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Car shaking and Check Engine after heavy rain

Alexander Reznikov Alexander Reznikov
New User | Posts: 1 | Joined: 04/17
Posted: 04/24/17
05:19 AM

Hello, I will try to explain the problem in as much details as I understand.
I am talking about Mazda Protege 2002, 160k mileage.

1.5 years ago my car would die 10 seconds after start; it shaked on D (and not on N), then the Check Engine sign came and then it died. About 15 minutes later, when I almost arranged a tow truck to the mechanic, it actually got better and I drove it to the mechanic. They read the Check Engine codes and said that, in fact, it does not look right so I should drive it a bit until the actual problem comes out. I did so, and about a week later Check Engine sign came again and it turned out that it is a misfire due to old coil. So they repaired (replaced?) the coil, and it got fine.

Then in December I got the very same problem again, with the same symptoms. This time the code revealed a problem with some solenoid (solenoid 2?); the fuel was injected in too big quantities, so somewhere there was no oil at all, and it caused a misfire. So they repaired it.

But then, pretty soon, I started getting the same problem. The car was drivable, and, in fact, the problem would go away after like 5 minutes of driving. The Check Engine light would go away in 3 days. Today I got the same thing again. It shakes on D (especially when I do not press the accel. pedal) and acts normal on N. It begins to act as usual after 5 minutes of drive.

And - maybe it is important - I noticed a while ago, and today it confirmed, that this happens only after pretty heavy rains (the car is not in a carport or garage).

Could you please suggest what can it be?

The timing belt, as well as any other belts, was replaced long ago, somewhere at 100k miles. Other than that, I changed the oil frequently and kept an eye on the car.

Thank you!  

Just Try It1 Just Try It1
Moderator | Posts: 2570 | Joined: 08/14
Posted: 04/24/17
08:44 AM

just for kicks.

invest in a 2 buck packet of spark plug boot lube..

invest in a can of brake cleaner .. just to give the spark plug boots a cleaning if they are dirty or greasy..  let them air dry for 5 minutes before putting them back in service..

please wipe with a small screwdriver tip some spark plug boot lube around the inside of the spark plug wire boots. but not up the middle inside the middle where it will get on the metal conductor..  the spark plug boot lube or silicone dielectric grease  will prevent high voltage from leaking out between the boots and the spark plug insulator..

have a look at a diagram i threw together for this reply..


please inspect the coils for signs of high voltage leaks..  i added that to the image. but this is what others look like when the highest voltage escapes the insulation.  with the hood open in a dark area.. or at night.. you should NOT be able to see little blue or purple flashes around the coil center core to the laminations .


there is one more thing that i would love for you to do.

the voltage drop test.. here is a link to an image you should be able to save to your computer and print it out..

this is what you will be seeing..


this is just one step in the diagnostic tree.. but its an important step..

you will also want to look around the engine compartment. you will find several wires with ring terminals that are bolted to the body or inner fenders.. those are the ground connections for sometimes individual devices .. sometimes groups of devices..  if the ground connections are dirty, loose or the wires are breaking. they need to be fixed properly.. what is misstated and misunderstood. is that a ground is not a safety ground like is in your house.. the Ground connections are HALF the circuit.. and also since Electrons flow from Negative to positive.. the ground or negative side has the electrons.. no tickey. no laundry.  no ground or bad ground.  you won't have a properly operating components.

why so many steps.   the engine is sitting on rubber mounts.  the alternator puts out electrons on the negative side..  how do they get to the battery.. thru the negative battery cable.  how do they get to the body to operate the headlights .. thru the smaller negative cable attached to the body .. why do test 4.. because electrons are lazy. they like to take the shortest route..  which is NOT up the long negative battery cable from the block then down the smaller negative cable to the body.. they want to go down the engine to firewall or shock tower cable.  or the electrons may build up and create some different voltages on the negative side.

i measured 8.5 volts one day on a chevy truck between the engine and the body.. the truck owner was wondering why it kept blowing out alternators every few months.

post what you find.. post what codes you get..  that is a real help to narrowing down what component or circuit needs testing..  Diagnose before replacing is the best way.. prove its bad.  

driftinJ driftinJ
New User | Posts: 16 | Joined: 04/17
Posted: 04/24/17
10:39 PM

That's quiet an explanation and great tip man, thanks!  

Matt 87 Matt 87
New User | Posts: 2 | Joined: 10/17
Posted: 10/22/17
12:19 PM

That's great tips for me  

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