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1999 F350 7.3 stumbles acts like 4cylinders quit

2K views 26 replies 3 participants last post by  Buffalohead 
#1 ·
My 99.5 F350 has been acting up this last week. Like four cylinders quit, then bounce back and it runs normal. Today it did that for two miles, then ran normal once I opened my gate. Truck has 138,000 miles, 6 speed. Has a Banks Stinger with chip. Getting codes B1318, P0303, and P1316. The IDM was changed about ten years ago and the ICP about three years ago. With the codes I got, I did the 50cent mod two days ago, and the passenger side UVC was loose but tightened up well with the quarter in it. Kind of at a loss as to where to start at this time. When it’s running right it runs great, but when this happens it’s a dog. Thanks for any ideas/suggestions
 
#2 ·
You either need another IDM, UVCH connector, or find where the wires going to that UVCH are chafing against the motor.

You Are, in fact, running on 4clys ;)

When doing the 50cent mod, did you look really closely at the UVCH pins and connectors for signs of corrosion/burning?

I assume you've seen this vid on the mod ->
 
#3 ·
Yes, that’s the first video I watched. Nothing screamed arced connection. When the IDM died, the truck started and ran about 30 seconds and died no more start until I put a new one in. The inside connections looks fine, so I didn’t really get a good look at the male pins. The glow plugs all tested fine though!
 
#5 ·
There's a particular spot where the bundle comes from that large square 42-pin connector over the dr side valvecover and routed over that valvecover back to the pass side UVCH. You have to Roll it Over to inspect for chafing there.

In that vid, you see how valuable a Buzz Test is in allowing the IDM to resolve Further codes that can help you narrow-down the reason for the 1316 & 303 (both pointing you to IDM issues).

If you're gonna keep & maintain the truck yourself I strongly suggest you get access to the special scanner software you need to do it.

To retrieve most of the codes you'll need to help and even do some testing look at the FORscan Lite or TorqueApp (you add an Android device and Blue Tooth Adapter for @ $30) OR the Windoze version with a USB adapter. I like this one for BT Android -> Amazon.com: Bafx Products - For Android Only - Wireless Bluetooth Obd2 Scanner Diagnostic Code Reader & Scan Tool - Scan, Reset & Clear Car Check Engine Light: Automotive

Just a few years ago you needed to buy a professional scan tool because our trucks need to have a scanner with a Library containing both the Ford Proprietary AND the Diesel Specific codes in it. Add to that, our trucks are Not, specifically, OBD-II so the Generic scanners the Auto Parts Stores have are of little use to us. But today there are some very good App based tools, that are close to what the pro tools do, for fraction of the cost.


As for the IDM itself, once suspected there really is no true test to go by. At the dealership they maintain a stock of "known good" used modules of all sorts and resort to slapping-in a test one to see if it's the problem. You can do this yourself if you know someone with another 7.3. All 7.3's use a similar IDM and you can swap one with a friend, as a Test, pretty easily and without danger of damaging theirs.

Otherwise, if you can eliminate the other causes (wiring/UVCH) I would just bite-the-bullet and order a refurb...
 
#6 ·
Would the IDM do this? Or should I replace the valve cover gaskets and harnesses first? We did move from Commiefornia to Montana last year, so should I start with hosing everything down and cleaning grounds? Also is TorquePro or the other diagnostic apps available for iPhone. We don’t have anything Android or windows based. Thanks
 
#8 ·
Absolutely this could be the IDM itself. Because of where it's located, every time the dr side wiperblade comes down, it pushes water down and over the IDM. Where, the little "vent" that fails after 10yrs, lets that water inside (the refurbers seal this vent up). This can cause all sorts of intermittent problems.

When either the UVCH connector or a chafe wire causes IDM codes it's actually more common to see just one or two cylinders drop-out. When they All go (the whole side) AND you've made sure that the UVCH isn't just "unplugged" under the valvecover, then the IDM is more likely. As I said though, a Buzz Test is useful in making the distinction and the best way to be sure, is to try a borrowed IDM (looks like on eBay, you can send yours out for @ $125 or buy one for @$250 and get $50 back from the core). Shop around before you Buy though ;)

Here to find out about app based diagnostic tools I can use with my 2001 Excursion.
Everything you need is in post #5.

Click on the link in the middle "FORD SUPERDUTY DIAGNOSTICS ON THE CHEAP" for the app specifics.
 
#11 ·
Still haven’t picked up a laptop, but did some testing yesterday. Started the truck and it idled fine for five minutes, then the passenger side quit. I verified with a non contact thermometer. Passenger side was at 92-98 degrees while the drivers side was at 203-215.
 
#12 ·
Replaced the passenger side valve cover gasket and uvch. Thought things in there looked pretty oil soaked and maybe glazed. No change with new one. Tomorrow I’ll pick up a laptop and get ForScan set up. Now I’m thinking that the IDM quit on one side. Is that common? Will ForScan test the IDM ?
 
#14 ·
Finally got ForScan up and running. Injector buzz test was all good. Cylinder contribution test I’m getting contribution/balance tests for cylinders 3 and 8, which I understand may be related to the ford cps they put in it. I do have another grey cps and a black one. Not sure what else to try as of yet. ICP at idle was between 4040kPa and 4340
 
#15 ·
Replaced CPS today with old black one. Got no PERDELS on 3,6,7,8 and 1was at .25-.63 2 at 0-.06 4 at .75-1.00 and 5 at 1.13-1.81. ICP at 540-560 and IPR at 12.1-12.5% at idle. Truck ran great. Cylinder contribution test was successful as was buzz test. Unless something is definitely wrong with these numbers, I’m gonna drive it and see what happens.
 
#19 ·
Before you throw the IDM under the bus,

Check internal and external harness at the valve cover extremely thoroughly.. Pull the jackets back and make sure the wires are in good shape and the plugs are good. Check the continuity at the harness for the valve cover and back to the IDM with a meter not a light, consider the harness a fail if you have more than about .02 ohms. The valve cover harness from outside should read less than 3 ohms for the injectors.

Yes the IDM does fail, however it is more often the gasket and harness under the valve cover or the external plug back a few inches. Remember to wiggle everything when checking.
 
#20 ·
Because of where it's located (the dr side wiper pushes water down the cowling and Over it), and the Vent hole you show is missing the covering, I would have to think that you most certainly would have had water going inside :(

Every rebuilt IDM I've seen has had that, problematic, vent completely sealed over...
 
#21 ·
I checked and wiggled and rechecked the wire looms and valve cover connections. I’ve been chasing this intermittent issue for over a year. When it’s dry, everything is great. The minute I hit the wipers or a puddle things get stupid. I opened the IDM vent because I saw the corrosion on one side. Didn’t hear any water sloshing since it was 5* in the garage. Very little moisture when it thawed out. The vent had RTV in it, but there was corrosion all the way around the hole on the RTV. First IDM failed at 12 years. This one is 11.
 
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