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Keep an eye on it while cranking and see what it drops to. The good news is that VREF is well within spec :)
 

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Try doing a koeo test with the icp plugged in and again with it unplugged. There's a code to be found somewhere. Try to get the truck to give it up

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Discussion Starter #23
tinman - I ran the key on engine off test with the ICP unplugged when I first got the scanner (didn't remember the ICP was unplugged at the the time) and the only code I got back was for the ICP. Did not rerun it with the ICP plugged in. Will do that tomorrow.

Pikachu - I'll watch the battery positive voltage while cranking in the morning also.

Thanks all for the help so far... much appreciated!
 

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Discussion Starter #24
Ok. Ran key on engine off test with every sensor plugged in. No codes. Unplugged the ICP and ran it again. Get the P1280 code returned. Plug the ICP back in, code goes away.

Have had the charger on the batteries since Friday. Battery Positive Voltage was 12.4V when I started the scanner today, and went down to 11.1V while cranking. I let it crank for a good 15 seconds or so. Cranked it again and it was showing 10.6V. Those values look good to me, no?

One question... I had AE track a few other items after reading some more posts. Ambient air temp right now is in the mid-90s here in Dallas. The engine oil temp showed as 91.4F... intake air temp showed as 94F... makes sense. Why would engine coolant temp show as 267F?? It hasn't run since Thursday of last week, but has been sitting in the sun... but 267F? Is that sensor off? Would that keep the computer from wanting to start the truck? Temp idiot gauge on the dash does not show high.

Oh, and exhaust back pressure shows as 16psi. That seem normal for just key on? I read somewhere else that it shouldn't be that high... but thought I'd ask to be sure.

Attached two screenshots that show voltage, and oil/air/coolant temps, etc, first with just key on, second while cranking.

One other theory. Back in 2008 right after I bought the truck, I put in a CodeAlarm 650 alarm and remote start. The alarm itself still works, remote lock/unlock works. I pulled the fuses for it just in case maybe it was interfering, but it made no difference. I've called and left a VM for the guys where I got the alarm to see if that system could have that kind of impact on the truck or not...

Any other ideas?
 

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The coolant sensor doesn't report to the PCM, so that number is artificial - it doesn't mean anything. Both the exhaust back pressure sensor and the MAP sensor report absolute pressure - meaning it would be zero in an absolute vacuum, but will show your atmospheric pressure KOEO. At sea level, that's about 14.7 psi. So, the 16 is a little off, but not enough to worry about. Do you have a tuner? I remember reading about the no start issues of one guy who turned out had accidently put his tuner in the no start position...
 

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Did you ever put the new ICP sensor in? If that first pic is KOEO, and you hadn't just recently cranked the engine, the sensor is biased. It's reading 160 psi with the engine off.
 

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Guess I would pull the drivers valve cover and verify the injectors are indeed firing. Look for oil pulsating out the vent while cranking. I would also check the checkvalve in the bottom of the fuel filter stem and make sure ot isnt blocked or not working.

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Discussion Starter #29
There's no tuner that I know of... not one that I've put in it anyway...

When I ran the scanner for the first time yesterday, ICP was between 2-4 with key on, and 2250-2280 while cranking. With the ICP unplugged it was showing 0 with key on, and a steady 2269.04 while cranking.

About an hour or so before doing the test today, I had pulled the fuses from the alarm and tried cranking the engine. So maybe that is where the 160 is coming from...

I guess swapping the ICP is next then. Looks like easiest way to get a wrench in there is to remove the alternator, no?

As for pulling the valve covers, I can do that if need be. Buzz test was good, but pulse width during cranking was only shown as 0.30 or so in AE... where "normal" is between 1 and 6.

This stuff is frustrating as hell... No codes, no start, no cause that I can find yet.
 

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Discussion Starter #30
tinman... whats the best way to check that checkvalve? I get fuel out of the drain valve, but the checkvalve I'm not familiar with...
 

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The big black post ia the checkvalve. The filter pushes down on it

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I wouldn't bother pulling valve covers yet. If your injector pulse width is only .30ms, rest assure the injectors are not firing. Try setting up AE to monitor RPM, Battery voltage, IPR duty cycle %, ICP pressure, ICP voltage (if that's available) and injector pulse width, then record it while cranking. Export the file as a .csv and post it. There may be something in the data that can shed some light on this. If all the required parameters are met, that engine should run unless the IDM or PCM is faulty.
 

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Discussion Starter #33
Roger that. I'll take the lappy out there right after work and hook it up and run the tests again. Looks like we're about to get stormed on, so probably won't be replacing the ICP today... we'll see.
 

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Watch the ipw from key on while icp is building pressure. Im thinking as icp pressure goes up, ipw goes lower.

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Discussion Starter #35
OK... here's the Excel file. Only interesting part to me was the injector pulse width value stayed there after I quit cranking the engine.
 

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I just got done reading through all the posts and I have a few questions.

#1 your truck doesn't run at all right now correct? When it died what exactly was the truck doing? Did it just die all of a sudden or did it stumble and then slowly die?

#2 if the truck doesn't run. When you try to crank the truck do you get any movement on the oil pressure gauge on your dash?

#3 does your tachometer move when trying to start your truck?

you need 500 psi for the PCM to fire the injectors.

Sorry if this is a repeat but don't think I saw it so,

Take your AE hook it up to the truck, and set it up to monitor ICP, IPR Duty Cycle (AE may call it ICP Duty Cycle), engine RPM, and fuel injection pulse width. Set it to record the values so you can review them, then crank the engine and see what happens. You should get a duty cycle of 14% as soon as you turn on the key. The ICP should be zero until you start cranking. Engine RPM needs to be at least 100 to start, and injector pulse width between 0.6 and 0.8 ms (going from memory here) for the engine to start. Battery voltage has to be at least 10.4 volts to crank. When you crank it, IPR duty cycle should rise (but stay below 40% or so), ICP should rise and get to 500 psi pretty quickly. It will probably go as high as 2000 psi, then settle down as the engine starts (if it does).

See if you are getting power from the two high voltage (1087 orange and 878 pink/yellow wires) lines from the IDM connector to the valve cover gasket connectors.

Good luck and I know how much of a PITA this is.
 

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Discussion Starter #37
Nyghtryderz - I think my previous post this evening with the Excel spreadsheet attached shows the data you're looking for as far as values. My original post explains what I was doing when the truck died.

When I start cranking the engine for a few seconds, the oil pressure on the gauge does move into the middle zone and stays there for as long as I crank the engine. Tach does not move, but AE does show engine RPM.

On the two wires you suggested, will they only have power while cranking? Or with key on?
Thanks
 

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Ok I reread your posts and sorry about the repeat as I stated in post above.

When was the last time you rescanned for DTC? I'm wanting to see the codes p1293 and p1294 when you do a injector buzz test.

If my memory is correct they should start to receive power as soon as you have the KOEO.
 

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Discussion Starter #39
KOEO and buzz test were successful, with no codes. AE pulls codes as soon as it connects to the computer, and I also tell it to refresh them at least once also. But it shows no current powertrain codes. (I do get a code about my overhead computer which hasn't worked in years) If I unplug the ICP or EBP sensor, I get a code for those... but with everything plugged in, no codes. No codes at key on, while cranking, or during KOEO or buzz tests.
 

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I was really hoping to see some kind of smoking gun in the data, but with the exception of FIPW, it all looks to be in line with what it should be. For whatever reason, the PCM is not telling the IDM to fire the injectors. When I get home later, I'll revisit this and see what could cause this other than a faulty PCM or IDM. If the IDM was the problem, there should be a code set, though. A bad PCM may or may not set a code. I'll dig in to this a little deeper when I get home this afternoon and see what I can come up with from the PC/ED book. In the meantime, of you happen to know anyone who'd be willing to let you borrow a known good PCM to try, that may be worth a shot.

I don't see it listed in your signature, but you don't have a chip or tuner installed do you?
 
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