08 6.7l wont start
#16
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I put the stock air box back in already. Still nothing. I was thinking the same thing... It almost seems like it doesn't recognize the key or something. Anybody know what the anti theft system does then? The key I have ( I only got one when I bought the truck, and I haven't gotten around to getting more yet, it has only been 3 weeks) still unlocks/locks the doors, and it cranks... But won't the trucks start and run once, then not start again until is sees a key it recognizes? Anybody know for sure how to diagnose/fix that? Or know for sure what the computer does?
#17
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so tonight after work i tried pulling off the cover plate from the egr deletes, on the intake and exhaust side, still nothing. however, on the exhaust side, you can see smoke from the cranking, and the computer kills the starter and shuts off the fuel just before it fires, but it still obviously is getting some diesel because there is smoke. what run permissive needs to be satisfied before the computer allows fuel? could this be a cp3? there were no fuel issues before this, and it does not throw codes after cranking. would a fuel rail pressure sensor fail behave this way?
#18
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Well I am still stuck on the butterfly valve in the intake horn. I am thinking it is stuck shut and since you have egr blocker plates, can't get any air at all. Seems like it uses up the little bit of air it has in the engine, then the computer cuts the fuel.
It takes just a little while to remove the butterfly valve in the intake, but maybe if you just slid the boot off and took a mirror you could confirm if that is closed. It is just like the butterfly valve in an exhust break.
When I did my deletes, Mine took a while, but it finally started shutting when I was driving down the road, I am thinking yours might have gotten stuck in the closed position.
I could be totally wrong, but if you don't get air, it won't run either. And it isn't that much to check.")
It takes just a little while to remove the butterfly valve in the intake, but maybe if you just slid the boot off and took a mirror you could confirm if that is closed. It is just like the butterfly valve in an exhust break.
When I did my deletes, Mine took a while, but it finally started shutting when I was driving down the road, I am thinking yours might have gotten stuck in the closed position.
I could be totally wrong, but if you don't get air, it won't run either. And it isn't that much to check.")
#19
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Well I am still stuck on the butterfly valve in the intake horn. I am thinking it is stuck shut and since you have egr blocker plates, can't get any air at all. Seems like it uses up the little bit of air it has in the engine, then the computer cuts the fuel.
It takes just a little while to remove the butterfly valve in the intake, but maybe if you just slid the boot off and took a mirror you could confirm if that is closed. It is just like the butterfly valve in an exhust break.
When I did my deletes, Mine took a while, but it finally started shutting when I was driving down the road, I am thinking yours might have gotten stuck in the closed position.
I could be totally wrong, but if you don't get air, it won't run either. And it isn't that much to check.")
It takes just a little while to remove the butterfly valve in the intake, but maybe if you just slid the boot off and took a mirror you could confirm if that is closed. It is just like the butterfly valve in an exhust break.
When I did my deletes, Mine took a while, but it finally started shutting when I was driving down the road, I am thinking yours might have gotten stuck in the closed position.
I could be totally wrong, but if you don't get air, it won't run either. And it isn't that much to check.")
#21
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I surrendered today... Got it towed to a shop. Turns out if I had it running I most likely would have had it at work today, so add lost revenue to the repair bill... Ugh. I will let you guys know what they find.
#23
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I was trying to duplicate your problem with another truck today. There is a wiring harness plug that might be loose just next to the master cylinder. 10mm bolt keeps it tight. Possible you loosened this connector and forgot to tighten it back up? There is also a ground wire to the battery that will give you a no start if it is loose. I guess you will find out soon what's going on with truck.
#24
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It has to be a electronics problem, like loss of power or ground to the ECM. On a Detroit series 60 if you lose power to the ecm it will crank and not start but you know it because you will not be able to connect to the ecm with a scan tool. Sounds like you can connect to the ecm, the only other thing I see is you said that you had the lightning bolt light on when it did start. That light says there is a fault with the throttle. I would think that it would cause a no start if it reads something out of range. I dont have a diagram for that truck but when installing your new intake you may have pulled a wire loose or shorted it out. Most sensors, like a throttle position sensor have a five volt supply sent to them to work with and then return it to the ecm. If the shop has trouble with it check for that five volt reference at the tps. I have seen sensors in the past that will steal the reference voltage from other sensors and cause all kinds of problems. The only way to find that is to unplug each sensor one at a time untill you get the reference voltage back.
#27
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Thanks bigiron, did you get the truck to crank for 3-5 seconds and then the starter cuts out? It seems like it is cranking until it would normally start, then stops cranking. I may have loosened the plug when I did all the deletes the day before this happened, and just had it fault the next day. I will see about giving that a shot. I work on huge stationary engines a good bit trouble shooting, and I have seen them do similar things, as in they have run permissives that are satisfied one at a time, eg, oil pressure, lube flow, engine coolant temp, etc... And the panel goes through the permissives one at a time, and if the parameters are acceptable proceeds to the next one, and then when it gets to one that is outside the parameters stops the start sequence, and this seems really similar. I looked up resetting the tps; key on, full throttle and zero throttle within 2 seconds, then it should ding that it has reset the zero and span, but it wouldn't reset for me. I must have tried 20 times. So I will give the shop a chance because I am working too long of days to work on it myself. Pretty hard to come up with the motivation to go look at my truck in the dark in -10c after a 14 hr work day.
#29
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the guy at the shop took a look at it today, and thinks that it is an injector issue. he said that the computer is commanding a start, and the starter cutting out is supposed to happen when the rpm get above a certain level, to prevent the starter engaging in a running motor. he thinks injector(s?) because it wont start, and fuel pressure is fluctuating wildly he said. i have dealt with this particular mechanic in the past, and have always found him to be quite good, so i trust to his judgment... however; the truck 1 hour before ran smooth, quite, not burning oil, no blowby, no issues. we will see i suppose. they are going to test the injectors tomorrow. if i need injectors, any thoughts on how i should go about it, or who i should get them from? i dont want a complete set unless they are all shot, and i think that the truck has too much power already for the tranny (which i dont want to fix next week...), so a stock power level is appropriate, as the trucks primary function is going to be work, and the key objective economy and reliability.
#30
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as an aside, i work in the oilfields in northern BC, and pretty much every company that i work for requires a "positive air shut-off", which is essentially a butterfly valve in the intake on a solenoid that is actuated by either a switch or overspeed sensor (a tach pickup, usually set to 3200 rpm from factory), and shuts off air to a motor to prevent runaway in the event of a gas leak, which provides a fuel source for the motor that cant be shut off with the ignition. however, the egr butterfly seems to be pretty much exactly that, only on a stepper motor. has anyone tried using it to prevent runaway, and if so, how did they wire it? an aftermarket kit is around 800 bucks, so if i could grab a switch and wire from work and make one... that would rock. anybody know the control voltage? is it 0-12V, or 1-5V?