LeeMajors19082

I posted a similar thread in Forced Induction, but I've yet to find the answer to my problem and I'm in desperate need of some new ideas. I'm praying to come across someone that's experienced a similar issue and gotten it sorted out. So here goes... the car's a built+boosted '95 Accord EX (F22b1) tuned on Neptune and engine mgmt has already been X'd off the list of possible causes, as has the ECU. So something from the wire harness forward is the cause of this problem. So far I've tried (again from the harness forward) new plugs, new wires, new cap, new rotor, new coil,...scrapped all of those and bought an entirely new distributor as a whole! VTEC's functioning normally, checked timing countless times, checked all the grounds I can think of, and basically went so far as to run a ground cable directly from the main ECU ground to the Neg terminal on the battery!? Everything else seems perfect!? The engine runs great!... right up until that point. And then it begins misfire/break-up and fall flat on it's face!? Occasionally the datalogs pick it up, other times they don't? Sometimes it logs as a fuel cut, sometimes it logs as an ignition cut, and sometimes it won't log it at all!? But EVERY TIME... it happens. Sometimes it'll happen around 4600RPM, sometimes 4800-5000RPM? Doesn't seem to matter if it's WOT or partial throttle I still get the same result in the exact same RPM range time and again. I'm at a total loss here and just cannot figure out wth I'm missing!? Can somebody PLEASE HELP ME figure this out?

Sharpie14l

What are you running for a fuel system and how old are the parts? Injectors and pump. Also how much boost?

LeeMajors19082

Walbro 255 (new) and FIC 850's (used[lightly]) the build's got less than 1k miles on it and we're running on WG pressure to approx. 9lbs until we get this sorted out. This has been this way since day one. <<<The rev issue I mean.

holmesnmanny

I would say it's something with vtec because that's the time that sohc vtec kicks in, around 4500-4800ish. Maybe a rocker is stuck or something in the program is not right.

If it was 4000ish I would say maybe a distributor sensor but since it's 4500ish+ I would say something vtec related. Normally people don't boost vtec engines.

http://www.civicforums.com/forums/17...explained.html

LeeMajors19082

Thank you for the reply... I guess I'm going to tear into the head today then? I just have one question regarding the possibility of a jammed up rocker: would VTEC engage at all if this were the case? Because we know for sure that it IS engaging and coming on prior to full spool (iirc the VTEC engagement is set around 3800? I verify that with my tuner.). This is just so strange!? smh...
Is it possibly this could have anything to do with any other sensors IAC, Coolant temp, etc? I know I'm shootin in the dark here. Or could the coolant level have anything to do with this? I ask because I realized yesterday that I never bled the coolant system after refilling it the last time. Thax again for your help

LeeMajors19082

bump

holmesnmanny

Put the vtec engagement back to stock and see if that fixes it or maybe if you could just turn off vtec and see if that fixes it. Are the injectors high impedance or low impedance? Depending on which ones they are would make resistor box needed or a delete necessary.

LeeMajors19082

They're low impedance and I'll try the vtec engagement tomorrow and update... thanks

v4lu3s

Has this happened since you put the car together or did it start more recently?

LeeMajors19082

Well to be honest I'm not 100% sure because during the initial break-in, etc... I never tried revving it out? But after about 3-400mi we had it on the dyno and it's been doing it since then. Now it's got about 1100mi on it in total.

v4lu3s

So did it do it on the dyno?

LeeMajors19082

Oh yea!...absolutely! Does it every single time you try to rev it out.

v4lu3s

So it's still untuned right? Where is vtec crossover set?

LeeMajors19082

No it's tuned as best we could to that point... and the vtec comes in around 36-3800rpm iirc?

LeeMajors19082

Ok so I'm feeling pretty stupid right now but I MIGHT have found something. Okay, so I probably should've done this a LONG time ago but it just never dawned on me...anyway, today I went out and I did that jumper wire trick on the test harness behind the glove box, just to see if anything would come up? Well I got the code-0 (solid cel). Now Idk if this is normal when using a P28 in an Accord but normally I don't have any CEL's with the car on except for the SRS and the ABS because both of them are fkd in their own way. But the CEL never comes on. I mean when I first start the car it does but I think they all do that as the car goes through it's little system check, no? Anyway, I have a code-0 when I jump the harness and I just wanted to ask anyone knows if this is normal with a P28/NeptuneRTP setup? Also keep in mind IF this is the cause of my issue it can't actually be the ECU itself as my tuner and I tried his own personal ECU and had the same results. So if anything it's something in the wiring or wire harness, right? Plz lmk if this is nothing or if this is a clear indication of why I'm having this issue with the revs? And then of course flame me for being such a fkn idiot and not checking this earlier. Thx fellas

v4lu3s

First, if you have no codes then the light staying solid is normal. Every Honda I have had for the past 20 years has done that and my current crx with a p06/2300 does that. If the light was on BEFORE you jumped it and it stayed on it would be a zero.

Second, if your tuner charged you to tune an engine that was not running right I recommend a new tuner, you got screwed if that is the case.

Third, was break in done on a stock computer with no turbo hooked up? I have not heard you say anything that eliminates engine management as a problem. It could still be a problem with the tune.

I would test with a stock computer. Either open wastegate wide open so no boost and put stock injectors in and test drive, or take turbo/manifold/downpipe off and header on with stock injectors. if it runs fine with the stock computer then you KNOW its the tune. If not then maybe it will help you get closer to what you need to know to fix it.

LeeMajors19082

Ok so I'm confused, you're saying that when you jump the harness and you get a solid CEL that's NOT a code-0?.. Because there wasn't a CEL before I jumped it? I've never heard this logic before. It's always been my understanding that Honda's will store codes even IF the CEL isn't on? Also the engine runs great, up until the fuel cut. Which on a F-series engine is near the top of it's rev range (redline is like 6200rpm) the break-in was done with the build complete ie. turbo, injectors, etc...etc... this has nothing at all to do with the tune or the ECU itself. We've tried every possible option from an engine mgmt perspective, which I didn't bother to describe in this thread because we're already beyond that, including removing any/all rev limits, fuel cuts, etc... we even used completely different ECU's with completely different NeptuneRTP/Demon units, started over numerous times with fresh basecodes and rewrote the tune from scratch... so again, this has nothing to do with the ECU?Demon unit itself(hardware), NeptuneRTP (Software), or the tune. Whatever issue I'm having is from the harness forward. Also, to be honest, I just can't see myself ripping the entire build apart yet. The fuel rail and injectors maybe, but I'm not taking the turbo off and all that ish just yet. It does the same thing in or out of boost, in gear, outta gear, under load, etc... I personally think it's something electrical, something sending a bum signal somewhere along the line. Could be the injectors though, from a mechanical standpoint, it could also be a rocker hanging up in the head around a certain rpm? I'm tending to lean towards electrical because of the way it's happening, the fact that it's actually causing a HARD fuel cut, that's telling me that something is sending a funky signal to the ECU and it's instantly cutting the fuel like some type of failsafe. Idk, first I'm gonna swap out the VSS and if that doesn't work the next move will be a new wire harness.

v4lu3s

Do what you want, it sounds like you already "know" what you know.

I am not sure why you are on here. Do you want people to confirm something for you? Because I can't since you have presented NOTHING that points to what you think it is.

If it was me I would be looking at Neptune sensor readouts since "funky" signal stands out very obviously. And funky signal that causes a rev limit around 5k rpm will almost invariably throw a check engine light.

If it was my 20 minutes to waste there would be stock injectors, stock ecu and no spring in the wastegate and I would be driving around seeing what happened at 5k rpm, but I am guessing that is a lot more than 20 minutes of work from you since you are resistant to doing anything.

LeeMajors19082

I'm not sure if you re-read your reply before posting it, but the way it reads you seem a bit perturbed? I'm sorry if you feel like pulling the build apart at this point is a great idea but I have to respectfully disagree. It's simply not a logical way to troubleshoot an issue. Thx for the reply tho!

TomCat39

Also another thing to note. When I was researching chipped ECU's, code zero is typical with chipped ECU's. It just means it's chipped.

Code zero on a stock ecu is bad. Your's is not a stock ecu.

I would have to agree with the post that recommends slapping in the stock injectors, opening the waste gate and using a stock ECU to test.

I suspect you will get very different results.

And yes, when you jump the service connector, the CEL is supposed to come on solid. It means it's in service mode and you can do ignition timing.

The other thing is like the other can't rev past 3000 thread here in this section... Maybe you are not getting signal from the distributor to ECU on one of the lines. I think the other poster said something about the blue wire.

Anyways, if the noise impedes the signal from the dizzy sensor then it will prevent high rpm. Maybe some shielding got damaged allowing noise cross over.

LeeMajors19082

I thought this may have been the case early on, and could quite possibly still be? I thought I had X'd it off the list of possible causes when I got the new plug wires but the reality is in my car I have SO MUCH extra wiring, that I'm sure is introducing a ton of EMI/RFI, that the spark plug wires alone aren't the only thing that may be affected..?

Also, at this point I'm not prepared to go through the process of reinstalling the stock ECU/injectors. This isn't like a Civic or Integra where it's a quick unplug/replug. In the Accord you have to repin a few wires on the harness etc. nothing major but still a pita none the less. Not to mention the VE is significantly different at this point and I'm not 100% sure it'll run the engine, let alone run it well enough to rev it out past 5k? Maybe if you guys could explain to me the benefit of doing this I'd be more apt to go through the motions? Don't get me wrong, the injectors may very well be the issue, I'm just not understanding the benefit of swapping in the stock ECU? And if boost had something to do with this, would it still happen in Neutral (when not in boost)? I honestly don't know?... so plz lmk if you think it would? And thank you for your reply.

TomCat39

How does neutral prevent boost? Does your car not product exhaust in neutral unlike every other combustion engine? I do not understand that logic.

The idea of putting in the stock ECU and injectors with an open waste gate was simply to rule out a bad ECU. If, when you do the switch and the rpm's goes past 5K with a close to normal stock setup, then you know something is amiss with the chipped ECU.

With all your ECU swaps, you are probably right that it's not the ECU.

You say you've done additional wiring, it's quite possible you've changed shielding or need some shielding to your new wiring that you don't have.

New spark plug wires alone will not be the be all end all solution. If you look through the ETM you notice Honda engineers shielded lots of areas in the wiring. Since you've added wiring, you probably also added noise.

Not that I think it will fix your problem, but Aurora Ignition Wires in Alberta Canada makes superior noise suppression wires that even the Dyno boys prefer over OEM carbon wires that need replacing every few years. Definitely a better wire than any of the others I've used and I won't have to buy wires again as far as I understand. It might help, but I think your noise was introduced with your additional wiring.

Best of luck.

LeeMajors19082

I didn't realize it still built boost while not in gear?... my boost gauge certainly doesn't move then? And I don't hear the BOV in neutral either? I'll have to go out and try that again though, maybe I missed it?

Now with the EMI/RFI I didn't add too many wires pertaining to the engine itself but there's an aftermarket alarm system along with a remote starter, and a pretty significant aftermarket stereo system which required several runs of 3/0 welding cables from front to back and a bunch of 3/0 grounding cables up front and a high output alt... anyway, do you think any of these things could be causing significant EMI/RFI?

TomCat39

I don't pretend to know forced induction. I realize there is a boost controller, maybe it has something to do with that. I also am picturing this done on 5th gen civic manual transmission and do not know how any controller would know if you are in or out of gear. I am making assumptions here. You could be right.

To be honest, I am not an engineer so I really don't know what causes EMI/RFI beyond the obvious COIL/ICM module.

I did find my 2 or 3 year old Accel wires allowed a lot of noise over the system to the point that I could not listen to AM radio at all (traffic channel). After I bought the Aurora wires, my radio is noise free.

Also I've spent time looking through my ETM for my civic and noting just how many different shieldings Honda Engineers put into place. Mainly around engine management portions of wiring but more than just one. There is even shielding on the O2 sensor part of the harness.

I can't see you not adding a little bit of engine management wiring or messing with it by adding a turbo, let alone your stereo stuff.

Here's some pics of the 93 civic ETM showing the shielding cylinders around sections of wiring:



Based off of what v4lu3s said in the other thread, I would think something is interfering with the ICM circuit at 5K rpm preventing the ECU from allowing the motor to higher RPM.

The other thing that strikes me is you say you've added ground straps.

I recall another person had changed the stock ground strap to a heavier duty ground strap (battery cable) and it caused enough change (impedance maybe) that it prevented the car from running. Maybe your added ground straps is interfering with the engine systems.

LeeMajors19082

WOW! I had no idea there was that much shielding in there!? Thank you for this reply! And I never thought about the grounds being an issue but I'm definitely going to check that out. And the part where you said something is "interfering with the ICM circuit at 5k", I recently read a similar thread to this one, where the guy was having an identical issue, and apparently it had something to do with his Starter being on the fritz and throwing all kinds of EMI out while revving the engine out!? Anyway, his mech/tuner replaced the starter and viola. I'm just curious if anyone else has ever hear anything like this? Or do you think a starter could actually produce that much, if any, EMI? Thx again man