Alex Bruene Posted July 30, 2007 Share Posted July 30, 2007 Is it just me, or has anyone else noticed that more and more often lately high pressure oil leaks are not setting DTCs? I have another one today, only making 40 psi ICP, but no codes... and certainly not the first time... Quote Link to comment Share on other sites More sharing options...
DwayneGorniak Posted July 31, 2007 Share Posted July 31, 2007 Once in a while, yes. Maybe the 450th reflash has a glitch in it and they will need to update the calibration to improve onboard diagnotics "again"! Quote Link to comment Share on other sites More sharing options...
Torqued_Up Posted July 31, 2007 Share Posted July 31, 2007 450th reflash /forums/images/%%GRAEMLIN_URL%%/rofl.gif now that you mention it I think you are right. I have a van that has a high pressure leak that needed help staring. I let it run a couple hours at idle with the IPR at 85% the last I checked. It stalled afer goosing the throttle. Still no code but I can hear the branch tube rattling against the rear enginee cover Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted July 31, 2007 Share Posted July 31, 2007 E-Van? Ambulance maybe? Battery shutoff that clears codes when the power is killed? I've seen ambulance guys burned by this before. .24 ICPV steady cranking, 1500psi ICP building up while cranking in scan data, no friggin codes! #1: Beware of battery shutoffs #2: Only believe ICPV! Good Luck! Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted August 1, 2007 Share Posted August 1, 2007 How about run down batteries? Often when wee see a truck towed in because the STC fitting let loose some idiot kept thinking just 30 more seconds and maybe she will start! There seems to be a crank it till it dies mentality that is more common than you think. Exactly how low does a battery have to go to kill KAM? /forums/images/%%GRAEMLIN_URL%%/shrug.gif All the way or is there a minimum voltage threshold? Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted August 1, 2007 Share Posted August 1, 2007 How about run down batteries? Often when wee see a truck towed in because the STC fitting let loose some idiot kept thinking just 30 more seconds and maybe she will start! There seems to be a crank it till it dies mentality that is more common than you think. Exactly how low does a battery have to go to kill KAM? /forums/images/%%GRAEMLIN_URL%%/shrug.gif All the way or is there a minimum voltage threshold? Excellent point. Doesn't the diag sheet say below 8.0v cranking will reset KAM? I'm pulling from memory as I am still on vacation (Hi Jim!) on the left coast and don't have my reference stuff with me. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted August 1, 2007 Share Posted August 1, 2007 Since I have access to the info I went looking... everywhere. The hard start/no start diagnostics state: "The 8 volt specification represents the minimum battery voltage required for engine starting." This is the only mention of a minimum voltage and the 8 volt spec is good for both the PCM and the FICM. Now, we can assume that the modules simply wont work with less voltage than 8 volts and that would be correct. We can make an educated assumption that the memory in the PCM is just like the memory in other modules which draw milliamps with the vehicle shut down suggesting a very low power requirement. But thats amps, not volts... which brings us back to the question of, at what voltage do we lose KAM? It is an interesting question. Somebody ask a HotLine engineer when you have one on the line! /forums/images/%%GRAEMLIN_URL%%/eeeesh.gif Quote Link to comment Share on other sites More sharing options...
GregH Posted August 1, 2007 Share Posted August 1, 2007 If the system voltage drops below about 6 volts, then all the modules on the truck will no longer function properly. Anyone driven a vehicle with a bad alternator? Modules will shut down one at a time, usually instrument cluster first, until the PCM gives up and shuts off. The 8 volt spec is given so there is a little wiggle room for manufacturing tolerance from the electronic component makers and Visteon, as well as variation in test equipment. Solid state electronics need a stable voltage source to operate. Really stable. Atmel and Microchip (my favorite) processors (and Motorola, like Visteon uses) can only tolerate a variation of less than one half of one volt before unpredictable operation occurs. And, if you go higher than 6 volts then the processor is in danger of meltdown. Now, when I say processor, I'm talking about the actual microprocessor located within all the modules on the vehicle. But wait. The vehicle supplies (about) 12V, right? Ok, so the batteries supply 12V. But the modules will operate until about 6 volts. That a wide range. And way above what solid state electronics operate on. Here ya go: all the electronics inside each module operate on 5 volts generated by an internal voltage regulator. This regulator requires a voltage higher than it's output voltage to maintain it's rated voltage. For instance, a 5V regulator will continue to put out 5V as the input voltage (VPWR) varies from 14.4V (charging) to 6V (dead). (Side note: Earlier generations of PCM's used the same 5V internal power source for the processor and memory to supply VREF to all the outside sensors that need it. Since that time, Visteon changed the design so the internals are separated from the outside world. Kill VREF now, and you can still communicate with the PCM. Two voltage regulators are now used.) Voltage regulators are short circuit protected. They sense the abnormal current draw and automatically shut down until the short circuit is removed. By the same token, they are overcurrent protected - it's the same feature. Voltage and current are interelated. Voltage is simply "pressure." "This is what I can put out." Current is the actual "work." Use the old comparison of a water pipe: Current capability is akin to the diameter of the pipe. Voltage is the pressure of the water in the pipe. So, KAM (as well as module operation) requires 6 volts minimum. How many amps? Well, the measure for the memory itself is really, really small. In fact, there is more energy wasted within the processor (as heat) and on the way there than the memory actually needs to function. It's on the order of hundredths of a milliamp (.00001 A) at 5V. (Another side note: in the past, the microprocessor goes into sleep mode and consumes an absurdly low current also. These days, the microprocessor stays more awake and the current draw is slightly higher since it has various housekeeping and monitoring functions that we didn't have a few years ago.) Anyway, hope this clears up a few things. Does this generate any new questions? Quote Link to comment Share on other sites More sharing options...
Alex Bruene Posted August 2, 2007 Author Share Posted August 2, 2007 It has nothing to do with dead batteries or anything like that. I think there is a problem with some of the flashes out there. As far as I understand, P2291 is supposed to set after 7 seconds of cranking without reaching 500 psi of ICP. I've had it happen (not set a DTC) on leaks that would only cause no starts on hot engines, and on outright never starts. And it seems it's happening more and more lately... like 3 times in the past 2 weeks. Quote Link to comment Share on other sites More sharing options...
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