What I've done so far. Hughes kit to fix plenum, new exhaust with new O2 sensors and new crank sensor while I was it, new distributor as I broke bolt taking old cap off, new plugs wires and coil.

Problem I'm having is under very light to no load (i.e. down hill or wind at my back) and very slight pressure on skinny pedal I get hesitation and bucking. With truck in park and I just crack the throttle to hold say 1600 rpm, engine stumbles badly.

I confirmed visually that the plenum gasket is holding and I have solid 18 inches of vacuum at idle. Based on what I've read here and others I replaced the TPS but still have the same issue. My code reader shows no codes pending. The one common thread here appears to me be that the condition this is happening at is while vacuum is high (i.e. no load) but under part throttle.

When it happens and I take my foot completely off the gas to coast the stumble goes away.

Can I get a second on a vote for the MAP sensor?
2001 Ram 1500 5.9

 

What brand crank sensor? Our trucks really dislike the aftermarket fellers.

 

Have you checked out the spark plug wire TSB?

 

When I first read that it only went up to 1999 but on second look I saw the note that could be some 00 and 01. Can't hurt to give this one a try as the truck seems to run quite well and with good power as long as accelerating or under load. I'll post back

 

if you put in a cheap crank sensor,then id say there is your problem, doubt its the MAP, engine wouldn't idle, how about your fuel sync?? did you set that after you put the new distributer in??

 

x2 on the fuel sync.

 

No I didn't sync. My bad and much appreciate suggestion as I believe that is likely my issue. Truck runs fine with good power accelerating or under load but light load induces stated issue.

I've been researching procedure and I don't think my cheap scan tool is up to the the task. Short term if I loosen the disty just enough to move it and run idle up to where it stumbles, can I simply rotate disty until engine stops stumbling and call it a day?

Thnx

 

Not really. If it runs good enough to drive, take it to any decent shop with a good scanner, and have them set it. Shouldn't be too expensive.......

 

This is how it should be set until you can use a scanner.

 

Well got truck back from shop today and still have the problem after fuel sync done. It seems to run a bit better and the problem seems to be harder to produce but never the less still there.

The shift points prior to having the fuel sync done, seemed weird to me and it was hard to get it to downshift but that seems much improved now. Bringing idle up to 1500 in neutral still stumbles and misses as before. Slight gas peddle in a mostly coast situation produces a buck or two but other than that, it's perfectly drive-able and you wouldn't notice a thing.

Just don't get it. I know cheap crank sensor was mentioned. It was a CarQuest brand that I've used many times before without issues. I'm unfortunately familiar with conditions associated with bad crank sensor and this just doesn't seem to fit considering it only flakes out under this specific condition.

I'm considering getting OBD2 software that I can monitor while I'm driving as well as double check the fuel sync. Is there any that would fit this bill around $100 or less?