So I found a 97 dodge on craigslist that I convinced the guy to trade me for my 1990 w150. The 97 is single cab, short bed 318 4wd and 5 speed. Mine is single cab short bed, 360 4 speed, 4wd. His is in better shape, but the catch is that his wont run right. He said it has a bad miss when its cold, and it jerks so much that the yoke broke on the driveshaft and so it needs a new driveshaft and the engine miss fixed. He said it runs fine when it warms up, but I was just wondering if anyone had any opinions on what could be wrong with it. I am kinda thinking that it could be distributor related, but that's me throwing an uneducated guess out there.

 

Plugs been changed recently? Plug wires in good shape and all attached at the plugs tightly? Plenum gasket been fixed? Distributor cap and rotor ever been changed? What maintenance has been performed on this truck to-date?

 

I have some unsolicited advice: Please take the time to compose a more descriptive thread title that something with one word. I makes future searches easier for other members.

 

Yup... next time in need some advice I'll search for "advice" and this thread will be top of the list, and answer all my questions.

 

Sorry guys. I just wanted advice from people that know more than me, so that's what I put as the title. Sorry for the confusion

 

It's impossible to troubleshoot properly on the internet, but missing when cold and fine when at normal operating temperature is often a failing oxygen sensor. Before pulling that trigger I'd want to disconnect the front oxygen sensor and run the thing from stone cold to full normal operating temperature -- if the miss doesn't appear you've found the culprit and can know that it's a cheap enough fix.

Missing so badly that it breaks a driveline yoke? I've never seen that. What I have seen, though, is a guy becoming so enraged (by being outsmarted by a pickup truck) that he spools up the engine and dumps the clutch. That usually takes out the ring and pinion, but it can splatter a yoke or break a u-joint instead.

 

Think long and hard about the trade...

The fact that it broke the driveshaft yoke would concern me. I mean, I wouldn't expect the yoke to go first, nor from just a misfire....

These trucks are notorious for misfires. There's a lot of causes too. Shorted/bad wires, cap & rotor, bad spark plugs (or wrong plugs), PCM grounds (to engine especially), bad or clogged injectors, low fuel pressure, coil, crankshaft position sensor, cracked cylinder heads, etc. The bad thing is that all of these are fairly common on these engines. So this could be as cheap as $16 for some spark plugs.... or... well..... expensive.

It might be missing on more than one cylinder too for as bad as it sounds.

*edit: Didn't see your post UnReg, but would a bad O2 sensor be the other way around? As in, it runs fine when cold, but misfires when it warms up and uses the sensor for fuel control?

 

It depends upon the definition of cold. If it runs okay right at initial start but then starts loping badly within a minute, and stays that way until normal/near normal operating temperature, then the symptom is consistent with a failed oxygen sensor. Or, perhaps, a wiring fault that robs the heating element of power, but you've really got to work at it to screw up that cable because it's routed well out of harm's way except for the last drop to the sensor.

PS: To explain a bit more: Oxygen sensors are signaling a voltage proportional to a chemical reaction, and that reaction process is one that just doesn't do much at low temperatures. That's why the sensors are heated -- used to be, when they weren't, that PCMs jumped through some heuristic hoops to figure out when the sensor's output indicated that it was probably up to temperature and could be trusted. With the heaters in there we can just set a timer and say that X seconds after energizing the heater the thing is probably up to temperature and can be trusted. Neither is really an optimal approach, but with the heaters we can go into closed loop earlier and so reduce emissions by a couple of particles and increase fuel efficiency by a couple of drops. And the complexity of the driver software is reduced with heaters in the circuits, which is always a good thing. Less code == fewer bugs. Unless I'm writing the code, in which case there are no bugs. There are undocumented features and undefined states, but no bugs.

 

We all know you didn't know the perfect thread title so it's all good! Please post your fix or what you decided to do. A miss on all 8 wouldn't cause a yolk to bust.
Someone was probably slammin gears as stated above. Has the plenum been fixed? And when does it jerk? Speed? All the time?
And UR you make my brain melt when you start that real tech stuff

 

So i looked back at the post, and he apparently did plugs, wires, dist cap, rotor, serpentine belt, alternator, and new PCM. Ive been thinking, maybe he crossed the wires for the plugs? I did that once and it bucked pretty bad and that might cause a bad u-joint to break. Ill have to ask him when the engine miss started. But thanks for all the help guys. Any more would be much appreciated. Im supposed to go pick up the truck this weekend. I also meant to ask, what length is the driveshaft I need? Ive been looking, and he said it is the 119" wheel base, but all I can find for that is 2wd driveshafts, and I would assume it would be shorter due to the transfer case. Is there anywhere in particular I can look? The salvage yard I normally go to didn't have one.