MAP Sensor
 

I ran my 97 honda cive DX through a monsterous puddle. Because of that I had to replace the cap, rotar, and distributor. I also replaced the spark plugs and wires. A few days later....it takes forever to start. When it does start it runs really rough for a minute or so and has really rich rich exhuast. It will chug between 2nd and 3rd at first and then it runs perfect. I can crank it right up within an hour or so after running for a while. And if its sits for more that that, I have the to repat the process. A couple days later, the check engine ligght comes on and the code is telling me "high circuitry" in the MAP/barometric pressure sensor. I understand the process of the air/fuel mixture to start at car, but no one at advance or autozone seems to agree that the MAP sensor is the reason why i have trouble starting my car. Before I put out another $200 for the MAP sensor, does anyone have any input on this? any help is greatly appreciated!

RE: MAP Sensor
 

Well if i am correct the MAP sensor is for intake manifold air pressure. Did that get submerged too? I mean its on the top of the intake mani so wed have to be talking a monstrous monstrous puddle.

RE: MAP Sensor
 

It didnt get submerged, I think its seperate from the puddle incident. I also used gas dry and fuel injector cleaner to rule out water in my gas but it hasnt worked either.

RE: MAP Sensor
 

Also, when it does finally start, rich smoke comes from the manifold. but it goes away just as fast it appears.

RE: MAP Sensor
 

did the ECU get submerged?

RE: MAP Sensor
 

Please forgive me. I am a girl ;) and learning more and more about my car, where and wht is the ECU?

RE: MAP Sensor
 

no need to appologize. The ecu is inside the cabin of the car. Its on the passengers kick panel (its under the carpet near the "Wall" where they put their feet)

RE: MAP Sensor
 

I dont think it got wet. there was nothing wet inside the car, and the floor board on both sides were dry. Firestone did a diagnostic on too. Would the dianostic catch a problem with the ECU?

RE: MAP Sensor
 

well if the check engine light is throwing a MAP code, then swap that map for a new one. Dont pay 200 for one thou.........call up some junkyards and see if they have em.

RE: MAP Sensor
 

What I would check is the catalytic converter. What could have happened is thermal shock to the very very hot catalytic converter and some materials cracked and/or clogged the cat. The exhaust may be getting restricted which in turn increased manifold air pressure, reduces lower end power, and makes it harder to start. You can try this:

First raise the car and look at the cat(do so after it has been sitting for a few hours so you don’t burn yourself). What you are looking for are signs of cracks on the outside and separation of the seems. Since you didn’t say it was making any exhaust noise I don’t think it will be cracked on the outside, but still easy to check.

Then tap it with the palm of your hand to see if you hear any rattling. This will tell you if any material cracked and is blocking your exhaust.

Then you can do a vacuum check on the intake manifold pressure as follows: attach a vacuum gauge to an intake manifold source(such as brakes or pcv hose). Allow the engine to reach operating temperatures. Gradually raise the engine speed to about 2000 RPM. Note the vacuum should read about the same as it did at idle. Then quickly release the throttle. The vacuum should momentarily rise then smoothly drop back down to normal. Should the vacuum rise slowly or does not quickly return to normal levels then the exhaust may be restricted.

A faster way to see if the exhaust is restricted is, disconnect the exhaust before the CAT, and try to turn it on when cold. If it turns on easier then either the CAT is clogged or the muffler. Good luck