Multiple misfires after plug change!
 

Ok, 2002 X5 3.01 M54 engine.
I replaced the valve cover yesterday. Since I was already there, replaced the plugs as well, I used the Bosch +4, funny thing, those were the old ones as well.
After replacing the plugs, she started funny, I got a check engine light, I ran the codes and it says multiple misfires.
I was wondering if those Bosch +4 need to be gapped? I dont know how that can be done.
Any thoughts?

^I don't like +4's on BMW applications. Prefer to run NGK iridiums.

All +4's should come pre-gapped afaik. Maybe you got a bad set? Or the parts guy grabbed a set off the shelf that isn't the correct part number for your car?

No you do not gap those plugs.

Check all the ground conections coming off the coils.

More than likely you forgot to attach the ground strap correctly. If it was running fine before then something you touched in the process is more than likely the problem.

Misfires
 

I will check that. Are you talking about that little ground wire that is bolted to one of the studs from the valve cover?
I will double check that.
I also do not like those +4 plugs :rolleyes:, When I bought it from Amazon, it said a set of Bosch platinum for BMW X5 , I never paid attention on +4 , I know my fault I hate myself for this :popcorn:

Misfire could be Coil boots thought
 

Your vehicle may have one of two coil types. One has coil boots on the bottom of the coils. Think short plug wires. Their life is 80K max or 5 years. They are cheap. Purchase and replace them. Note: Different ones for BOSCH vs Bremi coils. Aftermarket only makes one version to fit either. Buy the Bosch or Bremi ones, you will be happier.

Pulling the coils out and pushing them back in, is usually the end of the road for the the boots. Now the resistance in the boot is greater than coil output, hence no spark at the plug gap inside the cylinder.

Yes, there is a gap setting on these multi-prong plugs, but it takes a fine wire gaping tool to determine the setting. 99% of the time you are good out of the box but most people view each plug to make sure they were not dropped in transit.

I think we discussed the pros and cons of these plugs in another posting.

Coil Images below: Old style w/ Boot on left, New style on right

Coil Boots Views

The first question we have not asked is, Does the misfire get greater (MORE PRONOUNCED) on acceleration or all the time, idle through 3,000 RPM?

If you put your hand at the tail pipe can you feel the dropped cylinders on each side? (MisFire pulse). Is it random or constant?

Review and thoughts
 

Great video on 3.0 valve cover replacement that makes a point about the EGR vacuum line that runs along the back side of the valve cover. It also show the coil grounds and a few other tips and tricks.
https://www.youtube.com/watch?v=B-TLgNCmTlY

It only runs funny at idle.
I am going to ditch these Bosch +4 . I will also check the boots.

Ditch the Bosch +4 Autozone specials

You should be running NGK Iridiums or NGK Laser Platinums - BKR6QUEP or IX I forget the part numbers

We already posted this info but here we are a few days later........

Whoops, my bad, it was not this poster. Someone else with the normal 1st time plug change questions.

Ah I saw your posts on the last page, thank you for reminding me about the EGR vaccuum lines I need to check out in my spare time - Good call on the coils, he has a 2002 so I think he has the old style with the separate boots - My 2003 has the newer style on the right in the pic you posted on the prior page

Plug wire (carbon fiber) should have the 10,000 ohm resistance per foot standard. (Mag wire is a whole lot less). As these are 6 inches, so 5K max is the fail point. Personally I would just replace them as they are cheap. Add a dab of Die Electric gel.

Info source:https://en.wikipedia.org/wiki/Silicone_grease
Dielectric grease
Dielectric grease is electrically insulating and does not break down when high voltage is applied. It is often applied to electrical connectors, particularly those containing rubber gaskets, as a means of lubricating and sealing rubber portions of the connector without arcing.
A common use of dielectric grease is in high-voltage connections associated with gasoline engine spark plugs. The grease is applied to the rubber boot of the plug wire. This helps the rubber boot slide onto the ceramic insulator of the plug. The grease also acts to seal the rubber boot, while at the same time preventing the rubber from becoming stuck to the ceramic. Generally spark plugs are located in areas of high temperature, and the grease is formulated to withstand the temperature range expected. It can be applied to the actual contact as well, because the contact pressure is sufficient to penetrate the grease. Doing so on such high pressure contact surfaces between different metals has the advantage of sealing the contact area against electrolytes that might cause rapid galvanic corrosion.

Yes. I know this is not a College like MIT test posting, but it is good enough for a DIY site. This is to save myself from a response...:stickpoke

^^Dielectric (silicone) grease

I was having a brain freeze and winter coming on and all that.

Those boots are interesting little buggers. Most DIY do not even notice them until failure. They jump to coils right away on misfires.

Moving to the fine wire plugs will improve idle quality, replacing the boots will make it more so.

Check ground straps
Check EGR Vac line
Replace plugs with this

Excellent advise. Thank you. I just ordered a set of boots. I am picking up a set of NGK Iridiums today.
I will post the results here as soon as I get the parts. I will not get my boots until next week though arghhhhhh!

Cool info Stephen. However the plugs are defiantly not the problem. Those plus 4 plugs are what you get if you walked into a dealer. The part number is on real oem as the high performance plug. Ya you might get a lil better performance from an iridium plug (I don't race my X), but they don't last near as long.... I have plus 4 in 4 bimmers now with zero issues.

I had this problem and it was the plug gap... Seems that when I was inserting the plug into the spark plug hole some of the plugs fell out of the socket and messed up the gap... ( plug fell onto the end and closed the gap smaller than was specified) recheck the gap on the plugs for cylinders that have the misfire

I have the multi prongs in two of my BMW also. The 4.8is and the 3.0 seem to like the fine wire ones a little better IMHO. Both will provide long life 50K easy. I tend to replace them at 15 to 20 K in my vehicles as that tends to be every 3-5 years. For my M5 that would be every 10 years......

We used to see cars come in all the time at the shop with +4's in them... always ran better after replacing with OEM single electrode or NGK Iridiums. I'm guessing the +4's are listed as the performance plug because of a deal with Bosch and BMW.

Just my experience though. As you said they work fine in your vehicles so maybe it's hit/miss. Also never had an issue with short lifespan out of the NGK's except on my turbo 318is that I run a rich tune on. Lifespan on that car is 15-20,000 miles. 50,000+ on all our other ones.

To each there own. Honestly I could care less about what plug was in my e53. I just went off real oem. My piont was, his brand new plus 4 plugs are not causing the miss fire, unless one is damaged. Using a plus 4 plug will not cause a miss fire.

Can anyone elaborate on how to gap a 4 prong plug?

The only thing you can do is a visual check the gap on multi prong plugs to make sure they have not been dropped in transit after they were packaged. I have never seen a gap spec for them and every manufacturer has their own version of these things. They are sold as a long life feature compared to standard plugs. This technology is 15+ years old. The Plug manufacturers have moved on to single side strap/ground straps and precious metal plugs like Iridium etc.

There is a fine wire gaping tool which can be used to established a baseline. See the plug factory rep for any insight. I was a Champion Spark Plug Factory Rep for a few years and the lab testing completed at that time showed no value to multi prongs over single ground straps. The claim on multi prongs is a longer life and more consistent plug gap growth over time. Now that precious metal is used in the center electrode and ground straps, that value point is muted. See lab tests for answers if there is any :dunno:

BMW installed them at the factory for YEARS. Now they have moved on. It is just a piece of technology locked in time. Either of these plug types will fire and allow the vehicle to perform as engineered - naturally. The fine wire one just provide a little better idle and tip in acceleration feeling compared to the multi prong ones.

The OP has a misfire at idle. Only two things can cause that issue. Fuel (right mix) or spark. His only changes were valve cover removal, (Potential vacuum leaks) and ignition issues (Coils, Plugs, Coil/Plug Boots (Wires), Ground straps, electrical connections, etc). The recommendation is to review the install of these items and CONFIRM that they are indeed OK. New plugs are 99% ok out of the box. 1% died in transit by being dropped, stuck in oil/dirt then installed etc. Coils die from being over heated and or electrical shorts. A volt ohm meter will confirm windings are not shorted but that test will NOT confirm coil output, only a test with a lab scope will confirm total coil out put. And NO, the visual test of the little blue spark is not a test, its just a good guess.

See Bosch Fushion, and others images below. I have also attached some really bad plugs images that are multi prong plugs for those who think adding a prong solves oil fouling and poor fuel issues......:rofl:

Sorry for the rant on plugs and coils. One too many "bench racers" arguments over the years with techs and self proclaimed experts at race tracks in my Champion and Engine management years.

Awesome info Stephen. I might try some iridium plugs, just for kicks, in my Z:)

I believe my issue has to do with the boots on the coils, not vacuum leaks, lean fuel mixture or anything like that. The car has 126K miles, it was running perfectly fine. I was doing a valve cover gasket, since I bought the car last month, did not know the story behind the plugs, I decided to replace them.
As soon as I started it ran funny. I hooked up the code reader, it says multimple misfires.
Today I bought a set of BREMI boots and a set of NGK Iridiums.
I should get it next week. I will post the results here once I install it.

I think your on the right path....