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Unread 11-29-2012, 06:20 PM   #1
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1994 YJ Wrangler 
Join Date: Nov 2012
Location: Brighton, Colorado
Posts: 2
94 Sahara performance problems

I have a 94 sahara with about 140000 miles on it. Inline 4.0 with manual transmission. Everything stock except throttle body spacer. I am having concerns with power, and gas mileage, also starting.

The things I have done so far are, all new fluids throughout, new spark plugs, cap, rotor, throttle position sensor, map sensor, o2 sensor, throttle body spacer, air filter, fuel filter, coil, I think that is it.

When starting it takes about 7 - 10 seconds to start. Is that normal, seems a little slow.

Gas mileage:
Maybe all I will get but I feel in stock form I should be able to push another 2 mpg out of it.

This is the main one, The motor seems to have a lot of back pressure. For instance it seems to decelerate very rapidly, bangs out of gear when shifting periodically, and engine sounds like its rpms are higher then the gauge says. When driving it feels like gusts of wind are hitting the jeep when cruising at 45 and above. Trying to stay at cruising speeds in 5th gear can be hard, like going up small inclines usually 60 mph and above. Also accelerating in 5th gear is impossible most the time unless slower speeds. Seems like there is no change when pressing gas pedal to floor. I dont mind shifting to lower gears but do to the engine sounding like its running at really high RPMs I'm nervous to.

(Have read about mas air flow, cps, fuel pump, pick up screen, pressure regulator, injectors, catalytic converter, I dont know where to start exactly)
Can cooling system cause any issues?

This is my first post so if you need more info or any suggestions on future posts please let me know. Any other info you need just ask.

Thank You

Also pulled codes and none to mention, 12 and 55

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Unread 11-30-2012, 02:22 AM   #2
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1993 YJ Wrangler 
Join Date: Apr 2012
Location: Longview, Washington
Posts: 339
Ok first off what's the normal operating temp? It should be 210.
The stock header isn't the greatest and crack very early. I replaced my header and problem solved.

Also are you running bigger tries on stock gears? That could cause the issues
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Unread 11-30-2012, 07:23 AM   #3
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Join Date: Dec 2004
Posts: 5,634
Check your fan, if its a engine driven one it could be locked up. Makes a lot of noise and eats power.
When you turn key(click right before starting it) in the morning listen for the pump to come on and go off. Then turn key back to off and do it again, then try to start. The fuel lines may be dry and it takes a second for the fuel to get there. If it fires right away after doing what I said then let us know, we help you fix that issue too.
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Unread 11-30-2012, 07:15 PM   #4
Registered User
1994 YJ Wrangler 
Join Date: Nov 2012
Location: Brighton, Colorado
Posts: 2
Thanks for the replies! First I think my running temp doesnt get above 200 according to the gauge and my tires are only 2 sizes above stock, stock suspension so haven't gone larger yet.

Never thought about the fan, been out of the mechanic game for awhile, but tha does make sense. How would I check whether it is froze up or not?

I have done the fuel pump thing before and I didn't really notice a big difference. I will try it again though. I did test the schrader* port after it sat over night and fuel came out but not a spray like I was expecting. I also disconnected the vacuum line to the pressure regulator and plugged it. Went for a drive and didn't notice a difference in the way it ran at all. I did not the change in rpm when the vacuum line was disconnected so I am good on vacuum leaks. Also checked the simple function of the injectors and they all work at idle.

Thank you again.

Quick question, any tricks to getting the hard top to seat all the way down on the windshield. I was thinking of having someone sit on it, just wanna get rid of the whistle.
lunchbox639 is offline   Reply With Quote Quick reply to this message

acceleration , acceleration loss , deceleration , performance , power loss

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