Thread: Misfires after having new spark plugs & cat put in.. *yay* (+ hard starts)

It's so hot, I am on the way to the boat. A great day for hitting the river.

Stay cool... I did a brake job on an F150 yesterday and while it went well and was done quick, I was soaked and in need of a gallon of water.

Originally Posted by BillBoost37

It's so hot, I am on the way to the boat. A great day for hitting the river.

Stay cool... I did a brake job on an F150 yesterday and while it went well and was done quick, I was soaked and in need of a gallon of water.

Exactly what I'm trying to avoid lol. We don't have a garage and though we do have part of the driveway that reaches the back of the house with some shade (which is where Pumpkin is all the time, getting pooped on by the birbs on the tree) it's a bit narrow and uncomfortable for certain tasks. Have to do a skinny crab walk between him and the fence to do his right side when washing him lol
At least swapping the coils won't be uncomfortable, but doing the fuel filter later and the trans fluid+filter might require pulling him into the backyard for more room..
Now just to wait for a cooler day.

Quick update : my dad and I swapped coils on the cars over a week ago and I haven't felt any noticeable change in the problem. Still misfiring with stock coils, also dad hasn't noticed any issues on his car driving it with the MSD coils so surprisingly enough I guess they aren't the culprit here.
Honestly I've given in and ordered a whole new set of spark plugs yet again, but this time I went with NGK. Hopefully Pumpkin is just being a finicky little brat not liking those particular plugs I got him originally. I think if he ever gets back to his normal self after these plugs being put in I might just cry. (I really miss his responsiveness, it's been like 4.5-5 months)

have you taken the plugs out to see if one is cracked? or does it show code for what cylinder is misfiring? 100% sure the wires are on right? they run pretty well with two crossed wires.

Originally Posted by Scottydoggs

have you taken the plugs out to see if one is cracked? or does it show code for what cylinder is misfiring? 100% sure the wires are on right? they run pretty well with two crossed wires.

I had thought about checking the condition of the plugs to see if any were damaged or gapped incorrectly, but that last time I got the flashing (and then constant) CEL while on the freeway I checked and it was the code for a random /multiple misfire, so it isn't one particular cylinder every single time it happens I think. I might double check the wires later today and make sure they didn't switch them around too though.

Still haven't had the chance to changing the plugs... was only able to take cylinder # 5's plug to inspect it and it looked OK to me. However, area outside the spark plug wells is filthy and I feel like some of that crud has gotten into the wells, possibly even when the last guy changed them as the mechanics here obviously hate working on domestic vehicles and likely put little effort into doing the job the right way. I also have one other concern regarding the exhaust manifold heat shield's position...



Would this not be a problem with the heat shield touching one of the wire boots?? I couldn't seem to get the shield to align better with the manifold.

Not sure why image is being stupid..



I might have to stop using my phone for this before I pull my hair out lol.

Please remove the metal heat shields off of the plug wires as a test and go drive it.

BTW.. I just noticed you are in New England. Are you anywhere near West Springfield? Because I have a scanner etc and tend to know these cars well. It's often quick and easy to fix one once you reference a live scan.

^^ What Bill said. Heat on the wires = misfire.

You need to realign the heat shield. To do that, just puncture two holes in the shield, and use a regular hose clamp to tighten it to the manifold. A regular clamp like this:



Don't worry about any crap that fell into the cylinder wells. It was probably just dirt and its long gone now. Burned down to nothing.


Also, did you try the other suggestions:
1. Did you remove the Bosch plugs and replace with copper AC Delco? (it's repeated to death on this forum that our cars don't like Bosch plugs)
2. Are the spark plugs gaped correctly. Did you gap them?
3. You swapped coils you said.... Did you swap wires too? MSD wires work best with MSD coils. If you just swapped in stock coils, but kept the MSD wires, that could be a problem. You NEED stock coils, stock wires, copper plugs.

Let me clarify.. the heat shields I am referring to are the round ones on the boot of the plugs. Remove those and try it out. The exhaust manifold shield isn't really a concern of mine at the moment.

Originally Posted by BillBoost37

Let me clarify.. the heat shields I am referring to are the round ones on the boot of the plugs. Remove those and try it out. The exhaust manifold shield isn't really a concern of mine at the moment.

Ohhh. Gotchya. Yeah. Those boot heat shields too. Yes.

In the last week I experienced misfiring and burnt wires because they fell onto the rear manifold. Was thinking that heat shield touching the middle plastic boot in that photo would cause misfiring and burning as well.

Ahh, West Springfield..hm. A good 1.5-2hrs away from me haha. Don't know if that would be doable for me unfortunately... Anyways I also thought the heat shield touching the boot would be a problem, though if any you'd think it would be specific to that once cylinder (and I only once got a code on the highway for random/multiple cylinder). I guess I can try running him without the individual shields for the wire boots, though I'm a bit concerned in the long run how that would affect them since imo they must come with those for a reason.


So... a hose clamp around one of the pipes on the manifold going through the heat shield is what you're suggesting? I'll see if I can manage that haha. Is there a specific size hose clamp I should be looking for then to use?

As for the plugs, I have not swapped them out yet but I did purchase a new set of NGK's, the TR55 I believe. Just waiting on a good day/chance to work on those - even though my dad keeps insisting I shouldn't change them because the ones in the engine now are still new. Well yeah, but if the problem started happening after putting those in then I'm afraid it must be that Pumpkin does not like Bosch lol. Those came pre-gapped at .060, but I don't know yet if all of them are still properly gapped (I checked one and it looked fine, but not all) - I did wonder if the mechanic changed the gap on them or something.
And as for the wires, I did not swap them - only the coils. My guess is the coils themselves aren't bad as the MSD's are still in the 06 and my dad hasn't had any problems yet either - but it could be the wires...or the combination. Like I (might've?) said, I don't know how long those last provided no mechanic has yanked on them like a brute like they have to my mom's Bonnie, but from the service and part purchase records the previous owners gave me, it looks like they bought these coils and wires early 2010.

Ah, Pumpkin, the list with you doesn't seem to be getting any shorter. I got the trans fluid and filter changed recently because the fluid was yellow and if driven enough the temp was getting to the low 200's, also slipping for a split second if accelerating from a stop (not necessarily flooring it either) - here hoping that would help take care of that for a while so I could focus on this darned misfire and a few other things, but nah...the trans still gets hot and I even noticed today if its around the 194-206 temp range it gets to, it gets difficult to shift from park to drive. Please staahp Pumpkin I can't keep up with so many things x.x
Not to mention the coolant leak that I have a feeling is the water pump and/or those elbows...

Anyway I was reading the other day someone else's thread on what turned out to be an exhaust leak at the flex pipe area of their downpipe, and the sound they were describing their engine made when accelerating sounds a lot like what my car is doing (like a plastic bag flapping while caught on something), except I do notice the loss in power (and the RPM's do dip before eventually jumping back up), and the car does have a brand new downpipe/cat that was installed a while after these seemingly cursed spark plugs were put in. *head scritches*

OK - I don't know why I can't edit my previous post so I don't have to double post... but, should I toss the metal heat shields and get some of the nylon sleeves/protectors instead so the boots/wires still have some protection from the heat? I just don't want any problems down the road from not having anything there to protect them.

take the round metal things off the spark plug wires and toss them in the trash. dont need them.

that heat shield thats all messed up fitting, remove it, toss it in the trash as well. its not really needed.

Originally Posted by Scottydoggs

take the round metal things off the spark plug wires and toss them in the trash. dont need them.

that heat shield thats all messed up fitting, remove it, toss it in the trash as well. its not really needed.

Okaa, I wondered anyway why my car has it yet my dad's 06 and mom's Bonnie don't (though the Bonnie does have a roomier engine bay).
Gotta let the engine cool not a couple of hours though before anything as I had to drive my cousin home from school just now.

You don't have to toss them or get the other type to TRY IT.

Seems like you must be out by Boston since that's the only place in MA you could be and still be in the state lol.

Originally Posted by BillBoost37

You don't have to toss them or get the other type to TRY IT.

Seems like you must be out by Boston since that's the only place in MA you could be and still be in the state lol.

Actually I'm in RI, haha

Okay, anyone have ANY suggestions for getting wires off that just will NOT budge?? I was able to get the heat shield off #5 just fine but # 3 and 1 are being a huge pain. I don't know if it's just the wires or if the springs on the heat shields are what's being dumb, but I can't get either to move at all.

Also, is this slight exposed area between the plugs and the wire boots normal or problematic? I couldn't get the boot on #5 to fit in any further than where it is pictured, and I can kind of see the others that won't move also have that gap with just the spring around the exposed part of the plug.

grip twist and rip. i like to wear leather gloves during this, when they gone off your hands tend to fly into things.

when you put the wires back on you should feel a click as it locks in its tip connection in the boot.