E450 V10 Engine Miss

[whemme]

My 2000 Ford E450 motorhome with the V10 engine has a recent one cylinder miss at idle. As soon as I rev up the engine a little, the miss goes away. 108,000 miles on the V10 and all spark plugs and coils were replaced at 98,000 miles.

Anyone have an idea as to the possible problem? Partially plugged injector, bad spark plug, bad coil, valve problem???

[klutchdust]

klutchdust wrote:

DrewE wrote:
It might be worth checking the O2 sensor(s), or just replacing them. I understand that they do wear or drift over time, which can throw the whole mixture off a little. They aren't super expensive.

Mind you, this is rather a stab in the dark.

Exactly, chasing a misfire and back fire situation on my 08 JK toad and it's irritating. Code shows cylinder 5 yet items all check out.

UPDATE: Finally found the cause of my misfire, spark plug 5 had a hairline crack and once the Jeep was hot it would misfire. New plugs and wires solved the issue. Strange but it would not throw a code until it was pretty bad.

[ron_dittmer]

Yes, Glad it was fixed right. Not a bad price for something that could have gone around and around. On those types of problems, a good diagnosis is 95% of the project.

[hotbyte]

Good to hear it’s fixed!

[whemme]

Well my engine miss at idle has been solved by a Ford dealer. The problem was a cracked and loose electrical connector for the injector for #1 cylinder . Cost for diagnosis, new part, repair labor and taxes came to $245.

[Gjac]

I had this problem on my tow car but it would not throw a code. I drove me crazy for a while. Thought I had bad gas or water in the gas. After several weeks it would intermittently throw a code of miss fire on no 3 cylinder. After swapping coils and plugs I found it to be a very small crack in the plug insulation, a barely noticeable black streak. Apparently I must have dropped the plug when inserting it in the hole and cracked the white insulator. An easy check until it starts to throw a code is to pull the coil off each plug one at a time then reinstall and go to the next one, if you find one that makes no difference at idle very carefully check that plug. If you don't see anything switch that plug with the one next to it and retest then switch the coil. Good luck.

[ron_dittmer]

Hi whemme,

I wonder if your throttle position sensor (TPS) is faulty, just not faulty enough to store a code.

Since you have a ScanGauge-II, set one of the display settings to show the TPS number. I wish I could remember what the number is at idle, but that number escapes me. Maybe if you see that number at idle change erratically, it would tell you something is wrong with the TPS unit.

I installed a ScanGauge-II on our E350-V10 as shown. I set one of the 4 displays to TPS all the time to tell me how much throttle I am applying. It helps my driving for the sake of better fuel economy. Sometimes I don't realize how much throttle I am giving. When the number is real high, I'll back off a bit, drop a few mph and see the number drop dramatically.

Ron Dittmer

[klutchdust]

DrewE wrote:
It might be worth checking the O2 sensor(s), or just replacing them. I understand that they do wear or drift over time, which can throw the whole mixture off a little. They aren't super expensive.

Mind you, this is rather a stab in the dark.

Exactly, chasing a misfire and back fire situation on my 08 JK toad and it's irritating. Code shows cylinder 5 yet items all check out.

[Ozlander]

Same old same old. Remove known good ignition parts and replace with unknown ignition parts.
Got to have something to spend money on.

[DrewE]

It might be worth checking the O2 sensor(s), or just replacing them. I understand that they do wear or drift over time, which can throw the whole mixture off a little. They aren't super expensive.

Mind you, this is rather a stab in the dark.

[77rollalong]

it may not be enough of a miss for it to be picked up as yet by the computer, could try disconnecting each injector one at a time and see if one makes little difference in the misfire, then check the plug and coil on that cylinder, maybe switch coil with another cylinder and see if problem moves with coil. if no one cylinder seems to misfire would check for a vacuum leak in or around the intake, could be running a bit lean from that..

[whemme]

The spark plugs and coil over plugs installed back at 98,000 miles were Ford OEM parts. Since I have a Scan Gauge installed I just thought to check for engine codes and found none set. Puzzling problem!

[theoldwizard1]

First, are you certain it is a engine miss ? A good scanner will report the error code or even a "pending" code.

A cheap and easy fix, once you know which cylinder has the miss, is to remove and inspect the spark plug and coil. Look carefully for any sign of carbon tracks on the plug or the boot. If you see signs of carbon tracks, replace the plug and the boot and thoroughly clean the contact on the end of the coil. When re-assembling, grease the outside of the plug and the inside of the boot and the tip of the coil with silicon dielectric grease.

[rjstractor]

Plugs and coils replaced 10,000 miles ago makes them unlikely suspects- assuming you don't have a cylinder-specific misfire code. Electronic parts generally fail fairly new because they are made wrong (infant mortality) or when they are old because they are worn out. Plug or coil failure is a possibility of course but I would rule out other causes first, like a dirty MAF sensor. You don't run a K&N air filter by chance, do you? When I've had coils fail the motor idled fine but would miss under load, the opposite of what you're seeing.

[hotbyte]

Our previous MH had misfire that none of suggestions above corrected. Close inspection of plugs found cracked insulators (white ceramic part). New plugs fixed it right up. Mine was more misfire under load than at idle, though.