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Misfire after injector upgrade

Quailman

NAXJA Forum User
Location
Hunt Valley, MD
Hi all,
I recently did the 4-hole fuel injector upgrade on my 96 XJ with some eBay Bosch refurbished injectors.
Ran fine (great) for 2-3 days, then I started getting intermittent p0202 and p0302 codes for injector circuit failure on injector #2. It would misfire and run really rough, but then just go away. Sometimes a couple times a day, sometimes none. Happened again today, this time P0206 for injector #6.

Think I screwed up the harness during the install? Visual inspection looks fine though. Maybe garbage injectors? Part number on them is 0280155923.
 
I would suspect the injectors first, "been there,done that"!
 
Are failures for junky eBay injectors common? The guy I got em from had super good reviews but hey stuff happens right? I guess $55 for a set should’ve set off my “too good to be true” radar..
My first thought was that I chooched the connector on the harness, but that was when I was only getting failures on #2..

Problem is, my dumb self tossed the old injectors (one of them was leaky, that’s what sparked the upgrade. Why upgrade when I can replace?) so does anyone have a recommendation for a good set?
Thanks!
 
Start by checking the resistance of the injectors. Often on intermittent problems like that I found one way out of spec. I think they should be around 12-14 ohms. Anything over 20 I'd say is suspect, or less than 10.
 
Start by checking the resistance of the injectors. Often on intermittent problems like that I found one way out of spec. I think they should be around 12-14 ohms. Anything over 20 I'd say is suspect, or less than 10.

So the resistance would be out of spec 100% of the time even though the problem is intermittent? That’s good to know, that’s what I was worried about. I have a multimeter at work so I’ll check all 6 first thing in the morning.
I reached out to the seller but who knows if I’ll get a response.
Thanks!
 
Did you disconnect the battery and go through the procedure to clear the computer so it could relearn everything?

If it were me that would be the first thing I try.
 
Did you disconnect the battery and go through the procedure to clear the computer so it could relearn everything?

If it were me that would be the first thing I try.

I disconnected the battery plenty of times but didn’t go through the legit reset procedure. Most people say you shouldn’t have to.. I’ll try that though!
 
Injectors usually fail for physical reasons more than electrical and even more in "ebay" style injectors.
 
I disconnected the battery plenty of times but didn’t go through the legit reset procedure. Most people say you shouldn’t have to.. I’ll try that though!

I never really understood the procedure myself. I mean c'mon. Headlights on, headlights off, etc. But you know what? I do it anyway. LOL.
 
I never really understood the procedure myself. I mean c'mon. Headlights on, headlights off, etc. But you know what? I do it anyway. LOL.

Haha fair enough! I gave it a shot this morning, didn't seem to make any difference. I'm at work now and have both the positive and negative disconnected. When I leave, I'll go through the reset procedure again to see if it helps.

Good news though.. I heard back from the Ebay seller. He said they are probably fine, but is sending me 2 replacement injectors anyways just in case! (to cover the injector #2 and #6 issues)
 
Good news though.. I heard back from the Ebay seller. He said they are probably fine, but is sending me 2 replacement injectors anyways just in case! (to cover the injector #2 and #6 issues)

That is usually a bad idea, when they get done cleaning them they usually try to flow match sets of them.
 
That is usually a bad idea, when they get done cleaning them they usually try to flow match sets of them.

$55 for a set of six injector probably means little was done to them other than a quick cleaning and packaging, flow testing most likely wasn't done.
 
I will say that I've run injectors from Ebay before but it's more important to list the vendor. That is the only way to start holding them accountable for their sales and service.
 
So I tested the injectors, all are reading around 12.5 ohms "cold", and 14.0 ohms "hot". Seems normal..
I guess I'll see if swapping the two new ones in helps. If not, I guess it will be time to buy a new set from a reputable seller..
Thanks!
 
Tested the resistance on the injectors. Sitting around 12.5 ohms “cold” and 14.0 ohms “hot”, seems normal.
Now, it seems to be happening more frequently. And get this, the last couple times, it’s thrown codes for misfire on all 6 cylinders! P0206 for circuit failure on injector 6, plus P0301-0306 for misfires on every cylinder.
I was praying to the Jeep gods that it was air in the fuel lines since I never bled the fuel rail after the install but I bled the rail and no change..
I’m stumped
 
Thought I would share my solution for anyone with a similar issue. I swapped in the 2 replacement injectors the seller sent me, and right away had a check engine code for injector #4. After wiggling the connectors, the misfire went away (hadn’t observed this before).

I’ve determined the intermittent issue is due to a tolerance stack up of the loose China special adapters, and 24yr old stock connectors. In the long term, I’ll be purchasing some higher quality adapter pigtails.
In the short term, zip ties around the connectors to keep them from moving around seems to be doing the trick!
 
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