I did egr/dpf deletes yesterday, worked awesome, and i drove it for about 50 or 60 km, started and shut off lots of times. i left the air filter for today, a stage 2 AFE. soon as i started the truck for the first time, it threw codes, but ran. i turned it off, and now cranks for about 5 sec., and the computer disengages the starter, and does not fire at all. i moved the MAF/intake sensors over to the new intake tube, and the temp sensor has 5V to the plug, the temp sensor has 100, 200, and 3k ohms to what i assume the common terminal to be, so i believe that the temp probe is fine. the MAF on the other hand has no continuity to or from any terminals, but 12V to the plug. could the MAF sensor prevent the truck from running, even though all the egr/dpf components are deleted? i tried (i have an H&S mini maxx) returning the truck to stock, then re-installing the chip, still nothing. unplugged the batteries and let the capacitors drain (about 100mV left in the truck computer, the clocks reset and everything), no dice. ANY ideas (especially any that work) would be fantastic. i am an electrician, so complicated electrical diagnostics dont scare me... but i am fresh out of ideas.

 

Sounds like low battery voltage to me, did you try charging the batterys or having them tested? Try charging them overnight and cleaning connections and making sure they are tight. Any codes set? Usually a weak drivers side battery will cause that problem. Have the CCA tested after recharging should be 750 or higher. Computers don't like low voltage especially when cranking engine over. If low volts is detected the computer will shut down. Read the codes stored most likely low voltage code stored.

 

the battery voltage is good, i tested that first. one of the first things an electrician thinks of. both are quite new, and only drop to about 11.8V during cranking. and there are no codes stored! if you know how to read previously cleared dtcs that could help alot... i cleared the dtcs after the last start, and since i wasnt thinking that it wouldnt restart, didnt bother to write them down. just thought that it was a ghost issue, because i had disconnected the passenger side battery during install. i dont like welding anymore, you see. well, not inside the engine bay of my truck anyway. it seems like there is a run permissive that is not being satisfied, but could an MAF sensor prevent startup? it doesnt seem like it should. also, the MM can read the MAF readings, and it says 0 when the truck isnt cranking and goes up to 1 G/S when it is cranking. whatever G/S is. gallons per second? seems like a strange measurement for a gas. If the MAF is damaged/broken, could that prevent a start? thanks so much for your help!

 

Does the EGR Airflow Control Valve cycle open and closed without sticking when the ignition is cycled on and off?
May need a mirror and light to see the valve move. Have someone cycle the key while watching the valve. If stuck closed will cause a no start. Also turbo exhaust nozzle stuck will cause a no start. If it runs with the egr plate off then it's a stuck turbo nozzle.

 

That almost sounds like the anti-theft system has been tripped. You might try locking and unlocking it with the key fob then try to start, or try a different key.

 

The G/S is grams per second.

 

Did you remember to plug the fuel pressure sensor in?

 

I didn't unplug the fuel pressure sensor when I did the air intake, at least, I don't think I did. Where is that located, and how do I check if it is proper or not?

 

Also, tried the lock/unlock with the key, no dice. It does seem like the anti theft is tripped, as the computer only allows cranking for about 5 seconds, and no fire.

 

i looked at that bulletin, and the symptoms dont seem to line up, as the remote lock/unlock still works, and the vehicle cranks. i am still going to try that regardless, and thank you so much for the suggestions! however, i did forget to mention one thing about when the vehicle fired up for the last time after i installed the afe intake. the lightning bolt symbol on the dash came on, and stayed on until i turned the vehicle off. before i shut the truck off however, i check battery voltage via the chip, and it said system voltage was 14.5V.

 

I hate to say this but most everytime I get those symptoms it's a bad battery. Have you load tested the batterys yet? I would bet money you have a bad battery. Try disconnecting the negative battery cable on the right side battery then measure the voltage on the left side battery when you crank engine over. If it drops below 10 volts the battery is no good.

 

tried pulling the iod fuse, no change. still cranks for 5 sec, then no fire and disengages the starter. havent tried pulling the egr cover plate off yet, that will have to wait for tomorrow. checked the maf, it is fine. replaced stock air intake, no dice. had a charger on it all day, still no change. i will grab a load tester from work tomorrow and test them, just to be sure. also, not sure if this is related or not, but i noticed tonight that the cap for the power steering is MIA. it was there, i remember looking at it specifically, on sunday when i swapped the intake over, and now it is gone. wierd. would that cap have any interlock with any other run status/permissive? i dont see any limit or pressure switches on it, but i am grabbing at straws right now...

 

i also just want to thank you big iron for all your suggestions... even though they havent panned out yet, it keeps the morale up anyway. sure appreciate it.

 

You'll figure it out but make sure you load test those batterys before doing anything else. A weak battery will cause all sorts of problems on these trucks.

 

Well this may sound stupid, but I would put the stock Air box and filter back in and see if it makes a difference. The MAF, mass air flow sensor does calculate the amount of air and fuels accordingly. If the problem persists, I would go get a new one. I am thinking that it can't see air flow, and therefor, won't fuel. And since it won't fuel, it just turns the starter off.
I am just guessing, but if it was my truck, that is what I would do first. ")