Just drove 500miles with trailer in tow. Before i left oil was changed, alison filter, and fuel filter 1500miles prior to the rest. Truck had no signs of problems other than a little smokey untill warm. Started fine and idled good as well. Wasnt even halfway through trip when i noticed that it was idling very eratic ( dosent show on tach, but really rough. can feel it in cab. pop hood and motor dances from side to side) I noticed the rough idle in town at a stop light. Once back on the hwy i noticed that if the truck fell or was pushed into a 5-4 shift it would buck really hard(allmost like the key was turned off....then turned back on) Would only do this on a down shift. Woke up this morning unhooked the banks and had same problems, only now it will buck in any gear on a WOT run. Once to speed though its got lots of power to hold trailer at hwy speeds and smoothes right out as far as the shake at idle.Wanted to try changing fuel filter and realized that i didnt have one herehttp://www.dieselplace.com/forum/images/smilies/redface.gif Will try that tomorrow. Ive tried a search and found similar symptoms with the Fuel press regulator. Was wondering if a set of injectors might also be the problemhttp://www.dieselplace.com/forum/images/smilies/confused.gif The crankcase isnt overfull and oil smells good so i dont think theres any fuel in it. Seems weird that this came on as fast as it did, beeing that the truck was fine prior to leaving. Bad fuel might also be a problem but you would think that the problems would have started right away.Im going to try the fuel filter tomorrow and see what that does. Any ideas on what else might be causing this? Im thinking that shes gotta have a doctors appointment...........Hopefully just day surgeryhttp://www.dieselplace.com/forum/images/smilies/eek.gif
Changed fuel filter today and as suspected it was clean and problems still exist. If 6gun is unhooked it still idles rough but dosent hesitate as much as when its hooked up.........Another idea ive had is that the tranny is slipping and the banks is defueling once it sees slipage??? Still dosent explain rough idle.Ive had this posted in the "ask the techs" for a couple of days with no responce........anybody have any ideas:help:

Sounds like fuel pressure regulator. But don't know what affect mods might be having.
Doug

Had almost the same problem... after a fuel filter change my truck started to run pretty rough until it finally died. To make along story short, I did not tighten the filter enough so it was loosing its prime. After tightening and priming the filter, she was once again purring like a kitten...

Well shes got a doctors appointment on thursday:( Shop foreman figures its my time for a set of injectors:eek: Will have to resort to driving my company truck till then-:t

With an SLT you have OnStar onboard, have them run run the diagnostics program while you are driving under the described conditions????

good luck drive safe.

Well it started off with 4 bad injectors balance rates were way out on 2 on start up(cold) and as it got warm there were 2 more that were out. Had these 4 changed and then the test drive. Lopy idle still there. They get it back hook up Tech2 and the #7 injector( one they allready replaced) was way out:eek: Tear into her again change out that one. Road test #2......Lopy idle still there. Hook up Tech2 and WTF the other 4 are now out of wack:mad: So again they tear it apart and change out last 4 injectors. Road test #3....Lopy idle still there:mad:
So dealer says that it might be fuel. Had fuel checked and it came back at a 32 or a 35 IIRC. Dealer says they dont know what it is. Say they had talked to GM about it and it has them stumped as well. It goes back under the knife to do a compression test and to check out glow plugs.....all was fine. Dealer says to take truck drive that tank of fuel out of it and try another supplier. I load up my new 5er and head to the hills for some camping. Make it there no problem and make it home again without a glitch. Couple of days later head back for another 4 days of camping. Makes it there fine but upon backing into the hitch it stalls. Died like it ran out of fuel. Pop hood bleed fuel system, no air in it, try to start and nothing.:confused: Now im mad:mad: I cant actually believe that i was that stoooopid to pull the 5er with a truck thats not up to par:badidea: So i get it towed into town(truck) call a buddy to tow trailer home for me and wait for dealer to call and tell me that all they did was bleed fuel system and she started. But such is not the case.... Turns out i had the crankshaft relluctor wheel fall off and this caused the no start. So truck goes under the knife yet again.:eek: The bolts holding this cogged wheel on had loosened and fallen into the oil pan. Turns out they couldnt get all the bolts out with a magnet so the pan had to be taken off. My brother in law picks truck up today calls me and says shes runnin smoother than a babys bottom:) Could have this reluctor wheel have been the problem from the start? Is it possible to remove the pan without removing the tranny? If the tranny was removed how much of the Mobil 1 that i just put in there is still in there? Has anybody else had this relluctor wheel problem....is it a common problem?

No one has the answers to these questions?

absoutely! This is an issue from back in 01 and carries thru pressent. At least they finally caught it but if dealer/techs would read their PI's and bulletins this would have been caught before all this. Glad you're back on the road.

Was the tranny dropped to get the oil pan off.........

Sorry I didn't read your other questions. There is a lower and upper pan. If the lower was just taken off then just a brace has to come off. If they had to pull the upper pan the trans, flywheel and front differential(if 4wd) has to come off.

The fluid loss should be minimal to the trans, but of course the engine oil is gone.I bet they didn't have to pull the upper but you'll have to ask.Tim