My vehicle is a 95 Mazda
Protege, 1.5L engine, auto transmission. My problem is that the car runs perfect at
idle, but soon as i try to accelerate, even in park, it just bogs down, and
no power. Even if I put it in drive, it will not even move itself, and just stall. Spark is good, plugs are new Densos, compression, fuel pressure, (38 psi at idle) and spark plug gap
is in spec. The fuel pressure rises when I snap the throttle. All the
filters are new, and there are no vacuum leaks. I have even checked the
voltage values of the TPS, MAF, IAT, MAP, closed throttle position sensors and
load/no load distinction signal...and are all good at the PCM. The only thing that helps is when I spray air intake cleaner in the intake tube through the port where pcv valve enters. I give a quick spray and snap the throttle open, it revvs up properly. I don't know if anyone has heard of this problem before. As the proud owner of a 87 Mazda 323 which has been basically trouble free for years, i bought a Protege that needs a little love and care. CAN YOU PLEASE HELP? Thank you,
Brian

 

Sure sounds like bad MAF sensor but the little bird on my shoulder is telling me that is something else that have run accross before and was not MAF. Will give a thought over the weekend and see if little bird will tell me something that I am missing[]

 

I do appreciate the quick reply. I noticed you said to check the MAF, which is all I could narrow it down to also. At idle, the MAF reads about 1.8V, and about 2500-3000 RPM (when getting the revvs up with intake cleaner) it tops out about 2.9V. Since I don't have a better manual, I don't know what the range is. I don't know if this info might help, but it is the best I can do. It acts like it is starving for fuel, but isn't getting it through the injectors. The only thing I could guess is that the MAF is acting correctly at idle, but not off idle. Any help is very helpful, and THANK YOU in advance. If there is any more input I can give, just ask.

 

Can not think of anything outside of MAF that will give you this problem as long as your fuel pressure is good at rail. Obviously no mechanical fault or else engine would not rev normal when giving external fuel source. Has to be a lack of fuel supply to cause the bog down condition that you describe and loss of good MAF signal would be the most obvious cluprit. Top end of Maf signal should be close to 3.5 to 4.5 volts. Base reading of 1.8 not abrnormal. May be degraded due to forcing a signal with the intake cleaner but have never checked under this condtion. I hate to tell you to try a MAF without further check but at this point is where I would go to.

 

Hi Bkey,
I have almost the exact same problem. I spent $400 on new 02 sensors in trying to figure this out. It turns out, my mass airflow sensor had a thick carbon build up and that was the problem all along. Rather than buy a new one ($140/dealer only), I just opened the airbox where the air filter sets and used some special electronic cleaning spray that I bought at Advanced Auto for $6 and sprayed the hell out of the sensor tip with this spray. It is just like disc brake cleaner, but for electronics. I opened the airbox because the screws that hold the MAS in place were rusted through and I couldn't get them out. If you can lift off your sensor, go for it. Anyway, I sprayed this stuff and let it dry and it started right up and ran like brand new. I couldn't beleive it.
A word of warning, though: I drove it all day yesterday and it ran like new, but now this monring, my idle seems to have reset itself to a higher level. It has been running at 1500rpm sitting in the driveway. I haven't driven the car yet today but I'll let you know. I'm sure the idle will come down once I warm up the engine, though.

 

I can judge by the responses that the MAF seems to be the most critical part of the car. I even pinched off the fuel return line, which boosted the fuel pressure to 82 psi which helped very little and checked the vacuum, 20" at idle with a steady needle. I don't think the fuel injectors could cause this problem, do you? I could maybe see one fail...but not all four seem like a possibility. I will take the suggestion to clean up the MAF soon as I can get to a radio shack to get the electrical cleaner. I live in a rural area, and with skyrocketing gas prices, I will wait a few days to combine trips!!

 

Would not think injectors problem either. Your MAF is a little harder to clean than later models that pull right out of the air cleaner housing. I believe you even have a protective screen at the inlet that will make it even harder. Still can be done though if you separate the MAF sensor from the air cleaner housing. You can also use non clorinated brake cleaner from parts store. Clean by spraying only. Do not touch the wires as they are very fragile and if they break will be buying a new one.

 

Hey guys,
It's DEF not your injectors because I had those cleaned as my first attempt to fix this problem. I also had my fuel filter checked and both 02 sensors replaced. I'm telling you, clean that mass airflow sensor really good. Also, the electric cleaner spray can be purchased at Autozone (et al) for $6. Radio Snack will charge alot more. I also cleaned my connector, where the MAS and the wiring harness click together. Spray it all and look for the color to return on the tip of the airflow sensor. Mine went from black to gold with a red tip. Like new now. Make sure you give it time to evaporate. I waited 20 minutes.
Also, my idle 'problem' went away as soon as I put the car in gear and hasn't returned since. I think it was just cold, even though I live in Miami and it's 90 outside right now.
I am amazed how much power this little 1.6L makes. I'm really impressed and I still get great (30+) combined MPG.
Good luck dude.

MJA

 

I took a close look at the tiny thin piece of metal inside the MAF sensor that reads the air flow, and it was deteriorating at the tip. I found a local scrap yard that had exactly what i needed for $22 for a used MAF. ( I always prefer to buy used parts from a wrecked vehicle, at least you know why it's there) I did like ackerman73 said and cleaned it out very well with electronic cleaner, plugged it in, and it fired up and ran perfect! I never knew that this sensor could cripple the car so easily. So I wanted to say THANK YOU to babyhuey and ackerman73 for the help and advice.

 

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