Sep 21, 2015, 03:49 PM
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XJ Ask the Question Thread
No, I don't lick fish.
Joined: Mar 2011
Posts: 11,169
Likes: 26
From: Northern Kentucky
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0
I posted a few weeks back about having cold start issues. Jeep would stumble and sputter up to a start instead of just starting but, ran and drove fine after that. Long story short, I tracked it down to me running a different fuel. I thought I'd try 91 octane (because it didn't have any ethanol in it) and well after using up all that 91 I filled the Jeep back up with 87 (10% ethanol) and what do you know, back to normal and all is good.
Just thought I'd share that because I had a hard time believing that just a few more octane would do that. I think it maybe has something to do with the 4.0L's relatively low compression ratio and maybe spark plug gap? Any other ideas?
Just thought I'd share that because I had a hard time believing that just a few more octane would do that. I think it maybe has something to do with the 4.0L's relatively low compression ratio and maybe spark plug gap? Any other ideas?
WHOA!!...If changing to Octane(new tank of gas) solved this problem... then you need to take a copy of these posts and your reciept to the Vendor who sold it to you and.get your money back!!! ...You've got bad gas!!! ...2 kinds, had water inside it (a trick the Mtn. Vendors use to make more money... about 500 gallons watering to 20,000 gallons fuel) or "trash" in the fuel (from sucking off the bottom of the Vendor tank... which means you need to check your fuel filter imediatley .... even if its brand new.... and don't forget to tap it sharply on the outlet side to disslodge any trash during "blow through test"..) the, ethanol will absorb water out of the air" quicker so unless that 91 octane has been sitting for over 6 months it has trash... (91 octane didn't have Ethenol??) In that case they owe you for fuel filter, injector clean, and possibly a new set of injectors (if they don't clean up)
EITHER WAY - that is why your motor was having a hard time compressing the gasoline.... not because of the octane.
Member
Joined: Jan 2011
Posts: 144
Likes: 0
From: Arizona
Year: 1999
Model: Cherokee
Engine: 4.0L
Member
Joined: Dec 2012
Posts: 104
Likes: 0
From: North Ga.
Year: 1994
Model: Cherokee
Engine: 4.0
You beat me to it. UPPING the octane shouldn't cause a no-start condition, but bad gas most certainly will. Either what DucMan suggested is true, OR to consider an alternate scenario, the ethanol-free 91 octane is sold at a higher price per gallon (I'm assuming) so most people - not knowing or caring about the difference - go for the 10% ethanol variety. This means that the ethanol-free supply sits there for quite a bit longer and begins to varnish. It's also possible that there is a leak in the tank somewhere that is letting water into the tank... either at the cap -or- underground.
EITHER WAY - that is why your motor was having a hard time compressing the gasoline.... not because of the octane.
EITHER WAY - that is why your motor was having a hard time compressing the gasoline.... not because of the octane.
Between the "roundy round" boys and the "boat folk" there is a line for the " non-ethanol" pump at every station around here every Friday night..LOL...I worked a race shop in SC. for a while and we pumped "Cam 2" and filled "Nitrous" bottles..the line blocked the road from 3:00-6:00 every Fri....Here in the Mtn's...the "Big Name Brands" are carrying 91 "E-Free" at the island pumps it's so popular..."Quick thought"..the "No-Lead" fuels don't protect (cushion) the exhaust valve seats like leaded fuels..this is why in HP engines you change out the exhaust valve seats with stainless steel ones..the old Ford motors are a good deal...Ford didn't use "ValveSeats" and usually all that's wrong with them is where the exhaust valve's have sunk into the head..fresh valve job=good motor..
Herp Derp Jerp
Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
Tetra-ethyl lead was added as a cheap hack to get around poor fuel quality and part quality in early gasoline. TEL formed deposits on valves and seats that prevented little micro-welds from forming. These little welds ripping apart was the cause of premature valve seat wear... not pressure from slamming shut.
Moderator of Jeeps
Joined: Jul 2011
Posts: 21,029
Likes: 3
From: Frederick, MD from Cleveland, OH
Year: 1993 YJ Wrangler
Engine: 4.0 I6
Ask the Question Thread
Also, TEL in the atmosphere causes brain development problems in children. Seriously, look into the correlation of crime stats and TEL use in fuel in the US or any other country.
CF Veteran
Joined: Jul 2010
Posts: 4,930
Likes: 3
From: 802
Year: 99
Model: Cherokee
Engine: 4.0
[I]Not literally in the sense I want to actually start that discussion here/now..[I]
Newbie
Joined: Apr 2015
Posts: 14
Likes: 0
From: new york
Year: 2000
Model: Cherokee
Ok so that knocking noise seems to be gone but yesterday I drove on the beach and was in four wheel and all of a sudden this loud knocking noise started up. Doesn't happen in 2wheel. Not sure what's going on. I have a six hour road trip next weekend. Do you think I can make it? What should I do. Thanks
Newbie
Joined: Aug 2015
Posts: 1
Likes: 0
Model: Cherokee
On a road trip ..
Me and my wife are traveling around the country! We are having a few issues with are 1998 jeep cherokee classic first we started over heating so I changed the thermostat and replaced all the coolent, it continues to over heat. It doesn't appear to be leaking. The cat is bad and we need to fix it but are short on cash. I do all my own repairs i just need advice, I bought a new water pump but have not put it in. Im not 100%sure how to or if the water pump needs to be replaced. It started losing power today and feels like it's dragging. What should I attempt to fix first?
Moderator of Jeeps
Joined: Jul 2011
Posts: 21,029
Likes: 3
From: Frederick, MD from Cleveland, OH
Year: 1993 YJ Wrangler
Engine: 4.0 I6
CF Veteran
Joined: Jul 2010
Posts: 4,930
Likes: 3
From: 802
Year: 99
Model: Cherokee
Engine: 4.0
Me and my wife are traveling around the country! We are having a few issues with are 1998 jeep cherokee classic first we started over heating so I changed the thermostat and replaced all the coolent, it continues to over heat. It doesn't appear to be leaking. The cat is bad and we need to fix it but are short on cash. I do all my own repairs i just need advice, I bought a new water pump but have not put it in. Im not 100%sure how to or if the water pump needs to be replaced. It started losing power today and feels like it's dragging. What should I attempt to fix first?
The last part of OP where you state it's starting to loose power- as long as it hasn't over heated, I know you said it starts to, then it's more likely than not a partially/plugged cat. If the power loss and over Heat are correlated then I'd look to the coolant system for sure. Still, change that cat!
Moderator of Jeeps
Joined: Jul 2011
Posts: 21,029
Likes: 3
From: Frederick, MD from Cleveland, OH
Year: 1993 YJ Wrangler
Engine: 4.0 I6
Ask the Question Thread
Me and my wife are traveling around the country! We are having a few issues with are 1998 jeep cherokee classic first we started over heating so I changed the thermostat and replaced all the coolent, it continues to over heat. It doesn't appear to be leaking. The cat is bad and we need to fix it but are short on cash. I do all my own repairs i just need advice, I bought a new water pump but have not put it in. Im not 100%sure how to or if the water pump needs to be replaced. It started losing power today and feels like it's dragging. What should I attempt to fix first?
Also, does your fan have a shroud around it?
CF Veteran
Joined: Jul 2010
Posts: 4,930
Likes: 3
From: 802
Year: 99
Model: Cherokee
Engine: 4.0
I try hard not to be. Causation/correlation doesn't always add up and I'm learning you can find a connection if you want to.. Finding a legitimate source with good citation is hard to come by an there's so much misinformation in the media it's absurd... I digress, but I'm with ya.