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View Full Version : Everything just feels.... sluggish.



Jim311
08-24-2004, 12:49 PM
Lately my ZJ has just felt really sluggish. As I start accelerating it feels like it bogs down in the lower RPM range, but once the RPMS get a little higher it opens up and runs fine again. Gas mileage seems to have gone down a bit as well. I cleaned my K&N but saw little benefit from that. I have no catalytic convertor, so that can't be it. Where should I start trying to diagnose this problem? Oil pressure, temperature, and voltage are all doing well, and when I had the belt off last all the pulley rotated smoothly and freely. I'm thinking of changing the plugs since I have no clue how long ago they were changed, but is there anything else I should check? It also has the original ignition. I'm thinking about calling up Kolak or Kevin and asking them about thehir prices for an aftermarket ignition. How much mileage should one expect from a stock one anyway?

BigDaveZJ
08-24-2004, 01:21 PM
I'd try cleaning your throttle body too. It may not solve it, but it's cheap (like $4 for a can of cleaner) and it won't hurt anything.

Jim311
08-24-2004, 01:23 PM
That's a definite possibility.. didn't think of that. I'll check that first since it's probably easier and cheaper than upgrading an entire ignition system. I think I'm going to replace the plugs anyway. I bought the Jeep at 70k miles, so the plugs have definitely got some mileage on them.

Creech
08-24-2004, 04:04 PM
I'd do plugs, wires, dist. cap, rotor button....everything. Don't have to upgrade right now, just replace. I've always thought of plugs and wires and such as a 30K mile service. I know that some platinum plugs say they are good for more than that, blah blah blah. Replace 'em. First thing I've always done when buying a used vehicle is a complete ignition system tuneup, filter changes, and fluid changes.

Trancezj
08-24-2004, 04:06 PM
yeah, plugs, sensors, wires, air filter, clean throttle body and dealy behind it. If that doesn't work, you can do like me and cuss at it for hours on end and put a few fist size dents in the hood, that'll fix 'er right up.

JeepinHank
08-24-2004, 04:15 PM
That's a definite possibility.. didn't think of that. I'll check that first since it's probably easier and cheaper than upgrading an entire ignition system. I think I'm going to replace the plugs anyway. I bought the Jeep at 70k miles, so the plugs have definitely got some mileage on them.

Sounds like you just need a good tune up. Cap, plugs, wires, and rotor button. The Mopar CC cleaner certainly wouldn't hurt.

Also - I'd avoid the ignition upgrage. Twice I have been on a trail ride and run into someone with ignition problems. Once, we came up on a guy in a YJ on the trail, the other time we came up on a guy in a Bronco. The YJ guy was easy go get up and running. I want to say his rotor button fouled out on him. Anyway, I had the old one from when I did my last tune up. I gave it to him, and he was up and running. Even if that hadn't been the problem, we could have swapped parts off of the bountiful 4.0's that were parked along the trail to at least diagnose the issue.

The Bronco guy had one of those hi-perf. electronic ignitions (I want to say it was an MSD), and it died on him. Well, he was SOL. There was nobody in our group to help him out with a part, and no one knew anything about those systems. His only option was to try to get to the parts store before it closed. (This was about 5:00 on a Sunday afternoon so his chances of making off the trail and to the parts store before closing were next to nothing)

I decided something then & there - 1) If you're going to ride with jeeps - drive a jeep, and 2) Keep as much of the engine in the stock form as possible. I know it sounds bad, but when you think about it from a support & parts availability standpoint, you have to admit that its true.

JMO

Jim311
08-24-2004, 08:52 PM
Yeah, but I have a 5.2.... nobody in my club has the same motor as I do. I haven't really heard anything bad about the Kolak ignition, but you do raise a good point about parts availability. It would probably be much cheaper to replace the cap and rotor with stock parts however. At this point I'm flat broke so cheaper is better. I've never changed the cap or rotor... is it pretty straight forward? Thanks for the help everyone.

JeepinHank
08-25-2004, 10:44 AM
I've never changed the cap or rotor... is it pretty straight forward? Thanks for the help everyone.

cap & rotor are pretty simple... Just a couple of screws holding the cap in. Remove screws, replace, and reinstall...

One important thing to remember when you replace the spark plugs - make sure to check/set the gap to spec. It SHOULD be in your owners manual (not sure), but I know its in the FSM and Haynes-type manuals. If you don't have one - get one - even if its the Haynes-type it can be really helpful.

Make sure to get some of that di-electric (sp?) grease for the wire to plug and wire to dist connections. That will make your life a lot easier the next time you change them. Go ahead and get new wires - I promise you that if you haven't changed them in a while, you'll ruin a few of the originals.

Also check out the condition of the old plugs. That can clue you in to other possible problems.

There's a good write up on the Mopar CC cleaning method on JU if you can get the search to work. I think its on NAGCA too. If I have the time, I'll see if I can swipe it and post it over here.

Good luck!

JH

Jim311
08-25-2004, 09:17 PM
Yeah, I want to look at the plugs as well. The back of my Haynes has pictures of all different types of damaged plugs and why they're that way. Hopefully the plugs will be okay. Oddly the Jeep seems to be running better at night when it's nice and cool, and poorly during the day when it's hot, but the temperature guage isn't reading abnormally high or anything. I might just need an upstream O2 sensor or something easy like that.. I'm hoping that's what it is.

wwbmopar
09-04-2004, 08:47 AM
Never had a problem with my MSD 6A and it definantly made a performance/mileage differance. I do, however have it wired up to bypass it if it fails. I've learned the hard way with aftermarket electronics to never be too careful, ie. Jacobs ignitions suck. My ZJ did the same as yours at 74k. Plugs and wires cured it. Might want to also check your O2 sensors. If you do a lot of wheeling and in town driving they will only last about 50k regardless of what the service interval is.

Jim311
09-04-2004, 10:07 PM
I swapped the plugs and fuel filter this week. Seems to have helped with power but it still doesn't seem to be where it used to be. I think I'm going to pick up an O2 sensor as well. I put in some injector cleaner which seems to be slowly increasing mileage some as well. Oddly enough, the plugs were gapped to about .040 which is .005 more gap than is recommended. All the plugs looked okay.. most of them had a very light brown coating, a few a lighter whitish coating although very light.

wwbmopar
09-05-2004, 05:35 PM
sounds like the plugs are ok. The ashy looking stuf is probably from the injector cleaner. Check the cap, rotor and wires next. The O2 sensors are about $50-$60 a pop. Get the cheap stuff out of the way first. You may still need an O2 sensor, but if you drop $50 on it and find out its a $5 cap and rotor it'll suck.

dank
09-07-2004, 07:24 PM
Id upgrade and bring the stock parts on trail runs as spares or just always carry the coil. Thats what I do. You might want to check your dis cap to see if it loose, I have seen that cause the symptoms you have.