spark plug question

so it could still be a plug lead from the coil pack.

in that case, it's unlikely to be injectors - high load is where issues like blockage or insufficient opening show up the most.

ignition voltage requirements are highest for idle and high load, with, i think, idle being the worst. which is consistent with what you've described.

i think that if it does away with new plugs, and in just 5k miles, the plugs are as ashed up as they are and starting to miss, your problem is oil fouling. start the motor from cold, run it just enough for the miss to be present, then shut it down and pull the offending plugs. that way, they shouldn't be hot enough to have burned off any oil, and you'll be able to see whether all that black stuff on the plug walls is also present on the plug tip.

further thought on re-reading your second post:

1. use ngk plugs if you can get them for this vehicle. while i don't specifically endorse them, i've never had a problem with them, and i have every other plug manufacturer, sooner or later. especially bosch.
2. check out the e.g.r. system. these things tend to coke up and when they do, you get ignition flat spots that lead to hesitation and "misfires".

this last doesn't explain why new plugs should help of course, but egr blockage is very common and give drivability problems like you describe.

I've actually had a couple of issues with NGK.. Getting carbon stuck in the electrode.. Went back to regular plugs and all is well.

I try to sell what originally went in the vehicle.

Fords - Autolite / Motocraft GM - AC Delco Chryslers - Champion Euro & Japanese etc NGK & Bosch.

Though you can basically use brand plug in any vehicle some plugs just seem to run better in certain vehicles.

We have one customer who puts champion in everything, and we have another customer who wouldn't put champion plugs in a row boat.

I'll have to check the manual to be sure but I don't think this engine has an EGR. The plug wires were new when I put the Bosch plugs in, which is less then 10,000 miles. They could still be bad but they are not very old. I think they were autozone premium brand, might have been bosch.

Champion seems to be the "fram" of spark plugs. Most people I've talked to don't seem to have much good to say about them.

Don't know. But thinking on this, I always got 30,000K+ out of plugs in this truck and was just replacing them "because". So back around

It's got 150K on it and never uses any oil no matter how I drive it and never smokes. Been using Mobile One for the past 5 years. I had a caprice that developed a similar miss on just one cylinder and when I pulled that plug out it was filthy and caked with burnt oil deposits. As you saw in the photos, these plugs are fairly clean, two of them are almost too clean and the other one looks to me like it's the one that was missing and getting dirty but still looked a lot better then back in the old days of leaded gas.

only bad set of spark plug wires I've ever had were Bosch. '84 VW Scirocco, decided to give it a tuneup for no better reason than it had a ton of miles on it. less than 5K miles later, it was running like crap, dropped it off at shop, they said "your spark plug wires are crap, we replaced them" and it ran fine ever since. I've driven vehicles with tattered likely OEM plug wires that ran fine, only set of wires that I ever had that cause a problem came out of a Bosch box.

nate

they're not bad but they have a reputation of not taking kindly to oil fouling.

nate

That was my initial thoughts too. If you buy the injector theory as the problem it fits. If I can get to the injectors to OHM them I'm going to when I get home. I've had the truck since it was new and plan to keep it another 10-15 years so if the injectors OHM out bad I'll replace em all.

Ashton Crusher wrote in news: snipped-for-privacy@4ax.com:

EGR can be done in sneaky ways. My 03 Sentra Spec V 2.5L leaves the exhaust valves open longer to have some exhaust sucked back into the cylinders after the exhaust stroke. Early motors would damage the catalytic(right next to the exh. manifold...) under certain ordinary conditions,and the cat would flake off little chunks that got sucked back into the cylinders and proceed to tear up the cylinder walls. Nissan had to replace a lot of 2.5L motors.

Could be. Just looks like oil fouling to me. Won't hurt to do a compression test. BTW, my injectors caused bucking only at low speed during acceleration. Idled fine, and *seemed* to run fine at speed. Only other missing I've had on FI cars was fixed by new spark plug wires and/or coil packs. Never used a scope. Just ears and throw parts at it. Injectors are last, since they're expensive.

Take a spray bottle of water and spray the wires with the engine running and see if the miss gets worse, or wait until dark and see if you see any sparks jumping when the motor misses.

I meant to say spray on mist setting.

i've had repeated problems with bosch plugs - one set went bad inside 5k miles. literally, one morning, the car wouldn't start. i changed the plugs to a different brand, it fired up first time. just to be sure, i swapped the bosch back in, totally dead. i will never use bosch plugs ever again. ever.

all the lack of smoke means is that your catalytic converter still works.

actually, they've got very heavy ash deposits, and for only 5k miles, they're /way/ heavier than normal. this is supported by the black shiny stuff on the plug wall - excess oil.

no, it just looks like it's not getting /quite/ hot enough. other than that, it's pretty healthy.

ohms alone don't tell you much. basically, if you get resistance roughly per the book, you're good. people that are worried about a few ohms +/- are clutching at straws. particularly when the engine computer is monitoring them for you as well.

as for measuring resistance, it's not really possible for an injector to "gradually" go bad on the coil - it either works or it doesn't. and if you get say 150? when the book says 100?, you're still going to be ok.

it's important to get the right diagnosis. you're frustrated with it happening, but you're looking to throw parts at it and you're straw-clutching at one guy's story off the net by way of corroboration. reality is that if you're changing the plugs and that makes a difference, then that is much more likely the right track. and the pic you posted supports that.

I, and a lot of other folks, have had trouble with the expensive Bosch plugs. The inexpensive Silber plugs, though, are just fine and are the plugs of choice in air-cooled VWs and older BMWs.

--scott

I will probably just buy some genuine ford plug wires and do that first since the problem started within 5K of the change in wires..

for not a huge amount of extra cost look into magnacor plug leads. because they use a wire conductor, they can be more reliable long term than standard oem graphite. they have good quality insulation too.

another thing worth mentioning: when fitting new plugs, keep sweaty fingers off the insulators. sweat salt is hygroscopic and can leave a moisture conduction path for the spark. [same for rotor caps and rotors, though this may not be relevant for you.] never wire brush a plug - it leaves metal traces on the insulators and again, this can provide a leakage path for the spark.