Is this normal performance?

[advantiracing]

hi there

I am trying to find out if all mx-3 gs' have the same characteristics as mine.. this being when im in first gear (around lets say 4000rpm) and I release the gas and let the rpm's drop down to idle (still moving) the engine boggs down HUGE at around 1700-2200 rpm. This makes for very hard traffic jam driving. DOes n e one know what im talking about? Could it be the fuel/air ratio or is this normal in manual trans mx-3's?

[IanL]

Mine doesn't do that. It'll slow down nice and gentle, and pull away from 1300 rpm with just a tiny bit of snatch when the power comes back on. Try putting some injector cleaner in with your fuel.

[advantiracing]

i do that all the time when I change the oil...

[tical]

gotta be somethin wit your fuel cause i can come off of about 900 with no prob.

[gsemex3]

Mine is pretty similar after the engine has warmed up, and it only started a week ago. On cold starts the engine is ok as the thermostat takes over but as soon as it warms up it starts to bogg down on those rpm ranges when you release the gas pedal. Afterwhich, idling is very unstable until the engine stalls.
To keep it from stalling for now, my mechanic adjusted the fuel flow yesterday but the bogg down is still there. He said there is probably a vacuum leak and he will check it this weekend if he has the time.

[janis]

I think that it might be also the mass airflow meter or one or both O2 sensors IMO...

[advantiracing]

well where the mass air low sensor? is it the big jet-like diaphram between my intake filter and hose leading to the intake port? How do I know if its busted?.. BTW my car idles fine when not driving, so if it were a vaccum problem, shouldnt it be sqwrewy then to ( when not driving)?

[IanL]

Originally posted by advantiracing:
BTW my car idles fine when not driving, so if it were a vaccum problem, shouldnt it be sqwrewy then to ( when not driving)?

It could be (just to name one possibility) that the ribbed hose between the VAF and the TB has a hole.

Now when the engine is idling, there is no torque acting on the engine mounts, and the hole could be "closed". When driving, the torque on the mounts makes the engine tilt over, stretching the hose and opening the hole.

[advantiracing]

Nope. got that replaced with a new mazda part. It seems to be a fuel /air ratio problem . any takers wher to start.?

[IanL]

Originally posted by advantiracing:
It seems to be a fuel /air ratio problem . any takers wher to start.?

Well, any vacuum leak is a fuel/air ratio problem.

[gsemex3]

My mechanic has not checked the engine yet but will update as soon as done.

[advantiracing]

thanks, let me know..... traffic jams suck when the boggin is'a happnin

[gsemex3]

Ok! My engine problem seems to have been fixed!!! The black plastic/rubber tubing between the airflow sensor and the throttle body was cracked (between the ribbings) so there was a vacuum leak. This part was replaced yesterday (Saturday) and has been runniing well since. So, check ou this part as the cracks are well hidden. Hope this helps. Let me know. Thanks.

[advantiracing]

ya, i ad it replaced too, but the problem is still there.... i hope that u understand the problem..... i have to put more than normal amounts of accelerator down when ging from start, and then when im "gliding" in 1st gear from 3-4k rpm and let it drop to around 1200- 1000k rpm it suddenly boggs, and jolts the car... but it wont stall. TPS sensor? Clutch? i got nothin....

[IanL]

If you're sure there's no air leak, it could be an idea to check the resistance of the VAF and TPS sensors:

Remove the connector and measure the VAF between E2 and Vc (E2 is middle, Vc is next in line to the rear) As you move the VAF cone, it should vary smoothly between 200 and 400 ohm. If it jumps, you need a new VAF.

Do the same thing for the TPS between Vt and GND. (GND is bottom, Vt is 2nd from top). I don't know the values, but the main thing is no jumps as you rotate the throttle quadrant.