Intermittent miss


#1

1992 GMC 2500 4x4
5.7 liter
203000 miles
Auto
On a road trip grom wisconsin to texas. About 300 miles from home at 65?mph i felt a vibration. Not real noticable but it felt like rumble bar’s on the side of the road…not even as bad as actual rumble bars.
I thought it felt like the engine was missing. Just not sure. Today it did the same sort of thing on cold engine. Seems more likely to happen when i climb a hill or try to pass.
I havent done anything yet. Looking for ideas before i start with ignition inspection…


#2

When was the last tuneup?
Are these the original plug wires?
Does this '92 have a distributor based ignition system?
Last rotor and distributor cap change?


#3

Universal joint.


#4

Cap
Rotor
Plugs
Wires
Little over a year ago

I doubt universal. Seems sluggish with miss?


#5

I will however check universals. Thanks


#6

I did a search and was going to write it down. Now i cant find it.
Torque converter was mentioned and i believe egr


#7

Felt like the engine? Will it do it sitting still if the revs are increased in neutral? I was just wondering about a harmonic balancer. Take a look and check for a wobble.
CSA


#8

The problem with a symptom like this on a vehicle this age is that between fuel metering, compression, ignition, vacuum, and problems like stick or burned valves, the possibilities are almost endless. And CSA’s suggestion to check the harmonic balancer is a good one too.

You could start with a compression test. If you have a cylinder that’s significantly lower than the others that’ll give you a path to follow.

“Reading” the sparkplugs might offer a clue as well. If you have one that looks a lot different from the others, it’ll point to the “off” cylinder, and its condition could provide a good clue to the root cause of the problem.

Swapping injectors around might yield a clue too. As might unplugging the plugs one at a time while it’s shaking. If one has no effect, that one isn’t firing.

And, as always, a vacuum gage will probably yield a clue. It might point you to a valve problem.


#9

The rear end is junk. I can see where the drive shaft bolts to the pinion? Is off kilter in the housing.
What is the cheapest fix?


#10

The cheapest fix is probably for you to buy a complete rear axle assembly from a junkyard and swap it out yourself…


#11

badbearing wrote: “Seems sluggish with miss?”

Ah! You didn’t say sluggish before.


#12

I’m with TT on this. That’s your best option.