My ’95 Burb, has what seems like a slight miss between 45 mph and 50 mph. It only happens at this speed. Any slower, and the engine is smooth as silk. Any faster, and there is no miss. I have replaced the Lift Pump, OPS and PMD, and none of those made a difference. I am now beginning to believe that the miss isn’t engine related at all, but may instead be a Torque Converter issue. Is there a sensor on the TQ or transmission that I should check?

Is it a repeative 'miss' or a one time 'miss' as you cross a certain speed on the speedometer? Or better yet, is is more like a jerking pulsation of some sort? What rear are you runnin'?

It is repetative. It is sort of like a slight jerk. I am running a 4.10 locking rear. Could it be the rear end? why does it only happen fro 45 to 50 mph? That is why I thought it might be the TC. Seems to me that the TC would lock up at around 45 to 50 mph.

I'd put my money on that TC locking up. How many miles. Tranny been flushed ? They make an additived that help with T/C function. It's marketed by ATP I believe but a good complete flush would be where i started if it hasn't been done.

I'm with Bowtie on this one. My truck locks up in the 45-50mph range, maybe just a little higher if it's really cold out and I'm pushing it harder than I should. And I have 4.10's just like you. 265/75/16 tires.

How long has it been since you changed the tranny fluid?

But beware... changing tranny fluids has a tendancy of pushing a dying tranny over the edge. However, if your tranny is alright and the fluid is dirty, thick, and in need of change, this could fix you right up.

I was really talking bout more than changing the fluid I use a ol change place here and they have a machine the flushes your entire tranny and replaces ALL the fluid in it. I have seen the inside of my old 700r4 50,000 mile after we flushed it and it looked new inside. I am hooked on this being a real positve. Should cost about 70.00 or so but I believe money well spent. Check your quick oil change places for this service.

You're talking about the reverse flush, aren't you Bowtie?

HUM Not sure I know they connect to one cooler line and uses the transmission's only pump to move the fluid

Mine had not really a 'miss' but kinda a pulsation in at at just about the speed you have. It happened as the t/c locked up. If you held that speed, it would just kinda pulse, speed up, it would smooth out. After IP changeout (with bad optical & metering problems) it has run smooth ever since. Not sayin' your's is IP related, but just one of my experiences.

Our 6.5 does the exact same thing, a pulsation-like feeling. It only happens at those speeds, right after it jumps into overdrive (72km/h exactly, ~45 mph: 3.73 gear) up until 78 km/h. I guess a good describing word is it "shudders". It does that if you are very lightly accelerating in that speed range. I don't even notice it anymore (happens all the time, for many years now). As stated above, just either speed up a bit or slow down. We have had the tranny flushed numerous times and the oil has always come out fairly clean.

I guess a good describing word is it "shudders".
Hey now that rang a bell with me too, my 95 started to do that a couple of years ago, just ever so slightly, i thought it was something slipping in the tranny as it did it while at a shift point, if you back off the throttle for just a split second and back on, it would be gone. I put it down to clutch packs not fully engaging for that split second until you back off on the power. Maybe a good cleaner would fix this or a new filter in the pan, then again maybe not.:confused:

Thanks everyone for your input. The slight jerking motion has existed since I have owned the truck. At first I thought it might be fuel related, but it just didn't make sense to me, why it would only happen at a specific speed. It just kind of dawned on me the other day that it may have something to do with the TC. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>

Anyhow, the tranny fluid looks nice and clean, and the pan on the tranny is newer, which leads me to believe that it has either been serviced or rebuilt recently. Either way, it appears to be in good shape. I wonder if there is a exterior lockup sensor for the TC that I can replace. I would be curios to replace it and see what happens. Anybody know of such a sensor?

Is your truck smoking when it is doing this slight missing/slipping?Not to sound like a broken record, but that is how mine is feeling, but it has a light blue smoke when it is doing that. And it only happens 35 to 45 mph.

I have never noticed any smoke at all. But then again, I have never been behind my Burb when it was doing 45 to 50 mph.:)

Hmmmm....,

That's fuel metering inside the IP failing due to fuel solenoid wear. These new fuel blends we're getting could use a gallon of sVO poured into a tankful. the f sol is made to wearout IMHO. the rod and armature plate are hardend steel but the cap is fragile and the retaining screw seems undersized.