Code indicated #3 misfire, changed spark plugs and #3 ignition coil, changed oil and air filter, reset oil filter indicator, drove vehicle for 15 minutes and code came back, Went back code erased drove for 20 minutes and code came back again, what is the problem?

Hello Carlos,
It is a common problem with '99 Cady (Random Misfire Detected)

• Start the car and carefully pull the plugs boot out one by one, and put it right back (a few seconds is enough).
• Take Notice of of which one is affecting the RPM of the engine ( slowing down and and shaking erratically).
• With the engine Off.
• Use the appropriate socket and again one by one take out the spark plugs and check them for oil and heavy residue build up.
• If there is Oil in anyone of plugs, take the car to mechanic and let him or her do an evaluation or diagnostic.
• You probably need new coil packs and spark plugs.
• Change the oil and the air filter too, if they are dirty.
• Check also the fuel filter.
  
• If the code does not go away by itself, have it reset by a mechanic.

Best of Luck,
JP

From a reputable repair website:


P0351 - OBD-II Trouble Code

Auto Systems and Repair

Ignition Coil "A" Circuit Primary/Secondary Malfunction Our emissions expert has put together the following information about the P0351 fault code. We have also included diagnostic procedures you can take to your repair shop if the mechanic is having difficulty analyzing the code.
OBD II Fault Code

• OBD II P0351 Ignition Coil "A" Circuit Primary/Secondary Malfunction

What does this mean? The ignition coil or coils are responsible for igniting the air/fuel mixture inside the combustion chambers. Without reliable performance from the ignition coil(s) the vehicle will stumble and misfire.
Code P0351 indicates there's an electrical problem in either the primary ( the computer side ) or the secondary ( the spark plug side ) of the Ignition Coil "A" Circuit.
Symptoms

• Check Engine Light will illuminate
• Engine idles rough
• Engine misfires on acceleration
• In rare cases, the engine may not exhibit noticeable symptoms

Common Problems That Trigger the P0351 Code

• Defective Ignition Coil(s)
• Defective Spark Plug(s)
• Intake Manifold Vacuum leaks
• Carbon buildup in the Throttle Body air passages
• Defective Idle Air Control Valve or Electronic Body

Common Misdiagnosis

• Ignition coil(s) replaced when cause of the malfunction was a vacuum leak
• Spark Plugs replaced when cause of the malfunction was a vacuum leak

Error Code: P0303
Description:
Cylinder 3 - Misfire Detected
Possible Cause:
Wiring harness, igniter and fuel injector connectors.
Ignition system. (Spark plugs gaps)
Fuel injector No. 3.
Fuel pressure.
Running out of fuel.
EVAP canister purge valve.
Evaporative emission system.
Low compression, cylinder No.3. (check valve clearance and throttle plate for excessive wear)
Engine control module (ECM).

Error code p0300 indicates rough idle and p0305 indicates engine misfire in cylinder 5. Check for faulty spark plug and its wiring. Also check for ignition coil and distributor. Replacing spark plug and its wiring may resolve the issue.

There are a few things that can cause an engine misfire and hesitation. Does your van have a CoP ignition system? (Separate ignition coils for each spark plug) Or coil pack? You may have bad ignition coil(s); that would cause a misfire. If you have a dirty/clogged/leaky fuel injector for cylinder 3, that could also cause a misfire condition. When you replaced all the spark plugs, did you look at the plug from cylinder 3? Did they all look the same? Sometimes you can get clues to what is going on in your cylinder by how the spark plug looks: if it's white or glazed you are running too lean and could indicate fuel injection problem, if it's got burnt oil on it and it's sludgy you may have a leaky gasket or worn piston ring that is letting oil up into the combustion chamber and fouling the plug, causing a misfire. If your check engine light comes back on and it's the same misfire code, have the coil for cylinder 3 checked to see if it's weak or bad. Or you can do a home remedy check and swap a known good ignition coil from another cylinder to 3, reset the code, and see if the misfire moves to another cylinder. If it does, you know the coil is bad. You can pick up an ignition coil for pretty cheap on the internet ($30-$70) if that's the problem and they're simple to install (a pain if they're on a cylinder that's under the intake manifold, but just because you have to unbolt a bunch of stuff to get to it...time consuming but not too difficult). I have a 2001 Mazda Tribute and had a couple of ignition coils go bad, causing misfires. This seems to be a semi-common problem for early 2000's Mazdas.

A lean fuel mixture will not yield poor fuel economy but a misfiring cylinder will.You have already replaced the coils and the plug leads to the cylinders in question so they should not be an issue.Do the codes still indicate a misfire on cyls. 2 & 3? If so have you looked at the plugs? Has the oil leak around the plugs been stopped? Are they oil fouled? Could the pooling oil around the plugs be shorting the spark discharge to ground?or Valve Cover gasket is leaking. That's why you see some motor oil in the sparkplug sleeve (tube). removed the spark plug and My suggestion is to remove the sparkplug in cylinder 2 & 3 or whichever ones that the scanner indicated as "misfiring". Take a look at the sparkplugs and see if there's any oil around it. If you see any traces of oil, that means your gasket is worned out and need to replace.Good Luck in getting your problem fixed. If you need any further help - I'll try to help you the best of my knowledge and skills. You can repost on this

No 3106

P2106-- Throttle Actuator Contol System

Make a very long technical story short,
because I have the same car

You have 1 really bad COP Ignition Coil

$59.00 at auto parts and takes 15 min to install

You should have PO301 thru PO 308 Codes
as well as a lot of others

P0301 - Cylinder 1 Misfire Detected.

Causes:
- Improper spark plug at cylinder #1
- Insufficient compression at cylinder #1
- Incorrect fuel pressure
- The injector circuit is open or shorted at cylinder #1
- Fuel injector #1 may be faulty
- Intake air leak

Solutions:
- Perform Injector Service
- Replaced Spark Plug #1
- Replaced Injector #1
- Replaced Ignition Coil #1

P0303 - Cylinder 3 Misfire Detected.
Follow info from P0301.

P0316 - Misfire Occurred In The First 1,000 Engine Revolutions.

Causes:
- Damaged CKP sensor.
- Ignition System.
- Fuel Injectors
- Running out of fuel
- Fuel Quality
- Base engine
- Damaged Powertrain Control Module

Solutions:
Usually the P0316 is combine with a P03XX codes. The P03XX code indicates in which cylinder the misfire occurred.

From http://www.obd-codes.com/trouble_codes/
The P0300 is a misfire and P0506 indicates low RPM at idle.

A misfire can be caused by poor ignition (spark plug, plug wire, coil, ignition module/engine control module).
OR
Poor air/fuel (air filter, fuel injector, fuel pressure, fuel filter, fuel pump, bad gas, or engine control module).

Check your maintenance requirements and see if any of these items are due for replacement first.

When cleaning your engine, water/degreaser went down the spark plug ports. Try using a air compressor blow gun to remove the moisture from around the spark plugs and boots. The water was causing the engine to misfire on 3 cylinders at first and as the ports started to evaporate the moisture, the less misfiring was occuring. Dry thouroughly and hopefully coils do not have damage to them. Also check to make sure the boot is making good contact with the spark plug.