increasing intake pipe diameter

[ayousef]

Well, im sort of having issues after I installed a larger CAI with a diameter or 4".

I wasnt surprized to find the trims all over the place, fixed that as much as possible, turned LTFTs off, and smoothed out the cruise range using the narrowbands.

Dilema: since I cut the radiator shroud to allow for the filter to be installed, I now have my trims going up to 20+ when the radiator fans hit 80%, and when it slows down trims go back down

other problem is, Idle quality isnt as good as before, and cruising at idle speed in 1st or say 2nd gear in a parking lot is messed, the car cruises at 550rpms instead of the 750rpm idle speed, also car tends to want to shut.

I did not increase idle airflow tables, is this the next logical step?

[Mep_q8]

sounds like it... ur flowing alot more air in there then you are stock, so your RAF would need some adjusting..

[ayousef]

something is confusing me though, do I increase or decrease the table? and is there a proper way of doing it?

[carlrx7]

post a pic of how this is installed

[ayousef]

this is a picture, the shroud needs to be cut for the filter to sit the way it does. I have mine with a shroud on the filter as well to seal away hot engine bay temps from the filter.

[ayousef]

I did my best to get the car to cruise as smooth as possible, bumped the idle airflow a bit in the low rpm ranges, the car now cruises at idle speed no problem (not as smooth as stock but it does) it doesnt tend to want to die out like it did before.

Thing is, when the car heated and the fans kick in at 84%, fuel trims go way positive, since a small portion of the filter is exposed into the radiator airflow by cutting the shroud. I had the airflow vs ECT multiplier increased at higher coolant temps, that seemed to help alot.

The car still surges lightly at cruise/acceleration and deceleration. The only thing im afraid off is the fact that the car was tuned on the dyno with the dyno fan and did mid 11's and im now afraid that the car would lean out at higher speeds due to higher airflow onto the intake.

[69lt1bird]

Get a wideband and tune it. Use the base running airflow cfg on here and get the idle air cleaned up.

[ayousef]

Get a wideband and tune it. Use the base running airflow cfg on here and get the idle air cleaned up.

what makes u think this is not maf turbulence though? it is 4" (100mm?) after all, I will post up a log in a few mins.

[Japeatr]

i doubt you have increased your airflow enough to warrant more and an .2 derease in AFR leaner

but turbulence is a thought and caan be tuned for

[righton]

I believe part of your problem is related to the hot air from the radiator. I am running a swapped setup with the IAT sensor in a duct (with my air filter) on top of my radiator fans, when the fans come on my IATs soar. I don't recall exactly how much, but I thinked they jumped as much as 30 degrees in less than a minute.

[ayousef]

I believe part of your problem is related to the hot air from the radiator. I am running a swapped setup with the IAT sensor in a duct (with my air filter) on top of my radiator fans, when the fans come on my IATs soar. I don't recall exactly how much, but I thinked they jumped as much as 30 degrees in less than a minute.

btw I have that intake air temp soaring problem too, it jumps WAY too quick, however drops way too quick too, I got kinda confused and told myself it probably has something to do with the intake pipe being aluminum as opposed to the plastic? stock unit. You're now making me think otherwise, however remember the filter is in FRONT of the radiator so the fans are pulling from behing the rad, how is hot air getting to the filter other than it radiating heat towards the filter? This is very possible btw.

now while I havent noticed any relation between IAT and fan speeds, I havent LOOKED at the issue, but the fuel trims go up to 20+ when the fans go up.

My MAF Hz readings are jumping 3 to 4 cells at idle, so im thinking this is MAF turbulence, looking at the histogram with a 15,000Hz scale you can never SEE turbulence, I dont know whats a good range to set so the turbulence if any would be clear.

[ayousef]

i doubt you have increased your airflow enough to warrant more and an .2 derease in AFR leaner

but turbulence is a thought and caan be tuned for

You mean when I go WOT at high-speed vs the airflow going through the car on the dyno when we tuned it? (taking into consideration the dyno has a VERY strong fan)

I seriously hope you are right because the car was still tuned fat at 11.5, so a 0.2- 0.4 difference wont bother me. I did take the car to a very high speed not for the fun of it but to see if it knocks and it was still running 24degrees without knock.

[ayousef]

post a pic of how this is installed

Posted the picture above, and hoping to hear some insight on this. I did find you're thread on the 100mm MAF and thats exactly what im facing right now, my problems are NOWHERE near the ones you had, but they do exist.

I do beleive a honeycomb flow straightener could do miracles for big diameter intake pipes like this one, but I dont know if I want my DD ZR1 to be a test mule

I guess im putting back the stock cold air, but then ill need a new shroud as well

[righton]

btw I have that intake air temp soaring problem too, it jumps WAY too quick, however drops way too quick too, I got kinda confused and told myself it probably has something to do with the intake pipe being aluminum as opposed to the plastic? stock unit. You're now making me think otherwise, however remember the filter is in FRONT of the radiator so the fans are pulling from behing the rad, how is hot air getting to the filter other than it radiating heat towards the filter? This is very possible btw.

now while I havent noticed any relation between IAT and fan speeds, I havent LOOKED at the issue, but the fuel trims go up to 20+ when the fans go up.

My MAF Hz readings are jumping 3 to 4 cells at idle, so im thinking this is MAF turbulence, looking at the histogram with a 15,000Hz scale you can never SEE turbulence, I dont know whats a good range to set so the turbulence if any would be clear.

I completely sealed my duct and the heat still was sucked in from the front of my car, although the temps were quite a bit lower and the car was not moving.

Use your VCM controls to turn on and off your fans to verify whether the IATs are changing with respect to fan operation.

[ayousef]

now other than that, can I be hurting my car by having MAF turbulence and too much influence from the O2 sensors to adjust, although they are spot on at cruise.

Other than the surge, and the semi-crap drivability and tuning issues with the turbulence which looks very likely in my case since i looked at a log, am I incurring any damage to the engine?

Car was tuned on the dyno for mid 11's AFR and there is no spark knock at all.

[carlrx7]

you need a setup like the vararam

[ayousef]

you need a setup like the vararam

if this were a Z06 well talk vararam, but its a ZR1 and there absolutely NO cold air intake system for this car on the market, this is a custom one, yet it has been proven to work.

did you ever have any luck with the honeycomb flow straightners?

[ayousef]

Heres the log, I was pulsating through at times to collect data.

can we say this is MAF turbulence or what exactly?

[carlrx7]

yea, the honey comb stuff worked pretty good. i compare your maf reading at idle to mine and it does look more jagged, but not by much.

what size was the maf inlet stock? i thought the card styles were installed in 4" housings stock.

im thinking maybe an air leak after the maf.

[4evervette]

dont know if yours is killer bee 2
but bro this might be the answer for u :

http://forums.corvetteforum.com/c6-z...ean-issue.html

ahmed