AT FAB XJ
NAXJA Forum User
- Location
- Frisco Texas
Hot Soak TSB Fix Results
There are quite a few old threads that explain and detail most of this problem including the full writeup on the TSB.
This thread will highlight most of the issues if you are not familiar http://www.naxja.org/forum/archive/index.php/t-979567.html
Unfortunately there are not many posts about the results of people's fixes for this so I though I would post up our findings.
This Jeep has not run "great" since I bought it with about 80k miles on it. Even though none of the 4.0I6s are exactly smooth at idle, this one was a little louder and rougher than normal. It has always accelerated and driven just fine, just not well at idle.
Basically after a little over a year I have had an occasional problem with my XJ missing a cylinder on startup after it has been run hot and sat for about 15-20 minutes. It seems like before 10 minutes and after 30 I do not have any problems with it. When it has this problem, I normally let it idle for a minute and then start driving slowly and it goes away. The other day it was so rough it finally threw a misfire code which made me start looking into the problem a little more.
On a side note, this is my 14th Jeep and 9th 4.0I6 in the past 15 years and my shop does approx. 80% of almost a million dollars worth of business a year on Jeeps. I am just saying that we are "familiar" with them before we get too far into "dumb arse" comments.....
Anyway, all 4.0l Jeeps are capable of having a vapor or heat locked injector similar to the problem described in this TSB. We still rarely see a problem with this even in Texas. This is the first Jeep I have ever had a problem with and we didn't go straight to the fixes in this TSB. We first went through plugs and a coil which did not fix it. After researching and checking the AllData TSBs and Recalls I read this TSB again and figured it may be worth a shot.
There seems to be 3 decent and reasonable approaches to fixing this problem.
1. Complete the insulation of the injectors using the information from the TSB.
2. Install a "turbo timer" on the electric fan.
3. Cut vents into the hood allowing the hot air to escape and the rain to enter.
I am personally not a big fan of the hood vents, just not my cup of tea.
I don't mind a turbo timer but I'm still concerned about heat staying under the hood with this fix.
We opted for option 1 with insulating the injectors.
Since I get shop pricing and great deals on parts I decided that with 100k miles on my current injectors I needed to replace all of them with new OEM Jeep injectors at my special pricing of $50 each. I also ordered the insulator sleeves with the part number in the TSB. For good measure I also ordered a roll of foil heat insulation wrap from Napa. Just to be safe since I was replacing all of the injectors I decided to insulate all of them instead of just the 2 middle ones. Each injector "sleeve" from the TSB will insulate 2 injectors so you only need to order 3 if you plan doing all 6 like I did. You do exactly what the TSB says and cut the "sleeve" down to fit around the injector and then I wrapped it with the sticky foil insulating tape wrap.
It is not necessary to replace the injectors but I have had a sneaking suspicion of an injector problem since I bought this Jeep. And just to clarify, we never like replacing just one of something so I replaced all 6.
After completing all of this I was immediately surprised when I started it up and my "rougher" idle had disappeared. I have also ran it hot a dozen times and restarted it in the "heat soak" window and it no longer misfires. It starts quickly and runs smooth every time. I am glad I went this route and want to report that this fix works great.
There are quite a few old threads that explain and detail most of this problem including the full writeup on the TSB.
This thread will highlight most of the issues if you are not familiar http://www.naxja.org/forum/archive/index.php/t-979567.html
Unfortunately there are not many posts about the results of people's fixes for this so I though I would post up our findings.
This Jeep has not run "great" since I bought it with about 80k miles on it. Even though none of the 4.0I6s are exactly smooth at idle, this one was a little louder and rougher than normal. It has always accelerated and driven just fine, just not well at idle.
Basically after a little over a year I have had an occasional problem with my XJ missing a cylinder on startup after it has been run hot and sat for about 15-20 minutes. It seems like before 10 minutes and after 30 I do not have any problems with it. When it has this problem, I normally let it idle for a minute and then start driving slowly and it goes away. The other day it was so rough it finally threw a misfire code which made me start looking into the problem a little more.
On a side note, this is my 14th Jeep and 9th 4.0I6 in the past 15 years and my shop does approx. 80% of almost a million dollars worth of business a year on Jeeps. I am just saying that we are "familiar" with them before we get too far into "dumb arse" comments.....
Anyway, all 4.0l Jeeps are capable of having a vapor or heat locked injector similar to the problem described in this TSB. We still rarely see a problem with this even in Texas. This is the first Jeep I have ever had a problem with and we didn't go straight to the fixes in this TSB. We first went through plugs and a coil which did not fix it. After researching and checking the AllData TSBs and Recalls I read this TSB again and figured it may be worth a shot.
There seems to be 3 decent and reasonable approaches to fixing this problem.
1. Complete the insulation of the injectors using the information from the TSB.
2. Install a "turbo timer" on the electric fan.
3. Cut vents into the hood allowing the hot air to escape and the rain to enter.
I am personally not a big fan of the hood vents, just not my cup of tea.
I don't mind a turbo timer but I'm still concerned about heat staying under the hood with this fix.
We opted for option 1 with insulating the injectors.
Since I get shop pricing and great deals on parts I decided that with 100k miles on my current injectors I needed to replace all of them with new OEM Jeep injectors at my special pricing of $50 each. I also ordered the insulator sleeves with the part number in the TSB. For good measure I also ordered a roll of foil heat insulation wrap from Napa. Just to be safe since I was replacing all of the injectors I decided to insulate all of them instead of just the 2 middle ones. Each injector "sleeve" from the TSB will insulate 2 injectors so you only need to order 3 if you plan doing all 6 like I did. You do exactly what the TSB says and cut the "sleeve" down to fit around the injector and then I wrapped it with the sticky foil insulating tape wrap.
It is not necessary to replace the injectors but I have had a sneaking suspicion of an injector problem since I bought this Jeep. And just to clarify, we never like replacing just one of something so I replaced all 6.
After completing all of this I was immediately surprised when I started it up and my "rougher" idle had disappeared. I have also ran it hot a dozen times and restarted it in the "heat soak" window and it no longer misfires. It starts quickly and runs smooth every time. I am glad I went this route and want to report that this fix works great.
