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Discussion Starter · #1 ·
I should make my own mod thread for all of my mods but I don't plan on doing much. I just want to do some few simple mods to aid in tune accuracy and consistency. The best mpg's is the main goal because I have another vehicle that fulfills my power needs.

The reason for this mod is to allow the maf to see the actual airlow the engine will be ingesting. The problem with having the maf at the inlet of the compressor as opposed to in the cold side charge pipe is there could be a huge airflow difference between what the maf is reading from what's actually in the charge pipe due to pressure drop and IAT differences. If I move the maf into the charge pipe, the maf will see the true intake air temps and a more consistent airflow reading improving maf tunability throughout the operating range. Iat's can differ 30*+from the inlet tube to the charge pipe so the ignition timing tables will control timing much more acurrately and consistently as well.
 

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I have an ultra-gauge which uses OBDII so I can watch intake temps as seen by the computer, they're only reading 2 degrees higher than ambient air usually, but with use of the A/C and/or stop and go traffic I've seen the intake temps rise to as much as 148F
 

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Didn't have all this stuff with a carb, venturi effect would suck the correct amount of fuel depending on the jet size. But unfortunately, only good at sea lever, really noticed this when driving in Bogota, Columbia, carbs are running rich and the air is thin with a super strong odor of gas in the air. Airplanes compensated for this with a mixture level, but you sure had to learn how to use it or would carbon up your engine or toast it.

Better carbs have a bellows installed that would expand with altitude that shoved tapered rods into the jets, the calcuations for this would drive you nuts. Tried to maintain a 14.7:1 air fuel ratio, but only good for steady driving, when you hit the gas, this would decrease the AF ratio to 12:1 to gain more power, for this, an accelerator pump was added.

Essentially, a throttle body is just like a carb except fuel was removed. So a MAP, MAF, IAT, and a barometric sensors were added to control injector dwell. Timing advance or retard is yet another issue, centrifugal and vacuum advance was replaced by a combination of these sensors as well as adding anti-knock sensors. All these work in combination together with mass calculations done by a computer.

But mostly in so-called open loop mode, O2 sensor is worthless until the engine reaches normal operating temperatures and driving at a constant speed. Open loop does take over when you hit the gas, O2 sensor is way to slow to keep up with this.

All these sensors are working with harmony with each other, with OBD I open loop loop parameters would learn from closed loop parameters. This correcting data was stored in RAM, but if you disconnected the battery for a second, this data would be lost. Had to drive your vehicle at least 20 miles to relearn. Ha, had fun with this by calibrating all of the sensors so there was nothing to learn.

With OBD II, stored in flashram, so this data was not lost when disconnecting the battery.

But just saying, your MAF is working in harmony with all the other sensors, if you fool with it, not only breaking EPA regulations, but also risk either carboning up your engine or toasting it. Best to leave it stock.
 

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I'm with @NickD on this one. While we mechanic-types like to bad-mouth engineers for not factoring in real-life maintenance requirements, they do actually know a thing or two about air-flow, pressure differentials, and that kind of stuff. Moving the MAF will just skew the data in a way the firmware was not written to compensate for and you will likely degrade performance rather than enhancing it.
 

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Discussion Starter · #5 ·
I do my own tuning with hptuners. No need to worry about skewing the data. It will all be recalibrated to run great with this modification.
 

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I would really like to see the results of this mod. Seems to me it should work perfectly. Wonder if something like this would work on a stock gen1. Have heard of other vehicles having drastic changes to relocating the MAF for more accurate reading. Lets see some results!
 

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Discussion Starter · #8 ·
I had a custom turbo setup that used a draw through maf setup on my 08 Colorado 3.7. I reworked it for a blow through maf and it made a huge difference. It was very accurate and improved gas mileage, throttle response, and the whole nine yards. It was a night and day difference.
 

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Discussion Starter · #14 · (Edited)
I'm so happy with this mod. The car runs much smoother and the shifting actually feels better due to a more accurate airflow/torque calculation acquired partially from the MAF readings. No more mid range boost and fuel trims inconsistencies. Looking forward to getting the bnr catless downpipe. I really want to remove the resonator and second cat with a straight pipe as well.
 

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Very nice. You have some serious fab skills.
Looks like GM performance is selling an exhaust kit that's 50% less restrictive. It looks nice, but is expensive.
 

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Discussion Starter · #16 ·
Very nice. You have some serious fab skills.
Looks like GM performance is selling an exhaust kit that's 50% less restrictive. It looks nice, but is expensive.
I might come around to making my own axle back but I think a straight pipe in place of the second cat and the resonator will sound loud enough for me. I like how quiet the car is.
 

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Discussion Starter · #18 ·
I raised the shift points and now if feels like it pulls much harder and doesn't fall on it's face on each shift. Less rpm drop on each shift now. 40-80MPH seems much stronger now. I'll get a new video up when I get the chance.
 

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Discussion Starter · #19 ·
Wrapped the charge pipes in heat reflective tape and plan on making my own catless 304 stainless downpipe and heat wrapping the downpipe and midpipe.

I'd like to get the gmpp exhaust but it's pricey.
 

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Discussion Starter · #20 ·
Tried posting this 4 times so hopefully it works this time....
Wrapped the charge pipes with thermacool heat reflective insulated tape. I'll be making my own 304 stainless catless downpipe and wrapping it and the midpipe with header wrap to drop underhood temps as much as possible. I'd like to get the gmpp exhaust but it's pricey. I might just do a second cat and resonator delete pipe so it's not much louder than stock while keeping the stock muffler.
 
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