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Big_Katuna's avatar
Big_Katuna
Explorer II
May 02, 2015

UPDATE Turbo boost check stop engine CAT C7 error back

2005 FL CAT C7 40K miles. Fleetwood. I was getting check/stop engine light about six months ago. Bought Silverleaf VMspc for my laptop (which is awesome, great support) which pointed me to excessive turbo boost pressure. Had Sensor replaced. Drove several 1-2 hour trips no more idiot lights.

This AM leaving for a camping weekend I started her up and within a few minutes the lights were back on. Hooked up the laptop and it is the turbo boost error again.

I decided to go anyway since I am sure it is either a bad sensor again or wiring.
After driving while watching the screen I am more convinced it's wiring or a ground. It stays steady at 10-12 pounds of boost then jumps to 30-35 pounds, alarm goes off then drops to normal lights go off. 10-15 minute cycles.
Engine runs fine, all gauges normal. It is warmer and more humid now than last fall when it was serviced.

I guess I'll start checking connectors, grounds, call CAT and FL tech support.

Any ideas?
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  • Big_Katuna's avatar
    Big_Katuna
    Explorer II
    May 04, 2015
    So on the trip home it did it some more but I noted some more details.

    It rarely does it on smooth roads unless near full throttle and high turbo pressure eg 25 pounds or so.

    Cruising 55 on flat ground turbo pressure at 10-11 pounds it occasionally throws a code. I dont think its a waste gate issue as it is nowhere near full load.

    OK, so another symptom is that it did it A LOT on bumpy highway that
    was under construction, even at slow speeds, coasting 1-2 pounds tp.

    And it occasionally does it at idle. I am going to trying to wiggle wires near the ECM, inspect any plugs near the sensor.

    The exact code is PID 102 mode = not responding.
  • Passin_Thru's avatar
    Passin_Thru
    Explorer
    May 03, 2015
    If it is the turbo going out you can buy a new set of vanes and bearings and replace them yourself. It's not hard to do. Just remember the impeller is bolted on with a Left hand thread but same price as a new one.
    http://www.ebay.com/itm/C7-C9-CAT-3126-Turbo-Caterpillar-Diesel-Turbocharger-Brand-New-/181216867242 Remember to replace the exhaust spacer plate.
  • DSDP_Don's avatar
    DSDP_Don
    Explorer
    May 03, 2015
    Big Katuna.....from what you describe, sounds electrical, especially when running on flat ground and the gauge changes, but the engine runs the same. Grounds are usually the number one culprit.
  • Big_Katuna's avatar
    Big_Katuna
    Explorer II
    May 02, 2015
    What's odd (to me any ways) is that it does on flat ground cruise set to 55 mph 10-12 pounds of boost randomly. It will be fine for 10-30 minutes then it spikes to 35 on the screen. I'm reading up on causes and will be testing the waste gate when I get home.
    Also going to check my slobber tube as I read that can cause it.

    Also curious why a new turbo costs $4000 when they are on EBay for $500 brand new.
  • PF_PM's avatar
    PF_PM
    Explorer
    May 02, 2015
    Sounds like the waste gate valve is not operating properly.
  • Diplomat_St_Poo's avatar
    Diplomat_St_Poo
    Explorer
    May 02, 2015
    We also have a 2005 C7. We had the same symptoms three years ago. When ever we stepped on it going up hill the alarms and stop engin lights would come on. As soon as we took our foot off they would stop. Ran perfectly except for that.
    When we had it serviced they updated the engine codes. Good to go for the next year.
    Two years ago it started again. Around 60,000 miles on the MH. Ran perfect until you stepped hard on the accelerator. Took it in, they ran a bunch of test and this time not so simple. Bearings going on the turbo, could last for another 50k or have a catastrophic failure causing more damage. We decided to have it fixed. Cost just over 4K, ouch. A year later it's still running great. No more alarms.
    I did some reading and found a slew of folks that had the same issue with their C7. All in the 2004-2006 year range.
  • tinkerer's avatar
    tinkerer
    Explorer
    May 02, 2015
    My C7 Cat usually has about 26-28 lbs of boost under full load. Not an expert but there is a waste gate which limits turbo boost which possibly could be a problem if it's not working properly.;)

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