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IDM failure????

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First a little background on the rig in question. 96' F-250 7.3 and a 5 spd. The truck came to my shop on the hook, customer said it runs terrible(just bought it knew it ran like this, took the chance on getting a good deal). I start it up(very hard to get started), once it started sounded like it was running on 3 maybe 4 cylinders. I had to put it in 4low so it wouldnt die when I let the clutch out. Get it inside and check the oil and coolant. The oil looks like crude oil,below the add mark. Coolant looks terrible and no additive in it. The entire engine is covered in oil. I start to look it over: air filter plugged solid, drain out a fuel sample(very odd color and smell, API is high), Battery connections are green and fuzzy. Hook up the scan tool and all kinds of wierd faults that dont make sense. Gauge pod on the dash and and Banks sticker on the fan shroud.

 

I change the oil and filter. Replace the air filter.Remove the fuel filter and it is black the media is kind of twisted around and appears to be aftermarket. Drain the filter bowl and there is all kinds of junk on the bottom. All fuel lines are leaking. I removed the filter base, clean the crap out of the bottom and clean out the pressure regulator. Replace the leaking water drain valve and all the fuel lines to the filter base and transfer pump. Only had a 1/4 tank of fuel, I sucked the fuel out and put 10 gallons of fresh clean fuel. Resealed the high pressure plugs in the head(were leaking really bad, cause of the oil soaked engine).I cleaned the battery connections and every ground and power I can find, assemble the grounds with star washers. Now I look for a chip in the PCM, between the grounds and the chip I figure here is my wierd fault codes. Remove the chip. I tested the glow plugs and find two bad(one on each bank). I remove the covers and replace all 8 glow plugs. While I'm here, I inspected the harnesses and connectors very closely. UVC harnesses, and gakset connectors, ok. Locks broke off engine harness, replace connectors. Put the covers back on with two bolts(just in case, have to go back in). Start the engine and it runs much better but still hase a very definite miss on a few cylinders probably and runs rough. Fuel psi is about 55-60 psi.

 

Hooke up scan tool again the wierd faults are gone now, but still have a few faults(P0470 Exhaust psi sensor, P0603 internal control module KAM error). I figure that the P0470 not out of the ordinary on a 7.3, and P0603 is because the batteries were unhooked for a while. I perform injector buzz test, all cylinders click but the entire right bank(1,3,5,7) is much quieter than the right.I perform KOEO and get:P0470, P1293 Injector high side open bank 1, P1294 Injector high side open Bank 2. I troubleshoot the P0470 and find bad sensor and tube restricted. Clean out tube and replace the sensor.I perform all the pin point tests that are related to the codes and system. All the tests point to and IDM failure. I dont have a test IDM available. I have been listening Jim and am looking over the schematics for missing fuses, etc. now. My question is does it look to you that and IDM failure is likely in this situation? Have I overlooked something or missed a step? I will be double checking all my tests tomorrow. I apolagize for the long post, but wanted to give you guys all the info I had. Thanks a bunch in advance for any advice

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Yes, it's common to have an IDM failure where you lose one bank. I'd disconnect the IDM and ohm check the injectors at that point to verify circuit integrity to make sure you don't have some melted glow plug harnesses.

 

Good Luck!

 

 

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If you don't have 1 shorted injector that is shutting off the whole side, you probably have a bad IDM. You still need to follow the pinpoint test though. Assuming it is a bad IDM, when you replace it you will need to self test the PCM and clear the DTCs or the engine will still oly run on 4 cylinders.

I had a 96 Econoline doing the exact same thing a couple weeks ago. I too had a bad IDM. /forums/images/%%GRAEMLIN_URL%%/cheers.gif

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All the harnesses are good. I will definitely check for shorted injectors. If they check out ok, I will order an IDM. If I am wrong than I guess I have an expensive oops and back to the drawing board. The silver lining to that would be that than I will have a test IDM. /forums/images/%%GRAEMLIN_URL%%/grin.gif

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Yup, sounds like an IDM to me too. Something to think about though: They don't usually die...They usually get killed by something. I've had a few fail as a result of water intrusion, chafed wiring at the left valve cover, chafed wiring near the vc connectors, a shorted injector, and also a couple fried from loose uvc connections. "Causality" is the word of the day. So for everyone reading this who will inevitably deal with one of these in the future, I recommend following Robert's example, and at least make an effort to locate a root cause. An ounce of prevention may be worth a $1100 pound of SPW IDM cure later.

 

Experience is not the best teacher, it's the most expensive one. Ask me how I know /forums/images/%%GRAEMLIN_URL%%/cover.gif

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What a crazy week, havent had time to even look at that pick up till today. The fuel wasnt black, and I didnt find rubber pieces in the regualator. I did check the Injectors through the harness and they are all at 3.0 to 3.1 ohms. Since they are all the same I am assuming that this is the normal reading and they are ok. I am looking at the book now to try to find a spec for the injector resistence. I will order an idm tomorrow.

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Yes it is! I havent worked less than 55 hours a week in over a year. Found the spec in pinpoint test it is 2-4 ohms. Thanks for the assistance guys. Will the new IDM need to be programmed or are they ready to go out of the box? Never had to replace one before.

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Yes it is! I haven't worked less than 55 hours a week in over a year. Found the spec in pinpoint test it is 2-4 ohms.

 

Yes, but that's really too wide. My pump shop uses 2.77-3.17 ohms acceptable resistance and I think I'd stick with that.

 

Thanks for the assistance guys. Will the new IDM need to be programmed or are they ready to go out of the box? Never had to replace one before.

Plug and play on a 7.3.

 

Good Luck!

 

 

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Finally removed the old IDM to install the new one and heard slosh slosh. Ideas on how the water got into the module? The whole unit is sealed up with silicone, no visible cracks, connector seal was in place and the connector was tight. I know I have read something on this issue here before but having trouble finding it. If I remember correctly it is a bigger issue on the econolines. But I think some of you guys have fabricated up some shields to help prevent this problem. Thanks for the help guys and I will keep looking.

 

Guess I should have looked harder first. I found the thread I was looking for. In this 96 F-250 there is no bracket for keiths suggestion. I will have to get inventive to find a way to shield the vent hole. I am open to anybodys suggestions though

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