Injector Problem

jeddi20 · #1 12-01-2009, 09:17 PM

greetings yall, i have an 02 liberty 3.7L auto. while driving one day it started sputtering real bad, it died. i could keep it running if i kept my foot on the pedal and slammed it in and out of gear. when i got home i pulled the plugs and found that they were shot, i replaced them and ohm'd out the coil packs while i was there, i got about .6-.7 on between all of them. when i restarted, it still idles rough, but holds at 1000rpms. i got a check engine light and i took it to autozone and they pulled the code. #1 injector fault.
1st question. is this common for an engine with a 68,000 miles?
2. can i try the fuel injector cleaner before i replace?
3. new or rebuilt injector
4. can i just change one or do i need to do all six?

i would appreciate any ideas you have.

hundahunta · #2 12-01-2009, 10:48 PM

could be an failed injector but I would also perform a engine compression test...

2000izusu · #3 12-02-2009, 04:21 PM

try switching the #1 injector to cylinder#2. if the code moves to #2 injector than you know it is an injector problem.

and yes it is alright to just replace one injector, especially on a car with 68,000 miles.

no it is not a common occurence to have injector problems before 200,000 miles, but who knows it could be bad gas that caused the fault or it could be caused by substandard gas with the epa min. detergent?

also check the wiring going to injector #1

lastly if it was a compression problem it would have showed up as a misfire code (po301)

mike

hundahunta · #4 12-02-2009, 11:58 PM

could be an injector, but i saw a lot of 3.7 even 4.7 engines with a broken vavle spring, burnt valve and they don't throw a misfire code they throw an injector code..before even swapping the injectors I would check resistance of the injector and compare it with another injector, you can also connect a noise light or test light in place of the injector start the engine and check if it flickers...

rhandwor · #5 12-03-2009, 09:24 AM

A compression test should indicate a valve problem.

2000izusu · #6 12-03-2009, 06:50 PM

Quote:

Originally Posted by hundahunta

I would check resistance of the injector and compare it with another injector, you can also connect a noise light or test light in place of the injector start the engine and check if it flickers...

jedi just keep in mind i have had plenty of bad injectors show good resistance.

hundahunta · #7 12-03-2009, 10:41 PM

that's true ive seen a lot of injectors fail with good resistance, but it is a step diagnostic process to pinpoint the root problem...you can switch injectors from one cylinder to another and it will pinpoint you in a direction, but it's a lot of work to do. You can dg the problem with a few tests...more than likely it is an injector failure but at my dealership ive seen more mechanical problems than injector problems...

jeddi20 · #8 12-09-2009, 01:53 PM

alright, heres what happened so far. i ordered and replaced the number 1 injector. still runs like crap. i took it to jeep and they told me that the driver in the ecm is keeping the injector hot and it is dumping fuel into the cylinder. now they tell me that the injector that i replaced has been damaged by the old ecm and i need to replace it again. so far my bill with them is 800.

hundahunta · #9 12-10-2009, 12:31 AM

pcm should be covered 7yrs, 70k miles....

rhandwor · #10 12-12-2009, 03:02 PM

http://www.autopart.com/tools/toolsmain/tool/T_3401.htm
I would use a tool like this and check for voltage and ground.
I've found more loose connections or bad wires than computers.

jeddi20 · #11 12-14-2009, 10:43 AM

alright, here is the latest from the jeep dealership. they replaced the injector and its still acting up. when they performed a compression test they said it had none. they sprayed some oil in and did a leak down test. they said they think its coming from the head. they want to pull the head off and check for a bad valve, seat, or something. so far my bill for the repairs is sitting at a cool $1000. to pull the head and diagnose will be another 500, but they will put it toward the cost of the repair. my sister is not happy and feels that this is becoming a money pit. my question to yall is, when is enough enough?

hundahunta · #12 12-16-2009, 12:03 AM

Quote:

Originally Posted by jeddi20

alright, here is the latest from the jeep dealership. they replaced the injector and its still acting up. when they performed a compression test they said it had none. they sprayed some oil in and did a leak down test. they said they think its coming from the head. they want to pull the head off and check for a bad valve, seat, or something. so far my bill for the repairs is sitting at a cool $1000. to pull the head and diagnose will be another 500, but they will put it toward the cost of the repair. my sister is not happy and feels that this is becoming a money pit. my question to yall is, when is enough enough?

..

probably it has a burnt valve, possible the valve seat dropped from the head very common, this is a very common mis-diagnosis with a injector code

rhandwor · #13 12-16-2009, 09:13 AM

Quote:

Originally Posted by jeddi20

alright, here is the latest from the jeep dealership. they replaced the injector and its still acting up. when they performed a compression test they said it had none. they sprayed some oil in and did a leak down test. they said they think its coming from the head. they want to pull the head off and check for a bad valve, seat, or something. so far my bill for the repairs is sitting at a cool $1000. to pull the head and diagnose will be another 500, but they will put it toward the cost of the repair. my sister is not happy and feels that this is becoming a money pit. my question to yall is, when is enough enough?

Its quit apparent they didn't properly diagnose the problem in the first place.
I think you should demand the $1000.00 should be applied to the repairs.
A normal 1 or 2 hours shop time charge should be all it requires to find this problem.
They should be better than a shade tree mechanic at the rates they charge.
They are also charging you for parts you don't need.
At least demand they try the old computer after the heads are finished and its running properly.

fredjacksonsan · #14 12-20-2009, 07:15 AM

7/70 powertrain warranty. You said it occurred at 68k. This should be a free ride for you my friend.

jeddi20 · #15 12-21-2009, 02:26 PM

Quote:

Originally Posted by fredjacksonsan

7/70 powertrain warranty. You said it occurred at 68k. This should be a free ride for you my friend.

nice try, but the drivetrain is a 7/70, the powertrain is a 3/36.

thanks. i'm going to drag it home and pull the head off myself. she decieded to buy a new car. if i can get it running she wants to sell it, if i can't get it running it will be a parts car.

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