I have a 94 Civic DX with a B16A swapped in, running a P28 ECU with a P30 chip, and an A'pexi V-AFC. For quite a while now it's had the check engine light on, giving three short blinks and then solidly on when the code is checked. This, I believe, is the MAP sensor code, so here is my problem:
I have tried a number of different sensors, (originally was this style: GSR/B16 style part #3000, then a regular EG one: std. EG style bottom right part, and currently the GSR/B16 style part #2500, supposedly specifically for a B16) none of which have alleviated the code. This leads me to believe that it is a problem of wiring or vacuum tubing, but complicating this assumption is the fact that both the wiring and tubing appear to be in good shape, and if either the harness or vacuum tube is unplugged from the sensor, the engine immediately runs much worse.

Symptoms used to be nonexistent, but are getting much worse now with shitty gas mileage, hesitation at low rpm, and horrific exhaust stink. If anybody has any suggestions as to where else I need to be looking, help would be great!

Thanks,
Nik

 

If you have a buddy at a Honda dealer have him check your MAP values at the ECU with the Honda PGM Tester using the early OBD 3 pin plug. This will tell you exactly what signal your MAP is sending to your ECU and causing the MIL to come on and your existing problems. Do it before you waste your Catalyst!

 

I think you have an open in the wire somewhere. If you could run your own wires straight to the ecu, that would confirm this.
OR
have you tried another ecu, maybe a p30 or something else? ( if at least it doesn't give you the same code -you will get others- then the ecu is the culprit)

 

Thanks for the responses! I could probably get the MAP values checked, but not for free, lol. I'll go ahead and check the wiring more thoroughly, and maybe I'll see if I can replace the gray part that plugs into the sensor, since I've got one laying around.

Does anyone know where I could find a diagram of ECU pinout to double check it's plugged in correctly and such?

Also, an addendum to the original info: It used to have a Skunk2 chip with no check engine light, and just a really rich map. The light came on when the P30 was installed.

 

Bump

 

ttt

 

does the code show after some low rpm driving, or after decelerating thru a lower rpm range? and more frequently after having driven a short distance without reaching highway speeds for an extended period?

given your setup... i'd bet it was your o2 sensor

oxygen sensors slowly go bad and when running rich as you probably are they become slow to respond and even less responsive to being warmed up under there own power.

my car can run flawlessly with a new o2, after about 6 months it will start to throw either the map code, or fuel system code (43), and every once in a while the o2s code (1). it usually only happens under the conditions i mentioned above, but will happen randomly as well. it happens rarely but more frequently over time untill the sensor becomes completely unresponsive.

i have also seen a bad map sensor as well... but if it was bad you would almost guaranteed notice it on the vafc as your pressure would never reach atmospheric pressure at WOT or when the car is not running but key is on. my friends got stuck at 200mm hg and wouldn't go above, but would reach and greater vacuum up to 750 normally.

so check voltage from the map with the car off, then with the car at idle.. i think its around 2.4v at idle (~700mm/hg) and from there will change to real close to 5v or 0v i can't remember which way it goes right off hand..

the o2 can't really just be checked for sure. but pretty much if its less than .8v on a cold start its beat assed taken a **** on you. but chances are its slowly diein and it would need to be monitored to see how it changes values on and off the throttle... and with the chip and all you have, it'll probably only come off .8v at closed throttle on the highway with the car hot, when i'tll go down to close to 0.. again if your program allows it.

hope some extra info helps you or some searcher

 

The check engine light comes on pretty much immediately after start up.

Given the values you said should be sent out for pressure, I think there definitely is something wrong with the wiring or ecu.... I'm getting negative 530-540mmHG at idle, and negative 100-120 mmHG at WOT. No es bueno eh?

Anybody know where I can find the ECU pinouts?

 

ttt once mo!

 

ttt

 

again

 

Almost any map sensor will work. I used a map sensor from a d15 on my b16. Works great so I dont think thats your issue. Maybe a vacumm leak.