Changing spark plug type question

[djsubtronic]

Hey guys. I wanted to switch to iridium spark plugs back in summer but before I got around to ordering a set, one of my spark plugs fouled and the engine warning light came on. So I was forced to buy what was immediately available, and been using those. The other day I decided to order the iridium ones and I installed them today and went for a ten minute test drive.

I noticed two or three times, when putting my foot down at low revs, the car jolted as if misfiring. But this literally only happened about two or three times, and otherwise it was extremely smooth through the rev range and actually felt it was accelerating much more smoothly all the way up to 70 mph.

So I'm just wondering, were those just off-chance misfires due to ECU adapting to the new plugs, or should I be concerned about anything else?

Thanks

[JW1982]

Are the spark plugs of the correct type and did you check/adjust the electrode gap?

On the 1.4/1.6 Duratec Petrol engines the electrode gap must be adjusted to 1.2 mm. Original Ford spark plugs should already be gapped at 1.2 mm. Most aftermarket spark plugs are gapped at 1.3 mm.

[djsubtronic]

6 hours ago, JW1982 said:

Are the spark plugs of the correct type and did you check/adjust the electrode gap?

On the 1.4/1.6 Duratec Petrol engines the electrode gap must be adjusted to 1.2 mm. Original Ford spark plugs should already be gapped at 1.2 mm. Most aftermarket spark plugs are gapped at 1.3 mm.

They're the NGK LTR5X-11 which are supposed to be compatible with this car. I believe they are gapped at 1.1 but I didn't verify it.

[JW1982]

NGK recommends the TR5B-13 spark plugs for this type of engine. The NGK LTR5X-11 iridium spark plugs are listed as an alternative for the recommended TR5B-13 spark plugs. in fact both spark plugs should be fine. The electrode gap of the TR5B-13 should be adjusted to 1.2 mm. The LTR5X-13 has a 1.1 mm electrode gap. Personally i would only check this and leave the gap 1.1 mm.

 

I always used the recommended TR5B-13 for this type of engine. These are very inexpensive. Instead of the much more expensive iridium spark plugs I used the TR5B-13 spark plugs and just replaced them every other year. Never had any problems with these spark plugs.

[ejosr]

 I replaced spark plugs for the original MoFoCo I gaped them to 1.0mm and it made it worse.  

After reading a lot of articles regarding spark plug gap. My engine was shaking a lot more, I felt lost on performance it felt like towing a caravan.  Previous old spark plugs were 1.2m. So I set new one to 1.2m and it feels better. Less shaking and sharper throttle. Apparently 1.3m will harm your ignition coils.