I am racking my brains out on this one. I am getting stuttering or hesitation when cruising with partial acceleration. It idles fine and when I give it a lot of gas the stuttering goes away. It is most noticeable when cruising at 40-60 mph and giving it light acceleration, but then when I give it lots of gas and force it to downshift the problem disappears.

The check engine light was on (P0171 it think) but after replacing the Mass Airflow Sensor and a cracked vacuum line the CEL has been off for days, but it still has the above problem.

Other things I've tried ...
PCV Valve replaced.
Air Filter replaced
Seafoam Spray injected directly in front of the throttle plate per instructions to clean out carbon deposits.
All plugs checked, and cleaned.
Smoke test done to look for more air intake leaks...none found.
Carb cleaner sprayed on air intake areas of cold engine to find leaks...none found.
Fuel injector cleaner routinely run through a tank of gas.

Both Coil packs, all plugs and plug wires were replaced last summer, but I'm beginning to think I may want to replace the wires and coil packs one at a time to see if that remedies the problem. Also, the EGR valve and the port that comes out just behind the throttle body were thoroughly cleaned out about 3 months ago when I was trouble shooting another problem that was resolved after finding a crack on the brake booster vacuum hose.

Any help would be appreciated.

 

Check the big intake hose and brake booster hose very common very common problems on that engine

 

Also check transmission fluid

 

Hey Ihaase,

Your symptoms are exactly like mine on my thread posted today. Rev high and it is ok. Idle ok. Intermediate load runs rough. My codes are P0102, P0103, P0123. I replaced plugs and the hose that mazpro00 refers to is brand new. I am stumped as well. MAF is too pricey to just replace on a hunch. If you find your solution, please send me a note so I can do the same.

'01 Protege 2.0 L 5 speed manual.

Thanks
J

 

Thanks for the help. I have checked the air intake hose and the tranny fluid...both look good.
It is still stuttering under light acceleration with no check engine light. The local mechanic is also stumped and recommended fuel injectors get flushed/cleaned, which I haven't done. I am running seafoam in the gas on a regular basis.
I have checked the throttle position sensor looking for the voltage to jump as I slowly go to wide open throttle with the key in the on position (engine not running through). That test looked good. I did read that I should be getting close to 5.0 volts on wide open throttle, but it is only sending back 3.6 to the computer. Can anyone confirm what their TP sensor reads at WOT? The idle voltage is good at .5 volts and the power supplied to the sensor is a full 5 volts.

Here is a link to the TP sensor specs.
http://www.askatech.com/AskATechLive/AatFileShare/References/FastTrack/MA1213.pdf

 

WOT is never a true 5v. On the norm, 4.6-4.8v is expected. 3.6v is a little lower than I would like to see myself. Flush and clean injectors, I'm not quite on board with that. It sounds like your running every known chemical on the shelf thru your fuel. Possibly have too much additives floating around in the tank? Wouldn't hurt too run a tank or two without adding anything to it. Seafoam is a great product but would only use it every other or third tank. If your using the fuel in your tank up in a week or two, you could even for go the Seafoam. Dirty fuel injectors is not a common problem anymore. Carbon build up on valves and throttle plates is. You have already addressed that.

How old is your timing belt? Wouldn't hurt to change it out if it's time or close to it. In the mean time, throw in a fresh set of plugs and run all that "mixed" fuel out of your tank and see what if any difference it makes.

 

I am still trying to fix this car...argggg. I replaced the plugs and ran out the seafoam, but no change. It seems to be getting worse the hotter it gets. We had the car fully loaded driving in the mountains. The car was hesitating on acceleration , loss of power and it died a couple times on idle. We got a new CEL code, p1345 camshaft position sensor. The car drove fine once it cooled down and the CEL went OFF. I replaced the sensor anyway, but that didn't fix the hesitation or stutter on light/medium acceleration.

 

I am having the exact same issue With my 99 LX 1.6L. Has anyone found a fix?

 

Hello, just bought a 2000 Mazda protege (1.6) this last week and I’m also scratching my head on this same issue. I replaced both coils, the other spark plugs, cleaned MAF, inspected intake hose......I’m stumped. I did get a p1170 code for O2 sensor but from what I’ve read, replacing the sensor may not fix that code. Idle in park seems fine, little choppy but not terrible. Idle in gear could be better. Doesn’t stall but idles a little rough. I feel some blogging taking off from a light, but like a person said above, if you give it a lot of throttle, it accelerates great. At 60, if you feather the gas, same thing, it starts chugging. Give it more gas and she does just fine. I’m going to keep investigating if I find anything I’ll post it. My car has 51,000 miles on it.......low mileage one 🙂

 

Thanks, I would really appreciate hearing anything you find out about this problem. It is very frustrating!