3 Weeks old plugs, already misfiring again!

[crazy_canadian]

3 weeks ago I changed my (motorcraft, 1 year old) spark plugs because of a major misfire, I was runing most of the time on 4 cylinders. So I changed them without pulling the intake. And the car was fine. So as of today, it started to miss at idle while unclutching, and it's getting worse and worse. Under load it's already missing until about 3k rpm.
There was little oil in the rear plug well (gasket are also one year old, wtf?)
So, I need to change them AGAIN, wtf is happening ? I do not understand that one.

 

[firstgen89sho]

have you either checked your coil or your DIS module? either of those will cause your engine to only run on 4 cylinders

 

[crazy_canadian]

Yeah, coil seems fine. My DIS is cracked so the rear plus isn't cliping on anymore, but with tape it holds just fine, and it did for the last 2 years with no problems whatsoever.
What's bothering me is that the engine was fine after the new plugs, without toutching anything else.

 

[38SHO]

maybe one of the sections in the two components he was talking about is weak....

those plugs might not be getting the same power as everything else, so they get fouled up easier......

are you running factory gap? I.E. did u set it yourself and check it

did u ever change wires?

and is it always the same cylinders with that problem?

 

[yamahaSHO]

Is there a carbon trail on any of the spark plug wires (boot)?

 

[Brett]

Last time wires were replaced?

 

[hawkeye18]

+1 on wires. Why would you replace the plugs twice without replacing the wires? Replace the dang wires already.

Replacing the intake isn't that hard.

 

[Brett]

+1 on wires. Why would you replace the plugs twice without replacing the wires? Replace the dang wires already.

Replacing the intake isn't that hard.

Replacing? you mean removing? :angelnot: Just bustin your balls.

Don't even have to pull the intake, even for wires. Its a bitch to route them the same way with the intake on but it can be done, and can be done even faster if you don't mind them being routed a diff way then originally.

 

[hawkeye18]

See, the funny part is you're just as half-right as I am. You said "remove"... and what do you do after you remove it?

you replace it. anyhoo, you'll probably have to remove AND REPLACE (or, R&R) the intake, but it is doable. I haven't managed it yet, but others have.

 

[crazy_canadian]

The wires are one year old. I changed them at the same time as my plugs and VC gaskets.
-No there is no carbon on the wires.
-I used the preset gap for these plugs, the last set (motorcraft), I gapped them at factory specs.

It seems to come from the rear bank only, since my rear manifold to y-pipe ****** is broke, I can hear the misfire under load from underneath the car.
I will be ordering new double-platinium spark plugs this week, and will try to find time to remove my intake and look a bit further.
2morrow, I'll remove a front bank and a rear bank plug to compare and get a pic here online to show you guys. I'm a bit clueless on that problem, and it really **** me off. I'm working all day as a mechanic and have trouble figuring out my own problems.
Thanks.

 

[yamahaSHO]

Unless the plugs are just getting completely fouled or broken, I think your time could be better spent finding the real problem instead of swapping out plugs over and over.

I know what you mean... I can fix other people's cars just fine, but when it comes to mine, I can't seem to find problems... Or I just don't want to start taking stuff apart as it looks so good together.

 

[hawkeye18]

Ain't that the truth. I can fix everybody's car but my own!

If the plugs and wires have been changed, then I would be looking very hard at the DIS. They have many, many, many failure modes that can make it look like other stuff. They're very sneaky like that. AAP and AZ will test your DIS, given that they still possess the required adapter. Some of them lose it over time because it's rarely used. So call the nearest one and ask if they have the adapter to test a DIS.

Another (somewhat less likely) possibility is the coil pack. I haven't seen nearly as many of those go bad, but it does happen. If the transformer goo leaks out or whatever then it'll stop working.

But yeah, I'd say the DIS is your culprit at this point.

 

[Racer X]

+1 on the coil pack. Fought this very gremlin last winter.

 

[SeanMc]

+1 on the coil pack. Fought this very gremlin last winter.

Same here.

 

[crazy_canadian]

So, why is the problem going away when I change my plug ? Could it be the coilpack that's fouling them so soon ?

 

[SHOZ123]

If the coil is putting out a weak spark then this may be the case. But there should also be another plug that is fouling out also. They are paired to a particular coil. Diagram is the the "How Do I" Section under the thread titled Firing Order.

You should be able to compare ohm readings of the three coils and they should all be close to the same. If one is way off or if one has cracks onit then that's the bad one. Look at the bottom of the coil for cracks.

 

[luigisho]

You could swap out the DIS if another SHO owner is close enough to lend a hand. I would look for a cheap used one as insurance anyway. Try SV&HODAN. He sells used parts cheap and is very reliable.

 

[38SHO]

welp the last motorcraft's I bought on rock auto were way out of spec

as a mechanic u should always check that stuff... never rely on someone else

I'd make sure they are right and pull them out, as u say its not hard....

I know what you mean about fixing people's cars and not yours

I have an issue bugging the heck out of me right now, sometimes car bogs down or is just slow in general... sometimes u will feel it kick in right about 3500rpm and it feels like the secondaries are opening.. maybe even more of a power improvement..... I need to scan it tomorrow

things I've replaced along the way in search of this or to cure other problems

motor
fuel pump
fuel filter
different DIS, Coil, plugs, wires,
computer
different fuel rail/injectors/fpr

only things really the same are the TPS/MAF/IRCM/IAT/o2 sensors/ and one of the coolant sensors I reused from my 3.0, I can't remeber how many wires it had, but its one in front of the thermostat on the housing............ sucks I can't get any data on this car on the Modis scanner.....

something is wrong and its intermittent... so many things are different from the 3.2 swap and the problem is still there... frustrating