Or something like that. It's a long story and if you want to play catchup, here is my other thread that leads up to this question I have now:

https://honda-tech.com/forums/showth...3#post45343643

My car is on the tow truck currently back to the Honda dealer to try to fix these problems once and for all. I have owned the car about 3 weeks now. I am really frustrated.

Alright, so I was having problems on my P73 ECU throwing code number 9 which comes up as a CYP sensor failure or something, right? And when I plugged in the chipped P72, I would get the same code. Well, when hooked up with the laptop anyways. Otherwise trying to jump it with a paperclip would yield nothing but a solid CEL and no flashing. Fast-forward to my new engine bay wiring harness, complete and clean to fix the hack jobbed one the previous owner did. Thought that would narrow down my problems and tell me if my sensors really were bad after all, or if it was just the wiring. So with the wiring fixed, now more codes than ever are popping up and the car won't even run. I got about 20ft into the middle of the road before it stalled on me. Started up again though, only to stall once I pushed the gas to about 1800rpm. I coasted down a hill to the spot where the tow truck would come save me, yet again.

No one seems to know what's going on with my car, or they really don't care. I'm really needing some solid info on this and there seems to be a lot of misguided information out there in the Honda world and I'm having a hard time keeping up with what is and what isn't BS. Let me try to make it simple for now:

On my P73 ECU (JDM), I now get CEL codes flashing 3, 5, and 9. But when I plug in the chipped P72, I get 2 longer flashes and then 1 quick short flash. First off, can someone point me in the direction of decoding these? I know there is a list somewhere.... BUT more importantly, WHICH ECU IS TELLING THE TRUTH? I am about to throw some money down on getting this thing fixed once and for all, and I don't want to go throwing $ at sensors that may or may not be bad, depending on what ECU is talking to us.

So which ECU should I use to go forward in diagnosing my problems. Obviously I have something amiss with my Code 9, so I'm probably going to have to get that CYP sensor setup replaced anyways, but now with 5 more CELs popping up, I am throwing my hands in there in frustration.

Both ECUs suck, basically. I only drive on the P73 because it somehow runs my car halfway decent to get around town, despite stalling on me every day at random and also getting me about 10mpg. The P72 eats gas too, and is more jerky and rough than the P73. Both ECUs run my car in limp mode. On the P72 sometimes I can't even shift past 3 or 4000 rpms. I have never owned a Honda and I don't even know what "VTEC" is because I have yet to experience it.

Anyways, any help would be sincerely appreciated. I would even give out my number if this could be better explained over the phone by chance.

Thanks in advance, if anyone sees this.

 

I don't get why you are running a stock ITR and GSR ECU in a Prelude?

But here is the list of codes:
ECU CODES (Thanks to Drag III Integra)

1 O2A - Oxygen sensor #1
2 O2B - Oxygen sensor #2
3 MAP - manifold absolute pressure sensor
4 CKP - crank position sensor
5 MAP - manifold absolute pressure sensor
6 ECT - water temperature sensor
7 TPS - throttle position sensor
8 TDC - top dead centre sensor
9 CYP - cylinder sensor
10 IAT - intake air temperature sensor
12 EGR - exhaust gas recirculation lift valve
13 BARO - atmospheric pressure sensor
14 IAC (EACV) - idle air control valve
15 Ignition output signal
16 Fuel injectors
17 VSS - speed sensor
19 Automatic transmission lockup control valve
20 Electrical load detector
21 VTEC spool solenoid valve
22 VTEC pressure valve
23 Knock sensor
30 Automatic transmission A signal
31 Automatic transmission B signal
36 traction control found on JDM ecu's
41 Primary oxygen sensor heater
43 Fuel supply system
45 Fuel system too rich or lean
48 LAF - lean air fuel sensor
54 CKF - crank fluctuation sensor
58 TDC sensor #2
61 Primary oxygen sensor
63 Secondary oxygen sensor
65 Secondary oxygen sensor heater
67 Catalyst low efficiency. (same as P0420)
70 Automatic Transmission Malfunction w/AT Controls
71 random misfire cylinder 1
72 random misfire cylinder 2
73 random misfire cylinder 3
74 random misfire cylinder 4
80 Exhaust Gas Recirculation insufficient flow detected
86 ECT Sensor (Engine Coolant Temperature) circuit range / performance problem
90 Evaporative Emission Control System leak detected in the fuel tank area
91 Evaporative Emission Control System insufficient purge flow

 

Thank you! Why are codes 3 and 5 the exact same?

Anyways, I am running a P73 in my Prelude because some genius before me got rid of the Prelude ECU and put that in there and sold it to me. Along with a whole host of other problems (see my link in the original post). But I'm trying to fix things and narrow down the problem(s).... I just don't know which ECU to use to diagnose this ****.

What are the codes from the P72 then? Two long flashes followed by one short, quick flash? Someone told me maybe that's VTEC related?

 

I have no idea why 3 & 5 are the exact same thing, I was not the one who made the code of list. But why not get the proper prelude ecu. For the year and model of your car.

For the p72 ecu. Two long flashes and a short quick one indicates code 21. Which is VTEC spool solenoid valve.

You need the ecu for the make and model of your car. That is where I would start.

 

Why I didn't get the proper Prelude ECU is because it needs to be paired with a new key immobilizer unit which costs $500 and all this work has to be done at the dealer with a new set of keys (possibly) and total I would have been looking close to $1000. Looking back on it now, that might not have been a bad idea though, considering all the BS I'm going through with these other ECUs.

When I bought my car it had the P73 ITR ECU in it. Some retard before me decided that was a great idea. Anyways, the Phearable chipped P72 with the H22 map I needed that he sent me did not work.

To date, nothing is working. I am going to return my Phearable ECU and hopefully also sell my P73 ECU. We will see what happens.

I thought Honda-Tech was the mecca of all Honda info and Honda experts. It seems like a bunch of kids run the place now. The ones who used to know their s*** and give a crap about one another were all here 5-10 years ago maybe. Then they all grew up and bought different cars or something. It's a real shame coming here from my WRX scene where forums like NASIOC make Honda-Tech look like a joke. Go post up there with your issues and within 30 minutes you'll have 2 pages full and most likely your question will have already been answered.

I can't seem to get any exposure anywhere on Honda-Tech for help. Off to the Prelude forums now I guess

 

The ecu shipped to you was the same ecu setup that hundreds of our customers run without issues.
How so? their cars have the correct injectors installed & they don't have major sensor/wiring issues.
Examples of prelude customer's on forums talking about their car running properly:
http://www.preludezone.com/4th-gen-h...rable-ecu.html
http://www.tuner-junction.com/TJForu...ame-today.html
http://www.superhonda.com/forum/f146...-video-238637/


An ecu that is going to make a car run corrections that is throwing codes such as map sensor, Crankshaft Position Sensor does not exist.
These sensors are VITAL to the vehicle running properly. Without the correct injectors for the ecu and without resolving your malfunction indication codes the car is going to run poorly.

Concerning your map sensor code: What color wires are running to the 3 wire plug going to the map sensor on the top of the throttle body?
Do you have access to a multi-meter that has audible continuity testing?

 

I corrected my "major" wiring issues with a new engine bay wiring harness. Did you not see that in my other thread? I am not accusing you of selling me a "bad" or "wrong" ECU or chip, so please stop. I know you are a legitimate tuner and if I was in Tampa, I would pay you to look at my car personally. But that is not the case.

How do you know for a fact that I have the wrong injectors? Why would someone go through all the hassle of putting Integra injectors on my car when they half-assed everything else? The mechanic at the Honda dealer seems to think the opposite of your injector theory. He claims that instead the injectors are the correct sized stock H22 application, but it is the ECU that is at fault.

And if it was only merely the injectors and they were honestly truly Integra injectors flowing at roughly 240cc, then how does that explain the local tuner guy who helped me with the chipped P72 who changed my injector size/scaling in Chrome to 240cc to keep me from stalling out.... yet when I went on to fix my "major" wiring issues, the P72 still does not work? You would think since it is set for 240cc injectors or whatever since you are 100% sure they are that the P72 would work well enough now to at least get me to someone to help tune me, right? The codes the P72 is throwing are completely different from the P73. That is my question to you and everyone else is which ECU should I be using to diagnose these issues. When you have two ECUs telling you 6 different things, you know? But the car is acting the EXACT same way on both of the ECUs. It will not rev past 1500-2000rpm before dying. It won't idle past 500rpm if you're lucky. I have done all kinds of "idle control" maintenance i.e. IACV, TB, EGR, etc. Nothing helps. New plugs, new ignition, good clean fuel, etc.

Are you suggesting I go forward with the P73 and use it to narrow down my problems? For example, if the P73 is throwing me 2 different MAP sensor codes and the same old number 9 CYP sensor (that you say doesn't exist?), you're saying I should go ahead and replace that $300 CYP sensor and probably the $50 MAP sensor as well? And that will fix everything? What then, plug in the P72 and then diagnose the VTEC codes or whatever it's throwing? Probably replace the VTEC solenoid thingy as well that probably isn't cheap either? lol

My wiring issues are fixed. There isn't a single broken connection anywhere in the wiring harness now. And you yourself told me that the wiring on the ECU harness was factory (the shielding I peeled back). So what gives? The tech at the dealer said the sensors were all ohming out just fine. And he said why should I throw a few couple hundred dollar sensors on there plus labor all for naught? For it to turn out to be really the ECU that is telling us the wrong CELs? I mean, how do we go about diagnosing the real problems at hand when we don't have the right "brain" of an ECU to talk us through the problems it sees. Should I take the local tuner guy I met up to the Honda dealer with me so he can plug in his laptop and adjust the injectors and idle etc etc and check the CELs while the mechanic works with him to figure everything out? Or should I throw down on some $177/EACH Prelude injectors because you are so very confident that this is the answer? I just have a hard time believing that. Especially since there are no codes. Wouldn't you think it would throw a rich code? Or if it's fouling the cat, wouldn't it be logical to think the O2 sensor(s) might foul next as well?



I will tell you about the color of the 3 wires on the MAP sensor when I can get to the car. It's currently at the dealership.

Thanks for chiming in. I thought Honda-Tech was dying lol



EDIT: In one of those threads you posted, I see that someone was having that same VTEC pressure thingy issue as well, but otherwise his car would run. So that doesn't make sense if the P72 is throwing only that code yet the car is acting the same way on the P72 as the P73 which is throwing more "serious" codes i.e. MAP and CYP sensors...

 

The injector size assumption is simply a pure remote guess per the symptoms you are describing. (Car running awkward with no CEL) This was before you new you had any malfunction indication codes (your malfunction indication light was not working)

As mentioned before if the car is throwing a CYP code & map sensor code, the car is going to run like complete crap regardless of the injector size being 240cc or 290cc on a 290cc h22 map.

When a vehicle is throwing malfunction indication codes resolving them is as simple as:
1. Check the malfunction indication codes.
2. Use a multi-meter to test the wiring between the sensor & ecu.
3. Test the sensor it's self.
These instructions are in the factory honda helms manual and almost anyone can perform the testing with a decent multi-meter.

Concerning a code 22 or 21 (vtec or vtec pressure). The car will startup and drive perfectly fine while throwing these codes. Your vehicle was not throwing a code 21 on the previous wiring harness with the obd1 ecu. A code 22 is thrown by a usdm ecu when using a vtec solenoid that doesn't have a vtec pressure switch. The vtec pressure code will only pop up once the ecu trys to engage vtec. The code 22 can be bypassed easily, however this shouldn't be an issue for you as you should have a vtec pressure switch on your usdm engine/harness.

If you need a spare stock map sensor to troubleshoot with, let me know I have a spare stock one sitting in my laptop bag I can send you. You really shouldn't need one because the "honda-tech" should be able to ohm out the ground/power/signal wires to the ecu and also check the output voltage on the map sensor while the ignition key is on to verify if the sensor is reporting proper voltage at atmospheric pressure to the ecu.

 

Absolutely. The real question at hand here though is whether or not the P73 is the ECU we/I need to be using to diagnose these problems. The P72 is throwing different codes. The title of this thread was asking which ECU I should use to determine the real source of my problems. Are you suggesting I use both ECUs? Until they BOTH run right?

Either you are being condescending on purpose, or you really think I don't know anything about cars. My problem, again, is not whether or not the sensor(s) themselves are bad, but if the ECU that is telling me that they are bad is bad. Why? Because I have the P73 telling me I have a bad MAP sensor and a bad CYP sensor. But the P72 is only telling me I have a bad VTEC thingymajig. But the car runs the same way with both plugged in...which is not running at all lol

Alright so I'm back to square one I guess. You're saying that perhaps now the wiring harness is the problem? I can't say the car ever ran right with the old wiring harness, obviously, but how can it be running WORSE with a new and un-molested wiring harness?

Yea, exactly. He said he should be able to do that, but he won't let go of the ECU factor. He is 100% sure that it's the ECU that is at fault and won't even go any farther helping me diagnose the problem(s) without first putting the "correct" ECU in there. Only then will he go to work on tracing wiring issues. It's all I can hope for at this point, since no one here has given me a definitive answer as to whether or not I should proceed in using the JDM P73 to diagnose my CELs or use the P72 provided by Phearable or both.

With the old wiring harness, I would only get code 9 on the P73 (one time I got code 3 as well), and on the P72 I would get a solid CEL/no flashing.


PS: John, you sell injectors, right? Can you help me get my hands on a set of H22 injectors? If you really think that they are part of the problem...

 

The obd1 ecu may not throw the map sensor code & other codes until the car has been started and the codes are checked while the car is running. The obd2 p73 likely stored the codes from you driving/running the car as to where the p72 did not.

Check your map sensor's continuity (power, ground, signal) to the ecu on the proper pins & also check the signal at atmospheric pressure with the key on engine off to see what is going on...

Remote guess is you have tps and map sensor plugs crossed/mixed up.
Hence I asked what color the wires are going to the map sensor.

Just an educated guess, but you probably have some plugs mixed up/connected wrong?
The map sensor & tps are both the same style plug. IACV, IAT are the same style plug etc.

Obd2 p73 likely stored the cels from when the car was running on it. The obd1 p72 likely wouldn't throw any codes until the engine was running and the codes where being checked at the same time.

I do not sell stock injectors. I would not touch the injectors until the codes are resolved.

 

By golly John you may be on to something. When I was changing out my thermostat the other day I accidentally reconnected some wiring sensors in that area wrong and noticed that some are the same. I think it was another sensor I had in place of the MAP sensor. Whatever it was, I had them backwards I thought. Maybe I had it right initially.

I will go to the dealer tomorrow to look at my car and perhaps switch the wiring sensors back to their rightful spot. If that fixes it, I am going to feel really dumb. What color are the wires that ARE supposed to be going to the MAP sensor, just so I know before I start disconnecting and mixing up connections again

My fingers are crossed but that makes sense. That might explain why the car does the same thing with both ECUs plugged in and will not drive at all...

Is there a way I can clear the stored codes from the P73's memory? I guess just leave it plugged in and disconnect the battery for 30 seconds or something would do it?


Assuming this fixes the CELs and wiring issues, do you have any recommendations for a place to find stock Prelude injectors by chance?

 

Honda-tech Marketplace

 

Thanks... I don't have PayPal though. So I'm out of luck on injectors via that method.

Bump for anyone to tell me what color the MAP sensor wires need to be??? Headed to the dealer to change that now if possible.

 

Helms manuals online: google prelude helms manual prelude power forums has them.

Map sensor: Yellow/Red Grn/White Red/Grn

 

mtber was right. I did have the TPS and MAP sensors backwards. Don't ask me how. I guess I switched them around when I did my thermostat and housing gasket fix because I was in a hurry to get it running. So as soon as I swapped those two wires I was able to drive home from the dealership. Funny that the mechanic there didn't seem to notice that lol.

I guess I will be able to return my CKP sensor that I bought since I don't think I need a new one after all. It's gotta be the CYP sensor. That's the only code it throws with the P73 ECU now. Still runs crappy (slow and horrible mpg), but the CEL comes and goes, it's weird....

...But on the P72, it runs worse. I guess that's because of the CYP sensor? Btw, it does now throw the CYP sensor code on the P72 ECU also, along with that VTEC code again. I wonder why it doesn't throw the VTEC code on the P73? Oh well.

I am eager to get this thing fixed. I don't know if after a new distributor/CYP sensor if it will run right finally. Wouldn't it also throw codes for being too rich? Which would point us/me in the direction of new H22 injectors like Phearable recommended from the get-go.

So assuming a new distributor fixes my CYP sensor check engine light, my car will still run richer than Bill Gates and I assume I will need to address the injectors next.... still can't find any stock injectors. But I don't know why the P72 runs the car worse, even though I think the local tuner guy I hooked up with changed my injector sizing to 240cc just to keep me from stalling out.

 

Looks like I was right. I remotely diagnosed your problem(s) from over 1500 miles away on the internet.
Yet a factory trained honda technician can't figure out such a simple issue in person.

Concerning your vtec code, check the continuity between the a4 pin on the obd1 jumper harness and the vtec solenoid.

My recommendation:
1. Fix the CYP code as you seem to be doing.
2. Have the guy who messed with your ecu to begin with, re-burn the original binary data to the ecu we provided.
3. Try driving the car on the obd1 p72.
4. Try 290cc injectors if the car still runs awkward on the p72.

 

Yea, he even tried telling me the reason people run the P73 ITR ECU in the Prelude is because it can rev higher, that's it. He said, "you know these ECUs don't give you any horsepower, right"?.

Thanks for that pinout diagram too. I'll be checking that along with the rest of my plans for the car this week to include a new distributor.

1, I think I am on the right path there... I'll ask the tuner guy who tinkered with the ECU if he can re-burn that ROM from you. Maybe with the CELs resolved it will all work itself out.

I'm still on the lookout for Prelude injectors, just in case.

 

Hey I've got a buddy who has the phantom CYP code. New distributor, new ECU and new wires don't help. Now you know damn well that the CYP sensor is functioning if the car is running at all. Anyways, I've been all over the Internet and found a few other people with this same issue where replacing the distributor and ECU doesn't help. So if you ever figure out what is causing your code, please let me know.

 

^^^ If the ecu or distributor did not resolve your problem, then you have a wiring issue.

 

Well, I'm not sure what brand distributor everyone recommends, but I just picked up a brand new Cardone one at Advance for $260. Installed it today as well.


Old one:









New one:




Also installed all new spark plug wires (OEM Honda brand). I was going to change the coil to a brand new Honda OEM one as well but Majestic Honda decided to send me a cracked and broken one I'm waiting on a replacement from them.

Anyways, the overall results? Haven't driven it much more than a few miles around town. It starts up better and doesn't stall. It honestly feels a little more peppy. Could just be the new parts.

But the good news: CEL 9 has gone away. At least, for the time being *knock on wood*!!!! The first second I reconnected the battery and fired her up after all the stuff was installed I immediately got a CEL 3. MAP sensor again. Mind you, this is all on the ITR JDM P73 ECU. I haven't tried the chipped P72 yet. I still need to resolve my CELs before I can play around with getting the P72 to run my car better.

So I double and triple checked my MAP sensor wiring. It seems OK. The connection is good. I don't know why the code is on. And it didn't take long for it to figure it out because it popped up the second I put the key in the ignition for the first time. *sigh* so, here we go on chasing this new issue :/

I guess the good news is that I THINK I finally fixed the CEL 9 with a new distributor and didn't need to spend the time and money and hassle on a new CKP/TDC sensor as I originally thought...

 

I've run new wires directly to the ECU. I've checked the resistance at the ECU. The part I don't get is that if the ECU couldn't read the sensor, the car wouldn't run.

 

It may run, but run like crap. Sort of like my problems I'm trying to track down now...

 

I guess I know more today than I did at this time yesterday, which is always a plus. I'm still confused and frustrated though.... just as CEL code 9 disappeared (which is AWESOME) with the new distributor, the CEL code 3 for the MAP sensor came back. And at first, it was only code 3. I have spent all day trying to diagnose this issue. At the end of the day, it started throwing another CEL code. I think it's 21 or 22 like previously mentioned? Here is a video I took:




But anyways like I said I spent all day trying to track this crap down. Here is a break down of the voltages I measured on the MAP sensor at the sensor itself... these are with the key on, engine off.


With the engine running, the power and ground voltages stay the same while the sensor wire voltages range from 0.85v - 0.89v.

I checked the voltages on the same wires at the ECU harness and they all read the exact same as well. So there is no break in continuity or a bad ground I don't think? My MAP sensor reads:


So I went and bought a brand new MAP sensor at the auto parts store, just to double check that it wasn't my MAP sensor that was bad, ya know? Sure enough, the brand new MAP sensor checked out at the same exact voltages as my current one. So that was good to know that I didn't need to spend $70 on one of those...

I pulled the MAP sensor off while the car was running and there is definitely vacuum on/at the hole. The gasket is intact (o-ring). The connector seems plugged in tightly. I really don't know what's going on anymore. I do know that I went through 1/2 tank of gas today though. And I drove probably a total of 40 miles maybe? Emphasis on MAYBE?

I heard having a bad/clogged catalytic converter can/could cause a MAP sensor issue... and I definitely have a bad cat I know that. But I don't want to replace the cat and have it go bad a week later because I'm running so damn rich that it ruins the new cat. That doesn't help me at all.

It's interesting now that the P73 JDM ITR ECU is throwing the same VTEC (?) code(s) as the USDM chipped P72 from Phearable. My next guess/step is to go throw the P72 ECU on there and see how it drives now that the distributor issue is fixed....

Suggestions/comments welcome and appreciated!

 

dude my wife's 2000 Civic Si had to be towed home yesterday. I am rockin a phearable p28 with chrome if i recall correctly, and have been using if for like 6 years. I just went out to look at it and read codes 3 (MAP), 9 (CYP), and 20 (ELD). it did fire up for me just now but barely. i just replaced the distributor last year so I hope that's not it. I'm gonna start troubleshooting the sensors. I'll keep an eye on this thread in case you have an update on your situation.

 

The video you provided shows a code 3 and code 21.
Map sensor and vtec spool solenoid.

As mentioned via email. You need to check the continuity between the map sensor signal wire at the map sensor and the map sensor signal pin at the ecu.

You also need to perform a continuity test on on the vtec solenoid wire from the solenoid to the vtec solenoid pin on the ecu.

A clogged cat wouldn't cause a code 3 or code 21.