I have a P28 ECM in my 94 Accord. I bought it from a reputable vendor. Everything is working on the stock ECM. With the chipped P28, it won’t run at all unless I disconnect the MAP. Then it runs fine. Of course I won’t drive it that way because it can’t properly schedule fuel and air….blah blah blah. I noticed the PN for the 94 Accord and Civic MAP sensors are different. I’m going to check output voltage of the sensor tomorrow. Should I by the Civic MAP to rectify this problem?

 

All the MAP sensors are the same voltages PN does not matter. Also the wiring is the same for all 3 wire 90-97 Honda MAP sensors. Disconnecting the map with the P28 installed will be putting the ECU into limp mode, that is why it will run. If this runs great on the stock ECU, I would say there is an issue with the tune or the P28 ECU itself.

 

Thanks again. Output voltage is good. I’ve contacted the company I got the ECU from. We’ll see what they say tomorrow.

 

Just remembered something here. When running a P06 or P28 ECU on the 94-95 OBD1 Accord you may want to switch 2 wires at the ECU wire harness.

• Move the wire at ECU pin A6 to pin A11
• Move the wire at ECU pin A11 to pin A6

Accord
A6 = EGR
A11 = O2S heater circuit

P06/28
A6 = O2 heater circuit
A11 = EGR

 

Thanks. I did that when we got it. I’m also going to check the O2. But I’m certain it’s something with ECU

 

So all of this stuff I'm doing is on a car I bought for an enduro race and I've been running it at the local circle track. It has a fabricated dash and no CEL. How can I pull trouble codes without a CEL?

 

Oh....hearing that kind of makes my head hurt. Not a huge fan of diagnosing racecars with modified electrical over the internet.

How hacked up is the dash wiring harness, are the dash gauge cluster connectors still there? If they are then I may be able to help you with hooking up a bulb to the MIL circuit.

 

It makes my head hurt every time I take the hood off of it. The wiring is intact and connectors in place. I wired a switch into the VTEC circuit so if it stops working I can manually turn it on, even though it won’t properly schedule fuel and air. ABS, EGR gone. Thinking about getting Hondata in my P28 to help me out. Looks like the EZLynk I have on my Chevy 3500 and I love that.

 

So I'm guessing that you do not have the hardware and software to monitor/tune the chipped P28 that you have purchased?

If you are using this as a dedicated racecar, owning your own tuning setup would be beneficial. Unless you want to pay someone to tune it for you.

 

That’s one of the main reasons I’m looking at Hondata. I don’t want to pay someone to do what I can.
Im installing a wide band O2. All gauges are analog other than that. I wired in warning lights to the oil and temp. Everything I’ve added is on its own dedicated fuse block. Building this engine for it. This stuff is fun to me.