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I have a 97 PSD with almost 130K on it. When i first start it up untill it really warms up it idles funny. It will idle at about 500 rpms, and then it will jump up to about 7 or 8 hundred for a second or too, and sometimes it will go down to 400. It does it when you put it in drive too, even when you start to give it throttle and move, you can hear and feel it 'falter'. It will do it no matter what the temperature is outside, untill it gets to normal operating temperature, which it usually goes away. I was told it was probably my injector pump going. and this could also be the reason for me only getting 11 mpg (stock tires/no lift).
IF your due for an oil change that's a good place to start. These engines rely on clean, correct oil (diesel rated) to run right. Change the fuel filter and clean the FPR (Fuel Pressure Regulator) screen. Search this site for FPR screen.
Is the CEL lit up? Get it scanned for stored codes even if the CEL isn't on. It would be best if it was scanned during a cold start-up.
BTW:You don't have and injector pump. The injectors are fired electrically and with hi pressure engine oil. The engine idle is supposed to increse slightly when put into gear.
sounds like possible an icp sensor, its on the drivers side front of the engine under the engine cover screwed into the head, if I recall its a 3 wire sensor, unplug the sensor and start it up and see how it runs, if the idle is smooth, you'll need a sensor.
I just finished going through this complete mess of a poor idle, had a pluged screen like mentioned above, bad sensor, 2 injectors with bad o-rings but not at the point where it was dumping fuel in the engine oil and this made quite a differnce, the hpx line improves idle alot as well, consider doing this.
as for milage on my engine, it has 130,000 miles on it too just finished all of that junk, the idle is nice now. now to replace the camshaft sensor and thottle position sensor >
Oil is good, changed that and the fuel filter about 500 miles ago. The CEL isnt on, but i did pull P0603 when i did scan it (PCM Keep Alive Memory error is what the list on this site said it was, but i couldnt find any more information on it. i cleared it but it kept coming back) It does sould like the truck is being put into gear (idle increase) but this just keeps happening at idle.
This week ill try cleaning the FPR screen and checking the icp sensor. Hopefully this will work cause it seems like my idle problem is getting worse.
David, I posted a question on mine that just quit running. Do you think that icp sensor could be my problem? What is a icp sensor?
An ICP will not make the engine quit running, it'll set a code and fall back onto default values. hence if you unplug it your engine idle will smooth out if you were to have a faulty sensor.
ICP injection controle pressure sensor. supplies information of what oil pressure is present in the cylinder head that is used to fire your injectors
hpx line=high pressure cross over line, basically its a line that you can buy on this sight from one of the sites sponcers, it taps into the oil supply from one cylinder head to the other by removing plugs on each head and what this does it balances the pressures out from each cylinder head.
For my HPX line, I made one at work with hyd hose and some fittings and through it together, not exactally a do it yourselfer job, you need the lines and fittings that can work at high pressures so the hose clamp and fuel line idea you can through out in the trash
Now I am leaning towards the ICM. Is there a way to test it out?
an ICM or camshaft position sensor, when you crank your engine, if it DOES NOT show RPM's on the tach, then its likly the camshaft sensor, up here in canada it was $312 at napa, phoned Navistar and they had 10 in stock selling them for $132 gotta add taxes on that of corse and its in canadian funds.
as for testing the ICM, you kinda need one to swap out for testing as I dont know myself if thier is a way to test these things, my knowledge is limited as well, do you have a friend that has a power stroke????
Thanks for the information and looking for a decent price for me. However, I fixed it! Apparently, going the extra 1000 miles on the oil did it in. I changed the motor oil, including the high pressure oil reservior, used Amsoil this time, new filter, and tossed in a new fuel filter. Cranked for a few tries, did the same. Noticed my oil pressure came up. Let it sit for a few minutes, thought I would give it one more try (prayed some more)... and she fire up. Had one hiccup, then she ran smoothly.
It is a amazing that even though the oil was full in both the reservior and the oil pan, it must have been thick as molasses and that prevented the injectors from working properly.
I tried unplugging the icp sensor today, and that didnt make a difference. I talked to a few other people inculding a guy at ford and they said it may be the camshaft positioning sensor. My friend has a powerstroke and his idles just fine, so im gonna try swapping that tomorrow and see if that (hopefully) does the trick. Im also going to look into those high pressure lines.