Fuel Injectors question - JeepForum.com
 
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post #1 of 8 Old 05-15-2021, 05:04 PM Thread Starter
blueribb
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1998 ZJ 
 
Join Date: May 2008
Location: Pennsylvania
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Fuel Injectors question

1998 Jeep Grand Cherokee Laredo 4.0L
148,000 miles
Mint Condition

For the last few years the idle has been less and less smooth. The dash buzzes and the tach sometimes fluctuates between 400 and 750 RPM. It never stalls but sometimes it feels like it's going to.

I am not a mechanic and rely on a local service station to keep my Jeep in order. They have cleaned various parts to help solve this issue but nothing has helped. I had the plugs, wires, distributor cap and rotor replaced with new OEM parts. It runs a little better but still shakes a little during idle.

I am having the Idle Air Speed Motor replaced next week with an original Chrysler part ($100 from Amazon). If that doesn't work, I may want to change the fuel injectors. They have never been replaced. After searching for the original OEM Injectors, I found they are super expensive (around $100 each) and somewhat hard to find). I then found out that the original Siemens brand injectors are known for leaks and a lot of people are recommending using remanufactured Bosch Injectors (4 spray holes) as an upgrade. There's a company called CS Performance that sells a set of 6 OEM Bosch III for $127 on Ebay that will fit my Jeep.

I want to find out what you guys think about replacing the fuel injectors.

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Last edited by blueribb; 05-15-2021 at 05:13 PM. Reason: add photo
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post #2 of 8 Old 05-15-2021, 05:52 PM
yjsaabman
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1930 CJ2 
 
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Location: Elizabethtown
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I don't have any input on this topic, but I am definitely interested in the topic. Do you have a link to those injectors? I will be reading up on this.

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post #3 of 8 Old 05-15-2021, 06:48 PM Thread Starter
blueribb
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1998 ZJ 
 
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Location: Pennsylvania
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Quote:
Originally Posted by yjsaabman View Post
I don't have any input on this topic, but I am definitely interested in the topic. Do you have a link to those injectors? I will be reading up on this.

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https://www.ebay.com/itm/190827041197
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post #4 of 8 Old 05-15-2021, 07:32 PM
riiz
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1996 ZJ 
 
Join Date: Jun 2019
Location: Redlands
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Have them rebuilt. $50 for 6 injectors. I personally dont think the 4-hole injectors improve anything. They are a cheap alternative, if you have to replace injectors.
https://www.ksuspensionfab.com/store...Service.html#/
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post #5 of 8 Old 05-16-2021, 01:44 PM
mikem350
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1994 ZJ 
 
Join Date: Sep 2014
Location: Sunrise
Posts: 273
My '94 has same rough idle problems time to time. Whats works for me is to use Seafoam Motor treatment (add to gas) every couple fill ups.
My experience, it does work, but takes time. Root cause is clogged injectors.

Proud owner of two DD 4.0 ZJs
Flame Red 94 mint!
Silver 98 just hit 360k miles....runs great!
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post #6 of 8 Old 05-16-2021, 02:40 PM Thread Starter
blueribb
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1998 ZJ 
 
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Location: Pennsylvania
Posts: 56
Quote:
Originally Posted by mikem350 View Post
My '94 has same rough idle problems time to time. Whats works for me is to use Seafoam Motor treatment (add to gas) every couple fill ups.
My experience, it does work, but takes time. Root cause is clogged injectors.
I'm not much for additives but I'll give this a try.

Thanks
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post #7 of 8 Old 05-16-2021, 08:29 PM
PolkaPower
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Location: The Abyss
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It'll idle and accelerate smoother with new injectors but nothing else.


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post #8 of 8 Old 05-18-2021, 09:26 AM
Black93ZJ
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1993 ZJ 
 
Join Date: Apr 2018
Posts: 97
Garage
My 93 has the original Siemens injectors, but I have an injector pulser and scan tool that does actuations to aid in cleaning. I use to pull mine once a year, back flush the injectors, and then squirt brake clean while pulsing them to clean out any gunk left. Mine would stumble from time to time at idle, but my coil was going bad and once replaced it quit doing that. Also run Shell gas through it for a few tanks as they are suppose to be top tier gas, and run at least one to two tanks of the 93 with V power to see if it clears up before buying parts you may not need. I soley run 92 to 93 octane in mine and very rarely had any engine gunk problems.
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