Weather is unrelated as best I can tell, its been bone dry and cold or warm and damp and it still happens. Today was 78* and muggy and it was worse.

I will check the MSD stuff out this weekend. Still haven't had time to check out the plugs and cap yet.

Cam and crank sensors are about 2 1/2 years old. Not factory parts. I'll give it a good once over this week and see what's up.

Is my general guess about the TC flaring up and not bogging down correct? Never had one go out on me, and I'm just winging an educated guess.

Right now its more or less a gremlin in the works, just don't want to let it become a major problem if I can.

 

i'm agreeing that a 500 rpm drop from "normal" does not sound like a transmission problem. assuming 55 mph is about 1700 rpm with TC locked and OD on, a 500 rpm drop would take you down to about 1200.

a transmission problem would be more likely to release traction/slip/unlock. If as expected, you already have full TC lock at 55mph, then there is no TC malfunction that i can see which would cause rpm drop. already locked is locked.

i suspect temporary loss of fuel or spark, possible coil.

 

Cold snaps can make marginal oxygen sensors act up while cruising. Damp weather can show a failing ignition cable, call attention to a cracked housing on a TPS, and screw with a CKPS that's on its way out. Though it's not relevant to aim's problem (if it were weather related, which it's not), damp weather also makes IAC's more prone to sticking.

Yep, it's correct. If the clutch is slipping or disengaging the engine RPM will increase by a couple hundred RPM, the same amount as the drop when the thing engages without slipping.

I'd expect that if it was the OD at fault you'd have noticed sloppy, flaring 3-4 upshifts already. And also would have noticed if it were simply shifting into overdrive prematurely.

That's always a good choice.

 

Aim, I had the same problem with my truck on the way up to Wyoming 2 years ago. Happened about 3 times before I pulled over and disconnected my 6A and bypassed it. (Always use male/female wire connectors!) Got it back on the road and never had an issue since. I got tired of burning through spark plugs so the 6A is now an underhood ornament.

 

You might be Right Rocky,

Update: I think it's definitely spark/ignition related now.

Engine bucked a couple times today, got lucky and got my eye on the Wideband gauge, it ran FAT! down in the 9:1 ratio. That probably rules out fuel and puts Spark into play.

Gonna give it a tune up this afternoon, and inspect the coil and MSD 6A box contacts for any abnormalities. I'll run it on the box after I change the plugs and cap and rotor, if it does it again, I'll switch the MSD box off and just run the Blaster 3 coil to further isolate any issues.

Oddly, it seems to only buck when the engine is cold, not warmed up, so I'm not sure what that points to...possibly a bad plug? I guess I'll know when I pull them.

 

Check to see if you have plug wire or even the coil wire in contact with the exhaust manifold. That happened to me a couple of years ago due to a poorly routed wire. It felt like I was a competing in a pro-rodeo event. Popped the hood and located the culprit.

 

I think the Culprit was corrosion on the Coil terminal. Cleaned it with a brass brush and some terminal cleaner. a bit more driving and we'll see...

 

did you still change out the plugs ?

 

Getcha some terminal grease on there if you haven't already.

 

yes, I swapped the plugs and the cap and rotor.

I had some dielectric grease on there, but perhaps I didn't use enough. She's slathered with it now. I wanted to make sure I got all of the corrosion off the terminal so it didn't creep back up on me.