|12-22-2013 01:18 PM|
Increasing the octane above what the engine was designed for will not affect its mpg in the least. In fact, the higher the octane, the harder it is to ignite and the slower it burns. If running a higher octane gasoline by itself improved fuel economy, you can bet Obama or the EPA would have long ago mandated its use.
I'm not making this up, even the EPA agrees with what I said here.
|12-22-2013 01:09 PM|
Bosch plugs bad, High octane good.
On a side note, in my experience 4.0s and lightly modded 258s both really like 93 Octane. 87 is OK, but I get almost 10% better fuel mileage using high-test. I wonder if this is unique to my vehicles and/or climate. I advance the timing quite a bit on the distributor models, and usually use platinum plugs.
|10-10-2010 09:28 PM|
|bobsalmon||Jerry is right. Higher octane in any low compression engine does nothing for performance. Keep using 87 octane. High octane is used to prevent detonation in higher compression engines. Using a higher grade fuel will just waste your money.|
|10-10-2010 07:41 PM|
|moscoeb||Thanks, I got 23000, might explain why it occasionally idles slightly rough, looks like I got a(nother) project!|
|10-10-2010 02:48 PM|
|Jerry Bransford||25K miles is about as much as I'd trust conventional spark plugs, especially in a distributorless engine that will go through conventional plugs nearly twice as fast.|
|10-10-2010 02:42 PM|
|moscoeb||So with the stock plugs, what mileage should I start to think about replacing them? 2006 4.0L. Distributorless.|
|10-10-2010 01:57 PM|
Champion Truck Plug 4412
Just thought I'd throw this link out there:
ChampionSparkplugs.com - Cross Reference Search Results
Looks like it is true that the Champion Truck Plug (4412) actually has been discontinued.
Just an FYI
|08-16-2010 02:38 PM|
I finished the rest of them this morning. I'd recommend everyone watch it - good information.
During one of the modules the guy said the 3 most important things are fuel, spark, and compression. My wife argued - "No! The 3 most important things are finding the keys, lipstick, and the cell phone."
I'm not so old and closed minded I can't try new things. I've had lots of bad experiences with plats - based on experience. Starting years ago when they first got popular I still had my dyno performance shops - sold the last one in '84. Every time, with no exceptions, plats always caused misfire and terrible running. We did not work on imported cars - they seemed to work OK in some of those. I would not stock plats, nor would I install them.
I tried them quite a few times using my dyno - even experimented with the heat ranges - all bad results.
But I don't remember what they were - possibly Bosch. I threw the Bosch rep out - I would not stock or use his junk.
My mainstay was Champions.
Champion was very good to me - when we'd build up a race engine I'd call the Champ Rep - he'd come out to my shop and use his equipment - pyrometers, internal cameras, etc to determine the right plug to use. Things like indexing, reach, and the heat ranges at low, med, and high speeds as well as heavy and light loads. He'd spend 2 or 3 hours on the dyno. In turn I let him use the dyno for some of his projects.
I'd think Jeep would understand the reasoning behind the double plats with waste spark ignitions. Why don't they call out plats on the underhood label?
Now in my limited business at home - (I thought I retired) - when it's been a misfiring problem and I found plats, trashcan time. Using the plugs called out on the label has always worked - when it was a plug issue.
But - after seeing the video - and years have passed since I became prejudiced - technology must have changed - I'll try a set in my Rubi.
You can teach old dogs new tricks - it's just more difficult.
|08-16-2010 12:43 PM|
|08-15-2010 11:16 PM|
|08-15-2010 10:25 PM|
|marc1kim||My automotive teacher once told me when it comes to spark plugs, stick with OEM, all the high dollar stuff is just snake oil.|
|08-15-2010 09:40 PM|
Interesting - so far I've only had time to do module 6 - but I will do them all.
As both of us speculated a year ago, the misfire code for a particular cylinder is detected by that cylinder not contributing to the rotation. They showed a square wave pattern from the CPS - with a missing pulse. That's what the PCM is monitoring. I've seen that CPS pattern many times with my software, but I guess never with a misfire.
They said people expect more than 30K miles on a set of plugs, that's why the plats. My '03 Rubi new didn't come with Plats. It had what the label said.
I haven't worked on it for a while, but I'm still trying to make an adapter so a conventional scope pattern can be seen with the coil rail. It would be nice to see the scope pattern - it can tell lots of things at a glance.
|08-15-2010 06:58 PM|
|Jerry Bransford||Take that spark plug and ignition course Motorking provided above Rich, you will be surprised at some of the information contained within it. Especially what plugs DIS engines require which of course includes the newer distributorless 4.0L engine. Especially in the #1 module that is only about 15 minutes long. I completed all six modules, it was worth the just over an hour it took.|
|08-15-2010 06:19 PM|
Under the hood, top of the firewall, driver's side - a white label - it tells what plugs that particular engine was designed to use. Not all 4.0's are the same, some are different, due to small head changes etc.
Bosch and many of the others - especially many of the "trick performance plugs" go by "one size fits all." If it fits the hole, they say to use it. Just because a plug that's designed for a Yugo fits the hole it doesn't mean it's the right one. Ask your wife how "one size fits all" fits her.
|08-15-2010 04:50 PM|
|08-10-2010 09:00 AM|
|08-09-2010 06:40 PM|
|Ted_D||stopped in several places today and couldnt find a single Autolite APP985. NAPA ordered them and said they would be in 7am tomorrow. They tried and tried to sell me something else but I told them I would just wait.|
|08-09-2010 06:34 PM|
|sbregister34||I always recommend to use the OE plugs at my shop. Always had problems when varying too much in plugs.|
|08-09-2010 05:00 PM|
There is no knock sensor in the 4.0L engine so there is nothing in the computer that could advance the timing to take advantage of a higher octane, even if the engine's compression warranted use of a higher octane which it does not.
Trust me, your engine isn't running any differently with 92 octane. In fact, in an engine without a knock sensor to help with the engine timing, running a higher octane than the engine was designed for can even leave deposits in the combustion chambers behind. That is because higher octane gasolines are not as easily ignited and they are slower burning than a lower octane gasoline.
By itself and without an engine designed to run a higher octane, an engine will run no differently and have no more power or run more cleanly than a similar engine running the standard level of octane it was designed for.
|08-09-2010 04:51 PM|
|Wrangler97-EEK||You say nothin more than 87 octane? My 97 is not adjustable on timing and idles at 17 degrees btdc. You can tell the difference between 87 and 92.|
|08-09-2010 02:44 PM|
The platinums will last a lot longer, but like I said, the 4.0's love copper plugs. Another good copper plug (the one I use) is the Champion 4412 truck plug. Kragen/O'reilly will tell you they are discontinued but they are not. Call around. Carquest has them. It was explained to me they call them truck plugs because they're a heavy duty plug. Cost more than a buck, but great plugs.
|08-09-2010 12:34 PM|
P.S. Here's a slightly longer explanation of why running a higher octane fuel than the engine was designed to require doesn't help... http://www.wranglerforum.com/f5/gas-...tml#post715509
|08-09-2010 11:38 AM|
|08-09-2010 11:17 AM|
|08-09-2010 08:24 AM|
What is the best plug for a DIS 4.0 Jeep?
|08-02-2010 11:30 AM|
|Big O||Installed the Platinum Ir Fusion a few weeks ago and the engine is running smooth. Gained 1 MPG. Using Mid-grade fuel.|
|08-01-2010 06:58 AM|
|07-31-2010 05:21 PM|
Thanks Jerry, I removed the Bosch plugs and went with Autolite 985, just plain old plugs and I can't belive the difference it made.
Thanks again for the info!
|07-23-2010 01:11 AM|
|07-22-2010 09:00 PM|
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