engine missing then running perfect
 

hi guys ..... I have a 2006 mazda 3 2.0ltr manual transmission......


I will be driving along and it starts to miss, when I drop down a gear seems to help, but still does persist....then as suddenly as it started it stops.....also seems to vibrate as if my wheel is out of balance, but seems to be related to the miss firing.........any clues

Sounds like an ignition coil is breaking down. Your best bet is to buy all of them at once from Ebay. Maybe 50 bucks for the set. Check the air intake boot, clean the MAF and throttlebody. Pretty much all maintenance. If the check engine light came on then check for codes.`

ok...........so I tried changing the ignition coils....ran great for 3 days......same thing started up.......now engine light comes on......go for code reading.....


P2097 post catalyst
fuel trim system
too rich bank 1.


since fuel mixture was too rich I figured fuel not all burning.....I changed all spark plugs......seemed to run great for couple days.....engine light stayed on.


again problem starts....runs perfect for a minute or 2 ....will not hold steady idle now, constant rev 750-1000 rpm at idle.....misses on take off, but runs fairly smooth until its taxed....


engine light has gone off.

Bit of a tough one to diagnose without freeze frame data. When the check engine light came on the PCM recorded the event. This is freeze frame data. It tells the speed/rpm/ECT degrees/etc/etc/etc. Only some shops have that capability. The possible causes are upstream and downstream O2 sensors/exhaust leak,restriction/ECT/IAT/purge valve/fuel pump/PCM malfunction. I would lean toward MAF or a lazy O2 sensor. Have you added a good injector cleaner to the gas tank? Techron works well. I have to recommend you take it to a shop that can check for freeze frame data at this point.

DTC P2097

Target A/F feedback system too rich

DETECTION CONDITION
• The PCM monitors the target A/F fuel trim when under the target A/F feedback control. If the fuel trim is less than specification, the PCM determines that the target A/F feedback system is too rich.
Diagnostic support note
• This is a continuous monitor. (Fuel system)
• The MIL illuminates if the PCM detects the above malfunctioning condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
• PENDING CODE is available if the PCM detects the above malfunction conditions during the first drive cycle.
• FREEZE FRAME DATA is available.
• Are any DTCs is stored in the PCM memory.
POSSIBLE CAUSE
• Leakage exhaust gas
• HO2S malfunction
• IAT sensor malfunction
• ECT sensor malfunction
• A/F sensor malfunction
• Excessive fuel line pressure
• Fuel pump unit malfunction
• Purge valve malfunction
• Insufficient engine compression
• PCM malfunction

what about the camshaft positioning sensor ??