Hi all, I have owned a 2006 Impreza for a year now and just can't get it running right. The issue is, when under acceleration it has a flat spot when under 3,500 rpm. It sputters and gurgles until it reaches 3,500 to 4000 rpm then takes off like it should. I have had it in various mechanical workshops and have spent over $2000 replacing all the sensors, fuel pump, spark plugs, throttle body cleans ( twice ) And I only run premium unleaded fuel. What am i missing ?? Please help !

Welcome Bryan.

Is the car running a standard map to start, any other mods, uprated injectors etc?  Have you replaced the maf too?  

 

Hi Geoff,  thanks for your reply. The car is a totally stock standard, non turbo model. I have had it in to 2 different mechanics. The first guy suspected the fuel pump/filter and replaced them. He also changed the spark plugs to iridium type and did a throttle body and upper cylinder clean. After an $840 bill and no result we took it to another mechanic who specializes in Subaru's and did a scan and found 1 x fault code which was PO137- O2 sensor circuit low. At this point we replaced the front and rear O2 sensors. Still no result so took it back to be rechecked. This time they cleaned the throttle body and performed an upper cylinder clean ( again ) tested the coils for arcing and refitted. Then they tried a maf sensor from another vehicle and found some improvement so fitted a new OEM maf sensor. Still no result. 

I should mention every time it has been in for a scan It seems to drive perfectly for a day or so before reverting back to the same problem. I suspect that might have something to do with resetting the computer after clearing the fault codes though.

Regards Bryan

Problem solved, Today I had my Impreza in to my local Subaru Dealer for the air bag recall and asked them to run a diagnostic test on the car while it was there.

I explained all the things my other mechanics had done to try to fix the running issue. What they found was the ECU memory and something called the OBD memory hadn't been cleared after replacing the faulty sensors.They cleared the system and re-learned the idle. For the first time in a year my subie is running like it should. Happy days... 

Excellent news!! Sorry I meant to come back and suggest another Ecu reset but glad you sorted it. Enjoy 

pretty poor experience with your 2 garages work, just shooting parts at it based on hunches rather than proper diagnosis :-/

Expensive way fix what probably  really only 1/3 of the total bill if someone competent had been involved, shame the customer don't have more rights on poor diagnosis work as would get rid of a lot of the not so good garages pretty quick .

Wotcha and welcome - gald it has been fixed but yes a shame there was an element of easter egging before hand