anybody know anything about DTC 34 Injection timing stepper motor fault

[Martin R]

I cranked my DS4 pump 1/16 to the left to tune the timing a bit and that code pop t up 3 day' s after.

[DmaxMaverick]

You moved the pump out of its timing adjustment range (the stepper can't compensate for the change you made). The PCM doesn't like this. Moving the pump won't adjust the timing, like on DB pumps. It only adjusts the range limit to set an offset value. Move it back and start over with the correct procedure to set timing and offset.

[Martin R]

In 2007 to 2009 *DTC 81 DTC 78 DTC 34 (inj. tim. st. mot. fault) have pop't up. I lost reverse on the tranny and then overdrive so i got it replaced. Pmd was replaced and within the last year symptoms are coming back again, hesitations mostly winter stalling after start up mostly summer and hesitation up hill 2000rpm and up winter and summer. 4 months ago i removed the stock air filter and put an oiled cold air filter. The CDR valve pressure is released under the truck apart from being sucked in by the turbo. Better fuel millage and Hey i had never heard a 6.5 spool before. ( this attempt was to get cooler air in to protect the engine for future towing). Now a month ago i got installed a 3" down pipe to 4" Diamond eye perform. exaust, both ex. manifold's ceramic coated, new glow plug's, new injectors that leave a tiny film of fuel on the finger once in a wile 87 gpm water pump and rad flush and clean up. Next spring i'l do the 130gpm w.p job and i'l take your advice and investigate about that 97 intake manifold replacement. Now the truck was parked for a ten day's the front lifted, no weels. My brother (Diesel mechanic 10 years experience and human) did not have the right wrench for the the DS4 so we closed up the front cover and w.p and finished the job without correcting timing to compensate for the chain slack, poorly investigated lack of reading timing set and front cover chapter (Troubleshooting guide, D.page ) we started the truck wile lifted up still and the engine didn't sound right at all so we freaked out. Anyways the lifter pass.side fire wall was knocking hard for an hour and almost disappeared. We test drove the truck and everything was great. (Ex. system no Cat and muffler). The next weekend we loosened up the DS4 and turned it to the left a /16th. The week after that DTC *81, 34, 43 (Fuel temp circuit high(low temp indicated) wired rev sound and hesitation when accelerating, lower power lifter knocking and bad stomic digestion. (Should I get the timing proffesionaly done inj.press and housing tested cancel my cold air filter for the winter for stock aplic. -20deg celcius. Tanks for your time.

[Martin R]

What is the stepper motor and what's it's application.

[Robyn]

Stepper motor, controls the timing of the injection cycle.

Missy

[Martin R]

Now i noticed a fast idle step up when cold with my bosses 6.6 dmax and when you ether touch the brakes or the gas pedal idle goes down, is the 6.5 suppose to do the same thing.

[JohnC]

The duramax has an (optional) cycle to speed warm-up. The 6.5 does not. It has cold injection advance and idle enhancement to overcome cold running issues but it is not intended to accelerate warm-up.

The stepper motor advances and retards the timing ring in the injection pump under PCM command. DTC 34 means the actual timing does not match desired timing. It can happen if the range of adjustment is insufficient due to the pump position being out of the optimal window, or it can occur if the stepper motor does not work correctly.

[Martin R]

Thanks for the info guy's and girl's, now DTC 34 has a pattern in colder season for some reason but let's say the stepper motor is not working properly and it's shot inside the pump, what's my option's. Today i moved the pump back where it was when i bought the truck and advanced it towards driver side a1/16 +. In the test drive the code flashed at idle again and accelerating it disappeared again turned the rig off fueled up and it didn't come back on. fingers crossed.