Spark plugs problem
 

Hitting the 37,000 mark on my mileage I decided to replace spark plugs (a little bit earlier as Mazda recommends replacement every 60,000 miles).

I bought Denso ITV22 on PG and they were fitted in Mazda service during inspection.The gap was set to 0.65mm (0.026").

With the new plugs my car is simply undriveable. Acceleration from revs lower than 3500 chokes the engine, looks like a boost- or fuel-cut. WOT from 3500-3800rpms shows no such symptoms.

I suspected the map but it all started just after the plug replacement.I changed the gap to a narrow 0.85mm (0.032") but the problem still persisted. Just a while ago I switched back to the stock plug and the problem disappeared.

Plugs look like this:

http://misiekwaw.easy-it.com.pl/imag...vs_denso_1.jpg
http://misiekwaw.easy-it.com.pl/imag...vs_denso_2.jpg
http://misiekwaw.easy-it.com.pl/imag...vs_denso_3.jpg

Left is stock, gap 0.0315" (0.8mm), mileage about 37000 miles, right is Denso, gap 0.032" (0.85mm), mileage about 1000 miles

All plugs looks the same (all stock's and all denso's)

What's going on? Is the gap still to small? Denso is shit? ;)

My car has catback with test pipe, SRI and inlet, FMIC and custom remap.

The densos should be gapped to .025-.028.

.028
.028
.028
.028
.028
.028
.028
.028
.028
.028
.028
.028

it was .026 when installed and car becomes undriveable, I'll try regap it to .028

i bought mine about a month ago and i havent had any problems, gap is set at 0.28 and its running like a champ!!

The gap is defiantly not your problem. Either u cracked the ceramic on a plug or u damaged the iridium electrode. That one plug is black,black,black that plug is prob damaged.

on the photos are examples of stock plug and denso, please read before You answer

If all the Denso's are that black, then my guess is they are too cold for your modifications. Based on those pictures, it appears the tip of the plug is not getting hot enough to burn off the carbon deposits. Seems likely that you should stick with the stock heat range.

My 2 cents...

yes, all densos are smoked / black, all stock plugs looks like this one on the photos (I think stock looks OK)

Stock plugs look pretty good.

There are probably better images out there for this, but here's a good reference.


http://www.aa1car.com/library/reading_spark_plugs.jpg

Sorry, must have skipped over that part. Something still doesn't make sense I had those plugs in my car with just an intake and no problem. What tune do u have ? Cats with your amount of mods run those all the time. Also where do u live and are u at sea level?

Custom tune with mazdaEdit, I have an euro version of speed (MPS) and I cant use COBB AP, on stock plugs I dont have any problems. I live about 100 meters (around 330 foot) above sea level

So are u in Europe , and if so what octane do u use where u are? It's higher then 93 isn't it? If so then that's why u can't use them.

+1

I agree, too cold. Great for drag racing, but not so good when not at WOT.

I'm using 98 and 100 but this is RON octane rating

So the levels are the relatively the same as ours. It has to be somethin in either the Mazda factory tune or the remap if they touched maf cal or cl fueling conditions. Anyhow to make a long story short stay with the stock plugs.

MAF calibration? I was doing MAF calibration, my LTFTs was between -0,78 and 0,78 maybe 1,56

I'm using mazdaEdit, unfortunatelly I cant solicit (I do not know whether it's a good word, I asked for it many times and didnt received it) for map descriptions for epifan, so I'm not sure which of fuel maps in mazdaEdit You mean. I understand that when You writin cl fueling You mean closed loop fuel map.

Just put some new stock heat range plugs in and be done. Every car is different in how its mods relate to heat range adjustments. You want the plugs to be as hot as possible without getting KR and as cold as possible without getting that black sooty fouling you are getting on the Densos. With your mods and tune, it is obvious that stock heat range works best for you. That's what your tune likes. You can experiment a little with gap, if you like, but stick to stock heat range.

So, either NGK or Denso or OEM will all be fine as long as your choice is stock heat range and is also fine wire iridium center tip.

I just found Denso ITV20 in store in Poland. Should I use Denso or stock FoMoCo?

[Added]
What is a part number of NGK with stock heat for 2.3 DISI in 3 BK? ILTR6A-8G?

regaped to .028, its worse than on .032

Stock heat range .028 = :)

Yes, ILTR6A-8G is the NGK part number for stock heat range. My stock plugs came with BOTH FoMoCo and ILTR6A-8G stamped on them. Ford just rebranded them.

I do not know what the Denso number is. I've had fantastic results with NGK's in a lot of different cars over the years, but I'm sure the right Denso's would be fine, also.

Thx :)
I think after this experience with Denso I choose NGK ;)

I had some issues with the Densos one step colders simliar to yours. Car drove like garbage. I switched back to stock, then took my chances on the NKGs one step colders. Car runs like a champ!!

Just run oem plugs.....

The plug strap doesn't look right - it's roughly cut/chewed up on the edges. Either the plug is not firing properly or there is another issue causing you to overfuel the engine.

I am running denso 1 step colder on stock tune with custom intake, IC and exhaust with metalcat. No problems at all! Car is running strong and smooth.
Your spark plugs looks like to cold. Many reasons could cause this- too small spark advance, to much fuel?
If you dont have nocking with stock heat range, than stay there ;)

My car ran amazing when I traded the stockers for densos. They come pre-gapped outta the box, and lots of people say not to touch them at all. My guess is you fucked them up changing the gap.

The next set you get, try tossing in the car and seeing how it runs before you fuck with the gap. Then go from there.

We moved these sparks to another car (Speed3) and they works fine. Later I was found problem. Of course that was "user factor" - I screwed MAF calibration and on low RPM was much too much fuel. Thx for help.