# What the Boost is going on!



## smorey78 (Apr 8, 2012)

so i had installed my CAI from injen 2 months ago. at first i installed it as the SIR than a few days later made it into the full CAI setup. thats when i noticed the car surging and stuff like that. (SEE Thread http://www.cruzetalk.com/forum/10-engine-technical-discussion/6727-turbo-seems-surge-now-cai.html)
so i removed the cai part and made it back into the SIR. Drove about 2,000 miles like that with 0 problems. But the only thing i noticed with my boost gauge is that i never went over 12psi. Infact i logged that in the 2,000 miles i drove my avg. boost was 11.7psi. So today i installed the CAI part back on cause i noticed that intake temps were way up at 140* and its been very hot the last 3 weeks here 90+. so i figured forget the surge i want lower intake temps. Now i have only driven 159miles with the CAI setup and so far i logged 18.2psi avg. and intake temp are just a few degrees above outside temps. so what is going on. I mean i like the new psi's and the car feels much faster just not sure why a 12" pice of pipe would build more boost!


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## NBrehm (Jun 27, 2011)

It isn't, most likely the computer is letting you use more boost because of the lower intake temps, or rather isn't reducing the boost due to higher intake temps


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## smorey78 (Apr 8, 2012)

i thought it would have somthing to do with intake temp too. but looking at my loggs there were 16 days that ontside temp was lower than it has been with the sri on at night when i was driving. in other words temp was 66* and intake was 71* but boost was only 11.4psi. today was 98* and intake was 112* yet i boosted to 18psi all day with the CAI on! infact 2 days temp was only 54* and intake was 60* yet only was able to make 12psi. on on them days it was cooler out with the sri i should of seen higher boost...i did not. now the only thing that has changed on the car that i some how forgot about is the Dual magnaflow exhaust maybe thats what is doing it.


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## sedanman (Dec 10, 2010)

How are you getting 18 PSI anyway? Do you have the tune? I thought 16 PSI was max stock boost and 22 PSI tuned?


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## smorey78 (Apr 8, 2012)

no tune...and thats my question...how am i getting 18 psi with just an intake and exhaust


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## BladeOfAnduril (Apr 27, 2012)

Im not sure about the boost thing but I'd guess that you should probably have a tune with the intake and exhaust. They are probably throwing the ecu out of normal range. 

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## sciphi (Aug 26, 2011)

159 miles? The ECU is re-learning how much boost to make.


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## smorey78 (Apr 8, 2012)

yes it could be relearning but i am up to about 500 miles and still pulling 18psi


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## sciphi (Aug 26, 2011)

Has the weather been cooler/warmer lately? The stock intercooler does okay when it's below 80*F or so, but doesn't do so well at warmer temperatures. And, have you been doing more highway driving lately?


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## smorey78 (Apr 8, 2012)

temp has been 90+ for about 4 weeks now last week was 100+ all week. saturday was 92 on the way to work with SIR and only 12psi. After work switched to the full CAI and drove home. temp was 98 and ran 18 psi all the way home and has been for about 550 miles now. I live in southern maryland all i do is highway driving. there are no towns or cities. my avg speed to work at 14 miles away is 57mph. now this might matter...sea level for me is -67 feet below sea level. i know so guys up in the mountants say they only get about 12to 14 cause of how high they are! but it still don


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## sedanman (Dec 10, 2010)

I think your CAI is causing the MAF to misread airflow and is causing the computer to miscalculate actual boost pressure.


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## smorey78 (Apr 8, 2012)

now theres the answer. i guess i will run it till eather the ses light comes on or i get a tune


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## CruzeTech (Mar 23, 2012)

That makes sense in a way. Metered air makes the ecu do weird things. Problem with that is, if it's changing the boost and not adding fuel at the same time, you may be getting a lean condition. Since you are data logging you should be able to monitor that. I don't know what the fuel parameters are for this car, but running lean will make it feel fast, but it can also be detonating under boost. Trifecta needs to flash the check engine light for knock detection.


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## smorey78 (Apr 8, 2012)

under boost at 18 psi i do see that fuel pressure is going up and i have no KR yet. tomorrow i am going to check the air/fuel and see if its going lean. i will say that the car feels much faster for sure! you think that trifecta can tune for all this?


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## CruzeTech (Mar 23, 2012)

The trifecta tune is made for you to data log and email the tune back to Vince so he can tailor it exactly for your car. But the tune will be designed to either run the CAI or run the SRI. And for correct tune, not to be switching between the two. If after you get the tune dialed in you want to change something, you need to log and email him the tune to have it updated.


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## XtremeRevolution (Jan 19, 2012)

smorey78 said:


> no tune...and thats my question...how am i getting 18 psi with just an intake and exhaust


Here are a few things for you to consider. 

The Injen intake performs better as a CAI than as a SRI. In fact, it performs better as a CAI than any other intake simply due to the fact that it pulls air from much lower, therefore allowing it also to be much cooler. SRI mode basically pulls air from the very top of the engine bay, which is VERY hot, and gives your intercooler more work to do, thus increasing IATs. 

Colder air is more dense, allowing your turbo to create more pressure per revolution than hot air. Keep that in mind as well. 

Are your PSI readings absolute, or relative? Keep in mind that atmospheric pressure is 14.7psi, so if your average is just above that, well, there's your sign. 

Did you disconnect your battery after installing your intake? If not, you will need to in order to ensure that your fuel trims get re-calibrated correctly. 

Over the stock intake, your car will feel quicker partially due to the elimination of restriction in the stock intake. That's pretty much a given. The rest of it is the placebo effect. I have yet to meet someone immune to it unless they did this kind of thing for a living. I deal with it all the time while building home theater speakers. The prettier the speaker is, the better it sounds. 

Vince at Trifecta can tune and has tuned for any modifications anyone puts on their Cruze. While I personally run the Injen intake without a tune, I would certainly recommend the tune if you want to unleash more of the performance potential of this engine.


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## smorey78 (Apr 8, 2012)

XtremeRevolution said:


> Here are a few things for you to consider.
> 
> The Injen intake performs better as a CAI than as a SRI. In fact, it performs better as a CAI than any other intake simply due to the fact that it pulls air from much lower, therefore allowing it also to be much cooler. SRI mode basically pulls air from the very top of the engine bay, which is VERY hot, and gives your intercooler more work to do, thus increasing IATs.
> 
> ...


yes i knew that the CAI works alot better than the SIR. and i know the lower the temp the better the boost thats why i put the CAI back on in place of running it as a SRI. what i am saying is with the SRI i only get 12 psi and car runs very smooth yes it is very hot out now switched to the CAI and now get 18 psi and car is very aggressive. 18psi is measured by the boost gauge. fuel trim was reset with tech 2


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## smorey78 (Apr 8, 2012)

just want to make sure it is ok to run the car like this till i get a tune


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## CruzeTech (Mar 23, 2012)

Does the Injen CAI come with a CARB sticker?


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## smorey78 (Apr 8, 2012)

yes


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