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Old 06-17-2013, 10:01 AM   #1
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90 vs. 91???

What is the difference? Im noticing that a lot of parts fit a 91 2.5L 4 cyl but not a 90 2.5L 4 cyl.


Whats the difference... ? Help please!

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Old 06-17-2013, 10:15 AM   #2
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1990 and before used a carburetor. 1991 and after was fuel injected.

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Old 06-17-2013, 10:29 AM   #3
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All 4cly where fuel injected. the 6cly changed to fuel inject from carb in 91.. as for the change in the 4cly between those years, not sure.. could be emmission related perhaps.
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Old 06-17-2013, 10:31 AM   #4
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Quote:
Originally Posted by ChicoJeepy View Post
1990 and before used a carburetor. 1991 and after was fuel injected.
Incorrect.

All 2.5L YJ's are Fuel Injected from the factory.

1987-1990 use a Throttle body Injection setup (TBI), which has one big injector inside of the throttle body.

1991-1995 use the modern Multi-Port Fuel Injection setup (MPFI) which nearly every gasoline vehicle is designed with now. It uses one injector per cylinder, 4 in total, rather than one big injector.

Nobody makes aftermarket parts for the TBI, only the MPFI.

The change came when Chrysler decided to change the original 1987-1990 TBI design by AMC. Chrysler basically did a lot of re-designing for the 1991 model YJ.

1987-1990 6 cylinders were the carbureted 4.2L, 1991-1995 6 cylinders were the modern Chrysler 4.0 MPFI design.
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Old 06-17-2013, 10:42 AM   #5
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Quote:
Originally Posted by Xpress View Post
Incorrect.

All 2.5L YJ's are Fuel Injected from the factory.

1987-1990 use a Throttle body Injection setup (TBI), which has one big injector inside of the throttle body.

1991-1995 use the modern Multi-Port Fuel Injection setup (MPFI) which nearly every gasoline vehicle is designed with now. It uses one injector per cylinder, 4 in total, rather than one big injector.

Nobody makes aftermarket parts for the TBI, only the MPFI.

The change came when Chrysler decided to change the original 1987-1990 TBI design by AMC. Chrysler basically did a lot of re-designing for the 1991 model YJ.

1987-1990 6 cylinders were the carbureted 4.2L, 1991-1995 6 cylinders were the modern Chrysler 4.0 MPFI design.
Thanks for clarifying.
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1993 Jeep Wrangler YJ 2.5L AX5 Transmission Rough Country 4" Suspension Lift 27" Wildcat Tires and Stock Wheels KC Fog Lights OEM Push Guard White SmittyBilt Soft Top with Rugged Ridge Hardware CB Radio Full Sound System.....
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Old 06-18-2013, 12:48 AM   #6
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Thank You

Quote:
Originally Posted by Xpress View Post
Incorrect.

All 2.5L YJ's are Fuel Injected from the factory.

1987-1990 use a Throttle body Injection setup (TBI), which has one big injector inside of the throttle body.

1991-1995 use the modern Multi-Port Fuel Injection setup (MPFI) which nearly every gasoline vehicle is designed with now. It uses one injector per cylinder, 4 in total, rather than one big injector.

Nobody makes aftermarket parts for the TBI, only the MPFI.

The change came when Chrysler decided to change the original 1987-1990 TBI design by AMC. Chrysler basically did a lot of re-designing for the 1991 model YJ.

1987-1990 6 cylinders were the carbureted 4.2L, 1991-1995 6 cylinders were the modern Chrysler 4.0 MPFI design.

Much appreciated! So basically your saying that if its not fuel injector related/ emissions there isn't much difference between a 91 and a 90?

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