Misfire after spark plugs
 

I swapped my spark plugs last week 60k miles. Most likely original ones were in there. After the plugs were changed things were good for atleast 100 miles then I’d have slight hesitation when taking off from a stop in first gear but resolved itself after an hour. Then last night I was driving through a tunnel and I got on it alittle and out of no where flashing check engine light that would flash when I was heavy in the throttle. Tried restarting a few times but now the misfire stays. Codes are p0300( random misfire) p0301(cylinder 1 misfire confirmed) and p0305(cylinder 5 missfire) I ordered new spark plug tubes which I didn’t replace and will just replace those while I look around for a cause. Does anyone else have suggestions on where to look other than the classic swapping coils and plugs with other cylinders?

2001 2.7l 60k miles

could be a losse plug or coil or coil wire.

What plugs did you put in? Last time the coils were replaced?

I forget the brand but it was decently expensive and were ones I’ve seen many use on here. And no idea on coils, If I had to guess I’d say never but when it’s back up in the air I’ll check markings

Double check which plugs you used. If they weren't Bosch I would replace them with the correct ones.

Do they really make that big of a deal? I come from bmw and Mercedes so Porsches are kinda new to me. If they are really that picky then if I got like ngk ones you suggest still putting bosch?

I'd say that the Bosch plugs do not make the engine work like no other plugs. INSTEAD make sure that you have correct plugs.

I have a 2001 Boxster with 2,7 and the very best plugs I have found for the street and also several race weekends each year are there platinum tip NGK BKR6EQUP.

Previously I got info from a website to get the Bosch FGR6KQE 7413 to my Boxster, but these were not good and as I found out later these were also wrong ones.

Many report good success with the NGK, but also depends on exactly which ones you got.

Honestly for the price I just go with Bosch plugs. It's simpler and it is what comes from the factory.

Since you just did plugs the issue you are having is going to be plug related....or the parts you took off/put back on as part of the process. Prefer myself to just do it once and be done with it then try to save a few dimes.

I would doubt that the problem is that the plugs are not Bosch. Much more likely, as suggested by STL-986, one or more coils are not properly seated on the plugs or that a coil wire is not properly inserted all the way into the connector, they can be difficult and if you don't pull the rubber boot back you can't see if it is not seated.

Check for hairline crack in the coil - I had the same code when one of the coils was bad after spark plug change. Mine was cylinder 6 missfire.

Unless they changed from 1999, the coils are mounted on the plugs. There are no plug wires and you cannot pull back any rubber boot to see if they are seated.
I just worked on a Volvo Urban Assault Vehicle with a misfire on cylinder 6. Changed the plugs and swapped the coils between 5 and 6. The misfire did not move so the problem had to be the injector. Swapped injectors 5 and 6 and the misfire followed. These injectors are stupid expensive considering they are just rebranded FoMoCo parts. I used a battery to open the injector and blew it out with air from the outlet side then filled it with WD-40 and blew that through the nozzle. Misfire went away.
Any water that gets into the fuel system will cause problems as the holes in the injectors are too small to let it pass through.

I ordered the new tubes like I said. I remember buying the spark plugs in store and the autozone near me Carry’s the NGK IRIDIUM ones so I think that’s what’s in it I can verify when I pull them. My starter is making a horrible screeching sound when starting so I ordered that along with rear brakes, fuel filter(probably hasn’t been changed in years), belt and filters. I also bought the tool I saw on here to remove the tubes. I was going to order all new coils but I think I’ll just replace them if I find any cracked ones. While I’m in there is it fine to keep the ngk iridium ones if that is what’s in there? I was in a rush when I did them originally that’s why I was at autozone in the first place

Here is a question for you. Was it wet out, raining or drive through any puddles when you got the codes?

Believe those are the wrong NGK's. Most of the parts stores dont carry the correct ones and would need to be ordered.

Coils are not easy to detect if there are any cracks unless they are big cracks. The car should still be drivable (although badly).

It was raining when the flashing check engine came on but I mentioned the hesitation that was on a nice sunny day top down. I cleared the codes that night and left it in the garage came back 24 hours later and still missfire right on startup now. Can you provide the correct spark plugs I should buy? I’ll just order them now I don’t want to mess around with the wrong ones

cracked coils & rain do not mix. perfectly describes a misfire. if it were me I would just replace all 6 plugs & coils. You can get them from Pelican or fcp euro. Dealers price for the plugs isn't all that expensive either but their coil prices are.

What exact plugs would the dealer sell? My Porsche dealer is in the city and is a pain to get to I’d prefer to order online. Is it fine to replace only one or maybe 2 coils? I know replacing all is ideal but I’d prefer to get most of the life out of the coils that remain on the engine (if they are on good working condition)

platinum tip NGK BKR6EQUP.

This might be the one that’s in it. I recognize that model number either from buying or scrolling the forums here

I was talking about the coil wires not plug wires. There is a rubber boot over the connector that plugs into the coil and it is easy to think the connector is on all the way when it is not, hence the suggestion to pull the boot back.

Alright, but the connectors have a snap lock you can hear click when full seated.
Irridium plugs last longer than the cheaper ones. As long as they are the right heat range and gap the new plugs should not be causing the misfire.
Bought a new starter without finding out what the noise is from? PMGR Starter usually have a plain bush on the gearbox side and needle on the ring gear side of the output shaft. The grease in the gearbox or needle could have dried out. The armature end of the motor is commonly a bush also.
If it sounds as though the Bendix is not engaging it might need a new solenoid, about $20 from a starter supply.

This is the plugs I just pulled now, does not match what was said here previously

Look, don't over complicate things.
You changed plugs and have had an issue since. When you change plugs, you remove coils. Coils were (are) original and were at least disturbed when you performed the work.

If you have the right plugs, torqued to correct value, the most likely issue is coil or coil connection. Check connections to coils and drive the car. Check for misfires and codes. Clear codes if needed and drive again. If you still have misfires, Buy 1 or 2 coils and put them in offending positions if you don't want to spring for 6 right now. Clear codes, drive, repeat. You'll get it!

Please, post much larger pics.

Or, send glasses.

I LOL'd here Starter. LOL'd.

Look, as stated, you changed the plugs and there's now an issue...likely due to old coils being unseated, a connection is loose, or one or more has failed.

Should be an easy fix.:cheers:

Sorry for the picture, it was of the spark plug model BKR6EIX. On ngk website it says that is the correct one

Doesn't matter if NKG site says those fit or not, they are the wrong plugs. Get the right plugs & replace them.
https://www.pelicanparts.com/catalog/SuperCat/1044/POR_1044_ELIGNT_pg1_spark-plugs.htm

Still think you should replace the coils too

What brand of what you sent do you advise most, there’s beru(matches the coils) Bosch and ngk

All are OK just pick your price point. I only use Bosch for plugs myself

Opted for Bosch. I should have them in by Thursday

Although plugs come pre gaped it is only prudent to check the gap before you install them.
Look each plug over and check the gap...the condition of the porcelain...the sealing washer.
Same thing if you install new coil packs. Look them over....make sure there are no manufacturing defects check that your wiring connections are clean and tight.
Make sure the contact point of coil pack to plug is clean.
Make sure they are fully seated on the plug.

Make sure the part you are installing is correct for the car.
Never assume that a new part is good just because it is new.
simple things like this can save a lot of headache and tail chasing.

Bosch plugs are 4 prong....dont do anything with the gap

In the words of Ron Burgundy... That escalated quickly!

I agree that this is likely a coil issue. New ones are cheap, and knockoffs work fine. I put unbranded Chinese ones on 2 years ago and have had no issue. I'm sure this offends some...

Injectors can also cause misfires. You don't have to hunt down the oem ones (theyre not even made anymore, you are only going to find reman'd ones). But, it is quite easy to retrofit the Bosch 986.2 pintle plugs for our cars. I wrote up a diy on this and they are cheap.

You can and should check gaps on ALL plugs before install, single or 4 prong. To gap a 4 prong plug, you need a different gap tool (a wheel with a bunch of metric"feelers").

Iridium vs standard, Bosch vs ngk vs beru vs denso.... I'm not gonna touch that one with a10 ft pole. Needless to say, just make sure that they cross-reference too the original OEM part. I know all lot of guys will say "I don't care what the manufacturer says..." But all yourself this question - would would a company risk their reputation saying they their part will work if it won't? That's not exactly how capitalism works...

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Electricity follows the path of least resistance to ground.
Drop a plug on the concrete floor and bend one of those four prongs so there is very little gap.
That very small gap will be the path of least resistance to ground.
The spark will now....always jump that very small gap.
It will be a very weak spark.
Possibly causing miss fires.
There are gap specs. on plugs for a reason.
Plug gap should be checked no matter how many prongs they have.

I would also swap the coils. I had basically the same issue and symptoms you described 2 summers ago. Although my issue started on it's own, I hadn't swapped the plugs before.

Here is the kit I used. NGK plugs and Beru coils. No issues since.

https://www.ecstuning.com/b-assembled-by-ecs-parts/ignition-service-kit/99760210700ikt2/

60k miles and 20 years of service isn't bad for factory coils.

Also when you swapped the spark plug tubes what tool did you use?

I used a transom boat plug, 1" lol. Wrapped it in electrical tape and plucked all the oil tubes out perfectly.

Boat plug here too, haven’t removed them yet but I bought it off Amazon

Pulled coils, end of one where the rubber meets the spark plug was ripped and wearing away. Looks like some new coils are in the plan

So, did you manage to get rid of the misfire?
Just curious.

If so, did you try the new coil pack(s) with the previously installed NGKs? Or did you change two variables: coils AND plugs?

If I remember correctly I put the correct plugs in and also replaced the one coil that the rubber was bad on. Been running like a Champ until I dukes of hazard over a curb at 60 a few weeks ago.

You say you put in the “correct plugs” along with replacing the one coil. But I’m not convinced you had incorrect plugs in there before. The giant pic, haha, you included in your earlier post shows the exact same plugs I put in my car (also an ’01) in July. This car seems to like them just fine and, nearly 500 miles later, she’s still “running like a Champ” as you say, throwing zero codes. Stl-986 (different thread) all but guarantees she eventually will—I’ll believe it when I see it. If they’re the “wrong plugs” why would it take thousands of miles for that to manifest? Especially when plug issues are only one of several things that can cause misfires. I tend to agree with ike84: why would a reputable parts manufacturer (like NGK) risk their reputation by saying their part will work in a certain application (ie in a specific make/model) if it won’t? That just doesn’t make sense to me either.

I kind of hoped you’d replaced the coil and tried the new one with the NGKs still in there to see what would happen. But…if it’s runnin’ well now I guess that’s what matters.

Sorry to hear about your Dukes of Hazard moment…sh*&%t happens. I know. Ask me how.. :cheers: