Autolite HT1 Spark Plugs

[blacklimited07]

Replaced all 8 plugs today with the HT1's. Luckily the old ones all came out without breakage. The vehicle feels like it is running worse though. I think it could be due to the new plugs. Has anyone else had a similar experience with these?

 

[Mr. Alligator]

Did you replace spark plug wires with the spark plugs? How old are your spark plug wires?

Good luck with this project.

 

[94Eddie]

Replaced all 8 plugs today with the HT1's. Luckily the old ones all came out without breakage. The vehicle feels like it is running worse though. I think it could be due to the new plugs. Has anyone else had a similar experience with these?

I always use Motorcraft spark plugs. Some people report having issues if they do not use them.

 

[mountaineer2004]

^ What he said.

 

[blacklimited07]

Did you replace spark plug wires with the spark plugs? How old are your spark plug wires?

Good luck with this project.

This particular engine has coils over plugs. They look pretty old though with 5/8 being the original Motorcrafts. The other 3 are different brands , 2 are Denso's and 1 is BWD.

On Bank 1 I have a Denso, (2) Motorcraft and BWD. That bank also has bad long term fuel trims at idle around positive 16 that improves under load. Bank 2 I have 1 Denso and the other 3 are Motorcrafts.

When the vehicle is idling it will shake pretty violently sometimes, the RPMS also drop and it feels like its going to die. When driving it feels better.

I tried doing a power balance test but did not really notice a difference in the RPM when I unplugged each coil for most of them.

Not really sure what to do next. I could swap the coils from bank 1 to bank 2 and see if the high fuel trim follows. I recently purchased the vehicle and have already replaced the radiator, water pump, t-stat, belt, cleaned MAF sensor and throttle body. It has 146,000 miles and was sitting for a few years.

 

[Bill MacLeod]

I've been using HT-1 plugs for years with no issues.

Suggest cleaning the boots of the coils and applying some dielectric grease to the boots both inside and out.

 

[blacklimited07]

I've been using HT-1 plugs for years with no issues.

Suggest cleaning the boots of the coils and applying some dielectric grease to the boots both inside and out.

That's great Bill. I guess I am one of the unlucky ones. I took your advice and completely disassembled and cleaned everything. Right down to removing the built up corrosion on the contact points to the spring. The copper terminals had turned white they were so corroded.

After a couple hours cleaning and a pile of about 100 q-tips later I went for a test drive on the highway. It was misfiring pretty steadily enough for it to trip the CEL.
P0300 random/multiple cylinder misfire
P0301 - cylinder 1 misfire
P0304 - cylinder 4 misfire
P0316 misfire on startup

I swapped out the Autolite plug for one of my original motorcrafts on cyl #1 and the CEL's went away and has not returned.

The Autolite plug has a gap of .33 where as the factory gap is 0.45. I returned the Autolites and have some Motorcrafts ordered.

Both connectors on cylinder #4 are broken the injector/coil. I think that could be why I got the P0304 but not sure. I will be replacing the connectors along with a couple others on the other bank.

I put in a new fuel filter which seemed to improve my fuel trims and misfires. I did get some misses at about 4500RPM on highway though but at idle its no longer violently shaking.

 

[Bill MacLeod]

How did you measure the gap? Comparing the gap between an old (worn) oem plug and a new plug might be the reason. (just a thought)
But, I still have an old set of oem plugs and an old set of HT-1. The gap is different, but I don't have a method to actually measure what that difference is.
Can you measure the new plugs when you get them and advise?

Finding corrosion inside the coil boot is likely caused by moisture. #4 & especially #8 have known issues with water dripping from the screws above holding the hood seal in place. Some have used caulking on the screw to seal it. Others have put a drip shield in place.
I made a shield from scrap aluminum.