So the cut happened regardless of vtec enabled or not?

The thing with a mechanical issue (and by mechanical I'll assume that means anything other than software) there's not much that would make the car react the way you're describing.

I don't know of any factory honda sensors thats would trigger a fuel cut. Not by design anyway.

I would take a wire harness short off my list of possibilities. The fact that your issue can be duplicated consistently at 5k rpm tells me it's something else.

What are your plugs gapped to out of curiosity.

Whatever it is screams sensor/tuning issue in my opinion.

Most other issues would result in poor performance and not a total cutout, such as spark blowout, fuel deprivation, detonation, out of time, etc.

 

I agree with most of what your saying if not all of it? Lol! I don't necessarily think it's a "short" so much as a full blown bad ground or possibly a bum sensor? I know fudged up grounds can and will cause some VERY awkward behaviour. I think I'm gonna start with just verifying all the wiring is solid, then move on to testing all the sensors 1 by 1, and if I don't find anything there I'll move to the injectors. Or maybe I should start at the injectors? But I'm completely confident with the software and the tune thus far.

 

Is your speed sensor working? Why I asked this question? I had this problem a few years ago, I bought a transmission that did not have the speed sensor gear installed, Launch control set to turn off after 2 mph, but since the car never sees 2mph according to the ECU, my launch control set at 6000 rpm, I would get off the line and hit rev limit no matter where I set the launch control to. datalog shows no speed, I change the sensor, same problem, I put a snake camera in the speed sensor hole, no ring gear, problem solve after I installed a gear.

Long story short, check your speed sensor.

 

I have not checked that yet but I did order one as part of my "throw parts at it till something works" plan. lol! And I have been having a hell of a time shifting since putting the engine back in, especially into 5th... so there very well could be something weird going on in the trans? I'll know for sure once it get's here... thank you for that reply.

 

Okay so I'm having to revisit this because the issue has yet to be resolved. let's go through a checklist of what's been checked/replaced since the beginning:
ECU/Tune (checked)
Distributor (replaced)
Plugs (replaced)
Plug wires (replaced)
Starter (replaced)
All Ground wires (checked and some replaced)
MAP sensor (replaced)
Resistor pack (replaced)
Speed sensor (replaced)
Alternator (replaced)
And after all this the only thing that's changed is that A) the battery light no longer comes on as it happens and B) There's no voltage drop (it used to drop down to resting batt voltage). Aside from those 2 things the issue remains the same... Fuel cuts out right around 5k or in other words the A/F gauge goes completely lean and the engine breaks up. I can't rev thru it but it's also NOT like bouncing off of a rev limiter.
So what's left?... Fuel pump? Injectors? Fuel pressure regulator? I need some more help here fellas... thx in advance
Oh and on a side note I'm using a Walbro 255hp and it's LOUD which, to my understanding, is normal. But especially after long trips it seems excessively loud and definitely MUCH louder than when it's just staring out. Could the pump cause this type of an issue? Or am I just grabbing at straws here?

 

Sounds to me that the alternator being replaced was the key area for the battery light coming on.

When you say the ECU /tune is checked off, does that mean that you set the boost cut WAY over the limit? For example, if your boost cut is say 15psi, you may need to set it to over 20psi in case you're spking during acceleration and hitting cut-off of 15psi early (remember, I'm only using the numer 15 & 20 as a reference, not actual numbers)

 

My MAN! It's been awhile! I'm not sure what the boost cut is set at but I'll have a look asap. If you're familiar with Neptune RTP I'd be more than happy to shoot you a copy of the basecode and a few datalogs so you can have a look at exactly what's going on? Reading the settings, etc. is one thing but I still don't know enough about tuning to fully understand what the logs are showing me and how certain setting affects the tune?... so I could definitely benefit tremendously from your expertise on this. Lmk though? And if you wanna have a looksee PM me your email (i forget if I already have it?) and I'll send the files right over. Thx bro

 

I'm afraid I'm not a tuner either, so sending basemaps and datalogs to me would be like having the blind leading the blind. I do know setting parameters for several systems, so I'm sure Neptune RTP can't be that much different than anything else. These are just some ideas I was throwing out since I've been through a boost / ignition cut issue before in my software. Go ahead and try that first, my friend. Who knows?

 

Right on man, I completely understand. Well I went through and had a look at all the logs we took on the dyno (back in July) and during some regular driving and it appears that we tried all of the things you'd mentioned which I think is what had my tuner so stumped at the time...? We tried it with no rev limit, no boost cut, no vtec, and no ignition cut and each and every time we had the exact same result!? Which lead me to believe it must be something mechanical, but I'm beginning to run out of ideas/options? With that being said though, it IS very odd that it happens at the exact same rpm in every single scenario? Load, no load, boost, no boost, etc...etc... exact same result..? And oddly enough it happens in the rpm range, that I've heard described in numerous threads, known as being in "limp mode" (between 4800-5000rpm)... BUT I get no CEL, no codes, nothing like that? Plus, correct me if I am wrong, "limp mode" is/would-be controlled via the ECU!? As is the CEL, etc...!? So what I'm saying is you would think that IF something was faulty enough to trigger a "limp mode" response it would then in fact have to trigger a CEL or some kind of engine code, right? I'm telling you bro this has been extremely stressful, which is why I had to walk away from it a few months back and drive it as is, but I can't just leave it alone... I need to be able to rev it out so I can turn up the boost and finish having it tuned. We literally had to stop my dyno session because we couldn't figure this out and I've basically been throwing parts at it ever since, but to no avail..?

What are some things that could, mechanically, cause a fuel cut at a certain rpm. Like, forget the ECU and Ignition timing, spark plugs, vtec solenoids, all of that BS... and just narrow it down to: What systems/parts could, from a mechanical standpoint, stop the flow of fuel at a given rpm? Because this is exactly what's happening..... It's logging as a HARD fuel cut. Almost as if the pump is just shutting off. Hmmm?.. How exactly do the fuel pumps work, do you know? Like does the flow increase via an increase in voltage that is directly proportionate to the engine speed? And is that voltage regulated by the ECU or some other system? I guess what I'm asking is what turns the pump speed/flow up and down? Is it voltage? Or does it always pumping at the same speed/flow-rate and the amount that gets through determined by the FPR? I gotta do some research. Bro, thank you for your replies,... I really do appreciate it. And please lmk your thoughts on some of these questions/ideas I've been spewing. Thx again Shodan

 

fuel pumps are electrical motors, they dont know what the RPM of your motor is there performance is purely based on input voltage/amperage.
yes the fpr regulates fuel pressure without a fpr your fuel pressure would be through the roof

still sounds voltage related to me if your battery light is blinking, upgraded grounds is always well worth it IMO. I make my own with 4 gauge terminals, quality OFC wire and a good crimping tool
since youve replaced alternator you may want to check the wire coming off the alternator which feeds voltage back to the battery. have you done "the big 3" just google it if you dont know what im referring to

 

Thanks for the reply. I did a little research since my earlier post and figured out how the pump and FPR work, And for the longest time I was thinking it was electrical too, especially since the battery light was coming on right as it would break up!? But since I swapped out my alt that stopped happening. What I actually found was happening with the alt I removed, was that it was spinning WAY too fast. I had a high output Singer alt to support the amperage pull from my system but, as with most H/O alts, it came with a much smaller pulley wheel than what comes on the stock alt. And the pulley ratio is offset so much that at 4-5k engine rpm's the aftermarket alt was actually rotating upwards of 18-20k rpm! Which in turn burns up the internal regulator and causes the alt to stop functioning properly, etc...etc... you know. So whatever the alt has been replaced and I'm not getting the battery light or the crazy drop in voltage anymore BUT I am still having a HARD fuel cut around 5000rpm. And as for my grounds and power cables I currently have dual runs of 4/0 welding cables of each (+/-) going front to back (engine bay to trunk) to a small battery bank (3x group34's) and my big-3 is also done in the 4/0 but mines more like a big-4 (block/trans/sub-frame/alt-bracket) and I've also beefed up most the other ground connections I've come across, while making my way through the build... Nothing as big as my main grounds but iirc I used 4ga for stuff like the engine harness ground, you know, like the smaller ones that don't warrant really big obnoxious cables. lol!

Tell me this, do you think the FPR could be malfunctioning and causing this cut in fuel? Or the injectors possibly? Lmk what you think? Thx again

 

sounds pretty much the same as my setup i used 4ga works fine and definitely better then stock. I also have a HO alt i think its rated at 90A I dont really recall although I dont think it uses a overdrive pulley and who knows what it actually puts out I got it some from mexican guy on ebay that rebuilds alts LOL. IMO I wouldn't run a ground from front to back rather just ground the battery to chassis at trunk.

Hard to say about the FPR but I dont see why it would malfunction at a particular RPM (would need to verify via dyno or a remote Fuel pressure gauge located in cabin) it would be more likely to be the fuel pump not being able to keep up at higher RPMs in this scenario. are you able to log AFR's? using Hondata? what does your protection tab look like? theres an option for lean protection on that tab which could cause a cut, post a pic if you are able to. either way you would still need to verify via logs if this is a possible cause

 

I've got logs for days but I'm on NeptuneRTP and the tune/calibrations and datalogs have been gone over pretty thoroughly and all it's showing is that there's a HARD fuel cut around 5000rpm that cannot be explained via the tune...? I've heard of issues like this with the Walbro's and I've also heard of wiring them directly to +12v lead off of the battery helping them significantly? I guess I'll start there and see what happens? I'm just not looking forward to pulling the pump again.

 

depends on power level, I made 407 WHP and 310 torque on the OEM Wiring with my 7 year old walbro 255 that I pulled from my untuned delsol after it got totaled. I doubt this will be your issue unless your running lean

You dont need to pull the pump, I recently upgraded my wiring (just for the hell of it I had no issues on stock wiring) using a boch 40a relay and wiring to my capacitor in the trunk which has 4ga wiring from the battery up front, and using 10GA wiring for the fuel pump ground and relay wiring.

PM me your email and ill send the DIY i have saved if interested

 

I appreciate the offer but my pumps not accessible via "normal" means I have a "trunk-wall" with a nearly 6cuft box which was assembled in car so it's more or less permanent, like I can't just pull it out and access that port in the trunk to get at the pump anymore. All that aside, it doesn't run lean all the time but when the fuel cut happens it obviously goes lean then. Today I went out and grabbed a few FPR from the u-pull-it along with a few VTEC solenoids and pressure switches, I'm going to try those just to cross them off the list. And tonight I'm going to go over every single vacuum line, solenoid, and sensor connected to, or associated with, the fuel system/intake-manifold just to verify that I'm not missing something there in that area? This is becoming a very personal vendetta..... I just want my fkn car to REDLINE!!!!

 

did u try looking for that protection tab in neptune? neptune and hondata are very similar so it should have the same option. sounds like a lean protection to me. either way sounds like you have the issue narrowed down pretty well.....fuel system and your sure its not tunning so it would need to be fuel hardware.... fuel, pump, injectors, possibly even a clogged filter.

 

I'm praying you're right?... today after dropping my son off at school I took note of something I never noticed before, and this may or may not have anything to do with my issue, but... when under load and revving towards that weird cutoff point, I can smell fuel in the cabin? I never noticed this before but today was one of the first times since the build that it was cold enough to be driving with all my windows up. I'm definitely missing something

 

Ok so far today I decided to remove the catch tank and reroute the hoses to their designated locations (PCV/Upper plenum and the port on the far left of the VC that routes thru the EGR I put back to the small nipped on the intake pipe). Also while in there I realize that the VC gasket is leaking pretty badly so I pulled the cover to replace it and thought to myself, "maybe you should check the valve lash?", since I let the machinist do it while I was having it shaved/cleaned/etc.... well low and behold the fkn lash was WAY outta spec on both the intake and the exhaust sides!? WTF?!! This was a VERY reputable machinist in my area too! Smh... Anyway I re-lashed all the valves to IN/.010in and EX/.012in and I'm literally sitting here now as she warms up. Now, I doubt this has anything to do with my rev issue, but it's just the point, u know? So cliche' yet so fkn true... "if u want something done RIGHT, you gotta do it YOURSELF"

 

Lol trust no one ever sad but true. valve lash needs to be adjusted AFTER getting the valves done and IMO never hurts to check again after a few hundred miles.must be on a cold motor and It can also be tricky if you havent got the "feel" down not too loose not to tight just a small amount of drag on the gauge.
Pretty sure I found your rev issue so I dont think this is related.

 

DONT KEEP ME IN SUSPENSE 2K!!!!??? Lmao! You're absolutely right though, you really can't trust a lot of these shops/tuners/mechanics/etc.!? And to tell you the truth I think it blows that I have to say something like that but this line of reasoning gets proven to me time and time again. So yea I lashed the valves and got them back into spec but now I'm sure I fkd my tune all up because it's idling pretty lean now? I can't win. lol! And as I'm sure you already knew it didn't do anything in terms of my rev issue... so I'm stil SOL. But I'm stoked to hear that you think you may have found something!?... Talk to me Broseph!...what do you got?!

 

I sent you 2 emails, you have a rev limit set I didnt want to share too much here as I will leave that up to you as far as your tune goes and how much you want out in the open.

let me know if you want me to post it here

as far as the valve adjustment goes valve lash can effect that yes, sounds like the valves are opening more now and that is effecting your AFR, on the bright side more fuel + more air = more power

 

Okay I read the DOC... check your email.

 

I appreciate your discretion 2K, I really do. Thank you for all your help man. I'm gonna try changing those parameters you pointed out and see what happens.

 

Ok so I tried reaching out to some other boosted F22 guys but haven't heard back yet, so I thought I'd post this here and see if anyone has any thoughts/input on it or maybe someone could just explain to me how this works?...Anyway, I was going through some of the parameters of the tune and I came across this:

I'm not fully aware of how open/closed loop work, OR if this could have anything at all to do with my problem? BUT I wanted to ask, those of you who are more privy to these things and the ways in which they work, just to be sure... Because this is the only thing I've seen thus far (in the Tune) that's even remotely close to the RPM range in which I'm having my issue. So if anyone knows about the open/closed loop settings and/or if they could affect the ability to rev beyond a certain point plz reply and give me your feedback on this. Thank you in advance

 

yup I noticed that as well however closed loop is not enabled so it shouldn't effect anything