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Misfiring, where to buy injectors?

Then it seems like it's back to the heat soak issue. As suggested earlier, next time you shut it down after the hard use, open the hood. See if it helps. If it does, add the fan timer.
 
winterbeater said:
Then it seems like it's back to the heat soak issue. As suggested earlier, next time you shut it down after the hard use, open the hood. See if it helps. If it does, add the fan timer.
Click to expand...

This kinda sucks. I traded my 2.5L tj for this xj cuz i wanted the 4.0 and all i heard was the 4.0 is super reliable and i end up with a p.o.s motor that can't run right cuz of heat soak issues. I have to pop my hood just to make sure it runs right. That's a little 'tarded in my book cuz a vehicle should run without having to open the hood every time you stop or have to modify crap to make it run right. I put hood vents on this hoping that I wouldn't have to open my hood to cool it down but that didn't work. What a waste of time and money this junk is.

sorry for the rant...i'm just tired of this crappy 4.0.
 
Sounds like you got pretty unlucky, mine's been nothing but reliable even though I was running on ultra worn plugs/cap/rotor for a while. It idled really rough but *always* ran. The only time it has failed to start properly for me was in 20 degree weather after completely flattening my battery, with really dirty battery connections (now fixed) and the only set of jumper cables available turned out to be cheap chinese crap with 16ga wire inside extra heavy insulation made to look like the wire was thicker.

There's probably something really simple you can do to it to make it just as reliable as everyone else's, don't give up just yet...
 
kastein said:
Sounds like you got pretty unlucky, mine's been nothing but reliable even though I was running on ultra worn plugs/cap/rotor for a while. It idled really rough but *always* ran. The only time it has failed to start properly for me was in 20 degree weather after completely flattening my battery, with really dirty battery connections (now fixed) and the only set of jumper cables available turned out to be cheap chinese crap with 16ga wire inside extra heavy insulation made to look like the wire was thicker.

There's probably something really simple you can do to it to make it just as reliable as everyone else's, don't give up just yet...
Click to expand...

Well it is reliable. It never failed to start. It just misfires and bogs down when restarting it after drives. That drives me nuts and people/jeepers look at me like "wtf is wrong with your jeep?" and i have to wait a long time just to get it to go. I don't like to have fear when putting the key in the ignition. I just want it to start up normally like every other car on the road....
 
I believe there was a TSB for this - to install a heat shield and possibly also to recalibrate the computer.

some have wrapped their injectors with that heat-shield tape.....
 
JNickel101 said:
I believe there was a TSB for this - to install a heat shield and possibly also to recalibrate the computer.

some have wrapped their injectors with that heat-shield tape.....
Click to expand...

Mine has already been through the tsb. The heat shield is there but doing nothing obviously. I can't say if the computer has been recalibrated. How does the computer get screwed up enough to need recalibrated? How does that affect this misfire that only happens when i turn it off after a long drive? I don't understand that stuff too well....
 
JNickel101 said:
I believe there was a TSB for this - to install a heat shield and possibly also to recalibrate the computer.

some have wrapped their injectors with that heat-shield tape.....
Click to expand...

Problem is that most reports are that these fixes don't work. Just running the efan to cool it down after shut-off.

As far as the crappy 4.0 rant, I feel about the same with the 0331 head crack problem. Run forever, 300k miles, etc. etc. Yeah sure, just don't get a 2000, 2001. Whoops, too late. Maybe my next one.:flame:
 
winterbeater said:
Problem is that most reports are that these fixes don't work. Just running the efan to cool it down after shut-off.

As far as the crappy 4.0 rant, I feel about the same with the 0331 head crack problem. Run forever, 300k miles, etc. etc. Yeah sure, just don't get a 2000, 2001. Whoops, too late. Maybe my next one.:flame:
Click to expand...
:nono: Trust me, i'm never buyin an 00-01 xj again. I almost bought a 2.5L 5spd tj two weeks ago cuz i was fed up with this.

What drives me mad is that my gf's bro has an 01 xj 4.0 with twice the mileage as mine and his has zero misfire issues. He never replaced any ignition parts except plugs.
 
Just did some digging (I'm not too familiar with XJ fuel injection, figured it was about time) and from what I'm reading, the problem is that the fuel in the fuel rail boils and vapor blocks due to the heat from the minicats... and that the problem didn't exist on older generations because they had the fuel pressure regulator at the far end of the fuel rail, and a fuel return line. I guess this lets the pump break the vapor lock? Any reason a 2000-01 XJ couldn't be retrofitted to use this setup? I'm currently running a 97+ fuel tank and pump on my 96 with no issues, which is a little odd now that I think about it, because it means I have a pressure regulator built into the filter at the pump as well as one on my fuel rail.
 
kastein said:
Just did some digging (I'm not too familiar with XJ fuel injection, figured it was about time) and from what I'm reading, the problem is that the fuel in the fuel rail boils and vapor blocks due to the heat from the minicats... and that the problem didn't exist on older generations because they had the fuel pressure regulator at the far end of the fuel rail, and a fuel return line. I guess this lets the pump break the vapor lock? Any reason a 2000-01 XJ couldn't be retrofitted to use this setup? I'm currently running a 97+ fuel tank and pump on my 96 with no issues, which is a little odd now that I think about it, because it means I have a pressure regulator built into the filter at the pump as well as one on my fuel rail.
Click to expand...

Would wrapping the fuel rail in heat shield/exhaust wrap keep the gas cooler and avoid boiling?

So my rig has a fuel pressure regulator at the pump?
 
Any 97+ apparently has the regulator at the pump - in the best most awesome place possible, on top of the pump on the top of the tank. There is no fuel return line I guess.

the heat shield / exhaust wrap trick has been used successfully by some people, I expect it'd work better if you can make sure you get airflow through the inside of it.

EDIT: I'm betting the issue only really surfaces commonly when you have the 00-01/cali emissions package pre-cats, but again, on most of this I'm just blowing smoke out my arse, I haven't worked extensively on the fuel injection system.

EDIT2: for ER0/EP0 (gas) engines on 97+ it looks like I'm right, there is a vapor return line for the emissions control but no fuel return for a regulator. There is also no regulator listed in the diagram for the fuel injector rails.
 
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kastein said:
Any 97+ apparently has the regulator at the pump - in the best most awesome place possible, on top of the pump on the top of the tank. There is no fuel return line I guess.

the heat shield / exhaust wrap trick has been used successfully by some people, I expect it'd work better if you can make sure you get airflow through the inside of it.
Click to expand...

I have hood vents right above the injectors, probably doesn't help much for air flow but.....
 
3 things you need to do/check:
- NGK's are recommended for later model 4.0's...PN# ZFR5N.....they make a difference
- perform the injector sleeve TSB if you haven't already done so
- try cleaning your cooling system, if crud gets lodged in the jackets of the head then the whole top half of your block will be more prone to heat buildup
 
Fred85 said:
3 things you need to do/check:
- NGK's are recommended for later model 4.0's...PN# ZFR5N.....they make a difference
- perform the injector sleeve TSB if you haven't already done so
- try cleaning your cooling system, if crud gets lodged in the jackets of the head then the whole top half of your block will be more prone to heat buildup
Click to expand...

I just replaced my 3 month old champion plugs with another set of champion plugs with no change. I'm doubting the plugs are what's causing it so i'll leave that for last. I hate to keep replacing plugs.

can I use exhaust wrap and just wrap all the injectors and fuel rail? Will it work the same as the injector sleeve material? What kind of material is the injector sleeve stuff?

My cooling system is clean. The jeep was in a front end accident and the radiator was replaced right before i bought it and they flushed the system. It's as clean as new.
 
Fred85 said:
^you're missing my point about the plugs, Jeep actually switched their recommended plug once this misfiring issue came about with later model 4.0's....the NGK's were part of the solution to the problem

the injector sleeves are a fiber material
here is the TSB: http://www.wjjeeps.com/tsb/tsb_wj_1803103.pdf
Click to expand...

And where do I get this injector sleeve? Dealer? How much is it?

I don't like buying stuff from the dealer cuz it's always overpriced. Would cool-tape over some exhaust wrap work?

http://www.summitracing.com/parts/DEI-010408/

I got a load of exhaust wrap laying around and i figured wrapping it with that and then cool-tape it up would do the same...?

Any chance you can explain what the difference is between the champion plugs and ngk's and how the ngk's help this issue?
 
I did some testing today. It was misfiring nearly everyday this week so I decided to try the open hood test. I drove it on the highway to the mall, where it always misfires. I popped the hood open and waited 30 minutes. It started up PERFECTLY. Usually it stumbles and misses a little or misfires badly but nothing this time. I drove it another hour and half stopping, waiting, and leaving the hood open and no misfire at all.

This is telling me it's heat soak related...gotta be.

http://www.summitracing.com/parts/THE-14002/

I got some of that coming tmw and I'm gonna wrap everything up real good and see what that does.
 
Keep us posted how that works for you. I'm interested in this as I have a 2000 - albeit, with no problems like you're having - but I'm waiting for the day to come.

I replaced my exhaust when I first got the XJ - including the pre-cats. I wonder if old pre-cats create more heat and magnify this problem.
 
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