BCNUL8R

iTrader: (2)

Everyone I know on e85 uses the br7ef well over 20 psi without issue.

I would try br7ef’s gapped at 0.021 first since that’s so easy. Then have injectors cleaned/inspected. If neither of those things fix it then I’d suspect valve train.

ddnspider

iTrader: (26)

That's some healthy lift. It could simply be that the added boost combined with heavier rockers is causing the valvetrain to lose stability above 6k. That still wouldn't explain your clean plugs though. If you were getting spark blowout at higher boost or poor combustion from too cold of a plug you would have rich fouled plugs and you have clean plugs.

BCNUL8R

iTrader: (2)

Im thinking valve train as well, but plugs and injectors are so easy to change might as well rule them out before digging into the motor.

My buddy had had the same issue sounded the same and everything just didn’t happen till over 20 psi and it was the valve train.

455GTO

iTrader: (18)

Pulling the injectors today to flow and clean them to see how they look. Will be interesting to see what the outcome is. Also have a set of stock rockers with the trunion w/ bushing upgrade we will throw in to test with as well. I have a lot of spring pressure to have such a bad breakup on very low boost... Just hard to imagine these springs with rockers can't handle 10lbs and up to 15lbs. Exact same breakup on any boost over wastegate. I want to make 20lbs+ so whatever it takes to get there. 1100-1200whp is the goal for the setup.

ddnspider

iTrader: (26)

Maybe I missed it, but what is your boost controller? I.E. you don't have a Holley ECU or something that is cutting spark/fuel because of an "overboost" setting that is too low right?

455GTO

iTrader: (18)

Just running the stock computer with a Boost Leash Pro controller. HP Tuners for tuning and definitely not hitting the limiter as I can rev it out to 7100 on gate pressure.

ddnspider

iTrader: (26)

I gotcha, just something to rule out.

455GTO

iTrader: (18)

Update

Pushrod preload is within spec .080 intake and .040 exhaust. Cleaned the injectors and 1 had a small piece of trash in it but nothing major. Swapped to stock rockers and guess what!?

Still breaks up at exactly 6100rpms... This HAS to be an issue with it losing crank signal. It literally hits a limiter aka breaking up violently at 6100. I already replaced the sensor so unless it was another bad sensor it’s hard to imagine 2 are bad... Has anyone else ever had such a bad time with crank signal? Turned the motor over by hand and looked at the reluctor wheel and nothing out of the norm. It looked fine...

BCNUL8R

iTrader: (2)

I've seen this exact thing like I said buddy thought it was crank signal as well after checking out injectors. It ended up being the valve springs. No way to say for sure over the internet, but I wouldn't rule out needing different valve springs yet.

jayyyw

what lifters are you running?

Old Geezer

iTrader: (3)

Check the crank end play.

ddnspider

iTrader: (26)

If it was a sensor like the crank it would be solely rpm dependent, not boost dependent.

Kfxguy

iTrader: (1)

although he didn’t answer my question, I think it’s fueling related.

47ford

x2 need more info on fuel system.... what filters and have you checked them to make sure they are not plugged? Dual 450s running all the time or does one come on with Hobbs switch? Are you able to watch fuel pressure with a manual gauge because of the stock computer? I also had a similar problem and was losing voltage at the pumps.... just a few things I ran into best of luck to you!

ddnspider

iTrader: (26)

He wouldn't be seeing AFR on the wideband in the 10s if he had a fuel delivery issue.

Kfxguy

iTrader: (1)

I’ve had mine do that, cut out and it was way rich or lean and the afr gauge didn’t pick it up fast enough.

ddnspider

iTrader: (26)

He was sitting in the 10s on E85 at 10 psi, I feel pretty good that going to 15 psi isn't suddenly going to go so lean to misfire, that's all.

AwesomeAuto

God that is such a bad suggestion..

If it only happens under increased boost, it absolutely doesn't have to be a crank signal. In-fact, it is almost positively not a crank signal issue if that's the case.
You swapped out the heavy roller rockers and the issue didn't go away.
You don't have fuel delivery issues it seems.

That leaves spark.

I'm still sticking by this one.
Swap to a BR7EF, straight out of the box.
Ohm your plug wires while they are off to make sure you don't have a failing one.
Check the coil grounds, make sure they are tightly fastened to the heads on either side.

LilJayV10

iTrader: (39)

Yup. I was reading through the post and that's the first thing I thought of.

After that valve springs.

ddnspider

iTrader: (26)

Youre on pump gas. E85 is much more resistant to knock when leaned out and still wouldn't cause a misfire and OP said he has no indication of running lean. I agree logging fuel pressure is always a good idea but I'm more in the valvetrain camp, although I did say those plugs were cold given how fat that AFR was.