Hello all. I am stumped. I was driving down the road when all of the sudden the exhaust got a leak and lost power. The o2 sensor for bank 1 had blown out of it's housing so I replaced it. Idles fine just no power and it doesn't have that normal "warm-up" hi rpms when cold. So I disconnect the Cat, same thing. Plug in the reader and I have a lean code (which goes away after resetting). All of the following codes are there and come back after resetting: fuel sys1 ol,fault and Ignition coils A-E Primary/Secondary Circuit. So I believe it is running on 5 cylinders. From research all of the codes are related and it would appear that I have lost power or ground to one side of the engine ignition. BTW, this is on a F53 Motorhome so I don't have any sort of fuse guide.
Does anyone know if there is a fuse or relay for only one side of the engine? If so, any idea what to look for? the top of the engine is easy to get to because it is in a hole in the floor but all of the wiring is not. Not to mention there are several fuse boxes hidden around.
Thank you

 

This info is for my 2002 Excur and 2003 Exped, but I think it might still apply.
There is a fuse for the ignition coil power, but just one for all the coils.
The coils get 12v on a RD/LG (Red/Light Green) wire when Run is selected on the ignition switch.
The 12v comes from the ignition switch on the RD/LG and splits at the back of the engine to go down each side.
The wire in the harness might be broken/damaged between the splice and the first cylinder on that side, bank 1 #5.
If you are getting 12v to all the coils, the other wires all go to the PCM where they are grounded/ungrounded at the right times to fire the coils.
I don't know about the PCM design, but I don't think the ignition control function would be bank dependent.

 

When the O2 sensor blew out, did it hit the wire harness?

 

No, I think it just slid out of the steel threaded sleeve and was hanging. I probably could have soldered it back in as that is what it looks like was holding it in.

 

I just checked and with KOEO there is 12.46v to all of the coils. I don't know how to test the grounds since they are switched but it would be unlikely that it is mechanically the wire/joints on 5 individual grounds.
What do yall think about this scenario? 46k miles on factory plugs in a vehicle that regularly & for extended periods of time turns 5000+ rpm (30k lb vehicle going uphills). Then O2 blows out into open air, reads lean, PCM throws more fuel to bank of cylinders which fouls out the plugs. I know what you are thinking but I haven't pulled a plug because they have been in there 18 yrs and I have heard all of the horror stories on the 1st gen V10 2v's. I also don't know if the coil codes are there because the PCM doesn't see coil continuity between the + & - of the coil feed (no resistance) or it can tell there was no spark, which would allow it to see bad plugs .

 

Could be - if a coil misfires, the PCM might see the problem as a circuit failure because what it expects to "see" in terms of voltage is incorrect.

 

I unplugged all 5 of the coils on one side and started it up. No change in operation. TBH I didn't think it would start with only half the cylinders firing. Anyway, I back-pinned the + & - of the connector of one of the coils of the dead side and connected it to my cheap digital meter and started the engine. It intermittently read 0 & 3.04v. Auto ranging digital meters are slow to display so I believe that it was actually 12v but to check it I did the same to the working side and got 2.84v. The difference is probably voltage drop of the other 4 working coils on that side. I also connected the meter to dead side connector - and block ground with it on ohms. I got intermittent OL and 0.00.
So, it has to be in the coils or spark plugs. I guess I will see if I can get them out tomorrow and will update at that time. In the mean time I will read up on the best precautions to follow when removing the factory plugs.

 

Put the DVM on AC volts.

Did you check the injector voltage on that side?

 

Not sure where you "back-pinned' a test point. The leads from the coil connectors that go back to the PCM are normally open. The PCM will ground the circuit to build up current flow in the coil and when the circuit is opened the field will collapse firing the plug with the secondary coil. To completely check the coil circuits you could test each of the coil return leads at the PCM input connector for 12v. The last part of the circuit which is difficult to test is inside the PCM, but I don't think the coil grounding circuits are bank dependent in the PCM.

X2 what Krewat said, did you check the fuel injector power leads?
Similar to the coils, the fuel injectors get 12v on the RD (red) leads with the ignition switch in Run in my cars.
There is a splice behind the Bank 1 cylinder head where the voltage splits off to each bank.

Leaving the plugs in for a long time is increasing the risk of blowing one if you have never torqued them.
The plugs will come right out on the 2v heads and it's probably time to change your boots anyway.
How many miles on them after 18 years?
Try checking the torque on the plugs, the factory install was 15 or 17 ft-lbs, you might find a couple that are loose.
Torque the plugs to 22 to 25 ft-lbs before you blow one.
I change plugs and boots at 50k.
The horror story is leave the plugs is for over 100k and the chance of blowing one because it has worked loose starts going way up.

 

Thank yall very much for your help.

Did you check the injector voltage on that side? I just did that on both banks and it is constant 12.65v with KOEO and 14.08v with KOER. So both sides match. BTW, I used both wires at the connector for this test so I was testing + & -.
Not sure where you "back-pinned' a test point. I guess I really didn't back-pin but front-pinned. I had the connector to the coil unplugged so I stuck paper clips into the connection points of the connector and read the voltage, no load.
How many miles on them after 18 years? I got it with 39k on it. now it has 47,008. But I would think the RPMs per mile is higher on this because of the weight (36' Motorhome + towing a vehicle) it is running more RPMS then a truck would. So the truck equivalent miles, because of actual ignitions of each coil/plug, would have to be something like 65k or more?
I will let yall know more when I get the plugs out and I will replace the boots while I am at it.
Thanks again!
EDIT: I just removed the back one since it is the easiest to get to. I did not check it with a torq wrench but it felt like about 20# to break it loose. The tip is very brown and the gap is .053 I think that is a little wide but will have to check. I am going to need a second extension to remove the others and it is at my house so it will probably be tomorrow. The boot looks and feels great. not dry at all.

 

The one on your right (brown) is from the side not operating. The other plug is from the good side.

 

First, it's odd that the brown one isn't wet, unless it's been a while since it ran.

Second, it's odd that the brown one looks "normal" for an engine that's been "around the block" - The brown deposits are the detergents and crud that doesn't burn completely. The left one (white) looks like it's running a bit lean.

 

The picture is making them look a little lighter. It is more tan than white. I just changed all of the brown side (this is the side that I unplugged all 5 of the coils at the same time and it still started up and idled smoothly but at 780 rpms). The plugs where wet and smelled like gas. The auto store only had 6 plugs so I left the other 5 in place for now. Anyway, I plugged in the scan tool and started it up. After a few minutes it is idling at about 980 rpms and sounds a little better I think. But the O2 levels on the brown side are staying high. When I run it up to 2000 rpms boith sides are < .25v then when I let off, the light side jumps up to .825v but the brown stays about the same. It also through the same 5 codes I listed above about 5 bad coils on the brown side. I am going to order some coils and try that next unless yall have any other ideas. It just seems crazy that 5 coils went bad together at the same time as the matching O2 sensor came apart.
Oh, I did buy a second new O2 sensor in case the first was BOB with no change.

 

Try swapping all the coils from the good side to the bad side.

 

I only had 30 minutes so I installed the new ones. No help. I also used a new coil, plug, & jumper on top of the engine, no spark (See Picture). Next I think I will run a 12v+ jumper even though it is reading 12 volts at the connector. A corroded or loose splice will add resistance which will drop the voltage when you put a load on it. If it is not that I don't know of any cam or other sensors that affect only one side of the engine so I would guess it is the PCM.