Hey all!!! New to the forums, but been crawling the web for a few weeks now trying to fix this bus.

First, the story:
2006 E450 6.8 215k Auto
Picked up and drove it about 50 miles to it's new destination. Had 1/2 tank in it. Our entire fleet gets fuel (I assume...they gave me a card) from the same company, and there are only two locations around here. Very impressed. Didn't know it was a v-10 when I picked it up. Ran and drove GREAT. PLENTY of power, on demand, no lag.

While in a caravan with another bus (diesel) to my shop (I'm an orchard mechanic), it got stuck in traffic. I was told it overheated (105 degrees ambient so probably had the AC running...I did not use the AC, but I was driving it in the morning. Was told they added water...with it being 105 out I doubt it was ice cold. Ended up going on a 10mph detour (accident closed the highway) that took 20 minutes (normal is 60mph for maybe 5). Did not overheat the rest of the way to shop (10min at 60mph). Originally I was to get the diesel bus and they were taking the 450 back. Now that it overheated, it's at the shop.

Here's where it get's weird:
Go to move it around the side and into shop. Check coolant tank. It's green, but between the lines. No milkshake. Into reverse, hit the gas. Nothing. No RPM increase for a good bit. As I let off and hit it again I looked at the tach. CEL is on. Wasn't before. Full tank of gas. I had to feather the pedal to get it to go, and it was rough when it did. First thought is head gaskets. Into drive, feather gas. Once she was past the hesitation, she moved. Roughly.

Scanner pulled a misfire on cyl H (#8), cyl head overheat condition, and cyl head overheat protection mode. I figured when it overheated, the computer put it into limp mode and that was the misfire on 8. Kill a cyl so it doesn't overheat. Cleared the codes. Still has a miss, but no CEL. Didn't even get it out of the shop. Pulled coil 8 and it tested good. Pulled another (#5 I think) coil and it also tested good. Next was the plug. Pulled plug #8.

Side note. If I EVER get to meet the engineer, or their boss, that thought this engine design was a good idea, be it in truck or V.A.N. ..........moving on.

The gap, literally, is 3/16". .188". Motorcraft plug. I now assume the plug I am holding in my hand is 11 years old, and has over 200,000 HARD miles on it.
If I can post a pic, I will. Of course it's a missfire on 8...but, if THAT one looks like THAT?!?! Yup. ALL 10 LOOKED LIKE THAT. I don't know how this thing even started, let alone ran like it did.

Blew top of engine off with compressed air before changing plugs. Changed plugs, oil and filter, air filter. Used rubber hose to get the plugs threaded in as far as I could by hand before a wrench. Did not replace the boots. If it ran as it did with those plugs in it, I don't think the boots were causing ONE missfire. Die electric grease on plug and coil connections. Took for a test drive with doghouse off. She pings. BAD. Can't get her up to even 40 without the engine pinging so bad I thought I was gonna leave parts all over the highway. Only happens when I'm on the gas below 2,000 RPMs. Back to shop. Still no CELL. Unhooked both batteries overnight.

Tested cooling system for exhaust gasses, none. Change fuel filter. The one on the rig is a Motorcraft. If the plugs were that worn out...? The fuel that came out of the tank-side, was as black as coffee. Engine side was nice and clear. In went a new NAPA unit. The hesitation is still there, but I don't have to feather the throttle. Just a significant delay. Out for another test drive, still sounds like she's gonna come apart, but a bit more power is there. Still no CEL. More searching led me to the CAT.

After watching 5 different 'youtube mechanics' and countless forums (that's why I signed up!!!), I used an infrared thermometer on the cat. I determined it was clogged, which could also manifest with my symptoms. Cut it out and replaced with a straight section of 3" pipe. Before I put the pipe in I fired it up. Hesitation WAY better, but still there. Maybe she needs a few drive cycles for the computer to re-adjust. Let her run while I dropped the jack stands. Noticed some blue smoke out the tailpipe and smelled real rich. Took her out, drover her a bit harder. Definitely has the power back, but still sounds like a tank whenever I hit the gas. If I make her down shift, the pinging goes WAY down as she speeds up. But as soon as it shifts up, if my foot is on the gas, right back to the pings. The pinging follows my foot exactly as I get deeper in the pedal. Farther I go the harder she rattles, until downshift. Back to shop. Still no CEL. If it was bearings/piston issues, I would expect the pings to be more of a knock and get harder the higher the RMPs. Correct me if I'm wrong.

Tomorrow:
Checking fuel pressure, WD-40 vacuum leak test, cleaning the MAF, scanning the throttle and TPS together, ordering a knock sensor. I've used seafoam once before on my personal rig and it din't end well, so I'm VERY leery of that option. Can I check for a cyl balance like you can on the 6.0 diesel? My scanner can do that when I'm hooked up to the 6.0, but is that a scanner-side feature, or vehicle-side?

Anything else anyone can think of to check and/or test? I'd have a hard time believing this all happened, but it all has. If none of the items i HAVE fixed, fixed the problem, what could it POSSIBLY be?!?!? What set of dominoes fell to make it go from awesome to rubix cube in 60 minutes?!?!

Sorry for the long read, but this one's going in my book.

McMechanic

Oh. The manager of the yard I got it from says it never gave them any trouble. Considering MY drive, I believe him.

 

You're very thorough; nice job.
I wouldn't bother with the knock sensors though. I think it only allows 3degrees , so that won't likely help. Everything else you suggested is great.

Mine had had terrible pinging also and it turned out to be plugged cats. Did you check all of yours? Probably 3 or 4 on it. I had mine replaced with straight pipes and it was immediately 90% better, although still a little bit of pinging. Nowadays there's no pinging, even on hot Florida days. I guess there is still some while towing heavy. I'll pay attention today and report back.

That black fuel is very scary. You should get that 110% fixed before proceeding anything else.

Also try upgrading your octane. In Florida all the pumps have 87 and 89 and 90-something. I suggest you get a full tank of the next level up. It may be the end of your pinging issues.

Also I believe you are correct to reset the battery/computer and let it relearn. I believe that's big.

Please keep us posted

 

Oh and I wouldn't worry about the "rich" smell you mentioned; mine could wilt flowers for a 10ft radius ever since I removed the catalytic converters.

 

As far as I can tell, there's just the one cat. This rig is one of those airport transport busses, if that makes a difference. As for the black fuel, that's what i poured out of the filter. It didn't start off black, but even when i first poured fuel out, the pimp side was NOT as clear as the engine side. The black stuff was more towards the end. Just to be sure I'll pull the tank-side fuel line and let some drain just to make sure its cleaf from the tank.

This thing has a full 30-gallon tank. So unless i figure out how to drain all that fuel and get some 93 in her, the fuel octane is unfortunately gonna be the last straw. Considering the condition of all the parts so far, and we always get the same fuel (87 more than likely) and it ran awesome before, I'm kindof ruling out octane, for now. Would a couple cans of octane booster in the current tank suffice?

For whatever reason, I dinn't think to disconnect the batteries last night after deleting the cat...damn.

Thanks for the speedy reply. I'm working on it right now...

McMechanic

 

A very odd story. Not sure what to make of all of this. The knock sensor logic will pull only 4 degrees.

Before filling it up with higher octane, try just a few gallons. If it makes the ping better, it's ignition/compression related - but I don't know why the compression would jump UP

Waiting for more details.

 

I don't know what to make of it either. Like I said. This sounds like a mechanic tall tale, stealership style. Just a bit more background...I do all my own wrenching on my vehicles. One is a '97 BMW 528i, and the other is an '88 Samurai that I rebuilt the whole drivetrain and did a fuel injected engine swap. Backyard mechanic that now has an actual shop and real tools.

Just looked in the valley where i understand the knock sensor to,be and the only tbing down there is a pipe that goes into the back of the front cover. Appears not to have a knock sensor, but NAPA shows 3 different ones for this rig? Maybe they put it somewhere else in the bus version of the v10?

I get it that only 3-4 degrees probably won't eliminate the ping, but so far all the parts I have put in have made small improvements.

Like I said, tbe tank,is full. Unless I figure out a way to safely store 30 gallons of fuel, I can't try just a few gallons. Not trying to be negative.

Sorry for the typos. First post was from,laptop at home, nkw trying to,do this on cell phone with cracked screen.

Thanks for the QUICK replies guys!!!!

McMechanic

 

Also, i can't find the fuel pressure test port???

 

Found a loose hose clamp on the boit after the MAF. Tightened it and started her up. No change...maybe worse, actually. She's cold, but if i pin the throttle, there is no indication from the engine that I've even moved it. If I pump the trottle (like old school carb rigs), THEN she reacts.

 

Very thorough indeed. You obviously know how to go about troubleshooting an engine.

If it's got that many miles, and has been neglected for service as badly as the spark plugs indicate, I'm guessing it's been fed the cheapest (lowest quality) fuel for its entire life also. Likely there's horrendous carbon deposits everywhere. Maybe that explains the awful pinging? Not sure why an overheat condition would've suddenly caused the pinging to initiate so suddenly though.

Probably not related but have you bothered to check compression on all cylinders? Would be good to know condition for each as you go about troubleshooting. That's just my $.02, though.

 

I totally agree with the carbon being a possible cause for pinging issues.

I just got done running some live data tests. The two O2 sensors are NOT showing me the same info. One is a nice smooth waveform, the other is real sharp, jagged, and random. According to NAPA, this rig should have four sensors, but I can only find two. Both are about 6" from the collectors. Nothing anywhere around where I cut out the CAT. Which to me is strange. Why have only two sensors (driver/passenger banks) and both before the CAT? That tells me the comuter has no way of knowing if the CAT is working or not. My BMW has two CATs and four sensors. Also, if I do not in fact have a knock sensor, how does the computer know if it needs to retard (or advance) the timing? So...without a knock sensor this thing could ping itself to death and the computer would never know. If there is only two O2 sensors and one is giving bad info, the two banks of cylinders are pretty much fighting each other, right?

I already ordered the two (upstrram) sensors...different part numbers for up/downstream. Since mine are both before the CAT, I'm calling them upstream.

If I'm going to go about checking compression, should I also go ahead and replace all of the plug boots? How would a guy go about checking the injectors (in a bus, mind you)?

Before the live data (engine running) testing, I wanted to look into the throttle data. I removed all the intake boots and positioned a mirror so I could see the throttle plate from inside while moving pedal by hand. What was interesting is when you first turn on the key, the throttle plate clicks closed, then ooen to 5* (according to my scanner). As I move the pedal, the data shows I'm moving the pedal, but the throttle plate doesn't move until the pedal hits 6*. Once past 6*, tbey both move at the same time. When I take my hand off the throttle, the trottle plate returns to 0* then clicks back to 5*. Seems strange to me. Maybe I'm also having some throttle controll issues?

McMechanic

 

Had this big ole reply typed up. Like an idiot, I hit post reply but had no service while in bus. Nkw I gotta start over. Going to get lunch. Need some brain food.

 

Nope. Wildfire between me and parts store just shut down highway. I'll post up the live data I had. O2 sensors won't be in till Tuesday anyways. And I got 10 new plug boots waiting up there as well.

 

It's OBD-I - not OBD-II - so no sensors after the cat. To be sure, check the under-hood sticker.

It wasn't pinging before the overheat, right?

 

Idle at 650-700. CHT at 180*. Off idle I held it at 1,500 - 1,600 RPM.
Idle/Off idle
IAT 117*
MAF-V: .90/1.35
FRP-DSD (psi): 65/65
FRP (psi): 65/65
FuelSys: CL/CL
LongFT1%: 14/0
LongFT2%: 11/0
O2S1 V (smooth waveform): .04-.97/.07-.88
O2S2 V (jagged, random waveform): .29-.75/.39-.67
ShrtFT1%: -7 to 0/-5 to 9 (smooth waveform)
ShrtFT2%: -8 to 0/-6 to 8 (jagged, random waveform)

No RPM increase until AP% hits 5%, then the RPMs go up to 1k. AP% and APP1-3 (V) move together from 0-5%. TP1 and 2 (V) do not react until AP hits 5%.

 

No. No pinging before overheat. I was under the standing that anything after like 1996-ish was ALL OBD-2.