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Old 09-02-2009, 11:03 AM
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Highway power loss

Yes, another newbie question... I have an 89 YJ, 4.2, 5 speed, Weber conversion, HEI dist.
I have tons of torque in town, but when I'm in 5th gear on the highway, I have a tough time keeping my speed up, and passing somebody is pretty much out of the question. I haven't checked the timing yet, and I don't have much experience with Webers. I do get some pinging when I stomp on the gas, I have tried running higher octane fuel and get the same results but less clattering. Any suggestions?

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Old 09-02-2009, 11:05 AM   #2
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do u have larger tires than stock?

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Old 09-02-2009, 11:16 AM   #3
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My 89 4.2 5spd. had the same power loss problem and it was a clogged cat. When I replaced it all of the power it originally had came back. I also had a problem with pinging, but when I replaced the distributor it solved the problem. I also tried premium gas but that didn't work. I'm running a stock distributor. With your set up I would check the timing you might be too advanced. I would eliminate a bad cat.
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Old 09-02-2009, 11:19 AM
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2.5" lift, 31" tires. Nothing major, stock gears, Dana 30. When I got this Jeep last week, he said the chain in the t-case had been removed. It is locked in 2 wd. That's my next question / project:, doing a 231 j gear conversion and losing the chain all together.
I'll fill out my signature soon so everyone will have a better background for my issues. Thanks, Sonny
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Old 09-03-2009, 09:39 AM   #5
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Premius Gas will only help with engine knock.

Or, if you have a PCM tune that is tuned to Premium.
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Old 09-03-2009, 07:41 PM   #6
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If the power loss is intermittent, try removing the vacuum line from the EGR valve & plugging it with a screw.
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Old 09-04-2009, 12:05 AM   #7
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If you are pinging when you stomp on the gas then your timing is off and that will also effect your top end. You are too far advanced.
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Old 09-16-2009, 11:54 PM
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Well, I checked the cat, it was gutted, and all the guts were rattling around in the stock muffler. That gave me a good excuse to put on a flowmaster, sounds awesome!. Leaned out the carb a little, changed out the springs on the distributor arms. Now it runs much better on the highway, and when I slow down, I don't smell that funky unburned gas smell. So, changing my timing curve seems to have fixed the problem. Now I picked up a ProComp 16 inch electric fan. Gonna put that in if it ever stops raining here! The PO had taken the thermostat out of the Jeep, I have heard mixed reviews on what temp I should put in. What is the general consensus? 180? 195? The automatic thermostat on the fan is supposed to be 180 on, 170 off I think. Will that work with a 195 thermostat??
Thanks again for all the tips!

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