smog check (i need help)

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May 2, 2009 | 07:54 PM

bostonnj15

Thread Starter

Junior Member

Joined: Dec 2008

Posts: 86

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Year: 1990

Model: Cherokee

Engine: 4.0 Inline 6

smog check (i need help)

i have to go get my 1990 cherokee 4.0 inline six checked for smog. i know it will not pass. my friend put it on his to check it. it failed. what can i do to get it to pass smog

May 2, 2009 | 08:01 PM

Throttle Jockey

Senior Member

Joined: Feb 2009

Posts: 811

Likes: 0

Model: Cherokee

a complete tune up. and put some 93 octane in it before you have it tested.

May 2, 2009 | 08:04 PM

Schmoozer

Senior Member

Joined: Apr 2009

Posts: 501

Likes: 0

Year: 2001

Model: Cherokee

Engine: 4.0L I-6

I'm not sure but I think higher octane fuel will also help, someone correct me if I'm wrong.

May 2, 2009 | 08:10 PM

okcjeeper

::CF Administrator::

Joined: May 2008

Posts: 10,039

Likes: 16

From: Okc area

Year: 1991

Model: Cherokee

Engine: 4.0 I6

Also check your O2 sensor (I think 90 models had one), tuneup, clean the throttle body and intake, check cat converter maybe replace it, clean vacuum lines/system, also might replace the EGR valve.