No power until 5500rpm?

stevew145

Member
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Mazda Protege ES
I am now running stock boost, and I have no power until ~5500 rpm. Most noticeable in 2nd gear. There is a major lack in power, then its balls to the walls until 6500 rpm. My afr is about 12:1, intake temps are nice and cool, boost holds steady at 7 psi. What the **** is going on? I have never had this problem before. There is an audible change in the engine as well. Its almost like vtec. In the wet my tires break traction at 5500 rpm. Its strange because before at 10+ psi power was immediate and died off after 5500 rpm. I have tried resetting the ecu, my spark plugs are new and gapped at .030. I am unsure if my ecu is flashed or not. I bought an msp ecu off a member here and have no idea if its flashed. There are no engine codes. I was reading a thread here where others explained the same problem, but a solution was never found. VICS and re-flash were what people were saying the most. Anyone have similar experiences?
 
5500 is not too far after when the VICS opens up the chamber, but it isn't a night and day difference.

No one has cracked the ECU, so it isn't flashed.

If I understood your post correctly, you had an ES ECU and were running 10psi? Now you have an MSP ECU and you reduced boost to 7+psi with your MBC?

The stock MSP ECU, and I highly doubt this is specific to the MSP, is in closed loop until 4200 rpms. Depending on where in the cycle you are, the transition to open loop and the accompanying kick in the seat can be pretty brutal. You can easily see it with your AFRs though. I would think with your Carputer would be able to do is datalog your wideband. 5500 rpms is way too late though.

It sounds like you are actually running very rich under 5500 rpms. If the ECU is adding fuel when it enters closed loop, you don't go anywhere until those short term trims are gone. You say you have 12:1 AFR, but when? It certainly isn't 12:1 through the whole rev range. If you plot it, I think you'll see what is going on, and the only way to truly fix it is a standalone.

The stock ECU is like a box of chocolates, you never know what you are going to get.
 
I have always had the msp ecu. I am not running a boost controller anymore. The flash I was talking about was the re flash from mazda to fix the hesitation. With the ssafc there is an o2 clamp that puts the car into open loop at a set point in your pressure. For me, i go in open loop at -1. My afr is 11.5-12.2 through out from 3000 rpm to redline. My fuel trims are are sensible, +- 10%, doesnt go to 25% or anything.
 
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I don't think the SSAFC puts the car into open loop. I am pretty sure that is impossible. The O2 clamp just reduces the voltage of the O2 to zero, fooling the car into thinking it is lean and adding fuel. Normally in closed loop the car is targeting 14.7 AFR, or a .5v signal from the O2 sensor. With the clamp it will just keep adding fuel until it reaches open loop at 4200rpms.

It works, but the problem with that is those trims eventually go to long term and affect the open loop tuning as well. This is why there are a few hundred posts in the SSAFC thread that claim their tune went to s***.

If you actually plot your AFR (your AEM should have software to do this), you'll see it isn't always the same. Just looking at the gauge will not tell you what you need to know.

Since you have the BT scan tool, you can actually see your fuel status and see whether or not you are in closed loop. I tried everything to get the car to go into open loop under boost, but it was always 4200 rpms except for two special cases.

Get the plots and post some screenshots. What software are you using to see your OBDII?
 
I seemed to have this too, I have replaced the coils and it seemed to be better.... Idk just seat of the pants though.
I tried to post a video, but I had the "like vtec" feeling (friends even asked about it) and it seems to be faster all around now, so change the coils and make sure your gap is on the smaller side like .028 - .030"
 
i checked with my obd2 scanner and timing goes to 0, and jumps to about 13 when the power comes back. if i ease into throttle slowly it is less likely to happen. I dont hear any knock but i guess its possible the timing is being pulled because of detonation. i just have to figure what is causing the timing advance to go to 0.
 
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I was thinking the same thing when it happened to my car, so I checked my knock sensor resistance etc. but no luck. If you find out, I would really like to know...
 
I have no idea whats on the go. Im going to play with it today and see what I can figure out. Do you have the reflashed ecu? That is what I am leaning towards. I bought mine here, and dont know if its flashed or not.
 
I looked all over for a sticker... And I do not think it is reflashed.
but if you think it has good power just above 5200 rpm see if you can notice this in the video I took....
http://www.youtube.com/watch?v=lUcc715XjZ4

its hard to notice in a video, all you can really notice is a change in pitch of the engine, but It was much faster after 5200 rpm... I have been fxck'n around with poor autozone coils at the moment though... I have taken 2 in for replacements already... (but the reason for purchasing was the 2 yr warranty).... Is there anyone in your area that you could swap coilpacks with?


My other thoughts could also be detonation.... So you could try to swap out the knock sensor?
 
Interesting about the timing. I never bothered to look at timing when I was doing all my fuel investigation. I can check my timing tomorrow and see what mine does. It could very well be sensing knock and pulling timing.
 
I experienced something similar before. Little power before ~5500, and then all normal power passed that.

In my case, it turned out to be a dirty MAF sensor. I cleaned it with a MAF Sensor cleaner, and all was good after that. Actually, I first replaced with a used one from the wreckers; I then learned that one can clean those things.

Side note:
I had no CEL
 
that was actually something i considered but hadnt checked. i have another laying around, ill swap tomorrow and see what happens. its not the coils, its the ecu, whether its the ecu its self, or an erroneous input its recieving its hard to tell. for now im leaning towards a dirty maf.
 
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Swapped out the maf and initial impressions are good. My tune is WAAAAY off now. I also disconnected the battery after i swapped them to make sure I have a fresh start. My maf did have a fine layer of oily film covering it. My tune was too lean to test full throttle, but part throttle is much improved.
 
If you've tuned your car with the original (now dirty) MAF, then you might want to Clean it and put it back in instead of the spare one that you just installed. See if that makes a difference when compared to your spare one. MAF Sensor Cleaner is only like 15 bucks.

If you do buy the cleaner, get the "MAF Sensor Cleaner" and not "Brake Cleaner" (as I've heard recommended [to save a few $s]). In my opinion, it's not worth taking the risk and damaging the MAF with improper cleaner.

I'm curious. My MAF getting dirty was a rather unique circumstance. Under 'normal' driving conditions, one would expect the air-filter to prevent that from happening. Any idea what might have caused yours to become covered with "oily film"? Do you have a CAI, by any chance?
 
I'm curious. My MAF getting dirty was a rather unique circumstance. Under 'normal' driving conditions, one would expect the air-filter to prevent that from happening. Any idea what might have caused yours to become covered with "oily film"? Do you have a CAI, by any chance?

Not just a CAI, but also putting a K&N or other oiled air filter in the stock box. Most cone-type filters are oiled as well. The oil gets sucked in by the airflow and it coats the MAF wires. Happens all the time, it's a known major issue on the 3s, and our cars have the sensor right after the filter box as well.
 
First of all, the maf did nothing. Unplugged the knock sensor and all hell broke loose. Full power is back. No knock is audible, and never was. Its strange. There must be either interference in the wires, or the sensor its self is bad. I'm going to wash my maf with some quality maf cleaner tomorrow. The car does seem to run smoother, and the tune is more consistent. As far as the filter getting dirty, I have a relocated MAF, so the vent line from the valve cover is now before it, instead of after. I am thinking a little blow by over time has made it into my piping. When I saw an oily film, it is VERY faint. Enough to make the plastic shiny, but not enough to rub around with your fingers when you wipe it. I did overheat an engine (long story) and there was excessive blow due to a warped head. That engine has since been replaced, but I didn't clean the piping as I didn't realize how bad it was. I guess I have a big job ahead. I have unhooked the crankcase vent to intake hose for now until I can get a quality catch can. Im going to try re-connecting the knock sensor now to see what happens. My fuel trims are crazy too. long term of 21+%! I reset the ecu and that is what its doing. Oh well, it runs good.
 
This would be the first time I've heard of a knock sensor going bad, but everything fails eventually. Keep us in the loop.

Unless you tear your K&N, you should never need to replace it. Just wash it very thoroughly but gently until water runs clear out of it (might take several soap applications), then lightly oil it with the spray bottle. Lightly is key. You want it to just turn the pleats slightly pink. It should not drip. Oil only gets past the filter if you use too much of it.
 
When I unplug the sensor, everything is normal until the cel comes on. The code is for the knock sensor circuit open (duh). When the light is on its just like the sensor is plugged in. Clear the codes and it runs perfect again.
 
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