Tranny Problem

97' 4.0L Completely Stock XJ

When im travelling around 50kph i notice that the transmission has trouble selecting what gear to be in. The jeep doesn't accelerate and it starts to coast.

The local mechanic says it needs a tranny flush.
What do you guys think?


Oh ya and my oil pressure gauge fluxuates a fair amount travelling at constant
highway speeds. Is this ok?

To takers to help a noob out.

I had a similiar problem. I thought it was the torque converter locking and unlocking.

Turns out, it was a misfire. It got progressively worse until it became obvious that that's what the problem was.

and you fixed it by doing ?

i think thats what he is lookin for.

pete

At only 50kph? Isn't that somewhere around 30-35mph? Sorry, I haven't learned to think in metric yet - all my firmware works in inches, pounds, and miles.

First thing I'd like to know is, is this related to engine rpm or to road speed? You can check by shifting into Neutral, then slowly pressing the accelerator until you get to the same rpm that you'd be at for 50 klicks, and then see what happens with the engine. You have removed the load, and that will allow you to determine the severity of the problem.

A few visual checks are also warranted if a misfire is suspected. Check the spark plug boots for cracking or for "flat" black tracks (flat in the paint sense - basically nonreflective or less reflective than the material underneath.) Also check the distributor cap - inside and out - using a fairly bright white light. Take a look down the sides of the spark plugs as well.

Since it's a 97, and you don't say anything like it's been abused, I'm having you look for "carbon tracks" - where something has gotten onto a high voltage part and burned down to carbon. Since carbon is a semiconductor of electricity (it is used to make resistors, and is in the same chemical family as silicon, which is used to make semiconductor parts,) it provides a "drain" for electricity that will cause misfires. Don't belive me? Take a pencil, draw a REALLY dark line on a piece of paper, and test it with an ohmmeter. That's exactly how they make resistors, only they do it more precisely. Pencil "lead" is made of graphite, which is just carbon atoms arranged in sheets (that's why it's so slippery - the sheets slide over each other.)

Most misfires on later vehicles are cause by carbon tracking - and carbon tracking is caused by contamination of some sort. Clean the track (or just replace the part, which is usually easier,) find and correct the source of the contamination, and go on your merry way.

I'd like to hear what you find, and what you find out.

Carbon tracks are pretty easy to spot - under a decent WHITE light they look just like jagged pencil lines.

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