So iirc, I believe it's on HAmotorsports website, it says we need to swap wires A6 and A11 at the harness in order to use a p06/p28/p72 ecu in an obd1 5th gen accord BUT when examining the pinouts of both ecu's (stock accord vs p28) i found that those pins don't conflict!? Now there are a few that DO which I can ID for you if you'd like but right now I'm just concerned that I swapped those wires and didn't actually need to!? So my question to you all is, do you recall swapping ANY wires/pins at the harness/ecu in order to use a p06/p28/p72 in your turbocharged Accord setup? Thx in advance

Here's a link to the webpage I referenced regarding the pin swap:
94-95 Accord Pin Swap Information for installing a P06/P28 ECU

And here's a link to p0a-a51 (stock Accord ecu, a51 is automatic I was unable to find the manual a01 pinout but you get the gist) pinout:
Vehicle:Honda Accord 1995 - rusEfi

And here's the link for the p06/p28 pinout:
.:FFS TechNet : OBD1 ECU Pin out Schematics :.

 

The Honda shop manuals that I have show the following;

94-95 Accord P0A/P0B

A6 = ORG/BLK, ESOL / ES - EGR control solenoid valve
A11 = RED, O2SHTC - O2 sensor heater circuit

92-95 Civic P06/P28

A6 = ORG/BLK, O2HTCNL / O2 heater control circuit
A11 = ORG/BLU, ES / EGR control solenoid valve

That is what shows on both the Fuel and Emissions diagnostics diagrams and the Systems Wiring Diagrams, Engine Performance Circuits / ECU.

That being said, you would have to see what colour the wires are in your particular vehicle.

 

Thanks Ghost... It would appear that the website I was referencing has up some bad info. The wire colors are as you described on my harness A6 = ORG/BLK and A11 = RED.

Now with that being said there were a few other discrepancies that concerned me that maybe you could help me with? On the P0A/P0B A14 = Fuel Inj Air Control but on the P28 this is "empty"? And on the P0A/P0B A17 = "empty" but on the P28 A17 = Idle Air Bypass Solenoid? I'm just trying to verify first, that this info is correct, and second, that if it IS in fact accurate that these systems aren't vital to the engine function? As you know I've been chasing down a fuel cut issue and I need to be SURE that my foundation is solid before I can effectively troubleshoot anything else..? At this point I've been through just about everything trying to figure this out but to no avail, so I'm now starting at the beginning to make sure I didn't miss something small along the way? At any rate Thank you...as always you've been a huge help and I really do appreciate it.

After thought: What is the Fuel Injection Air control anyways?! And if it is on an empty slot would the car even run at all?

 

The A14 FIA is only found on the 94-95 F22B1 and some later F23 engines, this is why the P06/P28 does not have it.

The F22B1/2 did not have IAB's that is why Pin A17 is empty.

Nether of these are vital to engine operation, that being said, if you are running an F22b1 head and intake without FIA hooked up and operating. It could cause vacuum leak issues. The engine will still run but it will have open ports acting like a vacuum leak. The fuel injection air control system was Honda's attempt at increasing fuel economy. It would introduce bursts of air at the base of the injector to help atomize the fuel at the nozzle.

Here is a picture of the back of a 94-95 F22B1 intake manifold and the FIA ports.

 

Ghost you really are the man bro! Ok, so that's the exact system I thought it was and YES my engine/car is a 95 ex w/F22b1 and yes my original IM had those holes which I actually BLOCKED off on the F23 IM while prepping it for the swap and then at the very last minute I realized that my engine had the FIA so I drilled them back out before installing the F23 IM on my engine!? So basically I have an engine harness with an FIA connector which is connected BUT an ECU (P28) that doesn't support it, correct? And THAT is causing a vacuum leak, right? Tell me this Ghost, do you think THIS is why my newly built/boosted engine has never been able to rev past 5000rpm? Why it breaks up and goes completely lean right around 5000rpm? Lmao! Seriously though, could this have been the cause all along? Lmk? And again thank you for your help.

 

You are correct that the P28 doesn't support it. Whether or not it is causing a vacuum leak I cannot be certain. If you have everything hooked up properly and the solenoid is a normaly closed solenoid it wouldn't cause a leak. if a hose was unhooked or the solenoid is normally open, it would cause a vacuum leak. I don't have one of the solenoids or a circuit diagram with me right now to verify.

The FIA control system is not a primary PGM-FI circuit. I do not think it would be the cause of your rev limit/fuel cut.

What MAP sensor are you running?
What sort of tuning have you done?
Are you able to datalog all of your sensors?

 

I'm on a Motorola 2.5bar, using Neptune, and yes. If I can't datalog them all then I'm sure I can datalog most. If you'd be willing to take a look at the datalogs I can send them to you? You can view logs and even calibrations in Neptune RTP without buying a license. In other words you DL the software and install it (5mins MAX) and then you can look at everything, you won't be able to make/save any changes to the calibrations but you would at least be able to view them?

Also you were right FIA is not the issue.

 

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 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 us 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 its happening 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, 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 one would deduce 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 Ghost 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 pump 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, your knowledge on all things Accord is always so helpful. You're the reason why I do my best to answer other ppl's questions/posts/threads whenever I'm here... It's members like you that make this community and others like it (cb7Tuner.com in particular and the old cd5tuner site) such incredibly valuable resources. Anyway, Thank You.

 

You're welcome

The ECU determines rev limit. Only thing mechanical that would cause a rev limit would be fuel or ignition, but those parameters are still mostly controlled by the ECU. Small injectors or improperly gaped spark plugs (blow out) could cause engine to loose power at a certain point.

The fuel pumps in our return style fuel system are not variable flow. They run a constant flow based on a constant voltage (12v). The fuel pressure is regulated by the fuel pressure regulator, based on manifold vacuum. When the regulator sees vacuum it opens up the diaphragm allowing more fuel into the return line to the tank. Therefore reducing the fuel pressure in the fuel rail. When there is less vacuum (higher RPM) the diaphragm in the FPR closes therefore increasing the pressure on the feed side (Fuel Rail side) of the fuel system.

What fuel pressure regulator and injectors are you using?

Spark plugs and gap?

 

Ok that explains a lot...thank you.

I'm running the stock FPR, Walbro 255, and FIC 850cc injectors and my plugs are NGK BKR7E (iirc?) and I'm pretty sure they're gapped around .28

 

Well if the Walbro is working properly, fuel supply and pressure shouldn't be an issue. Those are good plugs and that gap should be good for boost.

Have you sent me datalogs to look at before? I've had people send them to me in the past and can't remember. I have pretty much all of the software to view and make changes to tuning files. I usually don't make any changes to files, unless it is glaringly obvious.

 

I might have but I honestly can't remember? PM me you email address and and I'll send them over this afternoon.

 

Hey Ghost here's a thought I just had... aren't the VSS and odometer directly connected on these Accords? I ask this because I'd read somewhere that the VSS could cause an issue like this, hence it being replaced, the thing is that my odometer still doesn't work..? And it worked fine up until shortly after installing the built motor. Anyway, I was just wondering if possibly all of this was somehow connected? Lmk...?

 

I was just looking at one of the settings in my current base code and it's got the VTEC pressure switched marked as being "disabled"? Why would the Pressure Switch be disabled? Isn't that what activates the solenoid? Here's a screenshot

 

Ghost, I also just noticed this:



Is it possible that when it's disabling closed loop that it's not working in open loop? Ie. Could this setting have anything to do with my revving issue? Thx

 

Did you ever swap those pins ? It is mandatory. That is likely the reason for your rev limit.

 

Yea I did... I should've explained this when I first made the post; so originally, when doing the build, I swapped A6 and A11 on the harness in order to connect the ECU (P28) to the Accord. As you know I was chasing this rev issue since way back in June/July. Anyway, I had to "step away" from it for awhile because I was beginning to obsess over it and it was making me miserable. FFWD to a couple weeks ago, the weather started changing, and I began to feel a new sense of urgency in relation to this issue so I started going back over EVERYTHING... I mean even ish I was positive about man! And when I started going through the wiring, the only diagram I could find for the OBD1 CD5's was the one I linked up above and it wound up being wrong!? (It sucks how much misinformation is out there) But the point of the OP was to verify that, cause I was afraid that maybe the pinout that was posted in that link was actually correct and that I'd swapped those pins out unnecessarily. Luckily that wasn't the case though and yes A6/A11 have been swapped since the very beginning.

Now one thing I didin't do, which I just learned about yesterday, was pull the R136 and R138 resistors off of the P28 board when using pin D10 (ELD) for the wideband O2 input (I was never able to get the Primary O2 [D14] input to read the wideband in Neptune). I have since removed the resistors but I don't know if it's had any impact on the rev issue (haven't had a chance to do a pull)? And we were able to adjust the offset enough within Neptune to read the wideband correctly while the resistors were still there, so it probably didn't change much at all..? I'll know for sure a little later today. Funny thing about this was that it wasn't mentioned anywhere in any of the installation literature? I just stumbled upon it yesterday while (as I said, going back over EVERYTHING) reading a thread on HAmotorsports.com about using the MTX-L with Neptune and which inputs should be used, etc... Here's a link to the thread though for anyone who's interested. I'm pretty sure this will pertain to other widebands using the D10 (ELD) input as well: • View topic - Wideband input

Also, and idk if this could play any role in the rev issue, I've got a huge amount of crankcase pressure building up in the head and I absolutely need to build a breather setup STAT!? I ordered all the fittings and hoses yesterday and I already have a VC with the bungs attached, but I'm still debating on doing a slash-cut return into the exhaust or just going straight breather to atmosphere style with a drain? Regardless I need to get it done right away as the pressure is literally blowing oil past the VC gasket and the grommets on the VC bolts!? And the PCV and the other line (far left side rear of the VC) are both already routed to a breather can!? They just don't have enough ID to excavate the pressures that are building up in there under boost. Anyway it's just another thing that needs to be addressed, and I thought it might be worth mentioning just in case it could have something to do with the rev issue?