Ok I have to start a new thread because H-T search blows hard (I'm sorry but it does), and I can't find the old thread that we were having this discussion in. If anyone can find this thread it would be greatly appreciated!!

Basically it was like this, I have a 96 OBDII VTEC...so I wanted to do an OBDI swap. I picked up an OBDI GS-R P72 ecu and my buddy just finished the conversion harness.

The discussion was regarding the use of a different ecu and a different engine setup. My engine is the H22A1, a p13 A12 ecu, 310-330cc peak and hold injectors, with an external resistor box. Thus these are the low impedance injectors (2ohms?)

The P72 ecu is from the B18C1, which has Honda's saturated injectors. Basically the resistors are on the injector, these are high impedance injectors (6ohms?)

So the discussion, which was with myself, Dirtylude and aklucsarits was over whether this would cause some problems. aklucsarits has experience of people throwing engine codes from and ecu swap like this, he could probably add more info here. Also, he was saying that it is bad to run a 'saturated' ecu on peak and hold, because it will be applying a constant "saturated" signal as opposed to the peak and hold style.

Dirtylude said that the two ecus drive the injectors exactly the same way. *edited for Dirtylude, he explains below*

ANYWAYS....

They can add more here, but basically this weekend we plugged the P72 into my prelude using an OBDII-OBDI harness (with added V-AFC harness NICE!)...fired the car up....NO CODES!!

Ecu worked fine, I had a low idle, but it was the same thing we experienced when we put it on my friend's JDM H22a. I went out for a few runs with it....redlined it from 1-4 and it works with no problems. Woohoo!! Progress! The only thing I can say to aklucsarits is that your friend's problem may have been specific to Hondata and not the OBDII-OBDI swap.

However, I won't say my results are without a doubt. This is a chipped ecu, and it's possible CELs have been disabled. So I need to do a test. I can probably borrow an OBDI prelude ecu to check to make sure...also what's something I can do to blow a CEL, but not do anything bad to my engine? Some sensor I can easily disconnect?

I welcome your questions and comments


[Modified by satan_srv, 10:27 AM 8/19/2002]

 

you could run them in a 5th gen (saturated injectors)... if there's no codes then you know it wasnt chipped to run with pnh...

 

what are you saying? If I put it in a fifth gen and no codes, I will know the ECU drives both types of injectors the same way?

want to run it in your car? I still have the harness, I should have called you on the weekend. I am booking some dyno time for the end of the week/weekend...you could meet me and test it.


[Modified by satan_srv, 9:50 AM 8/19/2002]

 

I never said Honda injectors were not true P&H injectors. Really, there's no such thing as a true P&H injectors. There's only low resistance (no resistor), and high resistance (resistor built in) injectors. Refering to injectors as Peak and Hold or Saturated is technicaly incorrect terminology, but everyone seems to do it anyway.

Peak and Hold and Saturated are two ways of driving injectors. It just so happens that Peak and Hold drivers are most commonly used with low resistance injector (with no external resistor) and Saturated drivers are most commonly used with high resistance injectors, or low resistance injectors with an external resistor.

Nice going with the swap. Matt did an excellent job on the harness then.


[Modified by DirtyLude, 10:07 AM 8/19/2002]

 

Yes he did! If our site was up I'd post pics

btw: doh! sorry for misquoting you! I was going by what you said here https://honda-tech.com/zerothread?id=202019


[Modified by satan_srv, 10:15 AM 8/19/2002]

 

The ECUs that we tested with were 100% stock - no Hondata. We had a 1994 P13 and later a 1995 P72 that we tested with. Two cars were tested, a 1997 Prelude and a 2000 Prelude. The harness we used was supplied by Skunk2. We did these tests about 2 years ago, so my memory of details is not the greatest. We also knew a lot less about our cars 2 years ago that we know now. (e.g. the first time we got togther to do some tests, we did not even know how to check what number code the CEL was throwing...)

But again, just to recap what I was saying in the last thread... In our testing, we consistantly got multiple CEL codes indicating the CYP sensor as I recall. Mazen (g5luder) had several CEL codes in our testing that only disappeared when he switched to a 4th gen OBD1 distrubutor based on Sun's suggestion. My contention in previous treads on this subject was that the distributor change was neccessary to get rid of the CELs. This was based on our own tests, and the experience of at least 1 other person who had done this swap.

What distributor are you using Satan_SRV? Does the 1996 distrubutor have all the sensors inside it? Or is it the 5th gen style distrubutor?

Good info, keep it coming.

Andrew

 

Hmm well if you can tell me the easiest way to check that, I'll let you know!

I'm thinking it would be a fifth gen style one, because the you can't manually advance the timing = which would say to me that the sensor has been moved to the crank. Is there a visual difference?

I will try and test an Stock OBDI p13 tonight, if I can find someone in the area with one...

 

Without knowing the wiring differences you would need to take the cap off of the distributor and look inside to see if all the trigger wheels were inside.

 

hmmm to tired to read it all, but if you want to build a knowledge article outof it.. i can put it on my website.

 

the 96 distributor is different of that of the 93-95 vtec distributors.

taht's one question i did not understand when i spoke to hondata about my set-up last year. i was concerned about the tripping the codes for the distributor since they are completely different. i just don't understand how it would read onto an obd1 ecu when the motor is completely obd2 wired. oh well, but i do know some people have not had problems. perhaps, it has more to do with specific set-ups.

satan, why exactly are you converting to obd1? not much of a benefit with just bolt-ons.

 

Because I can, and I wanted to see test back to back on the dyno just to see what happens. Also, a club member wanted to test his own conversion harness.

I was going to use it for Hondata, but I'm selling the P72 after the dyno, and saving for a standalone/turbo.

Haha I have no bolt-ons, just an AEM CAI. Go big or go home I say


[Modified by satan_srv, 3:26 PM 8/19/2002]

 

is it the same as 97+ distributors?

 

ah, i see. thanks for the clarification.

i'd stay all motor though. your car seems healthy as it is with that 14.8.

 

not when you have to drop the clutch at 6k to get it

so do you know if the 96 is the same as the 97 distributor?

 

Thanks bro, I have dyno and a comp test this week, so I'll know what's up with my engine.

Flavour, I haven't had time to check...but the Distributor should be like the the 97, because you can't manually adjuct the timing, which tells me the sensor has moved.

Okay new question. Can you run a JDM P13 ECU on a USDM H22A1? Yes or No? I was thinking this internal/external coil business may cause a problem. Anyone have experience?

It's just that I have a JDM P13 handy, but I don't want to bother if it's not going to work.


[Modified by satan_srv, 9:59 AM 8/20/2002]

 

yes you can, vince has a jdm p13 that he swaps with his regular one all the time. the jdm has more advanced timing stock...

 

Nice!! Tonight will be a 3 ECU dyno!!

Stock OBDII p13
Stock OBDI JDM P13
Chipped OBDI P72

 

Crap...this is on hold till I fix my crank pulley....so dynos on Thursday