Diagnosis: Shuddering?

[cKGunslinger]

1997 Dodge Caravan
130K miles
Automatic

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My wife's van has recently been exhibiting this annoying "shuddering/bucking" at certain times. When stopped (even in park,) and while driving. It's not large bucks, but a series of small, shuddery ones. There's no RPM gauge, but my ears can't pick up any change in engine noise. That is, it really doesn't feel/sound like the engine is idling rough or about to cut out, but I'm not sure.

If anything, it feels like the source is under my feet, but since it's a minivan, I think a part of the engine is pretty close to my feet Also, the engine temp doesn't get past mid-level (normal) and the radiator is always full, but the thing smells HOT. Like I'd expect to open the hood and have steam billow out. But it's always fine - just hot-smelling (like every car I've ever had overheat on me.)

Mechanically-minded-friend who drove it suggested it might be the heater coils?

Any other ideas or thing to test before I take it in and get a bill?

 

[cprince]

You should take it to autozone and get them to read the OBD II diagnostic code(if any) for free. That should be a good starting point.

 

[alpineranger]

Possible misfiring on one or more cylinders. Your car is 96+ so just use an odb2 reader to figure out if the computer agrees with this.

 

[nakedfrog]

Date of last tune-up?

 

[PingSpike]

Water in gas? I had a similar problem with my neon from that, but it only seemed to occur when accelerating.

 

[cKGunslinger]

Last tune-up? Unknown. This was the van we bought used for $2k last year.

I know several things were changed and replaced, but an actual tune-up? Doubtful.

The check-engine light is on, as well, so I might as well get it checked out. AutoZone will hook it up for free, you say?

 

[cprince]

Originally posted by: cKGunslinger

The check-engine light is on, as well, so I might as well get it checked out. AutoZone will hook it up for free, you say?

yup!

 

[cKGunslinger]

Originally posted by: alpineranger
Possible misfiring on one or more cylinders. Your car is 96+ so just use an odb2 reader to figure out if the computer agrees with this.

It does.

"Random misfirings, plus Cyl 6 is bad."

Now here's the thing, as far as I can tell, the only way to change the plugs on this thing it to pull the engine! :| Which probably means they haven't been changed anytime recently.

I hate having to take a vehicle in for maintenance that should be user doable.

 

[alkemyst]

Changing your plugs.

seriously, with a CEL why'd you think to just throw parts at it?

 

[cKGunslinger]

Originally posted by: alkemyst
Changing your plugs.

seriously, with a CEL why'd you think to just throw parts at it?

Que?

 

[funkymatt]

timing belt? and yah, get a tune up! new plugs/wires will do wonders

 

[alkemyst]

Originally posted by: cKGunslinger

Originally posted by: alkemyst
Changing your plugs.

seriously, with a CEL why'd you think to just throw parts at it?

Que?

You mentioned your check engine light had already been on. Why not have that looked at first?

 

[cKGunslinger]

Originally posted by: alkemyst

Originally posted by: cKGunslinger

Originally posted by: alkemyst
Changing your plugs.

seriously, with a CEL why'd you think to just throw parts at it?

Que?

You mentioned your check engine light had already been on. Why not have that looked at first?

Oh, that just happened, several days after the shuddering first started.

 

[alkemyst]

Originally posted by: cKGunslinger

Originally posted by: alkemyst

Originally posted by: cKGunslinger

Originally posted by: alkemyst
Changing your plugs.

seriously, with a CEL why'd you think to just throw parts at it?

Que?

You mentioned your check engine light had already been on. Why not have that looked at first?

Oh, that just happened, several days after the shuddering first started.

ahh cool...thought the light had been on.

It's amazing though that even mechanics will guess at CEL problems rather than pull the codes.

 

[mooseracing]

Originally posted by: alkemyst
It's amazing though that even mechanics will guess at CEL problems rather than pull the codes.

Alot of times pulling a CEL is worthless as well. It can be as helpful as Windows erorrs, sometimes its on the money and other times it's totally off.

 

[alkemyst]

Originally posted by: mooseracing

Originally posted by: alkemyst
It's amazing though that even mechanics will guess at CEL problems rather than pull the codes.

Alot of times pulling a CEL is worthless as well. It can be as helpful as Windows erorrs, sometimes its on the money and other times it's totally off.

Totally untrue. While you can't always expect to be told the exact problem, I have not encountered one time it did not show where to start.

Almost all FSM's have step by step break downs of component testing based on troublecode. You will not see these in a Chiltons or Haynes manual 9 times out of 10 though.

If you don't have a multimeter/know how to use one then it's not going to help.