Intermittent misfire problems

[joelslasers]

Let me start with what is done with my car engine wise:
-DOD delete
-livernois 1C cam (218/229 @.050 .600/.600 117.5LSA)
-full exhaust
-E85 flex fuel conversion
-squash dual 450lph pumps. 1 on Hobbes
-tvs1900 od rear cog (a little over 9psi)
-ID850 injectors

Sorry in advanced for the huge story following. This has been happening for a while now.

Okay, so onto my problem. Everything was running fine with cam, dod delete, and exhaust. I then installed the supercharger, injectors, and ethanol sensor. All good until one day, about a mile from work and I got on it a little bit, I had a misfire. No codes or anything because of the tune. But I could feel it. So I pulled into work and let the car sit. 10 hours later start the car and go home. Everything fine with no misfire. Couple days later same deal: got on it a bit and it started misfiring. (Keep in mind, sometimes it would run perfect at wot. It wouldn't misfire all the time). Installed fuel pumps soon after that and set for 60psi. Good for a couple days And then started acting up: any time you put a big load on the engine, it would misfire and keep misfiring. Seemed around 5psi or so (just to give you idea of load). Any time you got on it a good amount it would start misfiring until you turned the engine off for a while. Except like 2 times when it fixed itself while driving. Finally decided to see which cylinders were misfiring. It seemed to be only cylinder 8. bought all new coils, new plugs (looked fine though), and switched injectors 8 and 6. Everything good for a couple days. Then same deal. Found it was still cylinder 8. I could physically feel all the injectors fireing EXCEPT for cylinder 8. Also switched between first base tune and second tune a couple times in between all this stuff to no effect. Ohm tested injectors and they seemed all within each other. Also flushed them with brake parts cleaner. Did a continuity test for the positive wire for injector for cylinder 8 and Moved harness around and it seemed good. When it was misfiring, I also moved everything sound with no noticeable effect. Now it was misfiring almost any time you got into it a good bit. Lowered fuel pressure to 47 psi per recommendation. Got a little weird... It started acting up more, but a lot better at the same time: it would misfire under heavy load, but fix itself when you let off. misfireing any time you got into it a bit. Replaced ECM. Ran perfect for 5 days. Felt like a new car, even. Lol. Idled better, shifted better, and could now go wot just fine. Perfect. Then messed up 5 days later and is now getting worse as we speak. Someone please help... Don't know where to turn.

[-Ray-]

There's gonna be a lot of questions asked here. Not just by me.
First off, 47 PSI is not enough fuel pressure.
Are you running E85 all the time?
Are you getting a code for cyl 8 misfire?
How many miles on the cam and springs.
What are you logging with? EFI Hptuners?

As you know this misfire stuff can be hard to chase down. More info helps for sure.

[STL_G8GT]

I had an issue where the car would run poorly under load. I took apart the fuel rail and found a chunk of -something rubberish- stuck in the hat of one of the injectors. It would float in the hat until you got on the throttle and then it would get sucked down and impede fuel flow.

That said, you had the problems after the blower/injector/e85 conversion. Before you swapped fuel pumps. I would think a fuel blockage would be the problem, except the part about that injector not clicking.

You said that you don't hear injector #8 clicking? That's really important for you to verify... If it doesn't click at all then I would think a wiring problem, especially since you replaced the ecm.

Sent from my LG-D800 using Tapatalk

[jcmGT]

Figured you might try over here from the facebook crowd. Since it ran fine after ecm change, have you tried disconnect/reconnect the ECM itself? or gone back to your prior since it appears good not the source now? At lease it would eliminated the connector.

Happen to have access to HPTuners or know someone who does? Getting a log would really narrow this down. IIRC, you don't need credits to scan so you could borrow a interface.

[joelslasers]

Absolutely willing to answer questions. Haha
I was told 47psi is perfect as long as I'm tuned for it. It seemed to help a tiny bit. But I've since returned to 60 because I haven't retuned for it.
Only running 93 right now.
Getting no codes at all. However, if you unplug the injector or coil, it will throw a code.
I think less than 10k on dod delete and cam. I compression tested all cylinder per request from others. All showing around 180psi. Logging with efi live autocal. It doesn't seem to show much more than a 25% increase in that banks fuel trim during misfire along with timing bouncing around and other stuff like the like you'd fine during a misfire.

[joelslasers]

I can't feel injector 8 clicking during it misfireing. Can feel it clicking any other time. I can also feel with my finger the other clicking.
I'm also going to reflash the tune on it. Already left the battery unplugged overnight. Just to eliminate that. Cause it seems to get worse with time.

[jcmGT]

if the problem remains cyl 8 after you swapped the injectors, it's a wiring problem. Will have to find the poor connection/pinched wire as suggested earlier.

[joelslasers]

Is there any possible reason it could be tune related?

[mjones73]

The tune wouldn't kill one injector randomly. I'd say wiring harness has an issue also..

[joelslasers]

I tried testing the resistance between the ground on the chassis (jumping) and the plug for the injectors. The positive terminal reads reads ~12.3 on the 20K ohm setting. The negative read ~1700 on the 2000K ohm setting. I don't really know what it's supposed to be though. I figured the ground would have little resistance and the positive would read infinite resistance because it's off.

[jcmGT]

Any progress to share? Perhaps some Potassium 2-ethylhexanoate, Diethylene glycol, Ethylene Glycol contamination?