b20a ECU help

[Versanick]

So through many searches (help me if I'm a complete dink), I've found that I can use a pk2 ECU with my jdm gold top b20a. My ECU has been reflashed with much different fuel maps and it runs so rich that you can probably condense gasoline on a piece of cardboard behind my exhaust.

We tried unsuccessfully to make an 89 CRX Si ECU work. Is there a way I can simply reset my ECU for stock fuel maps? I would assume not, as 'reflash' actually changes the maps in the ROM of the ECU. Would I lose power using a pk2 ECU from my JDM ecu? Or only a few hp worth?

I need to save some gas badly. Is there a way to reset or do I need a different ECU?

[carotman]

You actually have the PH3 ECU? Is it from a 86-87 or an 88-89? (depends of the intake manifold you're using)

The PM6 ECU will NOT work with the B20A unless you use a different distributor. I don't think you would lose that much power with the PK2 ecu. However, it will run with less gas for sure.

Depending on how it was chipped, there is a way to return to the stock maps.

Just take a picture of your ECU circuit board and I should be able to tell you what to do.

[Versanick]

It's definitely a 1986 gold top, but using a 1986 LX-i stock a20 manifold. I'm still looking to buy a GUDE ported mani/TB to match my head port, but that's another story.

I'll get pictures ASAP. thanks a ton for the help cartoman.
I don't care what Phydeaux says about you, you're tha man!


(that was a joke. I don't think he said anything.)

[carotman]

Lol ok.

I wonder who actually reflashed an old PH3 ECU... This one uses different idling system and sould be different than the later 88-89 PH3 (much like the PJ0)

There is a way to chip them but it seems that no one actually figured the fuel maps for those ECU on www.pgmfi.org (PH3 and PK2). You usually have to keep the stock ROM intact and attach an external rom and controller to it (that's how pre 1990 ECU are chipped). You might just need to cut 1 wire on the external rom to deactivate it and reactivate the stock program. You could even use a jumper switch to choose the program you want to use (depends how the thing was chipped)

I wonder what are the differences between the PK2 and PH3 fuel maps... I have a stock PH3 bin here so if your actual rom was replaced there might be a way to put the stock fuel maps on the rom (I dunno if it's an 86-87 or 88-89). However, I run my B20A on a PK2 ecu without a flaw.

The only problem I see with you using the PK2 is the idle controls. The 88-89 controls were different and you would need to use an 88-89 A20A manifold or upgrade to a newer B series one.

BTW, the stock A20A and B20A intake manifolds are exactly the same... There is no power loss by using an A20A manifold on the B20A (86-87 or 88-89)

[thegreatdane]

Carotman, why wont the B20A distributor work with a PM6?
PM6 and PH3/PJ5 is both OBD0?

[carotman]

Yes, the B20A is OBD-0.
However, the conventional OBD-0 distributors use a distributor with a 16 teeth reluctor. The B20A has a 24 teeth reluctor just like the OBD-1 cars.

You have use another distributor if you want to use a OBD-0 ECU. However, the Vaccum advance B20A is a little different and uses a 16 teeth reluctor (Like the Euro B20A and people using a 86-87 teg distributor)

This also means you can convert the electronic advance B20A to OBD-1 without changing the Distributor. All you need is a 4 wire O2 sensor and a conversion harness.

The Accord and 88-91 Prelude B20A both use a 24 teeth reluctor and are swapable.

[thegreatdane]

Hmm, does any OBD-0, not pre-OBD, distributors fit the B20A?

So what does that make the PH3 ECU if the Distributor is OBD1?
I'd preferably like to run an OBD-0 PM6, but I was counting on using the B20A electronic advance distributor. Darn..

[carotman]

the B20A ECU (electronic advance) is an OBD-0 OBD-1 hybrid.

[Versanick]

So Al will take the pictures as soon as he gets home from work. Josh (b20a turbo) indicated to me that the fuel maps have been changed by whoever tuned it... Idk if that means a piggyback or something else... as you've shown you know more about it than I. Upon analysis however, (Al's a Subaru tech, and has a wealth of tools at his disposal), Al has found that I'm not pulling adequate vacuum until about 5500-6000RPM (presumably somewhere between the race cams, old vacuum lines, lines being plugged, and some bad filters and such in the black box)... and also he has discovered that for one reason or another my fuel pressure is somehow WAY too high. Note that an air/fuel analysis by RPM found mixes MORE RICH beyond 10:1 between 3000-4000rpm, where it couldn't even be read with the instrument used.. Al said he's surprised we're not launching fireballs half way through the tach when we take off..

So he's going to install a vacuum pump and clean up the lines, and fix the fuel pressure, and see from there. I told him also, as I said, to take pictures of the circuit board if this is still a huge problem. His original thought is that no matter how crazy the fuel map is, it wouldn't make the car run THAT rich. I had no idea, so I couldn't concur, but he might be right.

So we'll find out in a few hours, I think.
thanks again for all the info.. I'm learning a lot. Next is electronic ignition. we have no idea how to set this vacuum advance thing. with the timing light, trying to position the distributor, we can't see any numbers where we're flashing the light. And Al's set timing on a lot of cars. Elec advance would be such a blessing.

[carotman]

Vacuum advance ?!?!

You're not running a PH3 ECU then. The PH3 ECU has an output for the igniter and needs a 24 teeth reluctor. the vacuum dizzies have 16...

This must be a PJ0 or the SE3 (Euro B20A)

Tell me the part number on the ECU when you take the pictures.

[thegreatdane]

Just to straighten it out these are the correct Euro ECU codes:
Euro B20A 1987 = PJ5
Euro B20A 1988-1989 = PH3

PJ0 is for the A20A4.

[carotman]

Hmmmm, someone gave me SE3 as the Euro ECU code... I definetly need to dig into that.

I guess it depends if you're using an O2 sensor or not.

I wonder why they changed the ECU number in Eutope for 88-89 since the idling system basicaly remained the same throughout the years.

[thegreatdane]

87 Accords was without emissions, therefore no O2 sensor or EGR and their engine code was B20A2, however the 88-89 Accords did have emissions and the engine code was B20A8. That's why they changed the ECU.
So '87 B20A2 = PJ5
And B20A8 = PH3

I'm not sure if B20A2 was still sold in 88-89 in some countries, but if it was it would most likely have ECU code PH3 as well.

The plastic cover for the ECU has SE3 in the p/n. Maybe that explains it?

[carotman]

Any updates?

[Versanick]

I just sold my Sparco seat today for $300 and took pictures of the circuit board on the inside of the ECU and the labels on the outside. It says Accord / Prelude on the top of the box. Al's trying to figure out how to get the pictures on his computer right now to email them to me.

I'll let you know asap... thanks a ton

[Versanick]

Sorry for the very large image size. this is a pic of the sticker on the side. My other friend's camera has the circuit board pics and such. If you can tell by this, that's cool, but I'm working on the other ones. I don't know if Chuck knows how to get them from the digi to his cpu.

[carotman]

Hmmmm, that's hard to tell which ECU it is with that picture. Actually, the part number is the sticker located on the other side of the ECU beside the LED. However, this really looks like a PJ0 ECU so far

[thegreatdane]

Yea, that's not a PH3 ecu. That one is a Matsushita ecu and the JDM PH3's is of the brand denshigiken. I have a scan of the PH3 circuit board if needed.

[Versanick]

So the stock jdm b20a cpu is a PH3 but there is an 86-87 PH3 which does not account for electronic advance ignition, and an 88-89 one that does? My dizzy definitely came with the b20a and is definitely vacuum advance. So is there a different set of numbers after the PH3 such as PH3-003 or PH3-004? And I assume the electronic advance PH3 is also the 88-89 euro PH3? Or they are very similar

I'm assuming I should look for a pk2 to run my motor better if it's put together with a pj0 right now. I thought Josh had a ph3 in it.

[thegreatdane]

My JDM B20A ecu is from '86 and it's a PH3, so I believe in Japan all years of the B20A used the PH3 ecu. All of the JDM B20A's had electronic advance ignition. In europe however they all had vacuum advance and the 86-87 ecu's was named PJ5 and the 88-89's was named PH3 (but not the same as the JDM PH3).
Your engine code is only "B20A" right? And not followed by a digit after A. If it only says B20A, the distributor has been replaced with a vacuum advance distributor.

[carotman]

I'm sure you're running the PJ0 ecu with an Integra 86-87 dizzy and cyl/TDC sensor...

[Versanick]

My best reason to switch to obd1 is the electronic advance. But my number two reason is programmability/versatility. Something like a p28 is chippable among other things (not that I'd try to use one) and can provide me with the tunability that I am looking for.

I am contemplating if pk2 is the way to go for all practical purposes of being a relatively simple changeover (from my pj0 I see) and will at least provide my motor with better stock fuel maps and accurate ignition timing. I can't make anything work with these cams with no idle vacuum and such. The vacuum pump isn't helping.

So..

I suppose the project is to find an actual obd1 ECU that can work. (not including a GM ecu.. referring to Honda stuff) Upon searching other threads, it seems carotman has already found some ECUs that b20a5 dudes have found to run the car lean under 3000, among other things. Some research is required. Perhaps an f22 accord's unit wouldn't lean me out...

Another thing is that, when anyone is converting to a b16 or b18 (aftermarket or OEM) intake, I am curious why converting to obd1 isn't more common. For example, the limited vacuum ports and such that are found on most b16 and b18 intakes sort of limit many of the vacuum-run things (such AS ignition) that come on the a20's stock (and my b20, ugh), and using whatever sensors and such that are already inherent on the intake side of a b16 or b18 seem to beg conversion to a corresponding ECU...

My biggest wonder is how something like a p78 doesn't have the ignition timing way advanced from what the b20a5 (or b20a) would like to have anyway... I want my timing advanced, but not everyone wants it that much. Wouldn't the electronic control have the timing, for instance set at idle 20 deg BTDC instead of 15 like the a20's (and b20s?) like? I think my friend Vince's b20a2 is set as advanced as 24 degrees if I'm not mistaken...

Or is that not a problem, and doesn't apply?

[RobT5580]

My B20A is running a OBD1 convsion with the AEM EMS 30-1040 on it. You better off converting to eliminate all the crap and have tuning capabilities. Im considering getting a Honda ECU and going neptune possible since my tuner is so far away and its a pain. If i were in your shoes i would probably get a SAFC and an ecu being that they are relatively cheap.

[carotman]

Anyone has the Pinout for the 88-89 JDM PH3 ECU?

[Versanick]

Do you have any of them, carotman? I don't ever remember finding a pinout.. I'd love to have a real ph3 before Carlisle. I was considering p28 with SAFC.

Or just SAFC. I'd love to rev past 6950rpm though. My cams want to keep thrushing past. My torque clearly peaks as I hit the rev limit. I'm thinking 7500. I've considered even going carb. I am just SO hesitant to go away from EFI.