Firedrake

Ok, I'm tired of seeing all the posts about what ECU is best for the preludes and how the Hondata setup works, so for the betterment of the entire Prelude forum I'm gonna sit here typing for a while

This post is mostly for the 92-95 H22 or H23 people. If you have a 96+ motor, this post will assume you've got the OBD2->OBD1 conversion harness ready to install with whatever ECU choice you make. The only thing you need to do to convert an OBD2 car to OBD1 is install the harness. Some people will tell you that you have to change distributors because of the crank position sensor, but that is incorrect.

First, a note about chipping: Chipping is the process of socketing a stock ECU so that new fuel/timing maps can be burned onto a ROM and used to replace your stock ROM. There are lots of "programs" available, some are ok, some are crap. If you decide to chip your ECU, be VERY careful what program you choose to run. Always ask the person selling you the chipped program to tell you EXACTLY what kinds of modifications have been made to the stock map before you install it (have them tell you where VTEC crossover is, specifically what changes have been made to the timing and fuel maps, where the rev limiter is set, etc). There are tons of people out there selling "the ultimate ecu chip" that simply has no rev limiter, +10% fuel across the map, +10% timing across the map, and VTEC at some ungodly low RPM......ebay anyone? Hondata setups require you to be using a chipped ECU with some additional components soldered in.

P13 - This is the stock H22 ECU. It's good for a stock motor (duh ). It has the capability to be chipped, but the maps that are available are very limited in scope. If your motor is near stock, you will be fine with this ECU. You can get programs that have slightly more timing and fuel with a lower VTEC engagement and still be fine. If you want the capability to do some tuning and change VTEC engagement, an Apexi VAFC or similar MAP signal altering piggyback will work well. This ECU cannot be used with Hondata.

P14 - This is the stock H23 ECU. I would assume this ECU can also be chipped, but I've never seen it done and don't know of any available programs for them. This ECU cannot be used with Hondata.

P28 - The civic ECU and the cheaper most common choice. The P28 will NOT control the secondaries (IAB's) in the intake manifold on the H22, H23, and B18C motors. The intake manifold will stay on the shorter runners, and you'll usually lose 5-10ish horsepower from your powerband under 5500ish RPM. After 5500, the air velocity will be high enough that the shorter runners will start making power. Unless you plan on racing in the 2K to 5500 rpm range, this shouldn't affect you much.
The P28 also doesn't have a knock sensor like the P13, P14, and P72 ECU's. These ecus only use the knock sensor to alter timing under 5500 rpm. After 5500, the knock sensor can no longer make timing adjustments anyways. If you think that having a functional knock sensor under 5500 rpm is going to save your motor, you're wrong
The P28 IS Hondata compatible. In addition, there are TONS of various chipped programs available for the P28. If you're planning to run a chipped program in a P28, make sure the program is for your motor and not a civic. There are P28 programs available that mimic the stock P13 fuel and timing maps, but I don't see the point in changing out your ECU so you can run the same maps........

P72 - The GSR ecu. This ECU does control the IAB's and also has knock sensor capability, but is more expensive than the P28 ECU. Technically this is the best ECU to use, because it has all of the features, but usually these ECU's are overpriced. Knock sensor capability is mostly useless, but if you're running an N/A motor the IAB control might be something you want.
I've heard stories about people running stock P72's on prelude motors and claiming power gains. These people smoke crack. The maps on the stock P72 ecu are designed for the B18C1 motor, NOT for the H22. If this ECU makes more power, it's probably because it's running more timing or less fuel than it should be.
The P72 IS Hondata compatible. In addition, the Hondata software allows you to change where the IAB's open/close, so you can engage the shorter runners earlier or later if you'd like.

P74/P75 - The integra LS ecu's. These ECU's do not offer VTEC control, IAB control, or knock sensor control, and thus are perfect (and the cheapest) options to use on the H23 motors. These ECU's ARE Hondata compatible.

A note on Piggyback controllers (like the Apexi SAFC and VAFC) versus Hondata: A piggyback fuel controller alters the MAP signal in order to fool the stock ECU into thinking the motor is under more or less load than it really is. This in turn will alter the area of the ECU maps the computer is using to choose how much fuel and timing to supply.
The Hondata system directly alters the fuel and timing in the ECU maps, so you no longer need to mess with the signal coming from the MAP sensor. A Hondata system will replace any piggyback controller you're currently using and offer the same functionality. For example, the base Hondata s200 setup will do everything an Apexi VAFC can do and more. If you have a good local Hondata tuner, you'll be MUCH better off in the long run purchasing a Hondata system instead of a piggyback controller.

That's pretty much all I can think of for now Hopefully this will help people out in choosing an ECU, and feel free to let me know if you'd like info to be added.
Brian

satan_srv

If you really want to keep IABs you can just buy something like an MSD RPM activated switch...on top of that it would allow you to open your IABs whenever you want...

I run the IABs open all the time

racerx

Good post

So basically, an h22 running with a p72 won't need a fpr. What exactly does the ignition map do? Can't the slack be taken up with the distributor and the stock map used to adjust from there? Is there any other benefit besides being able to change where the secondaries open?

Sorry for all the questions but I've been wondering about this. I've always heard of and seen cars that weren't running right due to ecu swap complications.

satan_srv

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by racerx &raquo;</TD></TR><TR><TD CLASS="quote">So basically, an h22 running with a p72 won't need a fpr. </TD></TR></TABLE>


What gave you that impression? The P72 needs fuel adjustment to run an H22a safely...a V-AFC would be the best choice

ALLMOTOR18

p72..

I have one for sale.. it was used on an all-motor h22....

Let me know...

Jonathan_ED3

P72/Hondata

Unfortunately I'm not having the best luck right now with mine.

I sent in a p72 to get it socketed (because I DIDN'T want to use a p28 and lose my secondaries), and I got a p28 back. They say I never sent a P72

racerx

Satan SRV: Because the chip takes care of the fuel in a hi-po application.

To me, Hondatas chip is the only benefit with an ecu swap. Why not just get the stock ecu chiped? But then wouldn't the ecu need to be rechiped for every mod or two whereas the s-afc would just need a little finessing? And when you run into a problem where you suspect the ecu, the only way to know for sure that it is is to send it to hondata. The way I see it, whether you use a hondata ecu or somthing like a v-fac or s-afc, both are "patches". Ones just more difficult to diagnose and fix which ends up in more down time for the car.

Please correct me if I'm wrong. This is from what little I know about the ecu.

Jonathan_ED3

I haven't seen this mentioned, but what about EGR?

I know most people say ditch it, but if you want to keep EGR, you can't run the p28. Same with the IAB's.

Correct?

Hondata

Actually, since nitrous control is now a standard feature of all Hondata systems, you will be able to use the nitrous output control (either the Aircon clutch or Evap solenoid) to drive the secondary runners.



http://www.hondata.com/featuresnitrous.html

Firedrake

Hondata
I didn't even think about that, but it's totally correct. So now there is really no reason to get a P72 after all.......
Brian

fizzbob7

There was a mention that the knock sensor could only work under 5500rpm, but is that on all hondas, specifically JDM p13's?

If so, then that might REALLY point to the ks as my problem, because it will be ok when i'm really just redlining every gear, but if i drive normally it will act up under 5500rpm if i try to accelerate but as soon as vtec hits it clears up.....i don't wanna pay $130 or whatever for a ks either, and i already have my butterflies disabled anyway, but i DO have an egr valve (don't care if i keep it or not), so a chipped p28 should help me out then theoretically, right?

I don't have a lot of mods, and wanna go turbo later (possibly 2 years away) but wanna maximize the basic bolt ons and maybe cams or something with some headwork eventually.......but without use of the secondary butterflies, ks, and egr valve, would i run into any problems.....i don't suppose any codes would be thrown would they? Are there any other catches to this....any real drawbacks in a situation like mine?

and nice write up

ps......my sentence structure and writing "style" is better, isn't it mods

GimpyAccord

there are other ways to keep the IAB's with a p28. a clueful ecu hacker can use one of the auto tranny output (like say the converter lockup solenoid output) for this use. I don't think Hondata has caught up that far though... I'm sure they will sooner or later though.

I run a... umm non-hondata p28 in my Accord and no you don't see any egr codes or the like. Its nice to keep the EGR in place, but have it inactive. If I ever move to a state with emissions at least the car will pass a visual inspection. One thing to remember is that the p72/75/06/28 and a few others are all the same basic platform and it just depends on what you need to accomplish... esp if you have a block w/forged pistons a knock sensor will do you no good really ... thats just life.

Jonathan_ED3

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Firedrake &raquo;</TD></TR><TR><TD CLASS="quote">Hondata
I didn't even think about that, but it's totally correct. So now there is really no reason to get a P72 after all.......
Brian</TD></TR></TABLE>

What about EGR?

I've already failed emissions once due to the EGR system not working, and my brother has failed twice because of it.

Firedrake

Racerx: I believe you mean FMU, as an FPR is what hondas (and other cars) use to regulate fuel pressure. An FMU is similar to an FPR, but raises the fuel pressure by more than a 1:1 ratio per pound of boost. And yes, that is correct that you won't need an FMU with Hondata and the correct sized injectors/pump. The ignition maps allow you to alter timing values at every load/rpm value. If you advance the distributor, that will give you additional timing across the entire stock map, which you may not want. A Hondata unit is far superior to a VAFC, as I explained above.

Fizzbob7: Yes, to my knowledge that is on all hondas that the knock sensor only changes timing under 5500 rpm, so yes, a chipped P28 would be a good ECU to use in your application. Running a P28 with a Hondata would not throw any codes, and could be tuned to whatever setup your car had. Later, you can upgrade to the boosted Hondata unit for when your car is turboed.

Jonathan_EH: Are you failing emissions because they can tell the EGR isn't functioning, or because your actual emissions values are too high? I can't imagine that not having an EGR would make your emissions levels too high to pass. But you're right, the P28 can't control the EGR system.

Brian

GimpyAccord

How did they determine your EGR status (sorry ive never lived in a smog state). Did they hook up to the DLC and see that it wasnt working or????

Jonathan_ED3

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Firedrake &raquo;</TD></TR><TR><TD CLASS="quote">Jonathan_EH: Are you failing emissions because they can tell the EGR isn't functioning, or because your actual emissions values are too high? I can't imagine that not having an EGR would make your emissions levels too high to pass. But you're right, the P28 can't control the EGR system.

Brian

</TD></TR></TABLE>

They don't check to make sure everything is hooked up (to the best of my knowledge)...they just throw you on the machine and then if you fail, they start checking stuff.

The first time my bro failed, he had the EGR system removed.

The second time he failed, he had it back in, but the EGR valve was screwed up and the levels were OUT OF THE ROOF.

He replaced it with a new one, and passed like it was brand new.

I failed because I had the system in, but it wasn't working right (again, not failed because they SAW it wasn't working right, failed because I know that was the only thing NOT hooked up/running properly)

Having a P28, even though it doesn't look for the EGR, would put me at the exact same levels my car is at now....meaning I won't pass.

fastludeh22

iTrader: (1)

if you hav eyour car tuned w/out the egr you will still pass emmision's. i passed w/flying colors, and my car is modded from hell.

Jonathan_ED3

passed where?

I know people that tell me 'yeah, I passed emissions without a cat!'...but they're like in the middle of nowhere and don't even really have an emissions test.

I won't have the 400-600 bucks it takes to get my car fully tuned for a good long while....until then, I need to have the EGR.

fastludeh22

iTrader: (1)

here in gwinnett county, ga. turst me if theres one thing there strict on its cars.

Cm91h22a

Damn Brian you must have hade a lot of time on your hands there buddy. Good info for those who dont know!

By the way we'll probably be out at the track on sat. call me if you want to go,I'll be driving Averys car to try to get motivated to get my car back together.

LJR-LUDE01

good post, very informative.

CHK4TIX

great post, really helped with my decision making.

Firedrake

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cm91h22a &raquo;</TD></TR><TR><TD CLASS="quote">Damn Brian you must have hade a lot of time on your hands there buddy. Good info for those who dont know!

By the way we'll probably be out at the track on sat. call me if you want to go,I'll be driving Averys car to try to get motivated to get my car back together. </TD></TR></TABLE>

We still need to get that thing tuned for racegas! I'll probably be at the strip Friday and Saturday, I think Sal is going on Friday, but maybe he'll go saturday too......I think Dom really liked Averys car, because he sold the turbo civic and is now gonna do an H22 swapped turbo hatch....
Oh, and I'll bring Averys Hondata and a digicam to take more pix for the site.....
Brian

prelittlelude

so say one decided to go with a p28 and used the N02 to open the secondaries, then the only thing you would be lakcing is the knock sensor. and from what people have said here is that the knock doesn't do anything after 5500?

so then question is if we chose p28 and avoid the cost of a GSR ecu then what exactly are the down sides of not runing a knock sensor. if the car is tunned properly and high grade gas is used does the knock serve a purpose?

0Mike95lude

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by prelittlelude &raquo;</TD></TR><TR><TD CLASS="quote">so say one decided to go with a p28 and used the N02 to open the secondaries, then the only thing you would be lakcing is the knock sensor. and from what people have said here is that the knock doesn't do anything after 5500?

so then question is if we chose p28 and avoid the cost of a GSR ecu then what exactly are the down sides of not runing a knock sensor. if the car is tunned properly and high grade gas is used does the knock serve a purpose?</TD></TR></TABLE>

I'm guess the only purpose would be if you get bad gas or if someone fills your car with low grade gas, it will just have your ECU pull timing to resist detonation. The real question is, how much detonation would it take to kill a motor? No?