MX-3.com

When i first bought my mx-3 i'd floor it and you could feel the extra power at about 4000 rpms. Lately its not kicking in until well past 5000 rpms. Is this just a loose timing belt or is the engine starting to go?

With my GS I feel a burst of power at 4500 RPMS and ive got 130k miles on it...For some reason with the k series engines they all do that. My friend with a PGT said his old klde did the same thing and so does his new klze. I think its suppose to be at 4500...are you sure it hasnt always been like that?

why do the engines do that?
mine does it to its slugish until about 4000 rpm then it just goes.

yea mine does it at 4000 rpms, its not the timing or anything simple to replace, its just how the engine is ive got 152k, and im replacing parts in it constantly and its still the same, just another mean trick that mazda played on us, and as loosing your 4k boost it could be a number of things oil change, dirty air filter, spark plugs, more than likely all 3

The reason why these engines may feel 'sluggish' at lower rpm's is that like most other small displacement engines, they don't get their power untill higher engine speeds. The k8 is rated with 130hp at 6500rpm, so your not getting that 130hp untill 6500rpm. http://www.rs-productions.com/RSP_Motors/tech/sae-920677/sae-920677.htm has a pretty good chart showing all the k series power curves if you want to see what i meen about low power at low rpm's.

the reason you get such a pronounced "kick" of power at 4-4500 revs is because of the VRIS system on our engines.. do a search for it for more info.. <p>the only reason I could think that it would differ depending on how old your engine is may be because the VRIS shutter/actuator "sticks" and doesn't do as smoothly as it should.. it may not even be working.. <p>@ds

Yes, you can check the VRIS valves according to the data at Page F2-100 in the online manual, they work against engine revs. You really need two people, one to watch the rev counter. You would feel a lack between 2600 and 3900 if No 1 stuck open, and between 3900 and 4700 if No 1 stuck closed (What would happen if No1 stuck closed, but No 2 opened is anybody's guess, the condition isn't documented).
Mine seemed to work ok on the upper numbers (No 1 at 3900; No 2 at 4700), but not at 1900 - mine's an OBDII model, and I guess they deleted that opening point from the ECU - if you look at the Torque curve, that point makes very little difference.