Hey all. New to the Mazda world and forum. I was gifted a very nice 2007 CX-7 2.3l turbo from my brother in law 1 month ago and I'm trying to get it running well. He gifted it to me because he chased the issue I'm going to describe for about 2 years and couldn't get it fixed. Please know that with all that I am writing about...there has not been any CELs come on. I think that's a bit odd, but I don't have experience with Mazdas. The issue is the engine surges when accelerating. This usually happens around 2000 - 3000 rpm. If i barely push the pedal and let the car pull itself into cruising speed and change gears, there is no issue. But as soon as I give more pedal the engine surges again. From a stop sign, the engine will surge when getting into the pedal to get up to speed and it changes gears while it is surging, no loss of power. No CEL, no rough idle or rough shifting of gears. New MAF, MAP, plugs, throttle body cleaning, new air filter put in (along with new fluids) and still no change. I've read all over the internet everything from MAF sensor, wiring harness, coils, turbo, vacuum leak, upstream O2 sensor. It's hard to tell without a CEL. I have scanned it with live data and the values are as below at idle:
Fuel Sys 1 : CL
Fuel Sys 2: N/A
Calc Load: 23.5 %
ECT: 217 F
STFT B1: 0.8%
LTFT B1: 1.6%
MAP: 10 (inHg)
Eng RPM: 698
Veh speed: 0 mph
Spark Adv: 10.5 (deg)
IAT: 129 F
MAF: 0.35 (lb/min)
TPS: 11.8%
O2SLoc: O2S11, O2S12
O2S B1 S1: 0.295 (V)
STFT B1 S2: 99.2%
OBDSup: OBD
Fuel Pres: 441 (psi)
Command EGR: 0%
Command EVAP: 0%
Fule levl: 14.1%
BARO: 30 (inHg)
LAMBDA B1S1: 0.999
O2S B1S1: -0.16 (mA)
CAT Te 11: 1021 F
ECU volts: 13.117 v
LOAD Value: 17.3%
EQ Ratio: 0.990
Rel TPS: 2.4%
Ambient: 93 F
TPS B : 11.8%
ACC Pedal D: 31.4%
ACC Pedal E: 20.8%
Command TAC: 2.7%

I know that took up a lot of space and time for anyone to read or respond, but I would be so grateful for anyone to be able to help me out. I am 54 yrs old and above average mechanically inclined, but when it comes to reading values and scan tools...I'm a bit behind the curve. I've been on other forums for Ford and Mopar with my previous projects and drivers, and always had such great responses and courteous replies. I'm hoping to continue that trend.

I'm not sure what to do next. Maybe just get a new upstream O2 sensor and put it in? I don't know...seems that is starting down the whole rabbit hole of throwing money at a problem. Again, I appreciate your time and replies/assistance.

A local mechanic suggested that I put in a new Crankshaft Position Sensor. I told him there was no codes and he said that if it's been doing it that long and hasn't died or stalled, that the car "has relearned itself". Sounds a bit odd to me...but what do I know. Blessings, stoney

 

Update...somehow my brother in law remembered being told a while back he had error code P0103 and P0303 and thinks it may have been P0104. After reading on some on the internet, could this be as simple as the wiring harness?

 

Anybody care to help a fella out? Any ideas? thanks

 

P0303 is cylinder 3 misfire.

 

Thank you. Update....on these much cooler Nashville mornings the car still starts great but the idle is higher than on the warm/hot days. I also smell a "richer" smell from the exhaust. I tried cruise control today to see if it could be related to TPS and it still surged in cruise when the car demanded a little more acceleration going up a hill. I'm trying all I can not to have to take it to the VERY EXPENSIVE mazda dealership in Cool Springs (everything there is expensive).
Any more thoughts or assistance would greatly be appreciated. thanks and blessings, stoney

 

P0103 is related to the MAF sensor, you could by some MAF cleaner and try cleaning it.

 

Thanks Reaper,
I cleaned the MAR without any change...but here is an oddity that has me baffled. The surging has went away 2 times since I have had the car (1 month now) and both times it was after a full fill up, getting as much gas in her as I can. Does that spark anyone's thoughts or ideas? Is there a vent tube or something that is higher up that when the gas is full creates a vacuum and when the gas gets below it, it allows air to escape? I know that may sound stupid, but that's the only correlation I have when the car has not surged. thanks for your time.

 

Did you end up sorting the issue? I have a 2007 mazda mpv with the 2.3l turbo doing the exact same thing. Cleaned maf, cleaned throttle body, still doing it. No codes, no lights on dash