se93

My 1995 JDM H22a powered 1993 Honda Accord has the following problem:
Everything was working perfectly until all of a sudden:

I tried starting up the car and it would start and shut down
Strong smell of fuel and when starting it would start to backfire when depressing the gas pedal (this is the only way it will start with a stock ecu)
Once started, i get a code 3 (map sensor)
We also realized that the Optima battery on the car was not retaining sufficient charge to even start the car. One one occasion, i left the car on (two days before all this started) with a/c and audio system and the car in neutral. About 25 minutes later, the radio and DSP processor were flashing on and off and the corner lights were really dim. I depressed the gas pedal and the audio system turned on and lights intensified. This is when i suspected that my battery might be bad.
Well, i had the battery replaced, installed three different known functioning map sensors and still the same problem. We verified all wiring from the map sensor all the way to the ecu and all is fine. I replaced my hondata P28 ecu with a known working stock P28 ecu and the same thing. When using the hondata P28, the engine will simply not start up unless i depress the gas pedal. With the stock P28 ecu, it will start up, but backfiring and very, very slugging in accelerating.

Well, finally, i decided to check voltage directly from the alternator. We connected the voltmeter and at idle got 12.6 volts, and also with the car revving at 2000,4000,6000,7000 rpm's got 12.6 volts. So, we figured that the alternator is definitely bad and must be the problem. Now, with this in mind, i decided to start up the car with just power from the battery and the alternator plug disconnected. If the alternator was the sole problem in this, then the engine would start up perfectly, right? Well, to my disbelief, it did not. The result was the same problem. What on earth is wrong with this?

My car just recently came back from the shop where the Euro R intake manifold and 2.5 inch custom exhaust were installed. The vehicle was test driven several times before this happened and all functioned perfectly.

What is causing this neverending Code 3 and the inability for the engine to start up normally? I definitely have a defective alternator and have ordered a new one, but where do i go from here? What is there left to check? Oh yea, i can say that the map sensor that was originally on before this problem was tested on another car and was damaged during this process. I have another known perfectly working unit installed at this time.

Sorry for the extended length of this post.

TIA

Mark Perez

poison

get a new MAP sensor. any map sensor will work and yes, your alternator doesn't sound like a problem at all other wise you can't drive the car.

MAP sensor causes the car to go into safe or limp mode because the ecu is unable to tell the exact vacuum in the intake manifold.

se93

Hmmm, i installed another map sensor and got the same results. The alternator doesn't seem to be right because i can remember when accelerating the car to about 3500rpms, the voltmeter would read about 14 volts, which is how it should be. I can't keep the car on long enough to even move it an inch. Is there a specific procedure to get out of "limp mode"? I removed the backup fuse in the fuse box in the engine compartment, but still the same.

Regards,
mark

Mikey3000

did you ground the wire harness properly? the one on the passenger side that should be grounded to the fuse box. it's a thick black wire.

se93

I've got an update with regards to this situation.

The problem has been fixed, but there is still something strange going on. First off, the problem was due to a corroded wire (one of the map sensor wires) leading into the plugs going into the ecu. This was fixed, entire wiring harness was thorougly removed and checked. No additional problems were found. Car engages as normal and runs fine. The only problem is that the check engine light stays on and i still get a code 3 (map sensor code)

Any suggestions?

Regards,
Mark

poison

Have you resetted the ECU at all?

And if the car is running fine and throwing MAP sensor code, I'm not sure if that's too possible.

When the ECU detects a defect in sensing the MAP sensor and what it's supposed to do, the ECU goes into limp mode. So if you are throwing code 3 after you reset your ECU (disconect the negative terminal for a minute or so), and still gettin code 3 but not in limp mode at all.

See if that works...

KTeller8

press the brake pedal also to get rid of any electro's left.. cant hurt anything