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Unread 05-31-2011, 12:13 AM   #1
ColoradoCole
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Fuel Injector Problems

Jeep has 187000 miles, same injectors since it was brand new.

Today i was driving and the check engine light came on and i came up with a P0206 code.

The symptoms for this code will likely be a misfire and a rough running engine. Poor acceleration. The MIL will also be illuminated.

Causes

The causes of a P0206 engine light code could be any of the following:

Bad injector. This is usually the cause of this code but doesn't rule out the possibility of one of the other causes
Open in the wiring to the injector
Short in the wiring to the injector
Bad PCM
Possible Solutions

First, using a DVOM check the resistance of the injector. If it isn't within specs, then replace the injector.
Check for voltage at the fuel injector connector. It should have 10 volts or more.
Visually check the connector for damage or broken wires.
Visually check the injector for damage.
If you have access to an injector tester, activate the injector and see if it operates. If the injector operates, then you likely have either an open in the wiring, or a blocked injector. If you do not have access to a tester, swap the injector with another one and see if the code changes. If the code changes, then change the injector.
At the PCM, remove the driver wire from the PCM connector and Ground the wire. (Make sure you have the correct wire. If you're not sure, do not attempt) The injector should activate
Replace the injector

Im sure i need to replace the injectors but has anyone else had this problem, and what were your solutions.

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Unread 06-01-2011, 03:38 PM   #2
RedMountainRob
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Had problem w/starting second time after running a few minutes and stopping for anywhere from a few minutes to a couple of hours. Never noticed a loss of power after engine light came on, didn't really make a lot sense to me. Intermittent rough idling when engine light came on. Replaced injector and now starts like a dream w/no rough idle.
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Unread 06-03-2011, 12:20 AM   #3
ColoradoCole
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Thats interesting, my mil is turning on and off every other day, i know its the fuel injectors but the engine does run a little rough some times.
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Unread 06-03-2011, 04:38 AM   #4
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Try cleaning the grounds in the engine compartment.
Its cheap.

I think the way the computer fires injectors is by systematically and sequentially switching one of the injector leads to ground.
(I think with ignition on, not running, there will be 12V on both leads.)
Duration and frequency are in milliseconds.
That makes minor variations in ground resistance important.

The various harness grounds on mine were pretty corroded.


If I were considering new injectors, the Bosch design III coversion would be the likely choice.
5.0 Motorsports has a particular setup for the Jeep 4.0 that is direct replacement. (other brands, too)
http://www.fiveomotorsport.com/jeep-...1lb-0280156013


I've converted a mid-80s automobile to the design III, slightly different Bosch part number, and been very pleased. Plug and play. The 4-hole pattern seems superior --- really smoothed out my car.
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Unread 06-03-2011, 07:08 AM   #5
VMI Jeeper
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I had this problem/code on injectors 3 and 4. Replaced both injectors and problem went away for about a week and then came back with codes saying it was injectors 2 and 3. Turned out to be a bad battery. I know, might sound a little crazy, but a bad battery can do funny things to a car. Might be worth something to check out.
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Unread 06-03-2011, 06:27 PM   #6
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Quote:
Originally Posted by VMI Jeeper View Post
I had this problem/code on injectors 3 and 4. Replaced both injectors and problem went away for about a week and then came back with codes saying it was injectors 2 and 3. Turned out to be a bad battery. I know, might sound a little crazy, but a bad battery can do funny things to a car. Might be worth something to check out.
I've read other threads with similar conclusions --- battery aging.

Good point.
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Unread 06-03-2011, 06:29 PM   #7
Jerry Bransford
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187K miles isn't enough to automatically assume the injectors are bad. My previous TJ had more miles on it than that and its injectors were fine. When is the last time you changed your spark plugs and exactly what type and model spark plugs did you install?
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Unread 06-03-2011, 06:32 PM   #8
JBTJ
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Most modern fuels have additives to keep your injectors clean and lasting a LONG time.
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Unread 06-03-2011, 06:50 PM   #9
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Quote:
Originally Posted by Jerry Bransford View Post
187K miles isn't enough to automatically assume the injectors are bad. My previous TJ had more miles on it than that and its injectors were fine. When is the last time you changed your spark plugs and exactly what type and model spark plugs did you install?

I should add something.

The car that benefited from injectors is 26 years old.
It sat 10 years without running --- we named it the Rip Van Winkler.
It needed injectors. Badly. How did I know? I replaced everything else first.
They were likely badly varnished from sitting in old gas, no exageration, 10 years.
(Witch Hunter charges $17 to flow-check, clean, re-fit with orings, and re-flow-check them)
Instead, I found a deal for $20 for new design III units --- and went with it. Luckily it solved the problem (very vividly / no speculation)


Other cars, similar, 82, 83 84, 85, 86 --- are running original injectors ( similar to the Jeep 97/8 etc units)---- with ZERO issues.


Injectors, reinforcing Jerry's point, and JBTJ's point also, are over-engineered and unlikely to fail.


I think this is an interesting and helpful thread from an Australian Jeep forum.
http://www.ausjeepoffroad.com/forum/showthread.php?t=92236


Here's another thread that has interesting discussion and links about injectors.
Its car specific, so you have to look past that. These guys are replacing injectors not so much because they are bad, more because they are adding boost and need fuel, else have $ to spend to make the old cars perfect.
http://forums.rennlist.com/rennforums/928-forum/622410-injectors-choosing-the-right-design-iii-and-some-ii-info.html
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Unread 06-04-2011, 03:16 AM   #10
ColoradoCole
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I will have to check which spark plugs i have, i think they were bosch
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Unread 06-04-2011, 10:27 AM   #11
joshhtfld
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If it is a every other day thing it is not the injectors. If anything it is the wiring from the ECU to the power group like you have said as an options above. This more than likely be the root of your problem and this would be my first look. Just from personal experience with working with injectors
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Unread 06-04-2011, 04:36 PM   #12
ColoradoCole
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but if there was a problem with the wiring to the ecu, wouldn't i be getting more codes for the other injectors of is each injector individually wired?
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Unread 06-04-2011, 09:41 PM   #13
joshhtfld
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Each injector has its own powergroup and has a separate plug in even if all the wiring run together it will split at the injectors and each one will plug in. Atleast that is how my company designs them I do not know about Bosch
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Unread 06-04-2011, 10:02 PM   #14
TJJP77
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Why not try some of the suggestions from the service manual you had listed in your original post? One of the easiest things to do is move the injector to another cylinder and see if the code follows to that cylinder....
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Unread 06-04-2011, 11:15 PM   #15
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Quote:
Originally Posted by TJJP77 View Post
One of the easiest things to do is move the injector to another cylinder and see if the code follows to that cylinder....


Easy and usually quite effective troubleshooting...
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