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CAI, turbo and surge
- Thread starter Rainman
- Start date
Take a listen
Took it for a run this evening and had my son film. I will post the vid after I compress it to a manageable size. I also discovered that it doesn't happen at WOT, but rather about 3/4 throttle. If I mash it to the floor I get only a slight hesitation as I did before the CAI. However, if I leave it at 3/4 throttle, I get the bucking sensation. No turkey sound, but momentary loss of, and then recovery of power/acceleration (almost as if the car had hiccups). The sound that occurs here is more like burping than the turkey which I clearly hear when the BOV goes off. The car is NOT stalling here as my RPM do not change and I do NOT lose power steering or brakes. Just the bucking.
In the 2506 vid you can clearly hear the turkey under acceleration midway thru the clip. All turkey sound, NO bucking. However, in the 2514 vid you can hear the sound of the engine cutting in and out momentarily. Unfortunately, you can't really get a sense of the bucking too much, but it is fairly evident when you are riding in the car. I agree with Rocketspeed in that I don't think that the bucking is related to the turkey. Your thoughts are welcome.
R
Took it for a run this evening and had my son film. I will post the vid after I compress it to a manageable size. I also discovered that it doesn't happen at WOT, but rather about 3/4 throttle. If I mash it to the floor I get only a slight hesitation as I did before the CAI. However, if I leave it at 3/4 throttle, I get the bucking sensation. No turkey sound, but momentary loss of, and then recovery of power/acceleration (almost as if the car had hiccups). The sound that occurs here is more like burping than the turkey which I clearly hear when the BOV goes off. The car is NOT stalling here as my RPM do not change and I do NOT lose power steering or brakes. Just the bucking.
In the 2506 vid you can clearly hear the turkey under acceleration midway thru the clip. All turkey sound, NO bucking. However, in the 2514 vid you can hear the sound of the engine cutting in and out momentarily. Unfortunately, you can't really get a sense of the bucking too much, but it is fairly evident when you are riding in the car. I agree with Rocketspeed in that I don't think that the bucking is related to the turkey. Your thoughts are welcome.
R
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rocketspeed
Member
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- 03.5 Mazdaspeed Protege, Titanium Gray
The turkey sounds should only happen when you let off throttle, like when you shift or just let off the gas- it doesn't happen as you accelerate that I've ever seen. You aren't saying you're hearing this while accelerating, are you?
I'm guessing its the combo of mods you are running coupled with the engine management. I'd have to physically see your car to help more than that- maybe others can help more.
I'm guessing its the combo of mods you are running coupled with the engine management. I'd have to physically see your car to help more than that- maybe others can help more.
STAR 80 said:To most of you new turbo guys your like "what the hell is that sound?" But Gents before the days of this huge aftermarket support we have now with the advances in BOV design the Turkey or "Turbo flutter" is all you heard. Its the vacume source versus the mechanics of the particular BOV/BPV used. It simply the gate of the valve opining and closing very quikly. What everone hears with the MSP's is the air of the stock BPV opening and closing inside the intake piping. Get a SRI or CAI and it will become more evident. Go with a different BOV or share the work with say a stock and an aftermarket BOV or duel chanber BOV and the flutter will disapear all together. As the after market BOV choice would be doing almost all the work.
In turboed autos, turbo flutter is very hard to lose in any advent. In order to change fluttering It has been said that it is the choice of BOV's, but its more contingent to the spring setting versus the vacume pressure the choice valves are seeing.
And yes till around 6 years ago all turbo cars were using very different designs in venting the intake pressure, yeah you had fluttering but with 20+ psi believe me it sounded fkg crazy. Watch some footage from Subaru WRX's of the Colin McRea late 90's era and you would hear what I'm talking about.
Like I said to most of you new guys this Flutter, gobble, turkey is a strange sound but to the old the only strange sound is Pshsssss!
I have a better vid that I will try to compress tomorrow. As I, and others have said, I am not talking about the turkey sound. The sound that occurs with my bucking is different than the turkey. More importantly, it is not the sound that I am concerned with. The turkey doesn't bother me, nor does the sound that occurs with the bucking. It is the bucking, that noticeably shakes the car, that concerns me.
What I have discovered:
1. It only happens on acceleration.
2. It only happens on partial load (approx. 2/3-3/4 throttle).
3. It happens after the whistling of the intake is heard with partial load
4. It only happens on a roll. It has yet to happen on acceleration from a stop.
5. It does not happen on deceleration. However, if I accelerate hard, then let off the throttle, and then jump back on it at partial throttle I can induce the bucking which I can only stop by letting off the gas completely and then getting back on the gas much more gradually. I have not tried to power through it as the bucking gets progressively worse the longer I hold the throttle partially open.
6. It does not happen with full load. If I floor it then I get the regular MSP hesitation at 3700 RPM and then all is good to redline.
7. My boost seems to be OK as I spike at 7 PSI and then settle at 6.5 PSI steady.
8. My EGTs are normal and unchanged from pre-CAI.
Not sure what is going on, but I think that I will change the design of the CAI slightly so that the recirculating bung enters the CAI at an acute angle rather than at 90 degrees.
R
What I have discovered:
1. It only happens on acceleration.
2. It only happens on partial load (approx. 2/3-3/4 throttle).
3. It happens after the whistling of the intake is heard with partial load
4. It only happens on a roll. It has yet to happen on acceleration from a stop.
5. It does not happen on deceleration. However, if I accelerate hard, then let off the throttle, and then jump back on it at partial throttle I can induce the bucking which I can only stop by letting off the gas completely and then getting back on the gas much more gradually. I have not tried to power through it as the bucking gets progressively worse the longer I hold the throttle partially open.
6. It does not happen with full load. If I floor it then I get the regular MSP hesitation at 3700 RPM and then all is good to redline.
7. My boost seems to be OK as I spike at 7 PSI and then settle at 6.5 PSI steady.
8. My EGTs are normal and unchanged from pre-CAI.
Not sure what is going on, but I think that I will change the design of the CAI slightly so that the recirculating bung enters the CAI at an acute angle rather than at 90 degrees.
R
How does the flash work?
The car has been flashed, but the ecu has been reset. Do you lose the ecu reprogramming when you reset it? That is, is the ecu flash a firmware upgrade or does it simply change a preference file? This is an issue that I wondered about as well.
R
The car has been flashed, but the ecu has been reset. Do you lose the ecu reprogramming when you reset it? That is, is the ecu flash a firmware upgrade or does it simply change a preference file? This is an issue that I wondered about as well.
R
Dr.Sound said:^ seems like the car is not flashed.....
rocketspeed
Member
- :
- 03.5 Mazdaspeed Protege, Titanium Gray
The flash stays with you no matter what. Only way to get rid of it it to install a new non-flashed ECU.Rainman said:The car has been flashed, but the ecu has been reset. Do you lose the ecu reprogramming when you reset it? That is, is the ecu flash a firmware upgrade or does it simply change a preference file? This is an issue that I wondered about as well.
R
Now watch this and see what i'm talking about!
Fairly cool morning today on the way to work. It seems that it does it more freqeuntly when the weather is cool or when the car is moving at speed. It did it several times this morning. However, it was much warmer this afternoon (~29 degrees celsius) and it didn't do it at all. I drove in the same manner this morning and this afternoon.
This makes me wonder if it isn't a fuel-cut issue. Twice before I got the car flashed in the winter the car bucked violently (once only each time) under heavy accelaration when it was really, really cold (-30 degress celsius) right when the car hit around 3500 RPM and the turbo was in full stride. It scared the s*** out of me as I wasn't sure what had happened. I let off the throttle assuming it was either detonation from going lean (no mods at the time) or fuel cut. But it seemed rather violent for fuel cut which I have experienced once in the MSP at redline and several times in other cars without the same theatrics. The present bucking reminds me of the previous two experiences except that each time it occurs now it happens 3-4 times in very quick succession before I can let off and it only becomes violent if I don't let up on the throttle. I haven't checked my plugs to see if I am running lean, but my EGTs are OK, and my exhaust is as sooty as ever. The only thing that is out of the ordinary on my setup at the present is the fact that I have an third open 02 sensor bung from when my exhaust was corrected that I haven't filled with a plug yet. I don't think that this could be the cause because all the sensors are in their proper place and this sensor is downstream from the cat, however, I will get a plug tomorrow to see if it makes a difference. Any other suggestions or ideas?
R
Fairly cool morning today on the way to work. It seems that it does it more freqeuntly when the weather is cool or when the car is moving at speed. It did it several times this morning. However, it was much warmer this afternoon (~29 degrees celsius) and it didn't do it at all. I drove in the same manner this morning and this afternoon.
This makes me wonder if it isn't a fuel-cut issue. Twice before I got the car flashed in the winter the car bucked violently (once only each time) under heavy accelaration when it was really, really cold (-30 degress celsius) right when the car hit around 3500 RPM and the turbo was in full stride. It scared the s*** out of me as I wasn't sure what had happened. I let off the throttle assuming it was either detonation from going lean (no mods at the time) or fuel cut. But it seemed rather violent for fuel cut which I have experienced once in the MSP at redline and several times in other cars without the same theatrics. The present bucking reminds me of the previous two experiences except that each time it occurs now it happens 3-4 times in very quick succession before I can let off and it only becomes violent if I don't let up on the throttle. I haven't checked my plugs to see if I am running lean, but my EGTs are OK, and my exhaust is as sooty as ever. The only thing that is out of the ordinary on my setup at the present is the fact that I have an third open 02 sensor bung from when my exhaust was corrected that I haven't filled with a plug yet. I don't think that this could be the cause because all the sensors are in their proper place and this sensor is downstream from the cat, however, I will get a plug tomorrow to see if it makes a difference. Any other suggestions or ideas?
R
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Tip-in Detonation
Here is an update on the surge business. I discussed this problem with one of the service guys at Mazda who is also a local tuner. With the combination of CAI and the 3" exhaust, I am now bringing in more air than the ECU can compensate for under conditions of light load. This causes tip-in detonation as the ECU struggles to keep up with the influx of air. The initial throttle tip-in causes an air/fuel excursion lean enough to result in a "misfire" before boost comes on. This results in a momentary loss of power and the dreaded "bucking/surging" that I am experiencing. It also causes a consequent super-rich state that then gets burned off creating sooty deposits, which I have noticed along the back end of the car since I installed the CAI, and especially after my 1000km roadtrip last week.
Guess I have some work ahead. Gotta get the car tuned, but I'll have to get bigger injectors, a bigger fuel pump, and a fuel management unit. Since I was planning to do a FMIC and hardpipes it would probably be most cost efficient to do all these things and then get the car tuned. It is hard to believe that with only the exhaust and the CAI I have reached the capacity of our fuel delivery system. Perhaps the flash is aggravating the issue? Don't know.
Now I am paranoid of the bucking/surging. I don't want to be running lean all the time. Funny thing though, because my EGT values are normal, although I have to admit that I haven't checked them out right at the time that the bucking/surging occurs.
This is the explanation as I understand it. If I have mis-stated something or made an error I am open to correction.
R
Here is an update on the surge business. I discussed this problem with one of the service guys at Mazda who is also a local tuner. With the combination of CAI and the 3" exhaust, I am now bringing in more air than the ECU can compensate for under conditions of light load. This causes tip-in detonation as the ECU struggles to keep up with the influx of air. The initial throttle tip-in causes an air/fuel excursion lean enough to result in a "misfire" before boost comes on. This results in a momentary loss of power and the dreaded "bucking/surging" that I am experiencing. It also causes a consequent super-rich state that then gets burned off creating sooty deposits, which I have noticed along the back end of the car since I installed the CAI, and especially after my 1000km roadtrip last week.
Guess I have some work ahead. Gotta get the car tuned, but I'll have to get bigger injectors, a bigger fuel pump, and a fuel management unit. Since I was planning to do a FMIC and hardpipes it would probably be most cost efficient to do all these things and then get the car tuned. It is hard to believe that with only the exhaust and the CAI I have reached the capacity of our fuel delivery system. Perhaps the flash is aggravating the issue? Don't know.
Now I am paranoid of the bucking/surging. I don't want to be running lean all the time. Funny thing though, because my EGT values are normal, although I have to admit that I haven't checked them out right at the time that the bucking/surging occurs.
This is the explanation as I understand it. If I have mis-stated something or made an error I am open to correction.
R
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rocketspeed
Member
- :
- 03.5 Mazdaspeed Protege, Titanium Gray
The black sooty deposits on the tailpipe are universal to MSP's, we all run nutty rich when you're mashing the pedal.
He could be right, though, but your experiences don't seem to jive with what other MSP owners with the same mods have seen. There are a TON of MSP's with intake and exhaust running trouble free. There is a lot of variation among these cars.
The more violent bucking you describe I'm almost certain is fuel cut- its a rude awakening. Less violent hesitation- perhaps detonation. I do think that your combo of mods is causing something funky. The CAI is custom, right?
He could be right, though, but your experiences don't seem to jive with what other MSP owners with the same mods have seen. There are a TON of MSP's with intake and exhaust running trouble free. There is a lot of variation among these cars.
The more violent bucking you describe I'm almost certain is fuel cut- its a rude awakening. Less violent hesitation- perhaps detonation. I do think that your combo of mods is causing something funky. The CAI is custom, right?
The sooty deposits are now "over and above" what is normal for our beloved cars. It was there before, but NOT to the same degree.
I was wondering about why my mods might be acting this way, when as you mention, lots of others are running with the same combo. The CAI and exhaust are both custom. Exhaust 3" from S-pipe back, 1 hi-flow cat, crush bends, aluminized steel. The CAI is a temporary measure until my CF CAI (God forbid the CF guys should actually get the damn thing finished). It is 2.5" crush-bent aluminzed steel based in principal on the INJEN MSP intake. It has a single port for the BOV. The return from the valve cover is T-ed into the BOV recirculating line since the MSP didn't like atmospheric vent and I am not going to do a double set-up right now.
The more I think about it, the more I think that it is fuel-cut. I took it up to redline intentionally once the other evening to remind myself of the sensation of fuel-cut. The bucking feels almost the same, but it happens in such quick succession (three or four very quick bucks of increasing instensity, this being different than the one-time dying of fuel cut) that I got the impression that it might be something else. Furthermore, the fact that it only seems to happen at partial-load/throttle mystifies me. I would have thought that I would hit fuel-cut more readily when I mashed it to the floor.
The other idea that I considered was the angle at which the BOV port enters the intake. Like every other intake, it enters at a right angle, but I wondered if the air entry might be more streamlined if it entered at a slight angle. Anyway, now that I have heard another explanation for the bucking, I don't think that it is related to turbulent air re-entry.
R
I was wondering about why my mods might be acting this way, when as you mention, lots of others are running with the same combo. The CAI and exhaust are both custom. Exhaust 3" from S-pipe back, 1 hi-flow cat, crush bends, aluminized steel. The CAI is a temporary measure until my CF CAI (God forbid the CF guys should actually get the damn thing finished). It is 2.5" crush-bent aluminzed steel based in principal on the INJEN MSP intake. It has a single port for the BOV. The return from the valve cover is T-ed into the BOV recirculating line since the MSP didn't like atmospheric vent and I am not going to do a double set-up right now.
The more I think about it, the more I think that it is fuel-cut. I took it up to redline intentionally once the other evening to remind myself of the sensation of fuel-cut. The bucking feels almost the same, but it happens in such quick succession (three or four very quick bucks of increasing instensity, this being different than the one-time dying of fuel cut) that I got the impression that it might be something else. Furthermore, the fact that it only seems to happen at partial-load/throttle mystifies me. I would have thought that I would hit fuel-cut more readily when I mashed it to the floor.
The other idea that I considered was the angle at which the BOV port enters the intake. Like every other intake, it enters at a right angle, but I wondered if the air entry might be more streamlined if it entered at a slight angle. Anyway, now that I have heard another explanation for the bucking, I don't think that it is related to turbulent air re-entry.
R
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