Your Jeep - September 2014

    Your Jeep Tech Questions Answered

    Verne SimonsPhotographer, Writer

    More Smiles Per Gallon
    I am a big fan of the magazine and a subscriber. I have an 2005 Wrangler Unlimited Rubicon. It’s very stock with fewer than 50,000 miles right now. I bought it used 5 years ago, and just mailed in my last payment!

    I don’t do any hard four-wheeling, but love the Jeep (this is my 10th or 11th one since I was a teenager). It is very useful for our Pittsburgh winters and for taking the kids for “safari rides” on my dad’s farm in the summer. I used to work 1-mile from my home, so commuter mileage was not an issue. I recently changed positions, and now am commuting 70 miles per day. 65 of those miles are on the highway, with very little traffic. I was very disappointed to learn I am getting only about 14 miles per gallon.

    What are my options? If you could recommend the top three improvements I could do to improve my mileage, I would appreciate any opinions.
    Via email

    The top three mileage improvers, huh? Well, unfortunately, your Rubicon is destined to get fairly poor gas mileage -- all while being one of the most capable off-road vehicles you can still drive to work! The Rubicon package is great for off-road use, but unfortunately does not make a great commuter car. The brick-like aerodynamics are not helping either. However, I can make a few suggestions to try. First adding a free-flowing air intake system like the one from Airaid should help your engine breath more easily. This in turn should up your mileage a little bit. You can also add a more freely flowing exhaust, and that may help improve gas mileage a touch. I think probably the best way to improve mileage (besides slowing down and driving like a grandmother avoiding “jack-rabbit” starts) is to go to some narrow 33-inch all-terrain tires when your Rubicon next needs new shoes. Why would you do this? Well, the Rubicon is geared from the factory for larger tires with its 4.10 axle gears. Alternatively, you could buy a clapped-out Honda sedan and use it for commuting and keep the Rubi off all that wintertime salt.

    I don’t know if this is the right place to ask, but I am going to be rebuilding the front end on my WJ, brakes, upper- and lower-ball joints, maybe CV shafts, bushings or control arms, spring isolators and shocks. I’m thinking of going with the Monroe Sensatrack shocks, and was also looking at the Old Man Emu Springs. Can I use the stock-length shocks with the longer springs? Thank you for any information you can provide.
    Jamie Kirkendall
    Via Facebook

    This depends on if you are gonna also run larger tires and longer bump stops. If so, I’d say talk to Old Man Emu and see what they recommend to work with their springs. Generally, if your springs are taller, you may want a slightly longer shock, but if you don’t also lower the bump stops at the same time, the longer shock can bottom out before the bump stops do their job, possibly causing damage to the shock. This is one of the reasons a suspension “kit” (where all the components are designed to work together) is usually easier than assembling parts. I used some OME shocks on a XJ several years ago with a Rubicon Express lift and really liked them. Their price is decent, but I can’t guarantee you’ll like them like I did.

    Softer Ride for a High-Mileage YJ
    I have an 1988 YJ Wrangler. It’s a daily-driver with 215,000 miles and the clock still keeps perfect time! The Jeep is mainly stock with a 2-inch lift with shocks I bought through 4Wheel Drive Hardware (I believe Pro Comp makes the parts for them). I also have a 1-inch drop kit for the transmission and transfer case that came with the lift to keep the driveshaft angle reasonable. I run 17-inch steel wheels with 5x4.5-inch bolt pattern with factory JK-sourced BFG KM2 tires. The track bars are long gone. The issue is the springs. Now that I have run them for a while, I now know that the spring rate is way too firm for such a lightweight Jeep. It has a full-sized matching spare and a back seat, but nothing else. Radio was stolen a while ago and even the glove box is empty. Needless to say, it rides rough. Way rough. My wife won’t even sit in it anymore -- it’s that rough.

    I don’t have a custom-spring budget, but I gotta believe someone has to sell an off-the-shelf set of springs that will work well with a lighter YJ. I need an honest 2 inches out of the springs to keep space for the tires. Any more than that I’m sure would cause driveline issues. I like the current height, stance, and so on, and would like to keep it the way it is, only with a softer ride. Any input or thoughts you may have would be greatly appreciated. I’m mid 50’s now and need to smooth out the ride at least a little. Maybe a TJ someday.

    P.S. My Peugeot BA10/5 tranny has 215,000 miles on it and somehow has not blown up yet. Go figure. Still enjoying Jp after all these years. Thank you for your time. Let me know if more detail would be helpful
    Andy Wall
    Gaithersburg, Md.

    Well, a TJ will ride smoother than an YJ, that’s for sure. The coil springs and link suspension make quite a difference. Having said that, a YJ should ride pretty well especially as compared to all CJs (some of which have very different springs). One thing that you don’t mention is what shocks you are running. If the suspension kit came with gas-charged shocks, that could result in a firm ride. If that’s the case, and I was you, I would first try a set of softer shocks. Old Man Emu shocks and Skyjacker Hydro shocks come to mind as being fairly soft. I also like Bilsteins. If that does not do it, look into a set of Old Man Emu 21⁄2-inch springs for a soft-top Jeep or light load. Old Man Emu sells two sets of springs for YJs. One set is designed for heavily loaded Jeeps and the other for lightly loaded Jeeps. That should help smooth out the rough ride. Hopefully after the shocks or shocks and springs your wife will want to ride with you again. Oh, and good luck with the BA10/5…you may have just jinxed yourself, so start looking into AX15 swap.

    Dealer Diagnosis?
    I have a 2005 KJ with the 3.7L and a manual transmission. Yesterday, it started making a noise and the check engine light came on. I went to the Jeep dealership, and they diagnosed it as a number-four cylinder misfire. They told me I need new lifter and rocker, but I thought it was an overhead cam engine. Am I wrong? Any advice?
    Brandy Marie Mooney
    Via FaceBook

    Brandy, this is going to be next to impossible to diagnose over the Interwebs, but it seems like probably your dealership is omitting some diagnostic information, as there is a pretty big leap from a misfire code to a bad lifter/rocker. Your 3.7L does have rockers that transfer force from the cam lobes to the valves, and while it does not have lifters per se, it does have hydraulic lash adjusters that act as a fulcrum. That may be what they are referring to as a lifter because the function is similar. If this is a correct diagnosis the real question is what caused the problem. This could be due to a head gasket issue or oil pump failure. Either way, the cause needs to be addressed. All in all, the dealership could be trying to pull one over on you, but I’d give them the benefit of the doubt if they can explain a bit better what’s wrong, why it happened, and how the fix will prevent future damage. After all, you can always go get a second opinion and estimate if you still doubt the dealerships diagnosis.

    More Love for Private
    I enjoy the Private JK articles you are doing on the 2013 JK Unlimited very much. My wife and I purchased a 2014 JK Rubicon Unlimited last September. We’ve owned Jeeps since 1972, starting with a 1955 CJ-5, a CJ-2A, an M-38, a CJ-7, a 1959 wagon, a 1962 wagon, and a 2006 TJ that we traded in on the new JK Rubicon Unlimited. We have logged over 15,000 miles on our new JK. Quite a few of these have been off-road where I have dragged the bottom over rocks. It is a great rock crawler. We would prefer not to put a lift kit on the JK due to our friend’s mobility issues getting in and out of the JK. However, I would like to put 35-inch tires on the JK to give it a little more clearance yet still be low enough for our friends to get in and out of the JK and maintain the original ride. Your article where you put the MCE flares on and the Dick Cepek tires was great (“Private JK,” June 2014). I am thinking about putting more skidplates on the JK but am concerned about airflow and cooling through the radiator. We live in Florence, Arizona, and wheel in the summer when it is 120 degrees out. Do you have any concerns with the installation of the Synergy Manufacturing’s oil pan skidplate blocking off very much of the air flow path around the engine? Do the hoods I see with vents on them help with this air flow issue very much? Your input would be appreciated.
    Mark L. Stephens
    Florence, Arizona

    Mark, thanks for the compliments. My Commando Green JK is doing well, and I am thinking of what’s next for the Jeep. To answer your first question last, we have not tested to see what if any effect the vented hoods have on engine temp. That’s a good idea. I also live in Arizona, we are nearly neighbors, and I don’t worry about the skidplates causing excessive heat on my JK, but I guess it could be a problem. I’d be willing to bet that the skidplates won’t prevent or change air flow under the Jeep very much as the backs of the plates are open and that should create low-pressure zones that will help suck air over the skids -- I think that makes sense. Anyway, I have a feeling that this summer will let both you and I know if this is going to be an issue. Let me know if you have any issues. As for ease of entry and exiting a JK, I agree. My parents both struggle getting in and out of my Jeeps, but the JK is pretty easy even with the 35s. I also added some good grab handles from Quadratec (PN 14117.0002, $29.99 in black) to the rollbar just above the door openings. You want high-quality grab handles because if a cheap one fails, it can cause serious injury. I also contemplated the actuated drop down steps from Rock-Slide Engineering for my JK. I have seen these sliders/steps abused off road on a built JK and they still worked as a step after the fact. I ended up going with Synergy’s rocker guards, but it was a tough decision. Check Rock-Slide out.

    CJV-35U Web Page
    In the current issue of Jp magazine I just noticed your advice to Earnest Duskey regarding his CJV-35/U (“Your Jeep,” July 2014). I already have Earnest’s V35 on my CJ-V35/U web page, and I’d like to include the one you have your “eye on” too. Here is the web page link: What is “your” V35’s serial number? Got a photo?
    Bob Westerman
    Via email

    I currently don’t have a picture of the V35 I have my eye on and I don’t have the serial number for it either. I know, not much help, am I? Anyway, I’m going to add this email to our Your Jeep column so other V35 owners can get in contact with you and submit the info on their late military flatties. Until I can actually talk the current owner out of the V35 I spoke of, maybe people out there in Jp land can send in pics and info on their V35s -- to both you and us here at Jp. So Jp readers, if you have a V35 and its not on Bob’s web site, please send him a picture and the serial number for your V35. Also, please send me a pic and the story about your V35 or, heck, really any Jeep to, and we’ll see if we can get it into the magazine one way or another.

    Emissions Soap Box
    I have a 1990 YJ with a 258ci 6-cylinder. It has a Clifford Research intake manifold with a Weber carburetor, and full-length headers. In general, the Jeep has a very free-flowing exhaust. It no longer has the pulse air system or a catalytic converter. My question is, can I put a catalytic converter on it without a pulse air system or an air pump? I would like to make it legal, if possible. What can I do? Is there a converter I can put on that doesn’t need an air pump? Great magazine, and I would like to see the finished product of the Number Two YJ. Thank you.
    Via email

    Well, what makes your Jeep’s emissions system “legal” or not depends on your local emissions regulations and these regulations are usually not very clearly defined and may not make sense. Basically, I am not going to try to understand your local laws or interpret them for you, but I will say this: I doubt that adding a new catalytic converter to your YJ’s exhaust is going to hurt anything at all other than maybe the thickness of your wallet when you pony up the cash for the cat. Modern cats flow well and shouldn’t make much difference in power output, especially considering what you’re doing with your Jeep. Cats are also frequently used on vehicles that don’t (and never did) have an air pump or pulse-air injection system. Just look for a universal high-flow catalytic converter for the exhaust tubing size your Jeep runs, and once installed, it should help clean up the exhaust gasses.

    Now depending on where you are, you may find that your local emissions test requires one of two things. Some areas require a sniffer to tell a computer how clean or dirty your Jeep runs. This test has minimum and maximum level for certain exhaust gasses, and you either pass or fail based on what comes out the tail pipe. Other emissions tests require a sniffer test (like the one just described) and a visual inspection of the emissions system, generally requiring the vehicle to have all the emissions equipment that came with it from the factory. This type of test makes less sense because it is subject to personal interpretation.

    There is a good chance that if your Jeep is tuned properly it could pass a sniffer test with a catalytic converter installed. However, it certainly won’t pass a visual inspection if this inspection requires all of the original emissions equipment to be installed, let alone functioning. As said, that is up to your local laws. The problem with the visual inspection is it depends on who is doing the testing, what they notice, what they know, or how they are feeling that day to decide if your Jeep passes or fails. It doesn’t make sense to me. Honestly, what comes out of the tip of your exhaust pipe should be the emissions control folks only concern because that’s what has an effect on our environment. The presence, or lack thereof, of old, obsolete, and possibly non-functional emissions equipment should not mean anything. Then again, what do I know?

    As far as Number Two, it’s still around, now owned by my pal, Mike. Also, it did pass both a visual- and dyno-based sniffer emissions test in Arizona. Although the Jeep’s passing was not in thanks to much of the original emissions equipment because while (most) of the emissions equipment was present, most of the parts present were not functioning (however, the cat was present and functioning).

    Write Us!

    Got a tech question you’re just itching to get answered? Send it on in to Jp Magazine, Your Jeep, 831 S. Douglas St., El Segundo, CA 90245, or e-mail it to

    Related Articles