Thread: Did aftermarket TBI just get put on notice?

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I've been watching this guy for a while, he has forgotten more about carburetors than I will ever know, to me he's really impressive. He's managed to make this self tuning carburetor add-on which seems to work and is pretty genius, I think.

https://youtu.be/NNLud6_x3UM

I don't see the aftermarket EFI being put on notice, but then I've not really looked into the details of how he accompishes AI tuning of a carb, which is twisting screws and reading guages..... Truthfully it kind of boggles my mind how he can automate this, and make it reliable.

Originally Posted by rspears

I don't see the aftermarket EFI being put on notice, but then I've not really looked into the details of how he accompishes AI tuning of a carb, which is twisting screws and reading guages..... Truthfully it kind of boggles my mind how he can automate this, and make it reliable.

He does say it's not going to make a terribly tuned carburetor great, but it does make a decently tuned carburetor perfect. He pretty much runs a looped vacuum hose to a map sensor, and it controls the engine vacuum. If you watch the end of the video he shows it working and he was adjusting the AFR, full load, cruise settings. It was kind of neat how he'd be going down the road or at idle and showing what the AFR was, and he would turn the computer on, and bang it straighten it out to 13.5 perfect. I guess he's been tuning carburetors for 15 years and is a computer programmer during the week.

Yeah, I watched the video. I still don't see how his package can optimize air/fuel ratio and performance without touching the fuel supply, i.e. the jets and metering rods. Now perhaps his "setup" that he says is on another video includes optimizing the jets, metering rods, accelerator pump and idle mixture to presets before hooking up his "controller".

I did a search on Carb Cheater Reviews and copied this, which gives a pretty good explanation of what he's doing:

I don't think it does anything to the carb itself. It just messes with the AFR and using the wideband, it modulates a vacuum/purge valve to open and add air when AFR is too rich, and closes when it's too lean. MOST conventional (non-CCC) carbs are set on the rich side, so a calibrated and controlled vacuum leak will "correct" the AFR, or at least send it in the right direction, and helps band-aid the issue. Obviously continous readout and variability makes it respond. The shorter the vacuum lines, the better the feedback. If you have a stubborn carb you can't get tuned right, this may help. But for $383 for the rather simplistic kit...I don't know if it's not worth learning how to tune your carb yourself. For that kind of money you could just about get a good rebuild on your current carb. Just my opinion.

The ECM on CCC cars does just the opposite. It meters the fuel through the mixture control solenoid to try and strive for that 14:7 magical AFR among other things.

So in my mind he's using the carb as the "injector" but has zero control over the pulse rate to modify the volume of fuel, and he's assuming that your carb (or setting up the carb?) to be slightly rich so he can then tweak the air side to add more air through his spacer, basically a controlled vacuum leak.

I'd rather let my engine pull the air it needs, and adjust the fuel based on that air flow. I have to agree with the comment above, either learn to tune or spend your money on getting your carb rebuilt by Riley's Rebuilds!!

Thinking more about the Carb Cheater, when tuning a carb we look for the right main jets for optimum power at WOT, the right metering rods for mid range and cruise, and then the idle mixture and idle speed. A guy/gal could use an air/fuel meter to fine tune choices, but that's not the norm. What this guy is doing is assuming you've gut your carb pretty well dialed in, then using a modulated vacuum leak with A/F ratio feedback, to optimize, using that tiny bit of "extra"" fuel vs letting it escape to exhaust. The issue is if you happen to be a bit lean Carb Cheater can't do anything to add fuel, it can only add air
I can see some value, but I think it would take years to get $400 in fuel savings, and it adds a whole new level of complexity to a simple carb installation.
Thanks for posting, Seth! Kind of like a Mythbusters episode!!

Roger, think of it this way. Say you're new to old cars and old engines with a carb. This $400 unit could save you a $5k (or more) engine just by the data you receive from it. From the videos I've seen from a couple of other carb cheater users they love them. Granted both guys already had their carbs pretty well dialed in but both guys, this unit changed the way their engine ran and improved AF ratios. I can't see how that is a bad thing? This thing isn't a lot more than a good quality AF gauge. It sure has my interest. Also, this a heck of a lot cheaper than a LS swap.