Buckey Posted February 15, 2007 Share Posted February 15, 2007 What is the differance between a 4.0 L and 4.0 L HO motor???Or is there any differance??? Link to comment Share on other sites More sharing options...
offroader461 Posted February 15, 2007 Share Posted February 15, 2007 there is a bunch of differences and to my recollection is all in the fuel injection system.....completley different cylinder head, intake, injectors and throttle body not to mention the wiring harness...hope that helps` Link to comment Share on other sites More sharing options...
GirsMJ86 Posted February 15, 2007 Share Posted February 15, 2007 there is a bunch of differences and to my recollection is all in the fuel injection system.....completley different cylinder head, intake, injectors and throttle body not to mention the wiring harness...hope that helps` and you can easily turn a 4.0 into an HO buy rounding all the parts up. but my 91 seems to love going through regular gas more then my 88 did with just the normal 4.0L. so i run premium in my 91 and get about 425 miles per tank, on a short bed with the tiny tank IIRC. Alex Link to comment Share on other sites More sharing options...
Buckey Posted February 15, 2007 Author Share Posted February 15, 2007 I was just wondering cause I have a 89 comanche and the engine is runnin a little rough,and I have a 91 cherokee with 4.0 HO and I am gonna swap the engines just wanted to know what was compatible for the swap. Thanks Buckey Link to comment Share on other sites More sharing options...
GirsMJ86 Posted February 15, 2007 Share Posted February 15, 2007 unless the engine in your 89 is really high in mileage (over 300k) it still should be good unless it was abused. what is it doing exactly? might just need a few new sensors or something. Alex Link to comment Share on other sites More sharing options...
Pete M Posted February 15, 2007 Share Posted February 15, 2007 the engine is runnin a little rough Could you expand on that? You're contemplating a huuuuuge investment in time and money when it could be as simple as replacing the TPS or cat. Link to comment Share on other sites More sharing options...
Buckey Posted February 15, 2007 Author Share Posted February 15, 2007 It only idles,nothing else.Won't rev up,won't move other then idle.I have a 91 cherokee that I am just gonna change the engine.I keep thinking maybe a fuel pump or line but not too sure.The only reason I think this is cause it idles,now when my buddy pinches off the one line the pressure gains in the line and it idles a little bit higher but like I said not too sure. Buckey Link to comment Share on other sites More sharing options...
GirsMJ86 Posted February 15, 2007 Share Posted February 15, 2007 It only idles,nothing else.Won't rev up,won't move other then idle.I have a 91 cherokee that I am just gonna change the engine.I keep thinking maybe a fuel pump or line but not too sure.The only reason I think this is cause it idles,now when my buddy pinches off the one line the pressure gains in the line and it idles a little bit higher but like I said not too sure. Buckey sounds like you need to test the pressure the fuel pump is putting out. i am sure there are some other things you can do to fix it but the engine does not sound ruined or needing to be replaced. i would not be sure of the other things you can do since i have not had problems. i am sure other will chime in. Alex Link to comment Share on other sites More sharing options...
BIGMASS Posted February 16, 2007 Share Posted February 16, 2007 That is egzacaree what my 89 was doing. Would idle like a champ, but wouldn't take any revs. I'd deffinately check yer fuel pressure. I don't think the cherokee sending unit will fit in yer tank anyhow, so you might do the swap and have the same prob. From 88 XJ FSM 4.0L MPFI1) Remove cap from pressure test port in fuel rail. Connect Fuel Pressure Gauge (J-37730-1) to pressure fitting. Start vehicle. Pressure should be approximately 31 psi (2.7 kg/cm) with vacuum hose connected to pressure regulator. 2) Pressure should be 39 psi (2.74 kg/cm) with vacuum hose removed from regulator. If fuel pressure is not to specifications, check for kinks or restricting bends in fuel supply and return lines. Check fuel pump flow rate. Pump should deliver minimum of 1.06 quarts (one liter) of fuel per minute with fuel return line pinched off. 3) If flow is inadequate, check system for plugged fuel filter or filter sock. Fuel pump flow rate can be checked by connecting a hose to fuel test port on fuel rail and inserting other end in clean container. 4) To operate fuel pump, install a jumper wire into diagnostic connector terminals D1-5 and D1-6. Pinch off fuel return line to ensure that no fuel returns to fuel tank. If fuel pressure is still not to specifications and fuel flow is normal, replace regulator. Link to comment Share on other sites More sharing options...
carnuck Posted February 23, 2007 Share Posted February 23, 2007 Check the fuel filter first. Then check the TPS and Map sensors. After that, spray ALL the underhood connectors with electronic cleaner. Oh, one last thing: You cat's guts may be corking the muffler. (mine did that while cruising at 70. Couldn't go over 15 mph after that and I was on a 70 mph highway with no exits for 5 miles! I had to take a hammer and pound my muffler to pieces then it went like a rocket!) Link to comment Share on other sites More sharing options...
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