Truck jerks one solid jerk periodically at low RPM and moderate to heavy throttle. (not a symptom of being in too low of gear). Is this a transmission slip, or misfire? No codes are present. When this occurs, the RPM does not change. Only seems to be a singular large chassis jerk at a time.

This symptoms are new, and did not exist prior to the service below.

What has been done within the last week:

- New spark plugs (old ones were heavy carbonized)
- changed all undercarriage fluids with

$30 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90 GL-5 oil (Rear differential, front differential, transfer case, and transmission) Some of the oils were extraordinarily black. I added 25% Lucas Oil to the transmission per Lucas Oil Instructions.

I have read other topics where if these fluids were not changed enough there could be problems with new. If I have missed a thread that would describe this let me know, I had browsed the searches and saw people mostly talking about types of fluids.

Thoughts on diagnosing this would be appreciated.

Thanks!

 

Coil on plug, or coil packs? COP's insulators need replaced when putting in new plugs. Wires need replaced at the same time as the plugs, on coil packs.
What kind of particles were in the trans fluid? Small flakes and fine shavings are ok, chips and thick shavings are a sign of bad things. Brass=bushings, Steel=gears and bearings.
Check your clutch master and slave cylinders for leakage. Improper travel will cause hard shifting, since the clutch won't always disengage properly. Wear in the shifter bushings can also cause problems. I know for sure the 2gen has the bushing problem, not sure about the 1gen.

 

The plugs are Coil over plug.....are you suggesting replace the coils? At $70/each I am hoping to avoid this. Thoughts on a more accurate way to test them beyond a spark test?

Any thoughts on how to further diagnose whether it is a transmission related jerk or a misfire caused jerk? I will look into the clutch, but I do not believe this is the issue as the vehicle does not rev up during the 'jerk' (have a more technical term for that? haha)

 

The insulators on the end of the coil's tube need replaced when you get new plugs. They leak spark to ground when they go bad.

 

Ok, I'll go a head and pick up a set and see if it helps this weekend. I stopped at Autozone today and had them check for codes, and none showed up (Misfire Monitor stated OK also).....but with the alternatives, really hope it would be a misfire.

What are the odds the rear differential could be slipping skipping?

Also, as far as the transmission is concerned, if it were the problem the engine would rev, is that correct?

 

the diffs call for hypoid gl-5 oil, did the oil you used qualify for this?

 

I did use GL-5 oil, and per my axle code (and by testing the wheels) I do not have a limited slip differential, therefore did not install any of the LSD additive. I was curious if it were possible for a differential to 'slip', but upon researching seems unlikely or impossible as the ring and pinion gear is fairly solid. I have not heard any whirring etc which I have seen as examples of a bad differential, so thinking it is safe to cross that one off the list.

As far as the spark plug coil insulators go, I looked at the coils on the truck tonight, and they do not appear to be able to be disassembled, nor was I able to find any at my local parts stores. The coil packs looked to be in good condition without any cracks etc.....and again, no misfire codes.

So as it stands, my thoughts are transmission or yet unrealized misfire......aside from replacing the coil packs at $70/each, I am not sure how else to diagnose that one. I may just end up taking to my local shop to test drive for me.

 

I inspected the spark plugs and noticed some oil on one of the coils. Upon cleaning it I test drove and and no longer noticed the issue. I will be replacing the valve cover gasketing this evening.

Thanks!