4.0L HO or Not?

F

firstXJ

NAXJA Forum User

Location

michigan

• Apr 19, 2006

• #1

Sorry folks this question was probrably asked a million times but I have not been able to find a thread for it. How can you tell if you have a 4.0 HO or non-HO motor? is there a code in the vin? I asked this cause I have read lots of talk about the HO putting out more horse power and just wondered how you can tell what you have.

Thanx,
Paul

 

87manche

NAXJA Forum User

Location

Ohio

• Apr 19, 2006

• #2

87-90 non-ho
91+ HO
If you're unsure of the year it cam out of look at the intake.
Non-HO has three bolts holding the TB to the intake.
HO has four and the bolt pattern is square.

 

5-90

NAXJA Forum User

Location

Hammerspace

• Apr 19, 2006

• #3

1987-1990 - RENIX, pre-OBD, pre-HO. Very little performance aftermarket support that is CA legal.
1991-1995 - OBD-I, HO. More performance aftermarket support, easy to get diagnostic trouble codes
1996-2001 - OBD-II, HO. Similar to OBD-I, but more difficulty getting DTCs out of the system when needed.

5-90

 

ROBZ95Xj

NAXJA Forum User

Location

Keene NH

• Apr 19, 2006

• #4

didnt they make the heads more restrictive in 99?

 

5-90

NAXJA Forum User

Location

Hammerspace

• Apr 19, 2006

• #5

I think they reduced the exhaust ports slightly - but I haven't gotten an 0331 and 0630 casting to check... All I've got now is a 2585 (258) - I'm trying to collect the rest.

5-90

 

F

firstXJ

NAXJA Forum User

Location

michigan

• Apr 19, 2006

• #6

thanx all for the answers.

Paul