My Mazdaspeed Protege (MSP) currenet issues

[Sushi-Monster]

Hey Guys n Gals!

Its been ages since I posted on this forum. Looking for some advice/help with my current problems.

The car was running very badly in the 6 months. Would stall after revving past 3500 RPM when shifting back to neutral (think of accelerating from one stop light to another stop light). I would have issues trying to run the car past 4000 RPM after 2nd gear. The car would suddenly "buck" (felt like I had massive fuel cut) and "choke" violently. The car is also reporting lean. After replacing all the worn & cracked vacuum lines, I've stopped the stalling but still receive the same issues with some new ones. So far here is a complied list of problems I'm facing.


Car still reports lean. Is the DSM AFC to blame?
Car still "bucks & chokes" when I step on the gas or if I shift in 2nd gear after revving past anything over 3500 RPM. However it does not buck if I gradually step on the gas. I can travel all the way to red line in any gear without fail (haven't tried 4/5th gear naturally). Also after it bucks, there is a immediate boost lag. Is there still a boost/vacuum leak?
To stop the stalling, I disconnected the BOV. BOV is the HKS SSQV situated on the cold pipe.So far I'd assume it was the Denso BPV that was causing all my problems. After removing it and replacing it with a Forge BOV I was still receiving the same issues. I'll admit, this setup vents to atmosphere and does stall after boosting to neutral so it didn't really solve anything, but with BPV, I did not stall. Would it matter now if I acquired a Forge BPV?

The HKS BOV. Never would I thought that with a BPV/BOV setup I would still stall. Is the BOV faulty? I bought the BOV used and not sure if it is broken. However it works as it should. It only stalls under the same conditions as before. Go into boost and shift into neutral stalls the engine. Should I replace the BOV with a recirculating type?

As far as the car running lean, could there be a possibility that the DSM AFC is the culprit? I am still using the stock Superstock map since i'm running just a FMIC with a CAI. Everything else is still stock. Later, I will install a gutted/hi-flow catalytic converter mid pipe; until the car runs fine, I will not mod it any further.

As for a final note, I may just replace my entire Defi gauge set with something else. I was looking for something along the lines of a bi/tri-pod pillar setup from AEM's TRU-BOOST Gauge-Type Controller (http://www.aempower.com/ViewCategory.aspx?CategoryID=68) and Gauge-Type Wideband UEGO Controller (http://www.aempower.com/ViewCategory.aspx?CategoryID=67). If i did get the AEM wideband, would that eliminate the need for the AFC?

Any suggestions/help would be most appreciated!!!

[Fudgie]

Are you overboosting?

[Ricktalife]

check your pipes for leaks, i had the same issue with the bucking and it turned out i had a big hole in one of the pipes lol.

[funktownp5]

Check the wiring of the AFC, give the wires a good tug to make sure its

not that.

[WIMSPWI]

check for vacuum leaks, i am having the same problem and i run the ss afc....still havent found where my leak is yet though.

[laracroft]

I used to have the BPV and a BOV set-up. Didn't like it - took off the BPV and plugged that part of the pipe. Worked out much better. Check for vaccuum leaks like everyone else has said. It could also be a bad tune if you're running an engine management. May be a bad mix of air and fuel in the higher RPM bands - the computer may be trying to compensate.

[Sushi-Monster]

Are you overboosting?

Yeah, before it bucks, the boost stays at .5 bar then immediately shoots over 1 bar!

Otherwise under steady acceleration boot stays a little under .5 bar.

[Sushi-Monster]

check your pipes for leaks, i had the same issue with the bucking and it turned out i had a big hole in one of the pipes lol.


Once I find a shop with a steam machine, i will definitely check that option out. But as replaced all the vacuum hoses, I look over the piping. Everything seemed fine.

[Sushi-Monster]

Check the wiring of the AFC, give the wires a good tug to make sure its

not that.


Yep, the AFC is installed correctly. I even had my auto body guy even solder the connections shut.

[Sushi-Monster]

check for vacuum leaks, i am having the same problem and i run the ss afc....still havent found where my leak is yet though.

Where do you stall??? Are you having the same type of quirks I am? Are you able to drive freely in any gear without hesitation?

All my vacuum lines were pretty much corroded. Rubber hardens and eventually cracks. You'll find, like myself, that every vacuum line (especially the manifold line) has a small hole/crack in it.

[Sushi-Monster]

I used to have the BPV and a BOV set-up. Didn't like it - took off the BPV and plugged that part of the pipe. Worked out much better. Check for vaccuum leaks like everyone else has said. It could also be a bad tune if you're running an engine management. May be a bad mix of air and fuel in the higher RPM bands - the computer may be trying to compensate.

I'm thinking of getting rid of the AFC in place for the AEM UEGO Wideband. I haven't been able to find any AFC vs AEM posts in relation to A/F's. Would the AEM be a better choice overall since I can see the values digitally?

[special--k]

for sure its a vacuum leak. I had the same problem, i found a inch long crack in one of my silicone coupliers for the hotpipe.

[Sushi-Monster]

for sure its a vacuum leak. I had the same problem, i found a inch long crack in one of my silicone coupliers for the hotpipe.


Interesting, I'll go over the couplers!

[Fudgie]

Sounds like you are hitting fuelcut due to a faulty wastegate actuator. Make sure you have a solid hose connection there. Any check engine light?

[Sushi-Monster]

Sounds like you are hitting fuelcut due to a faulty wastegate actuator. Make sure you have a solid hose connection there. Any check engine light?

Yes there is a check engine light, but it only posts lean currently. How would I check on the wastegate as you suggested?

[Moonman8]

Another thing to possibly consider is the vacuum line going to the wastegate actuator is collapsing on itself under the heavy throttle/high rpm (think of a drinking straw when you suck on it too hard). That would cause the boosting problems and what seems like fuel cut (suddenly no boost, the car falls on it's face). A vac line with a weak inner wall will not be visible as faulty like a leaky line would so it may be worth a shot just to run a new line to the actuator nipple and see what happens. Just an idea.

[speed1016]

Could also be your upstream o2 sensor since you do have a CEL for running lean. If your interested in buying a wideband (cmahlig) has one forsale for 200.00 But this will not fix your problem nor will it replace your AFC.

[Sushi-Monster]

Another thing to possibly consider is the vacuum line going to the wastegate actuator is collapsing on itself under the heavy throttle/high rpm (think of a drinking straw when you suck on it too hard). That would cause the boosting problems and what seems like fuel cut (suddenly no boost, the car falls on it's face). A vac line with a weak inner wall will not be visible as faulty like a leaky line would so it may be worth a shot just to run a new line to the actuator nipple and see what happens. Just an idea.

Thanks for the suggestion. Sorry to reply back so late in this thread, but once in snows in Canada, you pretty much say good-bye to driving for a solid 2 months. Anyways are you able to post a picture of where that line may be?

[Sushi-Monster]

Could also be your upstream o2 sensor since you do have a CEL for running lean. If your interested in buying a wideband (cmahlig) has one forsale for 200.00 But this will not fix your problem nor will it replace your AFC.

I've considered that possibility. The cost of acquiring a new o2 sensor would be crazy. The EGT is not reporting anything for temperature. I'm praying that that sensor is not dead.

[lyserjic]

Don't discount a fuel pump problem. I had the same horrible bucking and stalling/ lean CEL issue with a bone-stock MSP. Replaced EGR, MAF sensor, coil packs, plugs. Issue was still there, no vac leaks either.

When I pulled the fuel pump, the problem became apparent. See my post about it here: http://www.mazdas247.com/forum/showpost.php?p=4331183&postcount=6

[Lt.]

Any update on the problems? I've been having the same boost then stall issue too...

[Metallic36]

Old post, but adding this in for reference.

You should have BOTH, that's why you haven't seen any AFC vs. AEM, because the AEM is a gauge, not a controller.. it's sort of hard to tell if your tune is causing this since you don't have a wideband. I would recommend keeping the AFC, and getting the AEM wideband. You are NOT going to be able to control the a/f ratio with the wideband, that is what the AFC does. Otherwise, nobody would need both. I have both, I would admit that your problems are probably in the map that you are running. With my car I can upload the Stock Supermap and it will give me fuel cut from hell, at 4K rpms it will start bucking, and all my power goes away at that point, and I have to slowly build it back up. If I change it to a different map, I have absolutely NO issues, and can boost all the way to 11 psi without any problems at all, very smooth and with power.



I'm thinking of getting rid of the AFC in place for the AEM UEGO Wideband. I haven't been able to find any AFC vs AEM posts in relation to A/F's. Would the AEM be a better choice overall since I can see the values digitally?

[Sushi-Monster]

Old post, but adding this in for reference.

You should have BOTH, that's why you haven't seen any AFC vs. AEM, because the AEM is a gauge, not a controller.. it's sort of hard to tell if your tune is causing this since you don't have a wideband. I would recommend keeping the AFC, and getting the AEM wideband. You are NOT going to be able to control the a/f ratio with the wideband, that is what the AFC does. Otherwise, nobody would need both. I have both, I would admit that your problems are probably in the map that you are running. With my car I can upload the Stock Supermap and it will give me fuel cut from hell, at 4K rpms it will start bucking, and all my power goes away at that point, and I have to slowly build it back up. If I change it to a different map, I have absolutely NO issues, and can boost all the way to 11 psi without any problems at all, very smooth and with power.

GuRL!!! If you have that map PLEASE SHARE!!! I'm almost to the point where I'm desperate for an answer.

Currently theres a check engine light and its reporting lean. I don't have the funds to check it currently. I was considering bringing it to a Mazda dealership to see if they could help in anyway, but people are advising me to not go there as they would charge an arm and a leg.

Do you have any ideas?

[JDM Sam]

Take the AFC off first. Then drive around to see if the problem is still there.

If you want to rule out the bov/bpv, take them both off, and use 1 bov recirculated or bpv like factory. The sound maybe cool, but you only need 1 valve.

Don't throw on more mods on your car until you fix your underlying problems first.

[githua92]

Yeah, before it bucks, the boost stays at .5 bar then immediately shoots over 1 bar!

Otherwise under steady acceleration boot stays a little under .5 bar.

If my conversion is right, 1 bar = approx 15psi and 0.5 bar approx 7psi. That sounds like a faulty wastegate actuator especially since you mention it holds steady at .5 bar then spikes to over 1 bar. Do you have a stock turbo? if so then you're generating too much boost and the only part that limits/controls the boost level is the wastegate actuator.

My car has the same spiking issue till I changed the wastegate actuator. Definitely keep away from 1 bar if its a stock turbo and motor.