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Topic Review (Newest First)
04-30-2013 11:54 AM
Deathmask Anyone?
04-28-2013 11:08 PM
Deathmask I depend on my jeep every day to get me to work and school so I can't be with out it for any time. So I've been trying to find an extra head to buy to send to the machine shop to get cleaned up and swap it out. Could I use a 4.0 head out of a 98' grand cherokee?
04-23-2013 06:50 AM
Deathmask Are there any tests I can do to make sure it's in need of a valve job? Or is there anything I can do other than a full valve job, like the TSB?
04-19-2013 11:31 PM
slathrum
Quote:
Originally Posted by Jerry Bransford View Post
That the misfires didn't follow the injectors eliminates them as a possible cause so it was a good decision not to replace all the injectors as was prematurely suggested. Have you checked each cylinder's compression & looked for variances between the cylinders?
Not really. Look, I'm not saying that the problem is completely the injectors. Obviously OP needs a valve job like you suggested. I would venture a guess that the reason those valves are ate up is due to misfiring that has been taking place for some time. Doesn't sound like its the plugs, which doesn't leave much else to look at.

It is entirely possible that they are not the problem at all though. They are, however, a common weak link that if not functioning perfectly can manifest some problems like misfires. Shoot, even if you don't upgrade them at least clean them up real good so that you know they'll be flowing correctly before putting them back in and moving on to everything else under the sun. I think you just might be surprised.
04-19-2013 08:20 PM
Deathmask Crap I was hoping I wouldn't have to do anything like that..... Alright thanks. Does anyone else have any helpful words about this?
04-19-2013 06:06 PM
Jerry Bransford I'd guess a valve job is in order if your engine isn't burning oil.
04-19-2013 06:01 PM
Deathmask I just did a compression check today. And came up with:
Cylinder 1. 125
Cylinder 2. 110
Cylinder 3. 140
Cylinder 4. 145
Cylinder 5. 130
Cylinder 6. 180

It does look like cylinder 1 and 2 are a little lower than the rest, and cylinder is quite a bit higher. Can someone help me with the readings I got?
04-08-2013 05:10 PM
Jerry Bransford NGK iridiums are very good plugs, as good as the Autolites, & I wouldn't replace them assuming they are the right model for the 4.0L engine.
04-08-2013 05:03 PM
Deathmask Correct, I replace the spark plugs with the right ones. But I did go with the NGK iridium plugs, I've read a lot of people have luck with autolites? Could that help?
04-08-2013 04:59 PM
Jerry Bransford Similar/correct compression levels among all six cylinders would be a pretty good indication the valves & valve springs are ok. New correct model spark plugs right? Another member found his misfire to be caused by a defective E3 plug that had a pin hole in the ceramic insulation.
04-08-2013 04:40 PM
Deathmask I haven't done that yet. I guess I'll check that the next time I have some spare time. If that turns out well what would be the next step?

If the compression test checks out ok should I look into doing the valve springs? I've read a few posts by people saying they replaced them and it didn't help any.
04-08-2013 04:02 PM
Jerry Bransford That the misfires didn't follow the injectors eliminates them as a possible cause so it was a good decision not to replace all the injectors as was prematurely suggested. Have you checked each cylinder's compression & looked for variances between the cylinders?
04-08-2013 03:56 PM
Deathmask Well hell.... I just checked my DTC's again and the cylinder 1 and 2 misfires are back but the 1 and 2 injector codes are gone. I need to get this fixed before the end of next month when my state inspection is due, unfortunately Houston requires emissions testing via the OBD port so it will fail....
04-03-2013 05:55 PM
Deathmask So the monitors finally reset today after almost 100 miles. Strangely enough the misfire codes and injector codes are gone (knock on wood) but the 1486 evap code remains. I read a post a guy made about how he got that code and lubed up the gas cap gasket with Vaseline and that took care of the code. Has anyone else had any experience with this code?
04-02-2013 09:31 AM
Deathmask I swapped the 1 and 2 injectors with the 5 and 6 injectors and cleared the codes yesterday so we'll see what happens. I'm really wanting to code to follow the injectors so that I have to reason to replace them all with the upgrades.
04-01-2013 04:46 PM
Deathmask How would I go about checking the injector and injector harness with a volt meter? What current and ohm reading should I get?
03-28-2013 11:24 PM
slathrum That sounds like a pretty smart plan. I didn't mean to imply that troubleshooting them shouldn't be done. I did that myself, and installed heat shielding and still had the misfire with DTC's showing up on the same cylinders. Replacing the injectors was the last thing I did, and it just happened to completely resolve the issue. Good luck!
03-28-2013 10:12 PM
viperx6x9x I agree, I don't like spending money unless the component really needs to be replaced. But if I ever have to replace an injector, I am just going to do the upgrade on all of them. For $100 that ain't a bad upgrade. Better fuel atomization can help with mpg's and at todays fuel prices that upgrade will pay for itself.

So swapping around the injectors to prove they are bad sounds like a really good idea. I try all the little things I can think of before I go buy replacement parts but I did not think of that one, thanks Jerry.
03-28-2013 10:01 PM
Deathmask I see both of your view points. Yes I would like to not spend money if I don't have to, but after seeing that demo video of the 4 hole injectors compared to the OEM injectors I was blown away by the design differences. I also like the feed back I've heard about doing the upgrade. I am going to try to fix the problem without buying them but I would like to upgrade them eventually.
03-28-2013 07:33 PM
Jerry Bransford
Quote:
Originally Posted by slathrum View Post
Yeah, been there and done that. Spent about $50 in high temp insulation with little to no benefit. The 4 nozzle fuel injectors vaporize/atomize fuel more efficiently. Do you disagree with that? I have personally experienced a realized benefit of a smoother idle, improved acceleration and the complete resolution of my misfiring problems with this upgrade. I understand that you don't see the value in that or doubt that it is possible, but I do. Others have experienced this as well. Like I said, maybe the fixing of the misfiring was just due to having a fresh and clean injector, but there are other benefits as well.
Once again, it is free, quick, and easy to swap the injectors around to see if the misfire follows a particular injector. If it follows an injector, the problem has been isolated to a fuel injector. If the misfire doesn't follow an injector, the problem is not with injectors.

This is just basic troubleshooting that is free and quick to do rather than spending big $$$ buying a new set of injectors that may or may not help. I guess some would rather throw parts at a problem instead of doing the simple and free basics first.
03-28-2013 07:31 PM
Deathmask
Quote:
Originally Posted by Jerry Bransford View Post
Exactly what spark plug brand & model are you running? Some types of spark plugs, especially single-tipped platinum plugs like the Champion 3034 or Autolite AP985 will cause misfires in 2000 and newer 4.0L engines after they have been installed a short while.

I really doubt it's a bad or clogged fuel injector, the OE injectors just aren't known for causing problems. And you can prove that one way or the other by moving the fuel injectors around to see if the problem follows any particular fuel injectors. Like swap your #1 and #2 fuel injectors with #5 and #6 and see if the misfires follow the fuel injectors. It only takes a few minutes to swap injectors around.
I think they are NGK iridium plugs and I think the plugs I took out were autolite.

I'm not sure if it's the injector either, the wires to the injector connectors have some of the insulation peeling up a little. Maybe it's not getting the correct power it needs. I'll try to test it with my volt meter later.
03-28-2013 07:21 PM
slathrum Yeah, been there and done that. Spent about $50 in high temp insulation with little to no benefit. The 4 nozzle fuel injectors vaporize/atomize fuel more efficiently. Do you disagree with that? I have personally experienced a realized benefit of a smoother idle, improved acceleration and the complete resolution of my misfiring problems with this upgrade. I understand that you don't see the value in that or doubt that it is possible, but I do. Others have experienced this as well. Like I said, maybe the fixing of the misfiring was just due to having a fresh and clean injector, but there are other benefits as well.
03-28-2013 11:55 AM
Jerry Bransford It makes no sense to swap out the fuel injectors until it has been shown the misfire will follow the injector from the misfiring cylinder(s) around. Not to mention that just throwing parts at a problem in hopes of a fix is very expensive.

And if the problem is heat-soak related, new injectors aren't the fix. There is a TSB for heat soak that basically involves placing foil-backed insulation under the injectors.
03-28-2013 11:52 AM
slathrum I would have thought that too, but switching around fuel injectors resulted in the same cylinder DTC's in my XJ. The problem was heat getting to the stock injectors, which apparently weren't up to the job. Unfortunately, our engines are designed to run hot and the injectors sit on an intake manifold that's directly about the exhaust manifold. It's a pretty common problem in XJ's. Doesn't seem to be talked about much in TJ's, but that might be because the symptoms aren't quite as severe. My TJ just happens to run similarly to how my XJ did before I did the swap, though I'm not getting any DTC's with my TJ. To me, it's worth the upgrade at $100 or so that's been proven to me in the past.
03-28-2013 11:24 AM
Jerry Bransford Exactly what spark plug brand & model are you running? Some types of spark plugs, especially single-tipped platinum plugs like the Champion 3034 or Autolite AP985 will cause misfires in 2000 and newer 4.0L engines after they have been installed a short while.

I really doubt it's a bad or clogged fuel injector, the OE injectors just aren't known for causing problems. And you can prove that one way or the other by moving the fuel injectors around to see if the problem follows any particular fuel injectors. Like swap your #1 and #2 fuel injectors with #5 and #6 and see if the misfires follow the fuel injectors. It only takes a few minutes to swap injectors around.
03-28-2013 10:56 AM
slathrum Well, I found a guy selling them on Craigslist too...
03-28-2013 10:34 AM
Deathmask Alright I'll have to look for a set. I've found a set or reman'd Bosch on eBay from a seller with 99.9% positive feed back, but I'm having a hard time bringing myself to buy a major component off eBay....
03-28-2013 10:15 AM
slathrum From what I understand, any year should work as long as it's a 19 lb injector. The main advantage to using those is that they have the 4 nozzles instead of one without having to buy the more expensive Bosch injectors. They must be getting harder to find though, cause I'm having a hard time finding the ones I used before. That website you listed was the place I got mine from before I think. The ones I used had an orange body.
03-28-2013 07:24 AM
Deathmask
Quote:
Originally Posted by slathrum View Post
Just Google mustang remanufactured or reconditioned 19 lb injectors. Seems odd, but that's the most cost effective way to go about it. They have the same improved 4 spray nozzles. I've found them between $100 and $200 that way, completely cleaned, rebuilt and flow tested.

Once you have the injectors, the swap is a piece of cake. You just bleed off the pressure at the fuel rail and then carefully unbolt and remove it. Definitely wait to do this until it's been sitting for a while. You don't want to press that relief valve on a freshly pressurized line. Make sure you have a rag to catch the small amount of fuel that will come out too. The old injectors may be a little gummed in there, but they will pull right out and the new ones go right in. Replace the fuel rail and connect all the wiring harness connections and you're good to go!
Is there any particular year or would any year work?
03-28-2013 07:17 AM
Deathmask
Quote:
Originally Posted by viperx6x9x View Post
Yeah i think you should stick with injectors and spark plugs for now. I am not too knowlegeable on how O2 sensors work, but it doesn't seem they would effect individual cylinders like your problem.

only other thing i can think of, is there a sensor on each cylinder that is telling the PCM it didn't fire when it should have? if so maybe those sensors went bad or have a bad connection.

you already replaced the coils and plugs, so that should cover the electricity delivery. unless somehow the plugs weren't gapped correctly, that could effect your spark.

best bet seems like it should be the injectors or maybe loose connection to the injectors. Maybe the injectors are clogged up, do you ever put any injector cleaner or fuel system cleaner through your jeep?
I might think it was the forward o2 sensors if there was a misfire in cylinder 3 also, but since just one and two have a misfire code along with an injector code I'm leaning more towards injectors.

I will check the connectors, harness, coil connection and plugs this weekend.

In the three weeks I've owned it I've ran two tanks with sea foam, one tank with gumout, and sea foamed the motor twice through a vacuum line.

Quote:
Originally Posted by showtime View Post
Have a 04 tj with similar prob.,replaced coil pac,o2 sensors and next step was going to be injectors,any one have a link to the injector upgrade.
For new injectors you can check precision auto injectors. I have not bought from them and haven't looked into the company so I don't know how reputable they are, I just know that they have the Bosch injectors and they've done a very through YouTube demo on the Bosch injectors that impressed me and made me want the Bosch injectors.

http://www.precisionautoinjectors.co...c?categoryId=3

http://www.youtube.com/watch?v=bHf-6ohkgbA
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