Misfire Saga

[DetroitST]

Hi all, just wanted to share my story (ongoing). I am tuned for e85 and a few days ago started misfiring. It was idling rough, and CEL came on so put the laptop on it and got 4,6 misfire. Sometimes only 6, sometimes 4,5,6. Tried to top off e85 at another gas station (only had 1/4 tank was reading at e81), but still was misfiring even after a top off (still e81). Took it in and here are the steps we took:

Swapped bank 2 sensor 1 O2 sensor (my call as there was a CEL for it) ended up not being that.
Reflashed my e85 tune to make sure it was a computer issue, not that.
Disconnected my catch can and reinstalled stock PCV in case was a vacuum leak, not that.
Pumped out ~18 gal of fuel, went to empty, poured 1 gal of 93 in, pumped that through to empty, then put 2 more gal of 93 in, flashed 93 tune, not that.

Finally put a snap on scan tool on and ran some tests, #6 injector doing all sorts of wonky stuff.

So tomorrow I get to call Nostrum and hope they warranty an injector which I'll report what happens. But more importantly hoping they have one in stock and will sell it without being in a set.

Anyway, I'll keep everyone updated. If anyone has an issue with their injectors, let me know how it went. Keeping my fingers crossed. They are really hard to get a hold of and communicate with so wish me luck!

 

[TMac]

You're obviously doing things with an eye towards the problem and yet....the very first thing I would have checked would have been the plugs. Maybe you did, but just didn't mention it?

 

[UNBROKEN]

Read the plugs and swap the coils around to make sure the misfire doesn’t follow a coil.

 

[Blown F-150]

I would also check the plugs. But if you have a scan tool, you should be able to pick up a bad injector with the proper load balance test.

Totally anecdotal, but injectors do fail so I would say that you may be on the right track. Just be thankful it didn’t fail open like DW’s are known to do on other platforms.


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[TMac]

The problem with diagnosis comes from the number of DTCs that are present. The misfire codes are almost always due to the ECU measurement of linear acceleration of the crank- it's measuring the speed of crankshaft sensor in real-time after the spark and senses that the crank has slowed (or not accelerated). That is usually a plug or coil pack. When that persists, you're going to get a "rich" condition since the O2 sensors are going to detect unburnt hydrocarbons. The codes continue to cascade from there- Cat efficiency problems, etc. The fact that you swapped bank 02 sensors only confirms the sensors are fine and it's confined to a single bank- it doesn't address whether it's an injector, plug, or coil pack. Check the plugs first. If they are fine, swap the coils from the unaffected bank to the problem bank. If the misfire switches banks, you have a coil problem, then try to isolate them. If that changes nothing, THEN you might try injectors- do the same thing as with the coils. Very unlikely it's a fuel problem with the e85 itself.

 

[DetroitST]

Thank you for the reminder, step 1 was in fact move coil and plug from 1-4 and misfire stayed at 4.

 

[DetroitST]

With that being said, since the scan tool showed an issue on injector 6, maybe it would be worth it to swap coil/plug from that cylinder? I also forgot to mention I did a compression test on #4, passed. Also did a computer compression test with the snap-on tool, also passed. Sorry it's been a long few days and my stress is causing me to forget some details.

I wasn't holding the tool, but I could see the graph of the injector test, #6 was basically off until under throttle and would even out with the rest of them. When back to idle it would drop off again. I'm not a mechanic or know the exact test it was called on the tool, only saw the graph. Mechanic leaned toward it being the injector as it's aftermarket.

#6 is hard to get to, but ultimately easier than the injector so perhaps tomorrow I will start there.

I appreciate the input all.

 

[Blown F-150]

Doesn’t matter aftermarket or not. I had a brand new OEM injector that would run rich under idle/low load on the 3.5 build (F150) and it was a pain to troubleshoot. That was after spending the dough to get the set flow tested in hopes of finding a bad egg before install.

I have my fingers crossed that I won’t have any issues with the XDI injectors about to go in it (even though they are basically a GM OEM injector).

Good luck and report back what you find.


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[DetroitST]

I also had a set of XDI injectors. Had 2 fail in under a year. Hope you have better luck. They laughed at me and blamed installation. They forgot they installed them. Then wouldn't warranty them even though it wasn't even a year from purchase. Excuse after excuse.

 

[TMac]

Cylinder 4,5,6 are all left bank. Just concentrate on that side. Since it seems like you've ruled out plugs, but have multiple hits on #6, I'd move one of the right bank coils and injectors (which would seem to be good) to #6 and see if DTCs move banks. Then #4, etc.

 

[DetroitST]

Moved injector from 6 to 1. Misfire followed to 1. Installing new set of injectors this morning. Hopefully that will end this saga. I'll post more in depth once I can breath again. Have fun pics of the engine all taken apart as well. Stay tuned.

Thanks for all who contributed.

 

[DetroitST]

New injectors are in and it works!

A couple photos mid install.

 

[TMac]

Excellent!

 

[UNBROKEN]

This is what has kept me scared away from any of the aftermarket injectors so far.

 

[DetroitST]

Ya I hear ya. It's excellent power but having used XDI and Nostrum's injectors both failing sub 1 year is a red flag for anyone who is trying to achieve near OEM reliability. Granted, I was very suspecting of the injectors day 1 last week and could have saved a lot of time and swapped them first. The prospect of having to eat the $1400 for a new set I had to go through the proper and necessary full diagnostic and testing to ensure I would get a warranty claim.

With that being said, my experience(s) with XDI are so far beneath disappointing they aren't even worth talking about imo.

At least Nostrum offered lots of support, answered every question I had and I do feel genuinely wanted to make the outcome as easy as possible.

As it goes with modifying cars, be ready to pay to play. Simple as that.

 

[UNBROKEN]

We use my ST for extended road trips so until there’s a Bosch option or something I trust…it’s not worth the risk. An injector swap in a hotel parking lot 1/2 way across the country doesn’t sound like much fun. lol

 

[DetroitST]

Now that I've done it twice. It could be done. Only like 5 tools needed. Even still, wouldn't be a fun time. The issue would be not having the replacements on hand. Luckily I live near Nostrum.

 

[Blown F-150]

Ya I hear ya. It's excellent power but having used XDI and Nostrum's injectors both failing sub 1 year is a red flag for anyone who is trying to achieve near OEM reliability. Granted, I was very suspecting of the injectors day 1 last week and could have saved a lot of time and swapped them first. The prospect of having to eat the $1400 for a new set I had to go through the proper and necessary full diagnostic and testing to ensure I would get a warranty claim.

With that being said, my experience(s) with XDI are so far beneath disappointing they aren't even worth talking about imo.

At least Nostrum offered lots of support, answered every question I had and I do feel genuinely wanted to make the outcome as easy as possible.

As it goes with modifying cars, be ready to pay to play. Simple as that.

Really disappointing to hear about XDI, but I don't have a ton of options on my truck. All well, we'll see how it goes as I already have them and just waiting on Turbos.

 

[DetroitST]

I went with turbos from turbo revolutions for my 2.7l and the quality was subpar. Hong also wasn't my favorite person to deal with. They did work though. I've heard better experiences with pure and other companies. Who did you go with?

 

[Blown F-150]

We use my ST for extended road trips so until there’s a Bosch option or something I trust…it’s not worth the risk. An injector swap in a hotel parking lot 1/2 way across the country doesn’t sound like much fun. lol

FYI, the XDI injectors are Bosch from a GM. But for only 15% more flow on this platform I don't see why you would do them.