CAT C15 /6NZ trouble continues

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by truck 307, Dec 20, 2017.

  1. truck 307

    truck 307 Light Load Member

    178
    315
    Aug 11, 2014
    0
    Thanks for the support guys. But no worries on the "nervous fidgety type that always has to be moving something". Trust me, i have longed for the day i can stop this working on the truck all the time and get on with thinking of something other than what it could be.Its driving me nuts.
    It changes so frequently, runs reasonable, an hour later runs horrible. It rained this morning horifically and the truck seemed to respond with bad stuttering. By 1pm today the temp dropped from +8 (celcius) to -7 and snow covered frozen roads and the truck ran somewhat better.
    I keep thinking electronis issue, a wire bare or compromised one way or another. I do have a ABS light coming on with brake application and sometimes without, leading me to believe my ECM is thinking im standing still, derating my fuel supply circuit (which , when i asked CAT and the shop i use, yes, that is a possibility) so come Monday im going to try pulling the fuse to the ABS to see if its effective along the same lines.
    I even promised myself to quit smoking once its resolved, now thats serious !!
    With so much work pending with other stuff on the farm, i need to get this truck of mine fixed and out of my hair. It crossed my mind to sell it, but i couldnt in good concience offload my problems on someone else, i wouldnt want it done to me, its by no means ethical.
    So, the problem is mine to resolve, but thanks to the help of so many out there, i know the end is in the realm of my future.
    Im off. Have a good night guys.
     
    bigguns and SAR Thank this.
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. pushbroom

    pushbroom Road Train Member

    1,779
    7,312
    Sep 1, 2012
    0
    Speed sensor is fine. Like swaan said, it is normal operation for the truck. When the synco slams from high to low it moves the tailshaft to complete the shift. If the tailshaft moves fast enough, the speed sensor will jump accordingly. It is not noticed during normal shifting as the speed sensor is already reading road speed
     
    bigguns, SAR, Oxbow and 1 other person Thank this.
  4. pushbroom

    pushbroom Road Train Member

    1,779
    7,312
    Sep 1, 2012
    0
    Abs is a different issue. It only can cut power to the engine if it has traction control. Normal abs is its own system seprate from the engine.
     
    bigguns, SAR and Oxbow Thank this.
  5. truck 307

    truck 307 Light Load Member

    178
    315
    Aug 11, 2014
    0
    I dont see myself as a "mad man" because i hit the splitter rolling to a stop from highway speed, found a anomally (did i spell that right ?) and thereafter my truck ran MUCH better so when truck ran bad again, i tried what , coincidentally ? worked the day prior( im sitting here finishing my log for the week laughing, i feel like i should wrinkle up my face, drool and let out a psychotic growl with 5 cigarettes in my mouth, being the "Mad-Man" i am )
    But anyway, one day it will all be behind me, and at that time, just like now, ill appreciate the help received from the so many strangers i never met..
    - and ill let out a crazy roar while laughing and drooling !
     
  6. truck 307

    truck 307 Light Load Member

    178
    315
    Aug 11, 2014
    0
    Had a good day running today. Zero stumbling, zero power drop off, wet roads / fair bit of snow today too. Weird, with no set pattern. Maybe the ghost of C-15 past has left, and i dont give a #### where it went or why, but for some strange reason i think my luck wont be that good.
    I serviced the truck over the weekend, finding the ABS wire on the front left steer especially, pinched on the wheel side end, of the brake cam tube. Gently i picked out corrosion etc holding it jambed in there, sealed it with liquid electrical tape, wrapped the tube with a sliced open one inch piece of rubber hose, fastened the hose to the tube with zip ties and the wire to the wrapped tube the same way. Reason being, since the washing of the truck in warmer weather caused off the scale stumbling like i lost 3 of 6 injectors type feeling, and subsequently a couple weeks thereafter at the do it yourself wash bay spraying road salt off the truck and the wash water fast freezing and then a top notch powerful /stumble free ride for a couple hours till i idled at my destination and (i can only assume) the frozen water making continuity somewhere on a compromised wire , melted and truck returned to rough running /stumbling thereafter, and my ABS light constantly coming on, i figured "do nothing and nothing happens",so i shielded the ABS wire. Also, changing my fuel filters could have had an effect also. Engine oil and all filters get changed at 15,000 klm max (just under 10,000 miles) , seeing as i run 140,000 lbs all day long, oil is the blood of the engine. I took a CAT SOS oil sample and sent it to CAT also. See what happens.
    To date, i believe 38 guys stating they have a similar /the same problem as im having, have phoned me. 5 of which are 100 % identical in nature and they and i keep each other up to speed on progression with identifying this strange and no pattern dilemna.
    Should anyone have anymore thoughts or ideas, your input would be greatly welcomed.
    Leave your message within this report, or text / phone me at ; 905 746 5505.
    Thanks again guys. Have a great day.
     
  7. truck 307

    truck 307 Light Load Member

    178
    315
    Aug 11, 2014
    0
    I checked with CAT today on the comment / advice by "Pushbroom" stating the normal ABS is a seperate system / different issue with its own seperate system from the engine. In part, yes, Pushbroom is correct, for trucks with ECM's pre 2000 model years. But according to the shop foreman at CAT, after 2000, ECM's collectively utilize data from the ABS braking system, as well as throttle position sensor, cam sensor and its redundant crank sensor as well as the truck speed sensor, boost sensor, fuel temp and barometric pressure sensor, in order to deliver the correct voltage to the injectors. He went on to say "imagine your truck is stopped yet throttled up to 1400 rpm. Now on the other hand your truck is throttled up to the same 1400 rpm but pulling a heavy load up a hill. If the ABS system notified the ECM "TRUCK IS STOPPED", THE FUEL DELIVERY WOUL;D BE CONSIDERABLY LESS THAN AT THE SAME ENGINE SPEED OF 1400 RPM BUT PULLING A HEAVY LOAD UP HILL.
    The ABS sensor is directorate # 1, with boost thereafter, signifying how much load in specific , with timing overseeing the delivery compliments of the crank and its redundant cam sensor, governed by fuel temperature and barometric pressure sensor.
    I had him explane it all twice, as although i understand it all, there was a considerable amount of specific information he was educating me of.
    In the end, he said "so the answer to your question for your 2003 Peterbilt is YES, the ABS system plays a significant roll in fuel delivery"
    Graig, the mobile tech helping me out and who loaned me a ECM to try out said the same thing last week, that the ABS system plays a significant roll in engine operation.
    Ive learned alot over these past months, with thanks to the many people who have assisted me both on this site, and calling and/or texting me as well.
    Much appreciated to all.
    Have a good night.
     
    bigguns and Feedman Thank this.
  8. pushbroom

    pushbroom Road Train Member

    1,779
    7,312
    Sep 1, 2012
    0
    Abs has no part in fueling of the truck. The only time they care what each other is doing is if traction control/ stability control is present. The engine gets its road speed form the sensor on the back of the transmission tailshaft, not the abs system. Cat gets its park brake signal from the cab not the abs. It isnt until the introduction of the Paccar engine does ABS have to transmit road speed to the engine.

    He is right that parked fueling vs driving fueling is completely different. However the park brake signal comes from a cab pressure switch and has nothing to do with ABS. Also if your cruise control works fine, there is nothing wrong with your park brake switch.

    No offense to any Cat guy but they are fan hub to flywheel. The know their Cat engines very very well but are not very familiar with much that isn't stamped CAT. Abs/ oem wiring is dealt with better at the dealer as they are (or should be) completely familiar with those systems, whereas CAT dealers would never fix that in their shop. The only time ABS can cut fueling is if it is equipped with traction control or stability control which as far as I can tell, your truck is not equipped with. CAT has no idea what ABS system is on your truck so they shoot for the safe response and say yes it can affect fueling.

    Regardless, if you think the ABS system is screwing up the engine, pull the fuses for the ABS system. Run without it.
     
    Last edited: Jan 17, 2018
    SL3406, bigguns, swaan and 4 others Thank this.
  9. truck 307

    truck 307 Light Load Member

    178
    315
    Aug 11, 2014
    0
    Thanks for your input. I'm not a heavy truck tech and was only a auto mechanic from 1981 to 1987 after which I moved on and never went back. So I'm way out of the loop on technology and reply on info from educated guy's like yourself.
    Thanks again. Much appreciated.
    Have a good day. !!
     
  10. pushbroom

    pushbroom Road Train Member

    1,779
    7,312
    Sep 1, 2012
    0
    No worries man. We are here to help. Just want to see your truck running 100% again
     
    Oxbow and SAR Thank this.
  11. truck 307

    truck 307 Light Load Member

    178
    315
    Aug 11, 2014
    0
    Thank you for your help.
    You know, ive been in this racket since Dec. 1981, with nearly all my trucks CAT powered. Working on the majority of needed servicing, repairs and diagnostics myself, learning as i go. Only a small section (about 30 ft X 30 ft) of my steel barn has a drop ceiling, insulation (whats left after the raccoons keep ripping it down) and a small oil furnas with salamander heater running on diesel for extra heat on those bitterly cold -30 degree days.
    Its rarely what youde call "warm" in there, but it gets me out of the snow, the wind etc,. . This engine, C-15 6NZ, has been a challenge to say the VERY least. I need to pay another visit to CAT, having them listen (and hopefully do something about) the clatter like tick, like a ball-pene hammer hitting a plate of steel. To me, ide say a rod, a sticky (or bent) valve or similar. Theyve brushed me off twice already and ive had enough. 13 months remain on my platinum warranty and im going to address this noise with a bit more gusto than i have in the past. Each time, a CAT tech says something different. One time ; " Its resonation from the heat shield on the back of your exhaust manifold" (Peterbilt spec, shielding exhaust manifold heat from the firewall, the windshield washer fluid box and some heater hoses in the area) So i took it off, knowing darn well it had zip to do with it, and of course the tapping noise remained, so i hauled off to CAT again for their next excuse, and that time it was ; " O, thats nothing to worry about", yet its so loudly predominent it can be heard from 200+ feet away, heard in the cab when driving, and heard by passengers who are by no means mechanically inclined, yet say " whats that hard tapping sound im hearing", or " your engine sounds like my dads Kabota lawn mower" or simply by another guy ; "Your engine clatter sounds bad , do you still have warranty"
    Not thinking this noise was anything more than another CAT engine rattle, and being reassured by CAT ( twice) i went chasing other posibilities.
    But anyway, with my 37+ years out here, never ever have i been so stumped and disappointed by the local CAT shop. Next week on Tuesday im off work for surgery, and when i get out of the hospital, im going to write that detailed strong letter to every tom, Dick and Harry with any clout at Caterpiller Canada, copies to everyone with a title of sorts at CAT, efforting to stir up some activity and hopefully get iit in and have them yank off the head for starters, checking all componenets from top to bottom.
    But ive got to get out of this truck now and finish the paperwork for the day.
    Thanks again pushbroom, your help is truly appreciated.
    All the best.
    Till tomorrow (or whenever we chat it up again)
     
    bigguns, SAR, Feedman and 3 others Thank this.
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.