Mitsubishi Diamante 1999 won't start right after rain

SERGA79

MEMBER
1999 MITSUBISHI

Hi everyone,
I just bought my Mitsubishi Diamante 1999, 88000 miles. The car runs fine. But after the first rain I had trouble to start up the car. Then when I finally started the rpm was jumping from 300 to 2000. The car died. When I came back in one hour the car starts like nothing was wrong before. When the car is hot if I turn the engine off for about 15 min the rmp jumps from 300 to 1500 until I push the gas pedal a few times. I had a full tune up done but this did not eliminate the problem. The check engine appeared once. I had the car checked and first mechanic affirmed that it is the airflow sensor the second - that is misfire on random cylinders. So it can be everything. After all I am reading in the net it may be the fuel filter which I didn’t change yet. ( The dealer estimated 128$ labor only)
Please help me out I’ve spent 700$ on tune-up and check-ups already. I cannot afford to spend more money to find unknown problems.
Thanks in advance.

3 Replies

SERVICE WRITER

MECHANIC
9,123 POSTS

Did the full tune up include ignition wires? I wouldn't think it was a full tune up if the fuel filter wan't replaced.

Stay with one mechanic you trust-too many cooks spoil the broth.

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Monday, January 1st, 2007 AT 8:31 AM

SERGA79

MEMBER
2 POSTS

NO I did everything including the wires, alternator cup. On Saturday I've installed the fuel filter. No changes. The problem stays. One night in rain and in the morning 15 min to start.

I do not trust any mechanic.

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Monday, January 1st, 2007 AT 12:52 PM

JASONLIVES2

MEMBER
1 POST

Your problem is either your mass air flow sensor or one of the 2 o2 sensors, although I would bet on the MAF sensor. I have a stealth twin turbo and I went through the same problem.I would get in the car and it would drive great and then I would park it, come back in an hour and it would be chugging like it was running on 4 cylinders. Next time you are under the hood and the engine is running, grab hold of the MAF sensor's electrical plug and gently move it up and down, also do the same with the wires going into the plug. If you notice any variation in engine idle, your problem is a bad connection and you should remove the plug and clean the plug and the prongs on the Maf sensor with an electrical cleaner. Sometimes you have to use a tiny brush on them but be careful not to bend them. If on the other hand, nothing happens manipulating the plug, then your Maf sensor's problem is internal. Now for the bad news. A MAF sensor on our cars run anywhere from $500 new to $125 used or remaned. The oxygen sensors however are not that bad ranging from $75 to $35 new. The problem is, which one do YOU choose to try first. It's hard to tell. My car won't even stay running when one of my o2 sensors are unplugged and the same thing happens when I unplugged my MAF sensor. I just got lucky and guessed the right part. Good luck! And I hope you do too! Rick

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Saturday, January 13th, 2007 AT 3:33 AM