I have a 1995 dakota 3.9 v6 magnum standard cab. My distributor cap went bad and she started backfiring bad. Got that taken care of. Now I've lost all power and its making this high pitched whistle only when I accelerate. Idles fine every now and then she'll stutter but hasn't stalled. I've narrowed it down to the left side around the exhaust manifold. I csnt find any kind of vacuum leake or really tell what it is. I'm smelling alot of exhaust up front and in the cab so I'm guessing the manifold gasket. I went out and got a pair, but before I get wrenching through the night I fugired I'd post up and hope somebody can help me determine the exact cause before I mess things up.

 

It may well be the exhaust manifold for the whistling; but I'd also be looking for a broken vacuum line somewhere, due to the stuttering.

(Actually, on a 1995, the hoses are possibly 26 years old; I'd be replacing for your cousin and mine, Justin Case, to prevent vacuum leaks.)

And on the "lost all power" - if the cat's plugged, you may easily be blowing back through the EGR or even any weak spot in the exhaust.

For a quick test, do this.

With the motor cold, pull the O2 sensor. Just tape it up or ziptie it to the frame.

Start the truck, see if the power comes back. Oh, it'll be noisy with that hole in the exhaust, but it's a quick test to see if the exhaust system is plugged.

If it's been burning oil, I'll just about guarantee it's plugged at the cat by now ...

That's a few things to check.

RwP

 

I keep thinking vacuum leak but can't find one for the life of me. The cat i don't think is plugged, I have full exhaust coming out of the tail pipe still. But I'll definitely give that a go. Ill post the video or link it in. Shes never burned oil. The older gentleman I got it from 4 weeks ago kept very good to the maintenance schedule. Everything was fine before that backfiring started. And that was all through the exhaust. Which is what has me thinking if the rest is OK it has to be either the manifold or where the exhaust hooks up to the manifold.

 

 

So, thinking the cat is actually clogged. At napa now getting a new cat. Will update if she works.

 

So did you remove the o2 sensor as suggested to test or are you just going to throw parts at it until it's fixed?

 

I did remove the o2 sensor. Cat was the issue. Replaced and she's perfect again.

 

 

The most expensive charcoal briquettes you will ever see!

 

One last comment that I want to make on this, from my experience with a cat and a Toyota Celica convertible:

1) Catalytic converters are very expensive because they use rare metals. To maximize the surface area of these rare metals, they are spayed on a grid system (like you saw above, except not broken) that the exhaust gasses must pass. This grid system gets heated to very high temps during use and the idea is that anything that is supertoxic will be burned up as it passes through it. (the catalyst - the rare metals- coverts the toxins in the exhaust.) The O2 Sensor checks to see how well that is happening and provides feedback to the engine.

2) Failures of catalytic converters often happen when the engine starts to burn oil. The oil gets on that grid system and the system gets overwhelmed. The system ends up overheating that grid system, failure, and the results are a cat full of those briquettes.

3) Like most things, if you don't fix the real problem (likely engine burning oil) then the problem (burned out cat) will return.

As with most comments on the internet, I may be wrong, you may not be burning oil and everything may be OK, and the cat just failed after 30 years of service. but if you are looking at another catalytic converter in 6 months, you may know why.