Increase in stumble occurance

[goonsquad]

Has anyone experienced an increase in the frequency of stumble (not hesitation!!!) in their MSP? I'm a little over 2000 miles and within the last 300 or so I've noticed an huge increase in stumble in my car. The first time it ever happened was on the way to work accelerating under boost up a hill that is about a 10 degree incline. It feels as if I've pulled my foot off the gas entirely for a split second (also similar to when an automatic car downshifts when you hit the gas hard to accelerate when you're already moving). It usually seems to happen when the car is pretty cold and often when going up an incline. However, I usually only drive my car to and from work which is about 5 miles each way so it is always cold! Anyway it's been happening a lot lately and it's pretty annoying. I hope the ECU flash fixes this problem.

 

[funnylittlman]

I have the stumble / hessitation as well.

It was pretty bad yesterday b/c of all the humidity. I felt the car start to do it's "normal" thingy right around 3.5K rpm's and I engaged the clutch. I heard the gobble noise (quite loudly might I add) and then disengaged the clutch. It went away.

The hessitation / stumble feels like there is too much air going into the manifold and the engine / ecu can't compensate for it. So next time you feel this hessitation try pushing the clutch in and starting over.

-fnny

 

[t3ase]

How much boost are you running?

 

[goonsquad]

It seems you are referring to the hesitation (a different beast in itself) but distinctly different from the stumble I'm referring to.

 

[goonsquad]

How much boost are you running?

10 PSI

 

[Notorious]

I have the stumble / hessitation as well.

It was pretty bad yesterday b/c of all the humidity. I felt the car start to do it's "normal" thingy right around 3.5K rpm's and I engaged the clutch. I heard the gobble noise (quite loudly might I add) and then disengaged the clutch. It went away.

The hessitation / stumble feels like there is too much air going into the manifold and the engine / ecu can't compensate for it. So next time you feel this hessitation try pushing the clutch in and starting over.

-fnny

I thought it was because there was too much fuel going into the engine and not enough air. It's just running overly rich.

 

[Heathen23]

My guess is you are hitting fuel cut when you are under peak boost if you are boosting 10psi. Is this happening more under cooler conditions? Particularly in 4th gear? If so it's probably fuel cut.

 

[goonsquad]

I guess it has been a little cooler here lately. This morning it was around 60 degrees and humid. I would say the stumble I'm experiencing is happening in 3rd gear usually. I didn't realize the fuel cut would occur so soon (10 PSI) but I guess you might be right.

 

[Emode]

its happens to me in late second gear, at 1/2 throttle and sometimes in third too.
More prevalent when its cool and humid, or warm and humid, humid being the key word here, it seems

 

[122 Vega]

Mine does this, I think of it like shutting the key off for a second or two then turning it back on. I call this the stumble. Then there is the hesitation where the car just creeps up the rpm band no matter what the throttle position is.

Reset the PCM, then try agn. Mostly it will do it when it is humid.

The dealer said that it is turbo lag. Even when I showed the tech that the turbo was at full boost on my gauge, he said then that it was because of the gauge/timer.

fuckers.

Britt

ps, I am at stock boost levels

 

[goonsquad]

Mine does this, I think of it like shutting the key off for a second or two then turning it back on. I call this the stumble. Then there is the hesitation where the car just creeps up the rpm band no matter what the throttle position is.

Reset the PCM, then try agn. Mostly it will do it when it is humid.

The dealer said that it is turbo lag. Even when I showed the tech that the turbo was at full boost on my gauge, he said then that it was because of the gauge/timer.

fuckers.

Britt

ps, I am at stock boost levels

This is just what I'm talking about. Have you reset the PCM/ECU? Did it make the stumble disappear?

 

[505zoom]

It seems you are referring to the hesitation (a different beast in itself) but distinctly different from the stumble I'm referring to.

Mine stumbles and hesitates, 2 totally different things. I do think they are both caused by the overly rich nature of our stock PCM and will both be fixed by the flash.

My guess is you are hitting fuel cut when you are under peak boost if you are boosting 10psi. Is this happening more under cooler conditions? Particularly in 4th gear? If so it's probably fuel cut.

I am running stock boost and my car stumbles like crazy, just like he described- it feels like you are taking your foot off the gas for a split second and then flooring it over and over again. All this while you are holding a constant position on the throttle.

 

[goonsquad]

I am running stock boost and my car stumbles like crazy, just like he described- it feels like you are taking your foot off the gas for a split second and then flooring it over and over again. All this while you are holding a constant position on the throttle.

Mine only happens once, not over and over again, but it still sounds like the same problem. It would be really nice if Mazda announced the problems/causes/solutions to all of the fuel problems along with the flash. I'd really like to know what went wrong in addition to just having it fixed.

 

[funnylittlman]

goonsquad

Just try what I typed above,

"It was pretty bad yesterday b/c of all the humidity. I felt the car start to do it's "normal" thingy right around 3.5K rpm's and I engaged the clutch. I heard the gobble noise (quite loudly might I add) and then disengaged the clutch. It went away.

The hessitation / stumble feels like there is too much air going into the manifold and the engine / ecu can't compensate for it. So next time you feel this hessitation try pushing the clutch in and starting over.

Shockingly my hessitation went away, but then came back. The only REAL thing to do is reset the ECU every 1K miles until the flash.. but just give it a try. Full throttle... feel the hessitation.... push the clutch in.... hear the gobble... get back on it.

Let me know

-fnny

 

[girth]

Yeah Goon, my stumble frequency seemed to increase around 1000 or 1500 miles. Basically mine stumbles EVERY time I drive it now --- I can recreate it at will by taking a 90 degree turn (normal turn) in 3rd gear and then put the gas at 1/2 to 3/4 throttle. Doing that it will stumble exactly as you describe at least once, and typically twice within a 3 to 5 second span. And it's a stumble as if I took my foot completely off the gas -- not a stumble because the RPMs are so low (which really isn't a stumble but rather "bogging" -- just figured I'd say that before somebody says I'm in too high of a gear for a slow speed). The stumbling happens under other scenarios but that's the way I can recreate it 100% of the time.

Aside from resetting your ECU constantly there's nothing you can do about it until the flash comes along and 'hopefully' fixes it.

 

[505zoom]

Mine only happens once, not over and over again, but it still sounds like the same problem. It would be really nice if Mazda announced the problems/causes/solutions to all of the fuel problems along with the flash. I'd really like to know what went wrong in addition to just having it fixed.

Yeah, mine started out just being once, sometimes twice. Now, sometimes it feels like it happens 3-4 times between 3-6K RPMs.