97 Jeep Cherokee Stuttering/Hesitating

Maintenance/Repairs
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1

Hello All

I have a 97 Jeep Cherokee with a 4.0 V6, fuel injected, 4 wheel drive with a 5 speed. It has developed a stuttering or a hesitation at times while driving. It’s hard to describe, but feels like the engine is not getting fuel or air at short quick bursts, thus a stuttering feel.

Some things I’ve noticed:
It happens mostly when the engine is cold, but can happen any time.
It seems to be worst during rain or snow.
At low throttle, it can cause the whole vehicle to shudder violently and at full throttle (gas pedal down for acceleration) it is very noticeable but doesn’t seem to cause the vehicle to shudder as hard.
I think I hear a metallic pop or clack when it happens, especially at high throttle.
It doesn’t seem to matter what gear I’m in.
It doesn’t matter whether I’m on a flat or a hill.
It doesn’t seem to matter what speed I’m going, but it is a little harder to notice cruising along at 65.

Maintenance History: The vehicle has had several things replaced in 2011: Alternator, crank position sensor, relay on the ASD, serpentine belt, spark plugs, plug wires, cap and rotor, battery, engine compartment fan.

The vehicle went into the shop when it started dying at stop lights or stop signs and starting hard. The diagnosis was the crank position sensor and that did indeed seem to fix that problem. Within a few days, however, the vehicle started running rough and would come close to stalling when idling at a stop. My mechanic sprayed a bunch of cleaner down into the air intake part of the engine (a part that reminded me of the butterfly valve on a small carburetor). The problem went away, but this stuttering problem started up about a day later.

If anyone has any thoughts on the issue, I’d love to hear them. The vehicle is going back into the shop at the end of January to be painted and I’m going to have them drive it for a few days to see if they can isolate and fix the stuttering while it’s there. So far, they don’t have any ideas what could be causing it, but to be fair, they haven’t been able to keep the truck for a few days to drive it.

Thanks!

2

I’d replace your fuel filter, if it has been a while. They are relatively cheap and would cause what you describe.
I’m frankly surprised a mechanic wouldn’t replace that first, after hearing that^ being an issue, unless he wants to milk you for all you’re worth.

3

My mechanic is a close friend, so I don’t worry about him milking me. And we have talked about the filter, but I believe the fuel filter on this Jeep is in the gas tank. So it was more of a last resort option.

I’ll probably just have to bite the bullet and replace it and the fuel pump just for good measure.

4

Don’t replace the fuel pump just on a guess. All you need is a fuel pressure gauge, and one can be rigged to check the pressure while driving. This will tell you whether or not the fuel pump is having an issue.

I’d like to know about the new plug wires that were put on. I once bought a set of cheap wires - whatever the cheapest were at a big box parts store. Well, I’ll never do that again. What you describe, especially the possible connection to wet weather & maybe even the metallic pop, just sounds like leaky plug wires. Before I did anything else I’d get a mister bottle of water, park the truck in dark spot, run it & mist the plug wires to see what happens.

Has there been a check engine light at any point in time? Currently? If so, get and report the actual error codes.

5

I’ll check on a fuel pressure gauge.

As for the wires, I don’t typically buy the cheapest, usually middle of the road. But I replaced the plugs and wires about 3 or 4 days before the problem started. So I’ll take your suggestion and check the plug wires this weekend.

As for the check engine light, no, it hasn’t come on at all. I almost wish it has, just so I could get a code from it.