p72 questions, and ecu in general - Honda Prelude Forum

ludeInDa513 · 07-05-2006, 11:23 PM

I tried the search and read threds for about an hour and didnt find all the answers I wanted so I decided to start a thred. I can get a p72 ecu for fairly cheap and the guys says the ecu will make my vtec kick in at 4400 and redline will be at 8200. Does that sound legit? Would the vtec be weaker then normal and would I lose a lot of low end power? Would this be better then lets say a p28 or what would the differences be? Would i get worse gas mileage and if it was chipped would that further lessen gas mileage? (im assuming so cuz it would make it run rich). As far as a hondata system goes, where can I go to read more about them because I am a noob. Feel free to answer one of the many questions proposed, and thanks for helping out a noob

AllMotorBB6 · 07-06-2006, 07:04 AM

you need to get the p72 socketed and chipped with an h22 basemap in order for it to work properly. Retain the stock vtec crossover until you get onto a dyno or atleast get street tuned.

alphajesse · 07-06-2006, 09:05 AM

You don't want to be running a P72 unless it has been tuned for your engine.

bdb · 07-06-2006, 10:16 AM

Yes, an OBDI P72 will work, but only after it has been 'chipped' with an H22 basemap on it. Then get it on the dyno with a Hondata piggy back on it -- you'll be happy.

marcucci · 07-06-2006, 11:09 AM

A little more specifically-

The P28 was in the 92-95 Civic EX and does NOT have IAB control (intake manifold secondary runner butterflies). If you are interested in top-end only, this is not much of an issue as the default state of the butterflies (without ECU control) is open. You can expect to lose some low-end torque as a result.

The P72 was in the 94-95 Integra. It DOES have IAB control. It also has knock sensor capability (the P28 does not) but the KS board in it is incompatible with the H22. you can swap the knock board in from a P13 (92-95 H22 ECU) but that requires some detailed soldering work. The KS is also limited in usefulness, a J&S system is much better if you actually want knock "protection".

Beware as there are OBD2 P72s which can't be chipped (make sure it is an OBD1 P72).

As mentioned, NEVER run a P28 pr P72 on an H22 without having it reprogrammed.

A 4400 VTEC point is a little low for most H22 setups. 4800 is ideal for an H22 with bolt-ons. Only dyno tuning will reveal the ideal point for your engine.

8200 IMHO is too high of a fuel cut for stock rods and valvetrain. You are inviting disaster. Set it to 7800 or less if you want to be safe.

ludeInDa513 · 07-06-2006, 11:49 AM

Thanks for the info. Also the previous owner of my car took out the butterflies, so im guessing the IAB control wouldnt really matter right?

marcucci · 07-06-2006, 07:52 PM

Correct.

BBYlude · 08-31-2006, 07:01 PM

With the butterflies still installed, would it be worth it to run a chipped P72 and have it tuned (it is required, right?)? Is the lack of the closed IABs at low rpms going to hinder performance noticeably? Or should I run a P13, which seems like the most cost effective solution. I don't want to have to get a piggyback program and get dyno time and tune it. I want to get an OBDI ecu (hopefully already chipped for a 5gen lude) and make it work. What should I do?

Artifex · 08-31-2006, 07:12 PM

Quote:

Originally Posted by BBYlude

With the butterflies still installed, would it be worth it to run a chipped P72 and have it tuned (it is required, right?)? Is the lack of the closed IABs at low rpms going to hinder performance noticeably? Or should I run a P13, which seems like the most cost effective solution. I don't want to have to get a piggyback program and get dyno time and tune it. I want to get an OBDI ecu (hopefully already chipped for a 5gen lude) and make it work. What should I do?

You might be confused about something. The P13 came with all 4th gen (VTEC) Preludes. They support IAB control. Both alternatives you mention support IABs. The P28 on the other hand does not. It is generally more abundant, and cheaper to get.

Running an off the shelf P13 chip doesn't really do much. If you live in California, it can be dangerous, because most aggressive chips assume 93 octane.

If you run Neptune, it supports both the P13 and P72. PGMFI tools and Hondata support only the P72. The ECU you should get depends on how you want to tune it.

BBYlude · 09-01-2006, 09:04 AM

I don't want to tune. I just want a stock obdI setup. I may, in the future tune it, but for now I just want it to be obdI and I want it to work. It is cheaper I think to run obdI when doing a 4gen H22A1 engine into a 5gen I believe, as well as power gains are more plentiful!

edit: It just hit me that the P13 is the obvious choice for money and simplicity. Thanks!

Artifex · 09-01-2006, 05:51 PM

Quote:

Originally Posted by BBYlude

I don't want to tune. I just want a stock obdI setup. I may, in the future tune it, but for now I just want it to be obdI and I want it to work. It is cheaper I think to run obdI when doing a 4gen H22A1 engine into a 5gen I believe, as well as power gains are more plentiful!

edit: It just hit me that the P13 is the obvious choice for money and simplicity. Thanks!

You should realize that in nearly all states, swapping an OBD1 into an OBD2 car is illegal. It violates smog rules, unless you are lucky enough to live in a state without smog (Florida, Arizona).

Solid · 09-02-2006, 12:15 PM

Quote:

Originally Posted by Artifex

You should realize that in nearly all states, swapping an OBD1 into an OBD2 car is illegal. It violates smog rules, unless you are lucky enough to live in a state without smog (Florida, Arizona).

Louisiana

eolife22 · 09-18-2006, 09:54 AM

p28 or p72 is better for NEPTUNE tuning?

alphajesse · 09-18-2006, 11:39 AM

p72 if you want to control the IABs. Otherwise, it doesn't matter.

Phat8186 · 09-18-2006, 12:08 PM

Can crome control the p72's IABs. I ask cause that is what I am going to have to tune my car with until I get to a Mr. Evans for Neptune tunning.

eolife22 · 09-18-2006, 12:09 PM

What is IAB's?

Phat8186 · 09-18-2006, 12:11 PM

Quote:

Originally Posted by eolife22

What is IAB's?

(intake manifold secondary runner butterflies).

Phat8186 · 09-18-2006, 12:18 PM

Quote:

Originally Posted by eolife22

What is IAB's?

Hey how do the Skunk2 stage 1 cams feel I have almost the same setup as you but never installed the cams. I am now on my way to go turbo so I dont think I will be using them anymore. I am interested on your take on how they felt in the car.

eolife22 · 09-18-2006, 01:31 PM

Quote:

Originally Posted by Phat8186

Hey how do the Skunk2 stage 1 cams feel I have almost the same setup as you but never installed the cams. I am now on my way to go turbo so I dont think I will be using them anymore. I am interested on your take on how they felt in the car.

I can feel gains at high RPM versus before the cams.... Cant really say yet because im still untuned though.....

and is it really a difference if you control the IAB's alphajesse?

alphajesse · 09-18-2006, 10:49 PM

Yes, if you have the stock IM, you'll get better low-rpm performance without sacrificing high-end power.