LNF Failed Injector?

[MarkTucker]

Hey, I am looking to see if anybody else has ran into Injectors failing on LNF cars? On cylinder #2, I am getting a strong misfire. I have swapped plugs around, swapped coils around, performed compression test, performed cylinder leak down test, checked wiring to #2 coil, and also used spark tester to confirm spark. Still strong misfire on cylinder #2 only. I am getting fuel to puddle on top of piston after running the car. I checked with bore scope camera to make sure it isn't leaking when engine is off. I have not pulled the injectors and moved from cylinder to another cylinder to confirm this for 100% but has anybody else had a injector do similar issues? Thank you.

[MikeM173]

You can't just swap injectors without replacing the seals. They are compression fit one time use. I don't know anyone who had had them failed, or I just haven't really paid attention. I don't see them failing often though.

[MarkTucker]

Yeah I know to replace the injector seals each time they are removed. I replaced the seals last time that I had them removed but that has been a few months ago now. Car was running great until yesterday, I started it up and it was misfiring very bad and narrowed it down to cylinder #2 with the scanner and then started swapping parts around and performing any normal test to find out why a engine is misfiring. But all of the tests that I have performed have been good. I was just curious to see if anybody has ran into a bad injector for the LNF cars yet. I am on 93 octane, so I am not maxing injectors out or anything that could have caused damage to the injectors from power level or tuning. Thank you

[MikeM173]

Have you logged it and seen what #2 is doing?

[MarkTucker]

Yeah when I just did a idle log of it, the INJ Pulse Width (msec) are all 4 pretty much equal.

[cobaltssoverbooster]

you can have them tested by any shop that has an ASNU GDI bench.

[MarkTucker]

That is actually my plan today, I have a local friend that has one of them exact machines. So I will keep you posted on my findings. Thank you.

[MarkTucker]

Sorry for taking so long to get back with my results. I got the injectors tested, and cylinder #2 injector did fail. He said he tried just cleaning it, and still bad. So I ordered a set of the Opel Injectors from ZZP. GM was wanting like $270 for 1 injector, so I went with ZZP for all 4 of the Opel Injectors for $350. Does anybody has experience with the Opel Injectors? I am looking to see what changes you have done to run these injectors. Any nice plug and play data out there for the injectors? Thank you.

[cobaltssoverbooster]

yes those are direct plug in and only require an offset change. Some of those come back flowing unevenly. its not zzps fault but i would send them back to your local asnu guy to get them verified. this goes a long ways in knock protection with the lnf.
the offset change is (X 1.1) to the injector offset. if you need to verify the offset post an additional low load log and i can send you the correct offset change. run it in as many low load conditions as possible to be accurate.

[MarkTucker]

Alright, thank you. I should be receiving the injectors in today, according to tracking number. So as soon as I get them installed, I will adjust injector offset from information you post above. Then post up a log like you have mentioned. Thank you.

[MarkTucker]

So, I finally got the car back together with the New Opel Injectors from ZZP. I changed the Fuel Offset by (x 1.1). And here are two logs so far of the car, I have EVAP solenoid unplugged and also have the MAF Correction 1 across the board right now. I did some MAF Calibration adjustments between the #1 log and #2 log. But can you look at the logs and see if you think I need to adjust the Injector Offset some more or less? Thank you.
LNF Opel Injectors#1.hpl
LNF Opel Injectors#2.hpl

[MarkTucker]

LNF Opel Injectors#3.hplAlso, why is my fuel pressure dropping so much in mid rpm range? Commanded is staying the same but actual dips down alot and then starts coming back up. Also in that range of where the fuel pressure dips, it runs really rich, but leans back out once fuel pressure comes back up.

[cobaltssoverbooster]

you can only adjust the offset multiplier if your maf hz calibration is stock gm. thats where that sensor was engineered to be at bone stock. then leave the base at all 1's like you have.
from the short log (#1) they look pretty close but since you said you made changes i dont know which one has the base hz table in it. get a long longer log file with low speed driving and then we can get a better low load average.
they are pretty close right now so it may not need much.

[Jaizero]

you can only adjust the offset multiplier if your maf hz calibration is stock gm. thats where that sensor was engineered to be at bone stock.

I know I'm bringing this back from the dead, but is this globally true? If I'm tuning for E47, do I want to keep the MAF/Hz curve stock, adjust the injector offset, then just tune the MAF base table?

[cobaltssoverbooster]

you could do that but i do a 10% shift method now.

first i set a value i think the constant should be based on the content of fuel.
then i command the maf base to all 1's and tune the fuel curve in very well. (the maf base stays a value of 1 for the whole test)
once its tuned in i monitor a single value cell and track its average value of fuel trim error.

i apply a forced increase of 10% fuel on the entire maf curve and record the results. if the computer isn't getting a 10% error back on the global cell based on the recorded value prior too, then the injector constant needs to be tweek'd.

the goal is tune it, command 10% increase, and see if you get 10% rich error in return. if you can do this then your constant is where it needs to be. doesnt have to be exactly 10% return. anything within 1-1.5% is close enough as the ecu tends to drift pretty heavily with environmental factors.

the methods above still work ok but its not as accurate as this 10% method. Basically your using the car ecu edit to force a condition and the scanner to review the flow changes. this turns your car into the flow bench. thats probably the best i can explain it.

[Jaizero]

Yup, makes perfect sense. So assume you add the 10%, but get a return of 15%, do you reduce the injector offset by 5%? How do you correct the injector offset? Also, do you just create a custom histogram with one cell of the MAF/Hz to take your average, or do you use the MAF base table to take the average?

[cobaltssoverbooster]

if it ends up over-fueling then you would decrease injector constant.
making the constant larger will command more fuel.

i tune on the maf hz histogram but i make a new custom one that uses maf hz as an x-axis plot value but i dont assign it any values. this defaults the histogram to one global cell that records all data. you can add filters to exclude any unstable regions as needed.

[Jaizero]

Good stuff, I'll give it a try. Thanks for the insight!

[The_Ghost]

To add a note to this, yes, LNF injectors fail. On our Solstice/Sky LNF forum, we've had several members whom have had injectors fail. 2 of them acted like they were plugged, and the third one just quit working all-together.

I believe I'm chasing a failed one right now. I posted a post on this forum 4 days ago. My issue is a heavy vibration around 1k. A DFCO AFR reading last year that was calling for 29.4 and getting 29.4, now is't suddenly calling for 27.58 and getting 27.58 under DFCO. So yes, injectors can go bad!