Possible MAP sensor problem?

I have an 07 speed3 where it kind of struggles during acceleration, somewhat stutters. While at steady speed, feels like cruise is on as if its trying to keep it at speed. It is not a misfire from plugs, coils, injectors. Fuel pressure is within spec KOER/driving. Im thinking it is a sensor issue? there isnt any noticable Vacuum leaks. The amount of stuttering i feel seems like id see a Vacuum leak or hose off. i have not looked at my MAF readings yet and my STFT/LTFT are within -10%/+10%. Primary o2 is less than a year old but is not OEM, it is NTK. I looked at my MAP sensor and noticed KOEO BARO is at 28.6 and BARO volts are at 3.** volts. MAP KOEO is at 28 inHg while my volts are 1.86. KOER my MAP reads 28 inhg while my volts are 0.5. While KOEO, shouldnt it be 4-5 volts while KOER would be 1-2 volts? i have no current, memory or pending codes.

I have a Snap-on Apollo-D9 if youd like snap shots or recordings. 

You state that the displayed MAP pressure value is the same with KOEO and KOER, at 28'' Hg, though the voltage does change from 1,86 at KOEO to 0,5 at KOER.

Did I understand this correctly? If so, was this read on the generic OBD2 side or Mazda manufacturer protocol?

Hi,

Youre right. The readings were read on my Snap on scan tool. Was not a Mazda diagnostic tool.

Thats just what i had seen while seeing why the car is somewhat struggling to accelerate.

I "suppose" you scanned the vehicle with Mazda software with the SO scanner. .. Under this protocol the scanner might display what's known as substituted values.

What are the map values in generic OBD2, koeo and koer?

Hi,

I appreciate you helping me. all i can see is inHg for my MAP which is 28.9 Koeo and 8.0 koer. Do i add 20 to my Koer value? Or is that a Vac leak?

The data shoes your engine is capable of pulling 20” Hg when idling. This is the difference between the actual pressures in the intake manifold when you compare the koeo value (basically atmospheric pressure) to the koer value.

I don't see a problem there , the numbers suggest the engine
does not have a leak issue and the sensor works fine.

Ill probably have to take a log while driving. MAF is original with 101k miles, o2 like i said is NTK which might not matter, but i just feel better with OEM parts.

If anybody stumbles on this. My fuel trims are -10.1 STFT and -7.0 LTFT at idle. My B1S1 mA is -.093 at idle.

I must have a fuel component giving me alil to much fuel?

How's the fuel trim at 1500 and 2500 rpm?

Hi,

At 1500 they are -0.7 STFT And -7.0 ltft

2500 they are 0.0 stft and -7.0 ltft.

Thank you!

Apart from the MAP sensor there should also be a MAF sensor. Did you try to clean this one?

Does the fuel pressure hold for a while after engine shut down?

I did clean the MAF and fuel pressure holds for awhile after shutdown.

The issue seems to only show itself while acceleration even during light throttle until 3k rpm then seems ok, and while at steady speed it has small hiccups. Should i monitor my throttle postion sensor and look at my VTCS solenoid?

Also, my spark plugs are less than a year old, however, are Autolites. I might try OEM NGKs that are OEM heat range.

I have ran into a vehicle where it had a misfire and owner used to cheap of plugs that made the misfire worse and had to use OEM plugs.

I don't like auto lite plugs very much and would change tem for something better. Of course it's worthwhile to watch the TPS as well.

Ok. Thanks! Ill monitor the TPS . Also, not sure why it didnt come up on my snap on tool, i have a carsoft MBII scan tool and read generic codes and a coolant temp code come up for being to cold. Coolant temp was sitting at 165⁰ F. Im going to look into thermostat and coolant temp sensor.

I greatly appreciate your feedback as well!

Just reading through the symptoms, are you certain the clutch is not slipping?
It might sound stupid, but it's hard to experience what you are feeling from this side of the internet

I understand what you mean, clutch isnt slipping though.

However, i got a P2188 which is rich at idle. Before i also had a P0128.

My thermostat definetly needs changed, could also be my temp sensor. My fuel trims are always negative and my ECT doesnt get above 170⁰. Driving i saw it get down to 164⁰.

Im going to replace T-Stat and probably my ECT sensor, then monitor everything again.

Hi,

Just giving everyone an update. I replaced my thermostat and my readings are alot better. ECT is where its suppose to be and my Fuel trims together are where they should be as well.

I appreciate all the help and input!

Hi, hope all is well with everyone.

I seem to still have an acceleration issue and one at cruising speeds. During acceleration it is jerky but not like a misfire and also feels like im trying to accelerate in a higher gear at lower RPMs. I get a feeling of it being held back or choked. And at cruising speeds you can feel a light stutter.

This happens only up until 3k, then seems to clear itself or catch up with itself. What do you suggest i look into?

Ive actually been dealing with this for alittle over a year, and the only CEL ive gotten was related to my thermostat being stuck open and rich at idle.

I appreciate all your help!