4 hole injectors and plug gap ? - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > General Technical Discussions > Engines & Drivetrain > 4 hole injectors and plug gap ?

Flowmaster's Force II Axle-back exhaust system for the 201FS: Wranger BRIGHT License Plate LED! Just $3! Great valueRough Country small builder parts in stock!! Awesome price

Reply
Unread 09-03-2013, 10:10 AM   #1
Terry777
Registered User
1997 XJ Cherokee 
 
Join Date: Oct 2010
Location: Coquitlam, British Columbia
Posts: 112
4 hole injectors and plug gap ?

Hi all, I decided to go for the crazy cheap upgrade of refurbished 4 hole injectors to improve my mpg.
My question is does this now change the spark plug gap , or to be more specific will I get a cleaner burn with a spark plug gap other than the one specified in the Haynes manual as the 4 hole will now be misting the gas and not just dumping it.

Haynes states 0.035 SAE or 0.89 MM


Looking for detailed technical answers, Thanks for your time


Last edited by Terry777; 09-03-2013 at 10:24 AM..
Terry777 is offline   Reply With Quote
Unread 09-03-2013, 01:50 PM   #2
Newtons3
Registered User
2006 TJ Wrangler 
 
Join Date: Feb 2013
Location: Baton Rouge, Louisiana
Posts: 722
With no other information than what you have posted, I dont believe you have any reason to increase plug gap. You may get away with 0.040-0.045 for a while, but you will greatly be increasing your chances of a missfire. Iridium plugs or good double platinums reduce the erosion rate of the electrodes and minimize this. Good grounds, brass contact cap and rotor, and low impedence suppression wires all increase the reliability of the spark at increased gaps. Also.the addition of a coil and/or ignition with more power (not just voltage, but current too), will help when jumping that gap and maybe allow you to jump an even wider one. In short- fuel type, plugs, available electrical power, spark plug type and duty cycle, compression ratio, and rpm all are big factors in plug gap choice. the ssay pattern of the injectors, within limits, has little effect on this.
Newtons3 is offline   Reply With Quote
Unread 09-03-2013, 08:26 PM   #3
Terry777
Registered User
1997 XJ Cherokee 
 
Join Date: Oct 2010
Location: Coquitlam, British Columbia
Posts: 112
Thanks for the detailed reply, I`m keeping my 97 XJ engine as stock as possible other than my air intake box hack...
With that said just going with NGK or Champ plugs the copper ones to rule out any other possibilities as I want to know exactly what is what if anything starts acting up. I`m in a condo so no street or garage to play in.

I`ll check and clean the cap and make sure it`s copper thanks for the heads up another cheap fix no doubt...

I took out my manifold air sensor and cleaned it along with the throttle body and the piston looking idle control valve, didn't have any affect that I could tell. Yep reset computer... Took out both O2 sensors last nigh cleaned them good with throttle body spray and my engine is idling smoother when stopped in traffic, I thought it stalled on a couple times not used to that :]

Still a little choppy at times so hoping the new plugs and injectors when they arrive take that away. If not maybe it`s time to swap out the fuel filter in the tank.

Thanks again, I`ll read over your advice a few times and go over the mentioned areas.
Terry777 is offline   Reply With Quote
Unread 09-03-2013, 08:31 PM   #4
Terry777
Registered User
1997 XJ Cherokee 
 
Join Date: Oct 2010
Location: Coquitlam, British Columbia
Posts: 112
Forgot to mention I always use Chevron and the grade just above the cheapest seems to be the best deal, I`ve clocked many miles using other grades and non can compare for stop & go with a mix of Hwy.
Terry777 is offline   Reply With Quote
Unread 09-03-2013, 09:14 PM   #5
Newtons3
Registered User
2006 TJ Wrangler 
 
Join Date: Feb 2013
Location: Baton Rouge, Louisiana
Posts: 722
Cool. Good Luck.
Newtons3 is offline   Reply With Quote
Unread 09-04-2013, 01:03 PM   #6
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,773
Stock gap on NGKs. Don't look back.
__________________
Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote
Unread 09-04-2013, 07:28 PM   #7
uberxj92
Registered User
1992 XJ Cherokee 
 
Join Date: Oct 2012
Location: umatilla, florida
Posts: 1,898
I run the 4 holes in my 92 xj with 4.7 stroker. Stock plug gaps. Just fine
__________________
http://www.jeepforum.com/forum/f177/92-xj-sadness-2075657/index2.html
uberxj92 is offline   Reply With Quote
Unread 09-04-2013, 07:32 PM   #8
Terry777
Registered User
1997 XJ Cherokee 
 
Join Date: Oct 2010
Location: Coquitlam, British Columbia
Posts: 112
Quote:
Originally Posted by cruiser54 View Post
Stock gap on NGKs. Don't look back.
Seems like Champion, NGK and Autolite are the most praised on here. Mostly the Autolite from what I got and they were the cheapest at Lordco so those the ones I picked, The copper ones...

The autolite were also the only ones gaped at .035 the others were .036 and I think .034 so not like it would really matter anyway
Terry777 is offline   Reply With Quote
Unread 09-04-2013, 07:32 PM   #9
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,773
Yeah. Here's a thought and I know it's out there, but Jeep ran 4 hole injectors with a .035" gap.........
__________________
Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote
Unread 09-05-2013, 06:43 AM   #10
vadslram
Registered User
1990 YJ Wrangler 
 
Join Date: Jan 2006
Location: VA Beach
Posts: 4,632
even keeping it stock if you are running the original coil you are cheating yourself. Over time they lose the ability to supply a hot spark.
Wires should be replaced every two years at the minnimum and the coil every 5.
You can get an aftermarket coils that directly replace the stock one but still supplies a hotter more dependable spark.
vadslram is offline   Reply With Quote
Unread 09-05-2013, 04:00 PM   #11
Terry777
Registered User
1997 XJ Cherokee 
 
Join Date: Oct 2010
Location: Coquitlam, British Columbia
Posts: 112
This is defiantly not my area of expertise, so with that said here comes a dumb question.
My 97 XJ does not have a coil I think they were added in 99 or 2000, can I just stick one in or is it more complicated than the Lego Jeep stuff ?
Terry777 is offline   Reply With Quote
Unread 09-05-2013, 04:38 PM   #12
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,773
DEFINITELY. Your Jeep has a coil.

Do the tune-up stuff before getting off on this coil rabbit trail.
__________________
Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote
Unread 09-05-2013, 05:07 PM   #13
Newtons3
Registered User
2006 TJ Wrangler 
 
Join Date: Feb 2013
Location: Baton Rouge, Louisiana
Posts: 722
Quote:
Originally Posted by Terry777 View Post
This is defiantly not my area of expertise, so with that said here comes a dumb question.
My 97 XJ does not have a coil I think they were added in 99 or 2000, can I just stick one in or is it more complicated than the Lego Jeep stuff ?
Um.... you do have a coil. Look forward of the distributor, by the motor mount. Follow the coil wire from the distributor cap.
Newtons3 is offline   Reply With Quote
Unread 09-05-2013, 06:56 PM   #14
vadslram
Registered User
1990 YJ Wrangler 
 
Join Date: Jan 2006
Location: VA Beach
Posts: 4,632
All spark fired engines have a coil. It takes the 12v and makes ~20000 out of it to create a spark. Some have it mounted inside the distributor cap others have an external. Yours is probably external. On the distributor cap there will be a center wire and it goes to a roughly soda can sized and shaped thing...your coil. But if you are unsure of the coil then you almost definitely need at least a good tune up and new wires. Then if you don't get no satisfaction replace the coil. they aren't expensive stock and only slightly more for direct replacement upgrade.
vadslram is offline   Reply With Quote
Unread 09-06-2013, 10:51 AM   #15
Terry777
Registered User
1997 XJ Cherokee 
 
Join Date: Oct 2010
Location: Coquitlam, British Columbia
Posts: 112
At least I warned it was a stupid question

Sure I`ve looked at it before wtf, not sure why that never registered. I got lost somewhere reading up about coil upgrades and the knot stuck...

Changed my plugs last night found the distributer cap and rotor covered in soot and worn beyond sand paper repair so off to Lordco for the brass...

I did the usual stupid move, got frustrated with one of the wires in a cramped area 3rd from the rear and yanked from the wire and boot together, the wired slipped right out with the end still on the plug. I had a large angled needle nose right beside me to...

Easy enough fix clamped the wire back into place but now the silicone seal is turfed, sounds fine can`t hear it missing...
Should I bother upgrading wires there NGK, look & feel new but are probably the stock cheap replacements.

Cheers
Terry777 is offline   Reply With Quote




Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.