I have a 2003 2500 LB7 LT3 96,000 mi. It has a K&N intake and hypertech PPIII set on level 3. I started it the other morining, with a half tank of fuel, and it was knocking, sputtering, trying to stall, and shifting hard. I replaced the fuel filter 3 times in the past 5 days and topped off the tank a few times. Its better, but still violently shakes between 1000-1800 rpm and is worse when towing (also pings at high rpms like low octane in a gas vehicle). DTC codes as follows per hypertech
P0300 Random/Multiple Cylinder Misfire Detected
P0302 Cylinder 2 Misfire Detected
P0303 Cylinder 3 Misfire Detected
P0308 Cylinder 8 Misfire Detected
P1226 Control Sleeve Sensor Malfunction
P1229 Intercooler Pump Driver Fault
P1235 Fuel Pump Control Out Of Range
P1244 Alternator Load Input Failed High
U1000 Invalid or Missing Data for Primary Id
Any ideas would be appreciated.

I would say,bad fuel!!!!! Also the hihg rpm "pinging" sound,is the Pilot injection shuting off,no need to worry about the.

either drain the tank or add a bunch of fuel additive to bump up cetane. i would get a small drill pump and hose and a 55gallon drum from a hardware store and drain it myself and refill with some good ol #2. also change your filter again too*

Thanks for the reply. I've changed the filter again and topped off about 30 more gallons with an additive, but doesen't seem any better. How much additive can i use? What happens with a bad injector or injection pump? I've also noticed that i can depress the primer pump again after first start up from changing the filter (i,ve never checked prior to problem). Is this normal? Any ideas on the misfire codes? Thanks again.

Thanks for the reply. I've changed the filter again and topped off about 30 more gallons with an additive, but doesen't seem any better. How much additive can i use? What happens with a bad injector or injection pump? I've also noticed that i can depress the primer pump again after first start up from changing the filter (i,ve never checked prior to problem). Is this normal? Any ideas on the misfire codes? Thanks again.
primer button is normal,it is only rock hard after pumping it,and replaceing the filter.one day i was wondering about this as another member asked the same question,so i went and checked mine,it took 4 or 5 pumps,then it was hard.it only needs to be primmed at filter chages unless you have an air leak.how many pump's did it take to get hard?

I just went out and pumped it, and it took 25 times. It always starts up right away though.

hopefully tolliwaker will chime in on this,i think he say's the 03 is prone to loose connections on the control modules,i think mainly the f.i.c.m. on the right front of the motor,it say's bosch on it.tolli where are you=chime in!went to get another 12 pack?

I accidentally added a tanks worth of additive to less than an 1/8 of a tank the other day, Drove it for about 10km's and completely cleared up my injector problems. Had one balance rate consistently over 10mm and now it sits around 2 in drive.


Although after reading over the thread again it doesn't seem like its an injector problem as much as bad fuel.

Thanks for the replies. I had a friend hook up his snap-on modis to and it came up with a bad cylinder 5 injector (i think it was the p1235 code). He turned that injector on and off with no change to vehice performance, any other injector and it ran worse. The good news is he found an update on ALLDATA (#04039A- 10-10-2006) that covers the 2003 silverado, and other various 2003 gm models and vins for injectors. Now i just need to deal with the stealership.

Thanks for the replies. I had a friend hook up his snap-on modis to and it came up with a bad cylinder 5 injector (i think it was the p1235 code). He turned that injector on and off with no change to vehice performance, any other injector and it ran worse. The good news is he found an update on ALLDATA (#04039A- 10-10-2006) that covers the 2003 silverado, and other various 2003 gm models and vins for injectors. Now i just need to deal with the stealership.
i am glad you have a friend with a snapy scanner,and all data,most pepole on this board don't know what all data is but,they do know helm's.i am surprized it was only one injector with all the codes your ecu spit.if the first dealer gives you any crap about warrenty move on to the next one.don't settle for replacing one injector,they alway's change out all 8 on the 01-03,glad you got it diagnosed before you went to the dealer,now you are well informed.
good luck

oh,i just looked at your sig. ditch all the aftermarket stuff before you go to the dealer.they are prick's about that stuff,play it safe.they will bone you if you just had a k/n drop in.make sure you have a delco.