Originally Posted by Synthetik

Injectors are maxed out? Where did you get that information?

I assume you hooked a scanner up to yours. What duty cycle were your injectors at?

Originally Posted by Synthetik

There's two ways to fix a lean condition. A new tune or a higher octane fuel. As far as I'm aware (someone correct me if I'm wrong), there is no way to load a truly custom tune to a JK. The 07 - 10 guys have the option of SuperChips and the likes but those are still only canned tunes. The only way to custom tune these pigs at the moment is with a stand alone. You'd be looking at a lot of wiring and a lot of money. No where near worth it on a stock motor.

Now, you said you're already running the SuperChips 93 tune and you're hearing popping? Are you sure you're hearing a popping sound or rattling? Rattling is usually what you hear when you run lean. Sounds like a bunch of marbles being bounced around in a can. Popping could be backfiring. Two different issues.

Stupid question. Are you running 93 octane fuel with the 93 SuperChips tune? Are you perhaps in a area that's at a really high elevation?

Originally Posted by DanieltheManual

scanner not needed, old fashioned calculation.

Never safe to be running higher than 85 percent consistently.. math is your friend...

Do you even know what size the injectors are.??what happens when they get dirty? I'm just pointing out things most people don't think about....

Originally Posted by DanieltheManual

scanner not needed, old fashioned calculation.

Never safe to be running higher than 85 percent consistently.. math is your friend...

Do you even know what size the injectors are.??what happens when they get dirty? I'm just pointing out things most people don't think about....

Originally Posted by JPop

A DiabloSport Predator can do custom tunes and they have been available for a few years. There is no reason you should run lean with the other tuners unless you have changed mechanicals beyond shorty headers, exhaust and intake, outside of being at a high altitude. If you are getting pinging, there's something else wrong although you can get detuned settings provided by the manufacturers. One of the biggest culprits is spark plugs. If you aren't running OEM spark plugs, test and pull them to make sure they are functioning in the appropriate heat range. They can be all over the board, and ideally the best way is to run a new set of plugs for a week and pull them to check their condition.

Other than that, most of this can be addressed by octane. Within range the knock sensors will do the job and issues are few and far between.

Originally Posted by Synthetik

Let's correct a few things here.

Running lean means there's too much oxygen and not enough fuel causing whats called detonation or pre-ignition. Basically the fuel is igniting sooner than it should be. To rich means there is too much fuel and not enough oxygen. A good way to destroy cat converters.

A full throttle pull on a dyno is not going to show if you're leaning out at partial throttle. At full throttle your ECU is in what's called open loop. Meaning it's not reading data from the O2 sensors in the exhaust. It's pulling from a predefined table that's programmed into the ECU itself. This same open loop condition is also in effect on a cold start until the motor gets up to operating temperature. At partial throttle the ECU is in closed loop. Meaning it's pulling data from the O2 sensors in the exhaust and adjusting the amount of fuel injected into the cylinder on the fly. You could try to have the shop monitor the AF/R under normal cruising RPM. You won't be able to simulate real world conditions such as changes in air temp, elevation or inclines but it's better than nothing.

You could also try to get your hands on a scanner. Hook it up to the OBD-2 port and monitor the knock sensor while driving and see if the ECU is pulling timing. If it does, you're leaning out.

There's two ways to fix a lean condition. A new tune or a higher octane fuel. As far as I'm aware (someone correct me if I'm wrong), there is no way to load a truly custom tune to a JK. The 07 - 10 guys have the option of SuperChips and the likes but those are still only canned tunes. The only way to custom tune these pigs at the moment is with a stand alone. You'd be looking at a lot of wiring and a lot of money. No where near worth it on a stock motor.

Now, you said you're already running the SuperChips 93 tune and you're hearing popping? Are you sure you're hearing a popping sound or rattling? Rattling is usually what you hear when you run lean. Sounds like a bunch of marbles being bounced around in a can. Popping could be backfiring. Two different issues.

Stupid question. Are you running 93 octane fuel with the 93 SuperChips tune? Are you perhaps in a area that's at a really high elevation?

Originally Posted by Synthetik

Not necessarily. Things such as load and environmental factors play a role as well. However I do see quite a few threads on here about people noticing their 3.8 pinging.

Mine pings with the stock tune and 87. Dealership refuses to acknowledge it as a problem. I'm forced to run 89. It was worse when I had my K&N intake installed. I put the stock air box back in and it pings less but it's still a problem.

Originally Posted by jaybrown

I thought jeeps were tough vehicles out off the lot. They are crap so many weak points and problems. The more I read this site the more I feel less confident

Originally Posted by Freewill

Great post!!

I would add that running lean means there isn't enough fuel (or sometimes high enough octane fuel) in the mixture for the existing engine parameters (settings).

You can change engine parameters without changing the actual fuel/air mixture and the engine will totally act like it is running rich or lean - because for the new settings, it is.

For example:

• A higher heat range spark plug will cause an otherwise well tuned engine to act like it is lean.
• Advancing the ignition timing will do the same thing.
• A very hot engine tends to act like it is running lean.
• Fuel with a lower octane than the engine is tuned for will make the engine act lean.
• Carbon build-up in the cylinders raises the compression ratio. A higher compression ratio needs higher octane fuel or the timing to be retarded.

One way to tell if an engine is running rich or lean is to read the spark plugs. This is a bit of an art. Getting a wide-open-throttle (WOT) reading is not too hard. Run the engine on the open road at full throttle for about 30 seconds. Now quickly let off the throttle, slip the tranny into neutral, and turn off the engine more or less all at once. (Watch out you don't lock the steering!!!) Coast to the side of the road and pull a couple plugs. Look at the ceramic insulator. A tan insulator is perfect. A white insulator is a lean engine. A dark or black insulator is running rich.

You can do the same thing at part throttle. Just run at, say, half throttle for 30 seconds and do the same routine as above. Shutting the engine off before changing the throttle position is critical. It only takes a couple seconds for the reading to change if you change the throttle position before shutting the engine off.

It might be interesting to read the plugs at idle. Used to be with carburetors and early fuel injection the idle mixture would be rich. I bet that with computer controlled engines they idle nice and lean now.

Long before analyzers and computer controlled engines, I could fine tune an engine with a stop watch and plug readings within a gnats arsehole. With an old-school engine its possible to start with an unjetted carb and out-of-the-box generic distributor and get it ready to test on the dyno with nothing but eyes, ears, and reading the spark plugs. But I'm just reminiscing here. You can't do much to tune a modern engine this way, but you can still learn a lot about what its doing by reading the plugs.

Good luck with it.

Originally Posted by Ryan0260

Try cleaning the carbon from the motor and see if it helps with the pinging. It helped with mine. Ran seafoam through the tank, and mopar combustion chamber cleaner through the intake