boost dropping

[bustanut]

Sorry for the new post,, but ive been a little concerned after my install of the mazdaspeed cai. Ive noticed that if im cruising at freeway speed in 6th and step on it that the boost will gain then immediatly drop and gain then drop gain then drop. I dont have a boost gauge but i can actually hear the intake sucking in air then pausing then working again. I can also feel this inside the car. If im looking at the speedo it noticeable goes from like 80-82 then slight pause of boost drop then 82-84 and so on. Once in a while this wont happen, and it is only noticeable in 5th and 6th. Is this some kind of computer issue where if i wasnt on it hard in the first few gears it affects the later gears? Im also thinking i just might not of noticed it before getting the cai. Well sorry for the long post and ill give you guys more details if needed, but really appreciate any feedback. thanks

 

[thewheelman]

That sounds like compressor surge. Did you disconnect the battery after installation of the CAI?

 

[bustanut]

you know i didnt disconnect the battery and felt like that may have been the problem but just 2 weeks ago after the install i had a stereo installed and they had the battery unhooked, (maybe just the positive, it did reset my clock though) and after that it didnt seem to make any difference

 

[bustanut]

you know i didnt disconnect the battery and felt like that may have been the problem but just 2 weeks ago after the install i had a stereo installed and they had the battery unhooked, (maybe just the positive, it did reset my clock though) and after that it didnt seem to make any difference

 

[bustanut]

wow, i dont know why it posted that so many times,, sorry about that hopefully it doesnt do it again with this message

 

[Speedy3]

I know that the Boost pressure peaks pretty high in higher gears, higher the higher the gear. I measured peaks as high as 19 psi, then an immediate drop when the wastegate opens down to 15-16 psi. maybe it's a load management issue where the ECU is getting off the map? Otherwise, if it is more of a stuttering, check my stutter thread. It turned out to be the plugs.

 

[thewheelman]

The whole idea behind unplugging the battery is so that the ECU adapts to whatever new parts have been installed. Right now, the computer is still thinking that the engine should be getting the volume of air that the stock airbox could supply. Your new CAI is providing much more air to the engine. Honestly, I'd start with disconnecting the battery for five minutes.

 

[lyric911]

The whole idea behind unplugging the battery is so that the ECU adapts to whatever new parts have been installed. Right now, the computer is still thinking that the engine should be getting the volume of air that the stock airbox could supply. Your new CAI is providing much more air to the engine. Honestly, I'd start with disconnecting the battery for five minutes.

The MAF sensor sees how much air is making it into the intake all the time. Please do explain how resetting the ECU will make the MAF read what it's already reading?

 

[thewheelman]

The MAF sensor sees how much air is making it into the intake all the time. Please do explain how resetting the ECU will make the MAF read what it's already reading?

The theory is that resetting the ECU will allow it to adapt to changes quicker. Besides, what can it hurt; you'll only have to reprogram some radio presets and possibly reinitialize your power windows (depending on your vehicle).

 

[matsuda]

The MAF sensor sees how much air is making it into the intake all the time. Please do explain how resetting the ECU will make the MAF read what it's already reading?

The physical difference between the stock airbox and the CAI will affect how the MAF is metering air. It is a good idea to reset the ECU because the fuel trims are reset. The fuel trims with the CAI will be different than that of the stock airbox which is proof that the MAF is in fact metering air differently.

 

[justa4banger]

it is a good idea to rest the computer, but it is true that the MAF reads what it reads. the computer should be able to compensate for this change. who knows.
Funny reading though.

oh and i recommend you get a boost gauge to see whats really going on. Or maybe you shouldn't so you won't find out your getting short changed on boost in upper rpm's

 

[Speedy3]

Sorry for the new post,, but ive been a little concerned after my install of the mazdaspeed cai. Ive noticed that if im cruising at freeway speed in 6th and step on it that the boost will gain then immediatly drop and gain then drop gain then drop. I dont have a boost gauge but i can actually hear the intake sucking in air then pausing then working again. I can also feel this inside the car. If im looking at the speedo it noticeable goes from like 80-82 then slight pause of boost drop then 82-84 and so on. Once in a while this wont happen, and it is only noticeable in 5th and 6th. Is this some kind of computer issue where if i wasnt on it hard in the first few gears it affects the later gears? Im also thinking i just might not of noticed it before getting the cai. Well sorry for the long post and ill give you guys more details if needed, but really appreciate any feedback. thanks

Did you figure this one out?

 

[Betelgeuse]

Sorry for the new post,, but ive been a little concerned after my install of the mazdaspeed cai. Ive noticed that if im cruising at freeway speed in 6th and step on it that the boost will gain then immediatly drop and gain then drop gain then drop. I dont have a boost gauge but i can actually hear the intake sucking in air then pausing then working again. I can also feel this inside the car. If im looking at the speedo it noticeable goes from like 80-82 then slight pause of boost drop then 82-84 and so on. Once in a while this wont happen, and it is only noticeable in 5th and 6th. Is this some kind of computer issue where if i wasnt on it hard in the first few gears it affects the later gears? Im also thinking i just might not of noticed it before getting the cai. Well sorry for the long post and ill give you guys more details if needed, but really appreciate any feedback. thanks

This has been discussed over on the 'other' forum. It seems that most people don't have the issue while a few do. I have an ms cai and haven't noticed any problems at all. It also doesn't seem dependent on the type of CAI according to a poll that was conducted recently. I'd take it in to the dealer to see if there's a reflash that might solve it.