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Discussion Starter #1
I dropped a dohc zc in my crx hf a while back, and ive been having problem after problem. What's going on right now is this:

I'm running on a chipped p28 that's untuned. I'm getting about 6 mpg with a slight studder in the idle.

FOR THE FIRST MONTH, it was running great with good mpg. Just recently, it started bogging down, would backfire, die, then fire back up on its own after about 2 seconds. After the backfire, I would get a huge cloud of black smoke. When I hit any rpm over 3k, this all ensues at the same time. When I had it parked, revved to 3k, it did the same thing. But I noticed that some white smoke came from the area under the distributor. I'm in desperate need of some troubleshooting. I've got a brand spanking new td43-u distributor on it right now, but it was sketchy when I first got it, so I have a new one on the way. Any input would be appreciated. Thanks!
 

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BATSLOMAN GIVES NO FUCKS.
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untuned p28......hmm, boy I wonder
 

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Discussion Starter #3
I thought this was somewhere I could post and maybe get some real answers. Not just smart ass comments. Thanks anyway bro
 

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BATSLOMAN GIVES NO FUCKS.
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ask questions.
gets answers.
butthurt ensues.




because logic. well lets see, if the computer doesn't know the timing, or fuel maps, and it just dumps a ton/pulls a ton, advances a bunch/retards more......but sure, lets get salty. makes it more fun for me




 

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Meat Popsicle
91 CRX Si
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I'm running on a chipped p28 that's untuned. I'm getting about 6 mpg with a slight studder in the idle.

Slo is right. You're running an untuned ECU so there is no telling what could be wrong. You're getting 6 mpg so obviously the tune is way off or you've seriously damaged something.

Did you get some kind of basemap for your engine?
 

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Discussion Starter #7
I have a very basic knowledge when it comes to car electronics. I have no idea what base map I'm running. The guys that made my harness told me to get a chipped and socketed p28 ecu to run the motor. Then said it would run fine with a basic map.

I bought it off of Craigslist, and the guy said it had a base map that was running his n/a dohc zc. Is this really most likely a tuning issue? Because I already have a pre-tune checkup scheduled for Monday. I'm good at the mechanical part. I can fix broken shit. Not computers.
 

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BATSLOMAN GIVES NO FUCKS.
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so do the basics.

timing
fuel
spark

clean the grounds
check the plugs/wire/rotor/cap ect ect
injectors firing/clean/pressure
timing/valve lash/inspect valves
compression test



if everything seems to be good, guess what
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
I have a very basic knowledge when it comes to car electronics. I have no idea what base map I'm running. The guys that made my harness told me to get a chipped and socketed p28 ecu to run the motor. Then said it would run fine with a basic map.

I bought it off of Craigslist, and the guy said it had a base map that was running his n/a dohc zc. Is this really most likely a tuning issue? Because I already have a pre-tune checkup scheduled for Monday. I'm good at the mechanical part. I can fix broken shit. Not computers.
Long story short, a P28 ECU is from a 92-95 Civic Ex/Si (I believe) and it can be "chipped" which means a ZIF socket soldered in place of the OEM "tune" chip and some sort of tune file is burned onto a chip that's inserted into the ZIF socket.

So you can run that ECU on various setups as long as you have the correct tune for your vehicle. Usually people will burn a basemap which should be the OEM tune for the engine, typically with expanded columns for boost.

If you don't know what's burned onto the chip that's in the ECU, you have absolutely no way of knowing what kind of programming the ECU is using.


Do all the things that Slo suggested and get to a tuner ASAP or start reading about tuning and invest in tuning equiptment.
 

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Long story short, a P28 ECU is from a 92-95 Civic Ex/Si (I believe) and it can be "chipped" which means a ZIF socket soldered in place of the OEM "tune" chip and some sort of tune file is burned onto a chip that's inserted into the ZIF socket.

So you can run that ECU on various setups as long as you have the correct tune for your vehicle. Usually people will burn a basemap which should be the OEM tune for the engine, typically with expanded columns for boost.

If you don't know what's burned onto the chip that's in the ECU, you have absolutely no way of knowing what kind of programming the ECU is using.
is there an adapter he can buy to see whats on it by plugging it into a computer? ive never tuned so i have no idea how it works.
 

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BATSLOMAN GIVES NO FUCKS.
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is there an adapter he can buy to see whats on it by plugging it into a computer? ive never tuned so i have no idea how it works.
depends on the software. hondata uses a usb to plug into a laptop, where as (I believe) crome uses a chip burner

and Paterico is correct, p28 is obd1 z6
 

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Discussion Starter #13
I was taking a closer look at the timing. My intake cam gear is off 1 tooth. Getting ready to fix it.

The transmission is fine. No slips, or bogging.


(Since last month)Also, brand spanking new distributor, wires, and ngk iridiums. That was my first effort towards a fix.

(Last week)Then it didn't want to start. Replaced the fuel filter and main relay. I didn't touch injectors or fuel pressure regulator. I bought a fuel pump, but haven't replaced it yet. But got it running again.

(Now)I have it dumping the exhaust after the downpipe since this morning. I'm pretty sure my cat is clogged from how rich it's been running. It was only used for 10k miles.


Thanks for the feedback. I'll keep you updated.
 

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BATSLOMAN GIVES NO FUCKS.
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theres another thing to check, cat and o2(s)

also, the chassis is odb0....do you have it converted to obd1?
 

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Discussion Starter #15
I have a very basic knowledge when it comes to car electronics. I have no idea what base map I'm running. The guys that made my harness told me to get a chipped and socketed p28 ecu to run the motor. Then said it would run fine with a basic map.

I bought it off of Craigslist, and the guy said it had a base map that was running his n/a dohc zc. Is this really most likely a tuning issue? Because I already have a pre-tune checkup scheduled for Monday. I'm good at the mechanical part. I can fix broken shit. Not computers.
Long story short, a P28 ECU is from a 92-95 Civic Ex/Si (I believe) and it can be "chipped" which means a ZIF socket soldered in place of the OEM "tune" chip and some sort of tune file is burned onto a chip that's inserted into the ZIF socket.

So you can run that ECU on various setups as long as you have the correct tune for your vehicle. Usually people will burn a basemap which should be the OEM tune for the engine, typically with expanded columns for boost.

If you don't know what's burned onto the chip that's in the ECU, you have absolutely no way of knowing what kind of programming the ECU is using.


Do all the things that Slo suggested and get to a tuner ASAP or start reading about tuning and invest in tuning equiptment.

So what if I just bought a pm7 to run my motor? I have the jumper harness already. Are the plugs the same on the p28 and pm7?
 

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BATSLOMAN GIVES NO FUCKS.
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shouldn't need a jumper if its meant for your engine. obd0. p28 is obd1
 

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Discussion Starter #17
I converted the swap to obd1. Exhaust cam sensor is screwed too. I have it on as a cap. Stock pm7 can't run obd1 right? Or would it be as easy as buying a different distributor and a new cam sensor with the pm7?
 

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97 honda coupe
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are you getting a solid check engine light? aka code 1. Sounds like the ecu is going into limp mode. 6mpg is pretty impressive that the engine still runs while its dumping that much fuel. At this point you should be able to smell fuel in your oil.

Remove/cut j1 jumper and report back.

edit: removed map sensor wut.
 

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Discussion Starter #20
are you getting a solid check engine light? aka code 1. Sounds like the ecu is going into limp mode. 6mpg is pretty impressive that the engine still runs while its dumping that much fuel. At this point you should be able to smell fuel in your oil.

Remove/cut j1 jumper and report back.

edit: removed map sensor wut.
What's the j1 jumper? There's a connection that's two wires and a plug. The wires are purple and black I think.
 
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