Engine Stutter at 3500 rpm's

[TX Speed Demon]

I think your friend may have it backwards. With a FCD the ecu reads less air than is actually there. SO you run the risk of going lean at high boost levels cause the ecu isn't dumping enough fuel cause it doesn't know the extra air is there.

An AF or EGT gauge would be a good idea though. The Fuel Cut is there for a reason as a safety measure. While it is intended to prevent detonation, it can show up unexpectedly when the MAF freaks out as we are experiencing.

Getting a FCD will get rid of the cut completly, whether it's happening due to a weak MAF, or whether it's happening due to a real problem. So while you won't hit the cut when when you don't want to, you also run the risk of not hitting it when your engine needs to.

If you keep the boost low you'll probably be fine, but there are no garuntees and you are eliminating one safety measure that could save your engine. Having a real AF gauge (like defi or another brand that tells you actual numbers) or an EGT could help you identify a serious problem fuel cut would have taken care of before it's too late.

 

[KyRaceFan]

A defi gauge that reads numbers is still reading off a narrowband o2 sensor, which is still not accurate.
The only way to read accurate air/fuel ratios is to have a wideband, like an AEM, PLX, Tech Edge, etc.

I sorta wish i woulda had the AEM wideband before i got the emanage installed. That way i coulda seen if the FCD was leaning it out up top. :/

 

[skrecht]

i had posted earlier of having this same problem on my stock '03 msp. I had a check engine light come on for a day or so only. It returned after a couple of days and stayed. I was at the dealers today, and though they were unable to finish the work today, they gave me a brief on what's going on with the engine light. I'm sure its not news for most of you, but i was told that the computer states that the car is running "lean". Will be back on Tuesday to deal with the issue. Not sure what they'll do since they had already tried fixing the problem by reprogamming the ecu (though i had it flashed new, the guy told me that it was the latest update). Anyhow, will keep you all posted on what they do on Tuesday that'll hopefully fix this and help all of us.

 

[hargs79]

i had posted earlier of having this same problem on my stock '03 msp. I had a check engine light come on for a day or so only. It returned after a couple of days and stayed. I was at the dealers today, and though they were unable to finish the work today, they gave me a brief on what's going on with the engine light. I'm sure its not news for most of you, but i was told that the computer states that the car is running "lean". Will be back on Tuesday to deal with the issue. Not sure what they'll do since they had already tried fixing the problem by reprogamming the ecu (though i had it flashed new, the guy told me that it was the latest update). Anyhow, will keep you all posted on what they do on Tuesday that'll hopefully fix this and help all of us.

Yeah, let me know how it turns out. Thankfully, the weather "fixed" my problem for the past few days by me...it's been pretty warm out. The first warm day I had, I reset the ECU and the problem went away until I was driving yesterday. So I'm still looking for a good permanent fix. Right now, I'm leaning toward just putting in a gauge pack w/ a boost gauge, EGT, and A/F right on my pillar, and then installing the FCD and a boost controller.

 

[skrecht]

here comes some more crap from madza. I took my car back in for the stumbling problem with a mazda bulletin specifically addressing this problem. (i found it on another thread, someone said it was an email from mazda and it does specifically address the stumbling issue). thought that they couldn't go wrong now. but guess what, they said they updated the pcm to those specifications written on that bulletin by mazda, and as soon as i took the car and drove it easy for a few miles for it to warm up before getting on the throttle, once on 4th gear, i tried passing and there came the jolt again. A chilli morning today proved the problem persists still, it stumbled violently on 2nd gear again. for now, they said that since they are not a mazdaspeed dealership and they were only doing warranty work since there is no other dealer in my vicinity, and since they found that the exhaust was "modified" (previous owner had just taken 2nd cat and resonator off and welded replacement pieces in place), they said they can't touch the car. So i will give an update in a few weeks when i have time to head out of town and have a speed dealer take a look. i hope someone else who gets this figured out posts a resolution cause i am ready to run my friggin car off a cliff and that should take care of the issues that plaque it......stumbling, idle issue and the friggin clunk

 

[hargs79]

stumbling and idle issue

I still haven't figured it out either. I replaced the PCV valve, and that seemed to quell the idling issue just a bit, I still stall going from 3rd to neutral sometimes, but I'm planning on adjusting the idle a bit in hopes that it will resolve this.
Resetting the ECU on a warm day seems to help the stumble, but I haven't really looked into it at all past this. I'm just planning on buying a gauge pod and intalling boost, AF and EGT gauges, and then based on what they say, installing the fuel cut defensor if necessary.
If you don't have it, here's how to reset your ECU:
disconnect the negative battery cable,
pump the brake a few times, I've been holding it down for a few seconds on the last time,
re-connect the negative battery cable.
I've got a different stereo in my car and if done fast enough, it will hold the stereo options, I'm not sure if that stock kenwood will or not, but it's worth a try.

 

[TX Speed Demon]

Skrecht - if it's a violent jerk, that sounds like fuel cut. Especially if it is cold wether dependent. So far the only cure is to get a FCD, but fuel cut is a safty measure. A FCD will eliminate the cut when you don't want it, but also eliminate it when you may need it.

The TSB you mentioned is probably for the hesitation re-flash. This just advances the timing to give you a cleaner pull when accelerating. It's a completly different issue than fuel cut. This re-flash is supposedly done on all MSP other than the 03s (black and orange) so if you've got a 3.5 or newer you probably won't notice any differance at all.

The clunk you can fix yourself. Check out the "Common MSP problems & fixes" thread. I've gto a post there with the part number. You culd order those and replace the bushings yourself with only a jack, jackstand, socket wrench in about 1 hour.

 

[skrecht]

SOLUTION for STUMBLE/JOLTING!!!!!!!!!!!!

What's up guys,
THIS WILL BE A LONG POST BUT VERY INFORMATIVE & HELPFUL. THIS IS 8 WEEKS OF HELL TRYING TO FIX MY 03 ORANGE MSP PROTEGE. IT'LL PROBABLY SAVE YOU THAT MUCH TIME!!!!!
I still do need some help for another issue mentioned below, so please send feedback!!!!
I posted before about the buck/jolt/stumble the you guys have mentioned at 3500 rpm or so.
My orange speed had the first reflash done when new. There seems to be new updates to the computer every so often since they said there was a new one from past several months. After that reflash, nothing changed, weather was nice and when it didn't jolt, car was awesome.
Jolting conituned. Went in with a printout of the Mazda BULLETIN that someon attached on this website. They said they reflashed it according to that. AFTER THAT REFLASH, CAR WAS VERY BOGGED DOWN. NEED SOME HELP HERE. Car lost that rush at turbo spool up around 3000 rpm or so and not just sort of slowly climbs the rpms with an ever slight hesitation and pulls throught after 5000 rpm. CAR IS DEFINITELY SLOWER AND LESS RESPONSIVE IN ANY TYPE OF WEATHER. NEED HELP ON WHAT TO DO, whether i can undo flash or what else to do
NOW FOR SOLVING THE STUMBLE/JOLT ISSUE.
I tried new mazdaspeed dealership that had a better grip on things. They suspected a vaccum leak because i had a check engine light that always told them the car is runnign lean. so they susupected a leak somewhere. After leaving the car only for a day and a half, the had put new tubing along with several other pieces they suspected that i believe come up to the intercooler.
Took the car and though it didn't jolt, the CAR WAS STILL SLOW AND BOGGED DOWN. I thought I'd gain some boost lost in the leak, but nothing changed. Later that night, check engine came back on. Took it in the next day and they were puzzled. They made some calls and called me up and said that my car needs a new turbo.
THANK GOD I PURCHASED 100K MILES WARRANTY, or else i would have been screwed at that moment. They were okayed for a new turbo and after several days, they got the turbo and gaskets and such and i saw a note about a changed turbo to intercooler pipe that was cracked.
I have a new turbo now (anything specific for breaking it in????).
I now have that whistle that i hear on 1.8ts that i never had when you get on the gas, and i love it. No more check engine light for the past week, the stock bypass valve makes all the right noises now and that is all fine and dandy.
THE PROBLEM WAS A FAULTY WASTEGATE ACTUATOR. That is what their diagnosis was. It might have been something else in the turbo, but all fingers pointed to this.
UNFORTUNATELY, I'M NOT ENJOYING THE NEW TURBO, CAUSE THE CAR IS STILL BOGGED DOWN. THIS IS THE NEW ISSUE I NEED HELP WITH!!!!
For those of you with the issue of stumbling, go into the dealer and pray that it'll stumble when they drive with you, or else you'll look like an idiot, as i did for the past 6 weeks. The guys i dealt with had seen all the recurrent problems with the msp and had a hunch at the beginning.
PLEASE PUT DOWN SOME INFO OR ADVICE YOU HAVE ABOUT THE CAR BEING SLOW AND UNRESPONSIVE. I need some feedback before i call them up again at the dealer. My car should be friggin happy now with the new turbo, but its not!!!!!!!!!!!!!!
Thanks in advace.

 

[DonSVO]

ok, a JOLT isnt the car going lean because of a funky A/F curve. its the car recieving NO FUEL. the ECU pulls timing and cuts injector pulse.

here's how it happnens: the car's ECU reads the airflow as a mass, not as boost. 10 PSI in colorado is not the same as 10 PSI in texas. so it reads off the MAF how much air is going in. you can hit the fuel cut at 8 PSI or 12 PSI. on days with low atmospheric air pressure, i could go to 10 PSI no problem. then on a rainy day or a cold day, the air is more dense and i hit the cut at 8-9 PSI. so, in short...

buy a FCD. hook it up. no more jolt.

 

[TX Speed Demon]

skrecht: do you have a boost gauge? You could be running less boost with the new turbo set up than your stock one. As for your bogging issues it is simply too much fuel. If it seems like you get cleaner pulls at partial throttle and it bogs down when under wide open throttle this is definatly it. Mazda did this cause in basic terms more fuel is safer for the engine. We have stock internals not made for forced induction applications and Mazda tuned the car to be safer/more reliable at the expense of performance.

Your options are to:
1) Get some sort of Air Fuel Controller. DSM Convert sells the cheapest one. You could also go for somthing like the MPI or haltech. These allow you to control the amount of fuel delivered in the engine. So you can set an air/fuel ratio that is tuned more toward performance and less toward safety.

2) Start Modding. You need to figure out a way to get more air into the mix. The easiest way is raising the boost pressure. Doing this however will put more stress on your engine. So it would be a wise choice to purchase some supporting mods that let your car get more air in, cool it down and get it out.

This is the route I'm going. I first bought an FMIC since it was the most expensive for me. This helped lessen the occurances of hesitation, especially in the summer, as the intake temperatures were decreased.

I then bought an SRI to get the air into the engine easier. All it really did was make my car sound cool.

A few weeks ago I upgraded the exhaust by replacing the J-pipe and midpipe with a 2.5" catless one. This helped the hesitation the most. I can roll into the throttle faster now and get clean pulls all the way through the powerband. If I go to wide open throttle too low in the RPMs it still bogs down till about 4K RPMs then comes alive and pulls like crazy.

This combination is enough to make the car much more enjoyable to drive. It's alot more responsive and does what I want it do a lot more often. Soon though I'll be putting an a MBC and raising my boost from a pathetic 5psi to 8-10psi so the real fun can begin.

 

[CasopoliS]

Car lost that rush at turbo spool up around 3000 rpm or so and not just sort of slowly climbs the rpms with an ever slight hesitation and pulls throught after 5000 rpm.

I have this too. Sometimes its is more pronounced, sometimes it is just a quick bog. When it happens there is like a 'honing' noise sounding like it is coming from the intake. Stock turbo but I have an Injen CAI, FMIC, and a bunch of other stuff.

 

[Yay-Boost]

skrecht: do you have a boost gauge? You could be running less boost with the new turbo set up than your stock one.

Agreed. The wastegate is what varies from car to car giving different amounts of boost in stock form. New turbo and wastegate is going to give you a different level of boost. My car came at about 5.5 PSI stock. The difference between 5.5 and 7.5 is huge. The car feels much better at 7.5! It may not be a huge change by horsepower numbers but it feels like a different car.

 

[hargs79]

Thanks

Thank you to everyone that's posted on this problem. I've definitely decided to go with the solution that I posted in my previous reply...it seems like the most people agree with some form of this.
Bringing it in to Mazda definitely will NOT help me, being that I've got 65k miles on my car and they didn't even offer me an extended warranty, so a new turbo is absolutely out of the question (I'm not spending 3g's on a stupid problem that will be fixed come spring, or 65 bucks from JoePmbc.) Plus the fact that they diagnosed an easy "throaty" exhaust problem around 3200 rpms as being a "sway bar bushing," and the fact that they took a week and a half to diagnose my kenwood problem (replacing every damn piece of electronics from the subwoofer back to the deck, when this is what I originally told them was the problem.) I don't want them touching my engine in the least...not even to change my oil for fear that they'll **** that up too and forget to put the plug back in.

I'm also playing with the idea of ******* with my MAFS...if anyone has any ideas about messing with this, I'll greatly appreciate it. I haven't even looked at it yet, so I'm not even positive about what it looks like, but let me know if there's anything simple that I can do to forego this problem. Thanks again everyone.

 

[Chewbacca]

I still have yet to find a mazda service department that is helpful is any way...

But anyway... Everyone seems to have their own opinions on why this hesitation occurs. This jerkiness used to piss the hell out of me... But once I started doing AIR FLOW MODS, things really smoothed out. The Turbohoses SMIC took care of 95% of all the jerky hesitation problems that I was having. It's pricey, but worth every penny. The car pulls to redline without any hesitation anymore! I still OCCASIONALLY get a slight (very slight) whiplash between gears (when I press the clutch), but it's nothing compared to before.

I got a apex catted downpipe coming in a week... Hopefully, that'll smoothen things out even more.

 

[CasopoliS]

I still have yet to find a mazda service department that is helpful is any way...

But anyway... Everyone seems to have their own opinions on why this hesitation occurs. This jerkiness used to piss the hell out of me... But once I started doing AIR FLOW MODS, things really smoothed out. The Turbohoses SMIC took care of 95% of all the jerky hesitation problems that I was having. It's pricey, but worth every penny. The car pulls to redline without any hesitation anymore! I still OCCASIONALLY get a slight (very slight) whiplash between gears (when I press the clutch), but it's nothing compared to before.

I got a apex catted downpipe coming in a week... Hopefully, that'll smoothen things out even more.

Did you go from stock setup to the SMIC, or from FMIC to SMIC? I did not get hesitation prior to my FMIC....but then again I have not had the FMIC in warm weather yet so I am waiting to see if its weather related. If its not, I am wondering if the long air path of FMIC's have anything to do with hesitation.

 

[TX Speed Demon]

I got a apex catted downpipe coming in a week... Hopefully, that'll smoothen things out even more.

It should. I've got a catless one on now and smoothing everything out seemed the be the biggest enhancement from this mod at stock boost.

 

[Chewbacca]

Did you go from stock setup to the SMIC, or from FMIC to SMIC? I did not get hesitation prior to my FMIC....but then again I have not had the FMIC in warm weather yet so I am waiting to see if its weather related. If its not, I am wondering if the long air path of FMIC's have anything to do with hesitation.

I went from stock to the Turbohoses SMIC... That stock intercooler is an absolute piece of junk.

 

[Rich24km]

my car has only gotten this slight jolt when i barely give it gas and the car goes into boost and i let off just enough to go out of boost and then back into boost. If it is going lean it, i wouldn't doubt it cause i mean I barely have the gas down when this happens. My turbo spools pretty easily because of my setup. It kind of sucks though cause i either have to down shift to take off or go slower to get up to speed when on the highway.

 

[hargs79]

my car has only gotten this slight jolt when i barely give it gas and the car goes into boost and i let off just enough to go out of boost and then back into boost. If it is going lean it, i wouldn't doubt it cause i mean I barely have the gas down when this happens. My turbo spools pretty easily because of my setup. It kind of sucks though cause i either have to down shift to take off or go slower to get up to speed when on the highway.

Sounds exactly like what my car was going through a little bit before I noticed this annoyance. Just read this thread over again if the weather gets cold and you ever experience what we're all experiencing, I think there's been a lot of good advice presented.

 

[Yay-Boost]

IMHO is it's all about boost. The mods listed above all help smooth the car out because they add more boost. Get rid of the fuel cut and bump the boost up and the car runs better.