Why a CAI on a TBSS???

[mcolvin]

Hey guys and gals,
Why would I need a CAI on a TBSS when GM has built them with a factory CAI.
Wouldn't I just have to add a K&N filter??

Thanks

Mike

[TrailblazerSS]

The airfilter connection is much smaller diameter than the MAF and the tubing to the throttle body. Opening up that connection and installing a smooth and straightened tube from the MAF to the TB has resulted in dyno proven 12 hP.

[mcolvin]

Thank you

Just needed an explaination!

[westbayou]

Should be noted that the "dyno-proven 12 HP" was with the appropriate tuning AFTER you install the CAI. Don't go thinking slapping a CAI on your truck without a tune is going to do anything. It could even cost you HP because it will whack out your A/F ratio unless you adjust the tuning. Lots of threads about this out there.

[fotowork]

I wouldn't think cai would make any difference to the tune as all the air goes through the maf anyway.

[westbayou]

Chris, would you care to enlighten them?

[BLK60SS]

I wouldn't think cai would make any difference to the tune as all the air goes through the maf anyway.

You have much to learn my friend. Welcome to the forum. :thumbsup:

[02redhawk]

I wouldn't think cai would make any difference to the tune as all the air goes through the maf anyway.


Ah boy, here we go again....!! :p

[Scalarrthu]

Ah boy, here we go again....!! :p
:yes: :suicide:

[Fishhunter911]

I wouldn't think cai would make any difference to the tune as all the air goes through the maf anyway.


Trust me when I say this, as this subject has been beaten to death for a long time. WHen you get rid of the Stock neckdown into the MAF, you flow more air then what the stock PCM is tuned for, this makes the upper RPMs VERY LEAN, and you know what that means... yeh dead motor after a while. You DO need a tune if you run a CAI with NO NECKDOWN @ the MAF.:yes:

[John Skiba]

As soon as I put on my wideband, I'll post charts of what the A/F looks like with the stock neckdown and without on the street.

I think Chris already posted Dyno graphs of what happens with no neckdown. I don't know however if he gave the car drive time without the neck down before redynoing??

[fotowork]

Please correct me if I'm wrong but isn't the purpose of the sensor to measure air flow. It's a lambda sensor, air flows over the wire and cools it changing the resistance, the PCM converts this analog signal to digital. I doubt that number will exceed the available range in the table. Please correct me if I'm wrong about this. The Corvette has a much better intake and exhaust systems than the TBSS an I would imagine the engine management would use the same parameters and tables with the same range of values as the vette.

[GTPprix]

Ok I'll do it.. just this one last time though.. I cant take it anymore..

When you remove the neck down from the MAF you skew the relationship to airflow vs frequency. It no longer measures the correct amount of air that is calibrated to pass through the no longer existing smaller opening at X-Hz. This results in a lean condition up top and typically a fat condition on the bottom. YMMV but it skews the fueling one way or another.. This normally isnt an issue on other GM vehicles because for the most part they dont have a huge neck down lol

[Trailblazer1]

I suppose that technically mcolvin is correct. The TBSS does have a cold air intake. What we are talking about however is a modification to the intake path that will permit more air to get to the engine. I guess calling our modified intakes a cai is, perhaps, a bit misleading.

[kenmosher]

Please correct me if I'm wrong but isn't the purpose of the sensor to measure air flow. It's a lambda sensor, air flows over the wire and cools it changing the resistance, the PCM converts this analog signal to digital. I doubt that number will exceed the available range in the table. Please correct me if I'm wrong about this. The Corvette has a much better intake and exhaust systems than the TBSS an I would imagine the engine management would use the same parameters and tables with the same range of values as the vette.

OK, just a few nits to pick! :D

Lambda sensor is an oxygen sensor (and is used in the exhaust).

The GM MAF actually produces a Frequency proportional to the air flow and has a "characterization" in the PCM/ECU that basically calibrates how different frequencies correspond to a certain airflow (normally a polynomial). If you change the way air is directed around the sensor, it can change the characterization and skew the readings (as Chris noted above). We see it with different intake tracts we mess with using the GM sensor on our ECUs. It requires a tweak to the sensor characterization or a tweak to the VE tables to compensate.

Early (in the mid 80s) GM used the "hot wire" style MAF, but starting with the turbo Buicks of '86 they started using a "hot film" style sensor. The resulting output of the hot film GM sensors is a square wave variable frequency signal.

[BLKBUTY]

What he said.

[John Skiba]

Why GM decided to do an offset reduced neckdown is anybodys guess. Maybe they didn't have to certify something if they used the same common filter in all trailvoys? Who knows...

http://forums.trailvoy.com/showthread.php?t=9899&page=4

If you notice at low flow it's almost identical to a Z06 table but at highflow (WOT) it's quite a different MAF table.

Flowing less or more is one thing, but the offset reduction of the tube at WOT flow is probably hitting one, two or three of the sensors in the MAF differently then normally in a straight open tube pre-maf. Just like you don't want any bends before or after a MAF, this looks like it has quite an effect on fueling according to Chris.

Heck, even clocking the MAF different from stock with the restrictor neckdown on may have an effect at WOT.

Someone with an OBDII CAN scan tool and a wideband can provide some very interesting street data. Who's got both on their truck? :)

I'm stuck waiting for my OBDII CAN software, so I have one out of two ready.

[ScarabEpic22]

What he said.
:iagree:
Listen to Chris, he has been tuning the TB SS since the first (consumer) one rolled off the production line (which he has:D ). And, he also tunes other LSx cars plus tons more.

[GTPprix]

:iagree:
Listen to Chris, he has been tuning the TB SS since the first (consumer) one rolled off the production line (which he has:D ). And, he also tunes other LSx cars plus tons more.

Dont just listen to me... listen to Ken Mosher.. TRUST ME on this one ;)

[ScarabEpic22]

Dont just listen to me... listen to Ken Mosher.. TRUST ME on this one ;)
OK, I will trust you (who is Ken Mosher?).

[fotowork]

Thanks for taking the time to reply. I don't often go a day without learning something and today was no exception. I guess it's about time to stepup to a Vector tune. Only five day down time huh?

[kenmosher]

That's me! :)

Been around this stuff for awhile...

[mcolvin]

That's me! :)

Been around this stuff for awhile...

This is all great and I am learning every day.

BUT..... To the FNG that is going to do the Vector tune and add the CIA that Chris is offering, How & where do I get the vehicle re tuned afetr adding the CIA?

Can I get it done by my local Chevy dealer????
(I work at one)

Mike

[JCattSS]

Thanks for taking the time to reply. I don't often go a day without learning something and today was no exception. I guess it's about time to stepup to a Vector tune. Only five day down time huh?
Ship it out mon, they get it tuesday, you get it back wed. morning. Takes less time to remove and replace than to read this reply!

[JCattSS]

This is all great and I am learning every day.

BUT..... To the FNG that is going to do the Vector tune and add the CIA that Chris is offering, How & where do I get the vehicle re tuned afetr adding the CIA?

Can I get it done by my local Chevy dealer????
(I work at one)

Mike
If you get the reg tune first, and then get the cai, Vector will retune for free.

[GTPprix]

Ken Mosher is an EFI God.. thats all I'm gonna say :)

[mcolvin]

If you get the reg tune first, and then get the cai, Vector will retune for free.

Does that mean I have to ship the ECM/TCM back to Vector after the vector tune and when I add the CAI?
It seemed like Chris was telling me that the CAI would come at a letter date.

[ScarabEpic22]

That's me! :)

Been around this stuff for awhile...
Cool, glad to meet ya!:D


As for the VMS tune, if you want a CAI and they cant get you one immediately, they can give you the CAI tune so you dont have to send your ECM/TCM back to them for the CAI retune.

Basically, if you want a CAI and a tune, get the CAI tune so you dont have to ship it back to them again.

[JCattSS]

Does that mean I have to ship the ECM/TCM back to Vector after the vector tune and when I add the CAI?
It seemed like Chris was telling me that the CAI would come at a letter date.
If you get the cai tune, you wont have to ship it back. If you get the regular tune, yes you will have to get it re tuned for the cai.
Maybe he should answer.

[mcolvin]

If you get the cai tune, you wont have to ship it back. If you get the regular tune, yes you will have to get it re tuned for the cai.
Maybe he should answer.

Can you get the CIA tune and wait till the CIA's are available?

or would that hurt the motor?

(silly FNG questions)

[bbradyc5]

Can you get the CIA tune and wait till the CIA's are available?

or would that hurt the motor?


(silly FNG questions)

Yep, no problem. It will run a little rich at WOT, but still more performance than stock while waiting for CAI kit to come in stock. Go ahead and get the CAI tune if you are planning on adding a CAI afterwards

[mcolvin]

Yep, no problem. It will run a little rich at WOT, but still more performance than stock while waiting for CAI kit to come in stock. Go ahead and get the CAI tune if you are planning on adding a CAI afterwards

Thanks buddy

It is nice to know what to do, when I really don't know what to do!!!