Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here XJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.

Upgraded injector swap problem. Need help

Thread Tools
 
Search this Thread
 
Old 03-05-2015, 12:33 AM
  #1  
Newbie
Thread Starter
 
abens8's Avatar
 
Join Date: May 2012
Posts: 7
Likes: 0
Received 0 Likes on 0 Posts
Year: 01
Model: Cherokee
Engine: 4.0
Default Upgraded injector swap problem. Need help

I swapped to the 784 injectors in my jeep. Bought them off a guy on eBay. Supposed to be refurbished and tested. Before I did the swap my jeep would start up right away now it takes a couple seconds to fire up. Could it be a leaking injector that's flooding my motor and if so how do I figure out which one it is. Didn't happen until I did the injector swap. If you have any ideas let me know.
Old 03-05-2015, 06:03 AM
  #2  
::CF Moderator::
 
cruiser54's Avatar
 
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,874
Received 1,526 Likes on 1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Default

Maybe. How many starts have you done with the "new" injectors?
Old 03-05-2015, 08:18 AM
  #3  
Newbie
Thread Starter
 
abens8's Avatar
 
Join Date: May 2012
Posts: 7
Likes: 0
Received 0 Likes on 0 Posts
Year: 01
Model: Cherokee
Engine: 4.0
Default

Originally Posted by cruiser54
Maybe. How many starts have you done with the "new" injectors?
Probably around 20 times. I just put them in last Thursday. It also starts right up when it's warm. Only does this after it's been sitting even if it's only been an hour.
Old 03-05-2015, 09:27 AM
  #4  
CF Veteran
 
Fred/N0AZZ's Avatar
 
Join Date: Jul 2013
Location: Monett, MO.
Posts: 7,554
Likes: 0
Received 14 Likes on 14 Posts
Year: 1999
Model: Cherokee
Engine: 4.0
Default

Did they look like new when you received them, and have all new O-rings?


Are you sure that you didn't accidently tear any of the O-rings when installing? If you don't mind me asking how much were they, cheaper than the seller here on the forum?
Old 03-05-2015, 09:55 AM
  #5  
Newbie
Thread Starter
 
abens8's Avatar
 
Join Date: May 2012
Posts: 7
Likes: 0
Received 0 Likes on 0 Posts
Year: 01
Model: Cherokee
Engine: 4.0
Default

Originally Posted by Fred/N0AZZ
Did they look like new when you received them, and have all new O-rings?


Are you sure that you didn't accidently tear any of the O-rings when installing? If you don't mind me asking how much were they, cheaper than the seller here on the forum?
They were like $70 with new O-rings. And they looked new. And I don't think I did I'll probably pull it off and look tonight and just check them.
Old 03-05-2015, 10:40 AM
  #6  
CF Veteran
 
Fred/N0AZZ's Avatar
 
Join Date: Jul 2013
Location: Monett, MO.
Posts: 7,554
Likes: 0
Received 14 Likes on 14 Posts
Year: 1999
Model: Cherokee
Engine: 4.0
Default

Reason I asked was when my son installed his and was having a problem, I kept asking him the same question and he said no.......After 2 weeks he did pull and check them and by now you guessed it.
Old 03-05-2015, 10:52 AM
  #7  
Newbie
Thread Starter
 
abens8's Avatar
 
Join Date: May 2012
Posts: 7
Likes: 0
Received 0 Likes on 0 Posts
Year: 01
Model: Cherokee
Engine: 4.0
Default

Originally Posted by Fred/N0AZZ
Reason I asked was when my son installed his and was having a problem, I kept asking him the same question and he said no.......After 2 weeks he did pull and check them and by now you guessed it.
What was wrong with his?
Old 03-05-2015, 11:07 AM
  #8  
CF Veteran
 
Fred/N0AZZ's Avatar
 
Join Date: Jul 2013
Location: Monett, MO.
Posts: 7,554
Likes: 0
Received 14 Likes on 14 Posts
Year: 1999
Model: Cherokee
Engine: 4.0
Default

Torn o-ring.
Old 03-05-2015, 11:15 AM
  #9  
Seasoned Member
 
kcdt58's Avatar
 
Join Date: Jun 2013
Location: Hickory, NC
Posts: 417
Likes: 0
Received 1 Like on 1 Post
Year: 2000
Model: Cherokee(XJ)
Engine: 4.0 L
Default

That's good info. I'll definitely be mindful of this when i install my 784s.
Old 03-05-2015, 12:13 PM
  #10  
Senior Member
 
docmedpros's Avatar
 
Join Date: Oct 2012
Location: Gainesville,FL
Posts: 989
Likes: 0
Received 2 Likes on 2 Posts
Year: 1996
Model: Cherokee
Engine: 4.0
Default

X2 on the O-rings. Those little buggers if defective will cause you a ton of problems.
Old 03-05-2015, 01:20 PM
  #11  
Senior Member
 
cbs_24's Avatar
 
Join Date: Jun 2014
Location: Eagle River, Alaska
Posts: 925
Likes: 0
Received 6 Likes on 6 Posts
Year: 1999
Model: Cherokee (XJ)
Default

Did you reset the ecm after the install? That could cause some problems when installing new stuff on an engine that is used to different parts.
Old 03-05-2015, 01:31 PM
  #12  
Senior Member
 
docmedpros's Avatar
 
Join Date: Oct 2012
Location: Gainesville,FL
Posts: 989
Likes: 0
Received 2 Likes on 2 Posts
Year: 1996
Model: Cherokee
Engine: 4.0
Default

Originally Posted by cbs_24
Did you reset the ecm after the install? That could cause some problems when installing new stuff on an engine that is used to different parts.
Not required for injectors, the fuel pressure at the rail is consistent, just has better atomization due to better spray.
Old 03-05-2015, 04:32 PM
  #13  
Senior Member
 
cbs_24's Avatar
 
Join Date: Jun 2014
Location: Eagle River, Alaska
Posts: 925
Likes: 0
Received 6 Likes on 6 Posts
Year: 1999
Model: Cherokee (XJ)
Default

Originally Posted by docmedpros
Not required for injectors, the fuel pressure at the rail is consistent, just has better atomization due to better spray.
I've seen a few people on here say their fuel mileage and other minor things suffered after the install until they reset. I installed mine with a 62mm TB, header and intake at the same time, so I definitely reset mine afterwards. If I was experiencing problems after the install and all the o rings are good and everything else is connecting properly, I would probably give it a shot.
Old 03-05-2015, 04:40 PM
  #14  
Senior Member
 
docmedpros's Avatar
 
Join Date: Oct 2012
Location: Gainesville,FL
Posts: 989
Likes: 0
Received 2 Likes on 2 Posts
Year: 1996
Model: Cherokee
Engine: 4.0
Default

Originally Posted by cbs_24
I've seen a few people on here say their fuel mileage and other minor things suffered after the install until they reset. I installed mine with a 62mm TB, header and intake at the same time, so I definitely reset mine afterwards. If I was experiencing problems after the install and all the o rings are good and everything else is connecting properly, I would probably give it a shot.


Yeah if he installed other critical parts id completely agree. At the same time when working on anything fuel /electrical related you should discharge static and remove the battery terminals which should reset the PCM and allow it to learn the new injectors.
Old 03-16-2015, 11:39 AM
  #15  
Newbie
Thread Starter
 
abens8's Avatar
 
Join Date: May 2012
Posts: 7
Likes: 0
Received 0 Likes on 0 Posts
Year: 01
Model: Cherokee
Engine: 4.0
Default

So I found out I had two torn o rings. Replaced them and I'm still having the same problem. Any suggestions?


Quick Reply: Upgraded injector swap problem. Need help



All times are GMT -5. The time now is 10:01 AM.