Hi all:

I'm usually in the 80-96 forum but I've been asked to work on a van that fits this one.

1998 E350 6.8L V10 Exact mileage unknown, but over 150k.

It's running very rough and has practically no power under throttle, especially when going uphill. Putting the pedal to the floor will get some kick out of it but not very much.

A couple of weeks ago I got a hold of a Genisys scan tool to use on it. I ran diagnostics/monitored engine function in park at idle with it and here's what I found.

-Misfire condition detected on cylinders 4,6,7
-No readings at all from 2 oxygen sensors (I think they were both bank 2)
-VSS indicates speed of 6 MPH in park

There's a lot more that I wrote down, including DTC's, unfortunately I can't locate my notes at the moment, but that's what I do remember and it seems relevant to the situation.

I've checked the resistance readings of the coils and although I didn't have a spec, the coils for cylinders 4,6, and 7 all read practically the same numbers. It was a pain to remove them so I didn't check the coils of any other cylinders, but "logically" speaking, if they're all reading the same, it's unlikely they would all be shorted so my conclusion is that the coils are good.

With the engine running, I used a long screwdriver to listen to the injectors at the misfiring cylinders, then listened to a couple of other injectors for reference, and the pulses sound identical/normal in comparison.

I've no clue how long it's been since the spark plugs were last changed.

I'm just looking for some direction on diagnosing the misfire as I'm sure that's a large factor in the lack of power and rough running. I can get a hold of the Genisys scan tool again if anyone can give me direction on specific engine functions to watch - I just don't have the experience with them to know exactly what I want to look for.

Also, I'm generally very busy and the only opportunity I have to work on this van is Mondays, so if it's a week or better before I update/respond, it's because of that, not because I'm abandoning the thread.

Thanks for any help you can offer.

 

First order of business is to change the DTC-indicated COP's OR make sure their individual wiring harness connectors are engaging and locking into place. Using DC resistance checks to determine whether a COP is good or bad tends to be 100% worthless. Testing some known bad COP's still shows factory spec readings---its not a reliable test at all. Unfortunately your assumptions relating to their viability isn't correct.

Next up is to pull and inspect the plugs AND boots---make sure they're refreshed as needed. Chances are they're all bad enough to warrant changing. I use nothing but Motor Craft plugs and NAPA boot #702418. Despite some believing Motor Craft plugs are not the best for Modular Motors there are too many stories of new other brand plugs causing issues here in the FTE Modular Motor forums, all displacements. (Autolite makes an alternative but in reality they're the same plug, other brands not so much.)

Once you've completed the spark plug issues begin looking for vacuum leaks especially from the PCV through its hose and fittings leading to the base of the throttle body. This has also been a source of poor performance and its just good maintenance to check such things anyway.

Attempting to help further will rely upon giving us any and all DTC's. These are also questions that can be addressed in the appropriate Modular Motor Forum---the chassis tends to be unimportant when it comes to most of the issues you've presented.

HTH

 

I know that bad coils can test good - I have personal experience with it. That said, just because they tested good, doesn't mean they're bad.

When I had the coils off the boots looked good - nothing that caused me to have a "Whoa, wait a minute" moment.

I understand your point about the coils, but I'm not gonna just replace them on a "chances are" stance, for 3 reasons:

1) The van belongs to a youth ministry that I'm involved with, and although the money is there for parts when needed, I don't want to just throw money at it and hope for the best. At about $50 each, I could put all new coils on it and not have solved anything.

2) I want to actually diagnose the problem. It could be that the coils are bad, and that there's a wiring issue in the coil harness, and that there's a timing issue with the computer, and that the crank sensor is messed up and putting out a bad signal, and that....you get my point.

3) Being new does not mean a coil is good (as I'm sure you're aware) and being old does not mean a coil is bad.

Thank you for the suggestions to look for vacuum leaks and inspect the PCV system.

Due to the time frame I get with this van (2 hours once a week) I have to be selective in how I spend that time. I will make it a point to remove the spark plugs and check as many vacuum hoses and potential leak problems as I can find.

When I find my notes I will post the DTC's.

Thank you.

 

When you find your DTC's here's a link to their definition: Actron®

It's free, just enter your vehicle info and scroll thru the list of codes for that year, make & model.


HTH

 

Thanks for the link - very nice to have that on hand.

So I found my notes, finally. When I initially checked DTC's, there was a bunch of them stored (and by "a bunch" I mean 9). I forgot to mention before that I wrote them down, then cleared them, and ran auto-testing/diagnostics in park at idle. For the sake of mentioning it, yes, the engine was up to normal operating temperature when I did this.

The DTC's that remained were:

P1000 - Drive test not complete (b/c I didn't do a drive test)
P0306 - Cylinder 6 misfire detected
P0307 - Cylinder 7 misfire detected

Also during diagnosis, I noted that no injector faults were present. I didn't note what the scanner said, but I do remember something about at least 2 o2 sensors didn't register any readings.

On Monday I was able to pull some of the spark plugs. The plugs in cylinders 6 & 7 looked oil fouled, as did the plug in cylinder #4. The plugs in cylinders 10 and 5 looked normal and that was as far as I went for the fact of ease of access. They were the original spark plugs (assuming motorcraft plugs were in it from the factory) so I'll be changing those for sure.

I also noticed that 3 bolts on the right exhaust manifold and 2 bolts on the left exhaust manifold are broken off, causing leaks on both sides. Looks like it's just due to age - I'm sure those manifolds haven't been off that motor, ever. So now I'm planning to pull the engine, not just so I can properly repair the broken bolts (and replace the ones that aren't broken) but also so I can actually access the rest of the motor and do quality work without trying to cram my hands into spaces that are too small for them.

No obvious vacuum leaks but I forgot to take my gauge with me to see what it was with the engine running. But since I'm pulling the motor I'll be able to give the lines a good once over and inspect for breaks, cracks, etc.

I'm also moving the van to my house so that it's readily available when I have time to work on it.

Thanks again for the continued advice.

 

Reading in the V10 forums it seems the exhaust manifold studs are almost always under discussion. Most who replace them do it in-frame but I'm sure pulling the entire motor will make this infinitely easier.

While its out check the coolant tube running under the intake---those have been know to rot away. Those can be changed in-frame but its no picnic from what I've read.

Best plugs are whatever Motor Craft spec's out---that too is frequently under discussion in both Modular Motor forums.

 

Thank you.

I'm sure replacing the exhaust bolts is possible in-frame, but from what I can see, I'm gonna need to drill the stubs and use extractors to get them out - there's far too much corrosion to suggest otherwise. Plus, if necessary, I can weld a nut to what's left and use that as leverage.

 

Visit the V10 forums, do a search for manifold studs---there should be at least 100 threads on that topic. I can recall 5 or 6 myself, within the past 18 months.

Hope this goes easy for you--not something I'd look forward to tackling.

 

So it took nearly a month of working on it just in my spare time, but I finally got this engine running again!!

I did pull the motor, and I'm so glad that I did. The old exhaust studs were very seized. I ended up loading the engine into my truck and driving it to work to use the torch to get them out. I had to weld nuts on all of them. And for those who don't know, here's a very handy trick for removing broken/seized bolts. Not just for exhaust work, but any seized bolt, especially if it's broken off:

1) Place a chunk of wax on the tip of a screwdriver or needle nose pliers.
2) Get the stud only glowing red hot.
3) Touch the wax to the base of the stud.
4) Remove stud.

The wax will suck down into the threads much like pipe solder, providing lubrication and allowing you to remove the stud with significantly less effort. Sometimes it takes more than 1 "treatment" but in the end it's well worth it. My father and I used this trick on an intake manifold bolt that was broken off nearly flush with the cylinder head, and after 3 "treatments" all we needed was a pair of needle nose pliers to remove it. The type of wax used doesn't seem to matter - I've used the wax from a toilet floor gasket and the wax from a candle - it's worked well both times. I will say, though, that using the candle smelled much better.

Anyway, after getting the exhaust studs replaced, I installed new motorcraft spark plugs and a new intake manifold gasket set. I also discovered that the vacuum reservoir was MISSING and that someone had simply zip tied the vac lines to the bracket without plugging them! So a trip to the junk yard later and I had a "new" one installed.

It sounds sooooo much better! It's idling smoothly and actually responding to the throttle. I'm yet to get it on the road for an actual test drive but just listening to it makes me believe that the new plugs and exhaust manifold gaskets/studs, as well as the vac reservoir, were the major contributors to the rough running of this engine.

Thanks again to all for your help and guidance!

 

Thanks for the update---glad all your effort paid off!

Neat trick with the melted wax---that too should find its way onto the V10 forum.

Did you happen to snap any photos of the area where that elusive vacuum reservoir is supposed to live? That's an on-going mystery we've not yet solved simply because no one here has ever seen an original installed anywhere on our vans.

 

I didn't take any photos (but I can, and if I don't forget, I will) but the one for this van is mounted on the passenger side frame, rear of the wheel. It has a plastic shield surrounding it and the vac lines hook in from the top. I wasn't even looking for it the first time I noticed it - all I saw was an empty bracket and 2 vac lines zip tied to it!

 

If there is a clear shot of that bugger still installed in its nest you'll be an all time hero here---no one has ever seen one, according to everything I've read in the past 4-5 years!

 

Is this what you're looking for? I'll post a new thread with more pictures if it is....

 

Wow---that thing is HUGE!

Not sure what that is but I don't think it's the heating/cooling system vacuum reservoir we're all looking for---my mind's eye says it would be rectangular and maybe 1" or so overall thickness, give or take a bit of course.

Since you have the E350 the part in your photo isn't something I've ever seen on the E250's with 5.4 motor.

 

Well I can't speak to the E250's and smaller vans, but according to this diagram, this is the vac reservoir for the heating and a/c system for my van...