Spark plug Autolite or OEM Honda

And timing belt, and spark plug change every 90 K miles or so.

Sounds like it could be a spark plug. For some reason the Prelude likes to eat through them. Shows the exact same symptoms you describe (loss of power, different exhaust note).

I installed a set of Autolite 3923's gapped to .032 and guess what? FIXED! unbelievable, after all this testing only to find out that all I needed was new plugs.

So, I went ahead with the Autolite XP iridium plugs. Right now, I cannot complain. Everything is running pretty good. I put these in to compare to the standard Autolite copper plugs that I put in my 2001 2.0L AEG in January of 2009. Here is what has happened so far. 1. Since the new plugs, my idle rpm increased about 50-100 rpm to low 800s to mid 800s . Whether this is good or bad, I don't know. This may consume a small bit more of gas though while sitting at a stop light. 2. Since the new plugs, I can also feel a small vibration that seems to come from the engine bay. This only happens on a cold start as I am accelerating from around 15-40 mph. When it's warmed up, it's gone while accelerating. This may come my new catalytic converter and flex pipe that I just got installed, but I don't know. It may also come from new front rotors and pads that I just put in that haven't had time to properly be bedded, I don't know. I am putting some new dog bone mount inserts in within the next few days as well. 3. Since the new plugs, my engine seems to have had a small performance increase in acceleration, response, and in smoothness; except in cold start accelerations as stated above. This may not make a big deal to some, but I am happy with this. 4. Since the new plugs, the best deal I have had is the lower rpms when I am using cruise control around 40-55 mph. I am serious when I tell you that my rpms went down a good 150-250 rpms at these cruising speeds. I do believe that because of these plugs, I will get a small boost in mpg; I will let you all know shortly. Also note that only the plugs and nothing else was changed at this interval. Can I tell you what happens at 65 mph+, no because I don't go on a highway to school or work. So, my overall impression with the iridium plugs is a positive one so far. I have gone just over 500 miles since the new plugs were put in.

Autolites last as long for me as the NGK's. Either of them last about 10k miles for me. Any longer than that and I start getting missfires. The Autolites can be found for about $1.00 each

Do not get Autolite, I've seen them cause trouble and issues in Honda engines.

Yesterday, I installed new spark plugs in my 2004 TJ. Going off [this thread](https://wranglertjforum.com/threads/what-are-the-best-spark-plugs-for-my-jeep-wrangler-tj-4-0.4196/) I purchased the Autolite XP985. Originally, I gapped the plugs to .04 based on [this thread](https://wranglertjforum.com/threads/spark-plug-gap-for-4-0.17415/). The jeep ran terribly and actually threw a check engine light.

I went back today and changed all the gaps to .035 based on the note under the hood, but I still think the idle is a bit rougher then what it was before the change.

I’d never put autolites in a Jeep, send em back and get champions or NGK depending on year and model.

I quit using autolite plugs somewhere between 1995 and 2000, got tired of all the comebacks.

I work on euro cars. If I'm diagnosing an issue that even has me think misfire and it has autolites, I'm done until they're in the trash can and OE is installed.