Why does the Mazdaspeed3 fuel cut so easily?

[bradboyd80]

what do you guys recommend as a good alternative for the stock BPV? nothing fancy, i don't care what it sounds like, etc. in fact i would prefer as quiet as possible.


oh lord, is this how it starts? first one thing, and then another? also thinking the MS CAI is in order as well

I actually just installed my Forge BPV and Injen CAI. Huge difference, and only ran me $400 total.

I know what you mean though....I started off with a motor mount, BPV, CAI and spark plugs. But as you can see in my sig, that list grew pretty quick. Haha

 

[MSMS3]

what do you guys recommend as a good alternative for the stock BPV? nothing fancy, i don't care what it sounds like, etc. in fact i would prefer as quiet as possible.


oh lord, is this how it starts? first one thing, and then another? also thinking the MS CAI is in order as well

IMHO, the best alternative to the stock BPV is the stock BPV. If it ain't broke, don't fix it. The Grass Roots article can be read two ways: Under lighter load in the lower gears, the Forge seemed to have quicker release and recovery. But under fuller load in third gear where the ECU's engine nanny is not holding power back, the stock BPV actually held boost as much as 1.5 pounds higher than the Forge. Go figure.

Unless the stock BPV can be shown to be leaking there is no performance based reason to replace it. The ECU nanny, if you have stock tune, is not going to let you produce any more power in first and second gear anyway. That negates any paper advantage of the Forge, IMHO.

Give me more boost from third on up. With my mods I'm spiking to 21-22 psi and holding steady at 17 psi, occasionally 18 (with load cut when that happens), so I'm very, very happy with the stock BPV and have chosen to spend my hard earned cash on mods that actually make power.

Grass Roots chart attached.

 

[squidmotion]

good stuff... thanks for posting this info.

 

[ericrapp]

MSMS3, just for the sake of discussion and not for any other reason. The point of the Grassroots graph is that the Forge closes quicker. Make no mistake folks, a better valve does Not make more power, but it might get you down the track quicker! Thank you for taking the time to put up the real info, sir! My rule of thumb is, also if it ain't broke do not fix it but if it does break, upgrade!!

 

[Prafeston]

I know this thread is a little old, but I've run into a bit of an issue with my MS3. Driving about 5 miles tonight I was experiencing some what seemed like fuel cuts. There was definitely some hesitation/no response at times when I was giving the car gas. I made it too my destination, watched some football and went to leave 3 hours later and my car won't even stay on. Starts right up everytime, but dies in less than 3 seconds. Trying to give it gas when it first turns on does absolutely nothing. I don't know what the issue is as I don't have any major mods. CP-E SRI is my only performance upgrade. I had a check engine light maybe 6 months ago that I tracked down to my MAF sensor so I took it out again and cleaned it, but that did nothing...not that I thought it was going to fix the problem, but I figure it was worth a try and about the only thing I could do without any tools.

Tonight was the first pretty chilly night of fall and I didn't let the car warm up really, but still it was only a about 55 degrees which isn't that bad. The symptoms seem to point to low/no fuel, but I just filled up from Mobil last night with 93 octane and couldn't have gone more then 10 miles since.

 

[MSMS3]

There are several things that may becausing your issue.

With only an SRI, I tend to doubt that you are getting load cut, which is usually the cut that happens when the stock ECU reaches its load (power) limit in the upper gears. I can't tell from your post what rpm range or gears, except that now you are having a problem even keeping the car running after it starts.

How many miles do you have on the car? Maybe it is a fuel filter issue? Maybe a dirty or clogged air filter on your SRI? Check the simple things first. It could also be bad gas, since you just filled up, or you may have managed to foul your MAF sensor again.

Another possibility would be your spark plugs, depending on how many miles you have on them, they could either be fouled from too much slow around town driving, or might have opened the gap up too much from too much WOT or high speed driving or simple wear over time. But if it's a true cylinder miss under less that WOT conditions, you ought to be throwing a CEL code.

I would not automatically assume a fuel pump issue until you have checked filters, gas quality and spark plugs and the MAF sensor.

 

[Prafeston]

Thanks for the response. Gives me some things to check out.

The car is an '08 with under 33,000 miles on it. I just bought it a little over a year ago with about 18,000 miles on it. I was kinda thinking a dirty fuel filter too. It was dark last night and I needed to get home to I just bummed a ride and wasn't able to check out the car in the light today. Hopefully I can get to it tomorrow. I did look at the SRI filter and it didn't appear to be dirty, but it was night and I didn't take it off or anything. Just check it's appearance real quick.

When I took the MAF out last night and cleaned it one side was pretty coated with black dust like stuff...was getting my hopes up that that was the problem, but alas it didn't work after cleaning. Weird thing is I don't think it's throwing a CEL and I know for a fact that on the ride over there there wasn't a CEL. It lights up when I start it, but if I remember right it always did that. Kind of like the initial checking of all lights on the dash thing.

How would I go about checking the quality of the fuel?

 

[rsvinylgraphics]

^ did you reset the ECU after cleaning the MAFS

 

[creedns]

if your maf threw a code cuz of a sri i am willin to bet you maf is shot. only reason the car would die like that. swap maf;s with someone if you can to see if it helps

 

[Prafeston]

^ did you reset the ECU after cleaning the MAFS

No, didn't think of it till doing some reading last night. That's gonna be the first thing I try tomorrow when I go back to the car.

 

[Prafeston]

if your maf threw a code cuz of a sri i am willin to bet you maf is shot. only reason the car would die like that. swap maf;s with someone if you can to see if it helps

Pretty sure I'm the only MS3 in town. I have a friend 100 miles away with one. The MAF was pretty crudded up with black stuff on one side. I got most of it off though.

 

[Prafeston]

Well, I didn't get much of chance to look at things this morning before work, but doing the battery disconnect to reset the ECU didn't help. I inspected the Air Filter on my SRI and it seems just fine. All connection on the SRI seemed good and I was gonna check my spark plugs, but taking the intercooler off and checking them was going to be too time consuming for the small amount of time I had to work on it. I do think it is throwing a CEL though, so my friend that lives 100 miles away happens to be coming through my town this weekend and he's gonna bring me his dashhawk.

 

[Hapa88]

I experienced what seemed to be a fuel cut on a few occasions when I went to the track. My mods are BEGi Cold Airbox, RB Exhaust and SU Test pipe. Everything else was stock and was running 91 Octane gas (SoCal) with NOS brand Octane booster.

Was at the Buttonwillow running the track and noticed on a few of the sessions topping out 4th gear WOT on the straight somewhere between 5000-6000 rpm, it felt like i hit the rev limiter or speed limiter (even though I knew I still had plenty of RPM before either). Power would drop and I would immediately release the gas pedal and get back on it and it would be fine. At first I thought it might have been my foot slipping off or I accidently hit the rev limiter, but it happened like 2-3 more times. . Any idea what it might be?

 

[ericrapp]

Test pipe. overboosting from the quick ramp up. Computer doesnt like it at all.
We tuned it out but there were two rpms depending on the gears (4-5-6)? i am sorry this was done quite awhile ago and i did not grasp all the details of the adjustments. But i think it was around 2800 at full thottle and maybe around 4700 again at throttle.
If i understand correctly, and i may not. The lack of back pressure from freed up exhaust causes little resistance for the impellers to just take off. Try throwing just the catalytic back on. Pretty easy.
I have an Aem cai and larger 3" smoothed turbo inlet 3.5 TMIC, 3" full exhaust.
But these are not what you describe. The cut is a hard cut. I mean hard have your seat belt on or hit the windshield.
I have had bad luck with octane boosters, lots of burbling and down on power. Because of Direct injection? not sure. I have run 100 octane from Delta sonic on occasion and never had an issue at all.
6100 with the stock tune the car starts to rein itself in and is laboring in the long gears at wot. The car likes to be shifted earlier than some with it's nice torque curve especially with stock tune, but the turbo map shows clearly i think, that it doesnt want to go much past 6000 before hot air is all you get.
do you monitor with a Dashawk or some similar data logger, looking for knock? and then timing retarding by ecu?
I hope i have not bored you but
i must say i am jealous of you on 3 occasions at least. 2 NSX'S really? and Buttonwillow to boot?
eric
Not fair Not fair at all Sir!

 

[MSMS3]

I experienced what seemed to be a fuel cut on a few occasions when I went to the track. My mods are BEGi Cold Airbox, RB Exhaust and SU Test pipe. Everything else was stock and was running 91 Octane gas (SoCal) with NOS brand Octane booster.

Was at the Buttonwillow running the track and noticed on a few of the sessions topping out 4th gear WOT on the straight somewhere between 5000-6000 rpm, it felt like i hit the rev limiter or speed limiter (even though I knew I still had plenty of RPM before either). Power would drop and I would immediately release the gas pedal and get back on it and it would be fine. At first I thought it might have been my foot slipping off or I accidently hit the rev limiter, but it happened like 2-3 more times. . Any idea what it might be?

Ericrapp has provided solid advice. I'd add one very simple thing: Check your spark plug gap. About 6 months ago I started experiencing what I was sure was some kind of hard slap down cut that I though was load cut. It was in the same rpm range you had your problem. I'm running catless dp/rp into stock CBE and at that time had stock ECU (now Hypertech tune) with a CAI intake and one step colder plugs. I put the stock secondary cat section back on and it did not fix the problem. I pulled the plugs and found out that a lot of hard driving had opened the gap up significantly. It seems that under high load conditions boost was actually blowing the spark out momentarily. When I let up, spark returned and combustion was complete.

Just a thought. Costs nothing to check the plugs. If gap is over .030, tighten them back down. Mine had opened up to .035-.038. They are now at .028.

Put the test pipe back in, returning to full 3 inch catless from turbo to the front of the CBE. No cut now under any conditions so far, although our version of cold weather is yet to come. No cut with the HT tune either, so far.

 

[Hapa88]

Test pipe. overboosting from the quick ramp up. Computer doesnt like it at all.
We tuned it out but there were two rpms depending on the gears (4-5-6)? i am sorry this was done quite awhile ago and i did not grasp all the details of the adjustments. But i think it was around 2800 at full thottle and maybe around 4700 again at throttle.
If i understand correctly, and i may not. The lack of back pressure from freed up exhaust causes little resistance for the impellers to just take off. Try throwing just the catalytic back on. Pretty easy.
I have an Aem cai and larger 3" smoothed turbo inlet 3.5 TMIC, 3" full exhaust.
But these are not what you describe. The cut is a hard cut. I mean hard have your seat belt on or hit the windshield.
I have had bad luck with octane boosters, lots of burbling and down on power. Because of Direct injection? not sure. I have run 100 octane from Delta sonic on occasion and never had an issue at all.
6100 with the stock tune the car starts to rein itself in and is laboring in the long gears at wot. The car likes to be shifted earlier than some with it's nice torque curve especially with stock tune, but the turbo map shows clearly i think, that it doesnt want to go much past 6000 before hot air is all you get.
do you monitor with a Dashawk or some similar data logger, looking for knock? and then timing retarding by ecu?
I hope i have not bored you but
i must say i am jealous of you on 3 occasions at least. 2 NSX'S really? and Buttonwillow to boot?
eric
Not fair Not fair at all Sir!

Thanks Eric for the suggestions. I guess I'll have to get a Dashhawk or borrow someones for the track to get a better idea what's happening.
I know I do occassionally get knock with Southern California's crappy 91 octane gas. They offer 100 octane at the track but it runs about $8.65 a gallon last time I was there, so I decided to look into octane boosters. Reason was mainly to try to get the octane just high enough so that there's no knock. I found this European Car Magazine article that tested them and found that a bottle of NOS Brand kicked up 91 octane to 93.7 octane. It seemed to do the trick because I didn't have any noticable knock. . .

http://www.europeancarweb.com/tech/0503ec_octane_boosters_tested/index.html

Anyway, it seemed to be the most cost effective solution (12.5 gallons of 91 octane @ $3.30 gallon + $12 NOS Booster VS 12.5 gal of 100 oct @ $8.65)
So $54 for ~94oct vs $108 for 100oct. I chose the cheaper and had a nice steak dinner after a long track day. (2thumbs)

Also I'll look into the plugs. I'm practically at 50K miles now anyway, so maybe I should just replace them since I'll already be taking them out to check them? Any recommendations for plugs with my light mods? Might get the Hypertech. . . so OEM spec? A step hotter or colder plug temp?

 

[MSMS3]

Also I'll look into the plugs. I'm practically at 50K miles now anyway, so maybe I should just replace them since I'll already be taking them out to check them? Any recommendations for plugs with my light mods? Might get the Hypertech. . . so OEM spec? A step hotter or colder plug temp?

Yeah, 50k miles, it's new plug time. Unless you go with a big catless dp/rp (which would raise boost about 2 psi), you should probably stick with the stock heat range plugs. HT's tune is based on stock heat range. I went with the colder plugs just to provide a little extra protection against detonation. Probably didn't quite need them yet. Usually have to be close to 50 hp up over stock to justify the colder step. But they are not fouling. I drive this car pretty hard. So you could probably go either way and be fine.

One sort of crazy thing is that the colder plugs (in my sig) are readily available at most auto parts stores and are cheaper than the stock range plugs, which seem not to be used in any other applications and are, thus less popular, less readily available and more expensive! If you go with the NGK's (my personal preference, although the Densos seem to do fine), they will come with a huge .045 gap and will need to be gapped down. Either way, be sure to get fine wire iridium center electrode plugs, which are much more appropriate for high boost, high compression, DISI engines. Stay away from the platinums or multi-tip types.

 

[ericrapp]

Well gentlemen, it seems that this info gather and share is helpful to us all. That is why i joined the forum a couple years ago!
I also had some concerns about spark blowout early on. I ate the stock plugs up early even with limited mods . I was swapping plugs and tightening gaps and hoping to dial her in by seat of the pants and looking at plug condition. I knew i was very rich before tuning.
My gaps opened up also, from wear. The factory gap was too big for anything i had read about boosted cars and my son in law tuning guru said i should be running closer to .029.
I am running two steps colder Denso now but thats a story for another day.

Be very careful when adjusting the gap, that tiny electrode is delicate. ( yes i broke one after trying to open the gap back up)?!.
I do not want to badmouth any octane boosters, just do not work for me. i am very anti knock myself haha..
In the olden days. as you folks might know, the best way to check your air fuel was to read plugs. and as correctly, and wisely suggested here it's a great first step.
Also do use maf cleaner ( spray) every now and then.
One of the other things i nearly forgot that might be big... I have the mazdaspeed cai. Well the air straightener was offered later as a fix for excessive turbulence over the maf. And i have read that some other CAIs at the same diameter pipe have benefitted. they are cheep too.
and it really made an impression. I realize they are different systems we have but its something to consider maybe.
Lastly, as i have over done this response due to my enthusiasm for you to get her dialed in i may have given too many options and cause some confusion as where to start.
If i may suggest that you make one change at a time.
If you are not logging data or tuning, give the car a good few start cycles for the ecu to get comfy again and see what you feel.
If nothing positive return back to as before and try another change. You sound as if you have a good seat of the pants opinion on the car already so you will probably know whats working and whats not i bet!
I have forgotten some things already, and my car is a work in progress i suppose.
We wish you luck, i think, and keep us up to date if you do not mind.
eric

 

[ericrapp]

speed limiter is set from the factory for 154.5 i believe for the 2007. I did gps mine on stock tires and wheels and the speedo was spot on.

 

[Number2]

I'm having the same issues with cut at higher rpms (fuel or boost: not sure) as well as exhaust popping detonation. My mods are HKS BOV, CP-E CAI, COBB Turbo Inlet, ETS TMIC, SU Test Pipe.

I have had these mods for well over a year (except the test pipe which I got in March of this year), and the only thing that I think might have changed is the ECU was unplugged and plugged back in so it had to learn everything again. Another thing that happened was the bracket for the CAI came undone and for a day, I drove around with the cai pipe sagging and getting bumped by the shifter when shifting into 1st, 3rd, 5th. Could the MAF being knocked around by the sagging CAI pipe cause damage that would result in this behavior?

Should I be experiencing this with these few mods?

I'm going to try cleaning the air filter, and checking the spark plugs as well as the MAFS cleanliness.