That is an instant red flag to me.
What makes certain spark plugs not work in certain engines?
- Thread starter Chris142
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Maybe some manufacturers try to cover too many heat ranges with few part numbers.
What was the source of info that the Bosch was supposed to set at 0.043 In a Audi. That sounds too large a gap for an Audi. Perfect for a Silverado.
Alldata
I just know Champion never once worked in any car of mine
I can see how some may think that way, but remember it requires more energy for the spark to jump a bigger gap. The resistance of a spark plug, limits how much power goes thru the electrode, and jumps the gap to the ground side of the plug. You will have a crisper spark on a plug with a smaller gap. It will look more blueish. The wider you make the gap, it may look more orange. If you were to open the gap to 75-100 thousands, good chance you won't have any spark to jump the gap.,,
What Audi/engine?
And also the more potential for spark blow-out in forced induction applications. Typically as you turn up the boost the gap should get smaller and potentially the heat range should be colder.
> 40 years ago I changed the plugs in my father in laws 1979 Honda Accord, pretty sure it was a CVCC. Pulled the OEM NGKs out and installed Champions. It ran like crap. Plugs were gapped and not cracked. Put the NGKs back in, it ran fine. Since then, I stick with OEM.
On the Sportwagen I've run (while having an aftermarket tune): OEM NGKs, OEM NGKs from another vehicle (1 range colder), Densos, NGK Rutheniums, and a current aftermarket plug that's 2 steps colder and is non-projected and gapped to 0.020" (OE gap is 0.028-0 030"). They all have felt exactly the same to me/no difference 
I believe it was an 18,a4 with a 2.0.
Ya ButI don't order the parts. I just put them on.On the Sportwagen I've run (while having an aftermarket tune): OEM NGKs, OEM NGKs from another vehicle (1 range colder), Densos, NGK Rutheniums, and a current aftermarket plug that's 2 steps colder and is non-projected and gapped to 0.020" (OE gap is 0.028-0 030"). They all have felt exactly the same to me/no difference
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Saab had an anti-knock system that relied on copper spark plugs.
I read that GM used some of that technology on the Ecotec engines in Europe but I don't know about the US.
I read that GM used some of that technology on the Ecotec engines in Europe but I don't know about the US.
Wow, that gap on that plug is giant - alldata called for 0.04+ on gap? The gap on those Bosch's was just too big when you opened them up leading to the misfires, it had nothing to do with the brand I suspect. I bet those Bosch would have worked just fine installed as they came with the tighter gap, what I see is they are set to 0.027". Factory plugs are those NGKs and the ones I've measured were in the 0.03-0.032" range out of the box.
AutoMechanic
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I’ve seen that before too. We stuck NGK in our Jeep once and it ran like absolute garbage and put Champion in it after and it ran fine. Had a Camry towed in recently to my shop someone put Autolite in and took them out put factory Denso in and it ran spectacular. I don’t know what it is but brands don’t like different spark plugs. I haven’t had to ever gap a spark plug except maybe 2 or 3 times.
I was one of the tuneup wizards in the Lowell, Ma, area in the 70's. Got a lot of mistakes and bad work from other area shops.
Gap being that far off from OE is a red flag. Also the large gap spec from alldata for a VAG turbo engine is a red flag that would have me double checking OE spec on that motor.
Some odd designs just don't work everywhere like the original bosch plats from 30 years ago with the ceramic shrouded center electrode.
Then I have found plugs with varnished wire terminals that won't conduct with coil sticks - the old steel collar terminals will scratch thru the varnish and make a contact, but not most coil stick spring terminals. I file the varnish off the terminal tip with a point file.
Then there are external insulator height differences - again an issue with coil on plug reaching the terminal.
Then there is resonant waste spark with shared double ended coil that require a certain electrode design to reliably "backwards fire"
Fords used two different part numbers that had to go in the correct hole number.
Then there is basic heat range not overlaping the factory O.E. tuned choice, certain ground electrode materials and thicknesses and heat sinking ability.
HTH - Arco
Makes perfect sense to me.
When I changed the factory plugs in our '06 TSX with the mighty K24, there were 2 NGKs and 2 Densos. Ha!
Bosch in particular tries to use one plug to cover multiple heat ranges. i/ wont use them unlesss they were OE.
Seen too many weird issues.
Seen too many weird issues.
I got a set of NGK copper for my 2006 5.7 hemi. Plugs were supposed to be gapped at .44, the .35 feeler would not go in. I opened every one of the sixteen a little bit until the .44 feeler would barely go in.