Curtis Whitehill Posted December 6, 2012 Share Posted December 6, 2012 1994 CH613 with an E7 400 that studders and smokes at idle until warm. After temp reaches 180 degrees truck quits studdering and smoking at idle, but between 1300-1600 rpms it has a bad studder and smokes horrible. It is not really down on power, it is not using coolant, not using oil, very little blow by. Truck has 365,000 miles on it. Checked for a shorted Rack Position Sensor, found nothing. Has all new reman injectors. Any thoughts? Quote Link to comment Share on other sites More sharing options...
rsb502 Posted December 6, 2012 Share Posted December 6, 2012 Timing sensor, one on the pump one on the engine, one goes out the pump can't advanced properly. Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment Share on other sites More sharing options...
Curtis Whitehill Posted December 7, 2012 Author Share Posted December 7, 2012 Changed Timing Sensor on pump, had no effect on runability. Any other suggestions? Quote Link to comment Share on other sites More sharing options...
krismoriah Posted December 7, 2012 Share Posted December 7, 2012 Myself and another guy on here have the same problem. My engine is an 1998 E7 400 with 395,000 miles. Engine starts up and stumbles, then pours out the white smoke and chugs and stumbles for about 20 seconds then clears up on mine. After about a minute it runs really good..then if you shut it off after warm and wait a few minutes or more it will do the same thing. My local mack guru says to pull the injectors...that in his opinion one or more are leaking off after shut off and filling the cylinder with fuel..then on startup the remaining cylinders fire and the loaded cylinders burn off until they are dry then it runs good... that is a theory not proven...but sounds like a possbility.Since you have all new 'reman' injectors...that possibly kills that theory. I replaced the oil timing advance on my pump...but mine was bad anyway...someone had been beating it with a hammer before me and it finally gave out... this was a great possibility in a fix...but it solved nothing for me. Still looking for answers here after about a year. Quote Link to comment Share on other sites More sharing options...
Curtis Whitehill Posted December 7, 2012 Author Share Posted December 7, 2012 This one does it at any RPM if you slowly bring it up, just steadily give it more and more throttle. But if you hammer on it, it stumbles, skips, throws some white smoke then clears up and runs the way its supposed to. Going down the road is its fine if you are hard on the throttle, but again if your little with the throttle just maintaining speed or trying to speed up just a few miles an hour it smokes and skips.My other thought was Rack Position Sensor or the Pump itself. Either way the pump has to be sent to a pump shop. However I would like to test the Rack Position Sensor before I just tear the pump off and send it out to get rebuilt. Does anyone know the pin out proceedure or way to test the Rack Sensor and the Rack Sensor Wiring from the V-MAC Module. The truck has the V-MAC 1 electronics and Bosch Module. Quote Link to comment Share on other sites More sharing options...
fjh Posted December 8, 2012 Share Posted December 8, 2012 You guys !(Most) of the time it is the timing advance solnoid block that causes this problem!On the odd occation the econovance can be hanging or have broken spring, there was a ts buliten about removing the screens in the inlet ports on this be sure you have done this also there is a bulliten for re routing the oil suply line at one point make sure it comes from the left side of the engine piston cooler gallery and the hose is in good condition!the hose may be falling apart inside! just some stuff to try! 1 Quote Link to comment Share on other sites More sharing options...
krismoriah Posted December 8, 2012 Share Posted December 8, 2012 fjh,I had to replace the econovance in mine, when i got it the only way to start it was to bang on it with a hammer as someone else had done before me...I read the posts about the screens...i cannot find any screens at all in mine...i took everything apart even the new econovance...no screens. mine is a 1998 so maybe someone had already done it and the new econovance didnt have them? I will re-look at my oil supply line...perhaps you are correct..its worth a try. Quote Link to comment Share on other sites More sharing options...
jimmy joe Posted December 10, 2012 Share Posted December 10, 2012 I had a smiler problem with white smoke and shutter, it turned out to be engine brake coming on slightly. I had to change a solenoid and that solved it. It could be a bare wire or one spool hanging up once in a while. Just something else to consider. Quote Link to comment Share on other sites More sharing options...
krismoriah Posted December 10, 2012 Share Posted December 10, 2012 Engine brake doesnt work until oil reaches certain temperature...so this is not my problem at startup. Quote Link to comment Share on other sites More sharing options...
staxx Posted December 10, 2012 Share Posted December 10, 2012 Had a engine brake solinoid once that wasnt screwed in all the way and was bypassing causing engine brake to hit slightly Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted December 10, 2012 Share Posted December 10, 2012 Had a engine brake solinoid once that wasnt screwed in all the way and was bypassing causing engine brake to hit slightlyYears ago it was common for the jake selnod o/rings to get hard and let enough oil thru to cause a small miss.For those who have never seen it it was a problem to find. Thats whan we all made jake block off blocks to run a cummins with out the units on.Mack jakes was almost not heard of then. Quote glenn akers Link to comment Share on other sites More sharing options...
krismoriah Posted December 14, 2012 Share Posted December 14, 2012 changed the oil line going to the econovance...the old one was brittle and thought it wasnt getting proper oil at startup....no help. Still burns your eyes out to startup and chugs hard lots of white smoke at startup.... Quote Link to comment Share on other sites More sharing options...
oilburner Posted December 19, 2012 Share Posted December 19, 2012 Man i had a guy tell me his did this brand new, took it to the dealer sevral times and never did fix it. Mine does pretty much the same thing, at start up it will do this for about 20 30 secounds but it has no response for the fuel pedal when it is acting up, have a new injector pump and injectors, never helped at all. Quote Link to comment Share on other sites More sharing options...
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