Catchy slogan. Cost me $600 for a pro last time to tune my car. If that tune lasts for 5 years till I have to retune IF did something radical enough, that's $120 a year. Would it be less expensive considering time (which is money) spent learning everything from beginning to end till my work as as good as the pro's? On a "one off" job, I don't think it will. Learning how to do brake jobs and buying the tools to do it so I can do it for all my cars, I agree.

I know of one guy who does tuning as a side job when time permits. So how long did it take you to get to pro level, assuming you are at pro level?

 

Time is money only if you can exchange your labor for a fair wage. If you're already working all you care and need to then you can choose to do other things with your time than make money. But if you insist... My current wage is about that of 1/4 shop labor rates. Not only can I put in 4x the time as a shop and essentially break even, I learn in the process. The Corvette in question requires no hardware to retune aside from a laptop and ALDL interface cable. No MEMCAL chips or burner required as with the old ECMs. With the capabilities of the flash PCM and the software tools involved the tuning is also easier than with older ECMs.

I'm no expert in engine tuning. My expertise is in telecommunications electronics, but you don't need an electronics background to use these tools, learn about your car and edit the PCM programming.

 

I agree it doesn't take much to master making changes to the program whether it is an older MEMCAL unit or this vehicle. What I am saying is that to understand what exactly the program does is going to take a long time. Knowing how to make the change is easy. Knowing why you are changing what, that is the big expense of time. Weigh it against this being a "one off" for the most part, I can't see how it is worth it from a financial standpoint. If I were doing a lot of changes daily, it is worth it.

This is not a job that needs to be done daily, weekly or even monthly. Unless you make enough mods, you could probably set it and forget it. Say you spend 40 hours learning how to do the tweaks, how much more time to learn till you are as good as the pro? As I said, it cost me $600 for a dyno tune. How many hours of your time would that buy till you feel you can do as good a job as they did. Say you are worth $25 an hour. Think you are as good as the shop after leaning it for 24 hours? Think after 24 hours of leaning time you are ready to go pro?

 

If one has a good understanding of how to tune an engine with a carburetor and distributor then the fundamentals of engine tuning are understood. Aside from injector offsets, and those only change with an injector change, it is not difficult to make fueling changes to accommodate engine changes. Ignition advance changes are even easier.

Data logging will show where the PCM is adding or subtracting fuel to maintain stoichiometric combustion. That feedback covers part-throttle operation very well. WOT operation is a bit more work as you really do want a wideband O2 to accurately hit a target A/F outside of lambda and it's not as easy to hit the target the first time through.

The MAF equipped cars like mine and the original poster's sense how much air is being consumed and the PCM injects the correct proportion of fuel in response. This makes the MAF cars easier to tune and less in need of retuning. Longer duration cam? That's going to throw off MAP sensor readings as vacuum went down at low engine speeds, but the MAF measures the actual air flow rather than looking up what it should be in the VE tables for a given RPM and MAP value.

You really are invested in this idea of being a pro and in defending having spent $600 to tune your car. I'm investing in knowing more about my car and being self sufficient. I am not investing any more time in explaining myself.

 

I'm invested in the idea of having a good job done so I can drive the car without having to spend a lot of time getting ready. I'm perfectly fine not being self sufficient but able to have more time to do what I want to do as opposed to what I have to do.

 

This isn't going to end well. "MAF measures air and ECM puts the right amount of fuel in". Sure... it's that simple. I have no idea why there is an Oxygen sensor, TPS, IAT, CTS, etc. on my car.

 

I think he's approaching this as a hobby, learning as he goes. If he messes up, then he'll have to learn how to fix it which is great in my opinion. And maybe he will share his failures and successes on this forum for others.

 

Yep, that's the primary difference between MAF fueling and speed-density fueling. IAT and CTS are fueling trims. TPS is used as a transient enrichment and for activating WOT enrichment. TPS is also used for load sensing (Alpha-N) in MAF-only systems if the MAF sensor fails. Early Bosch TPS didn't actually sense throttle position with a potentiometer, but used a switch to give on-off pulses for throttle enrichment. The O2 sensor is there for emissions as catalysts operate well only near lambda. And narrow-band O2 sensors really are lambda sensors. Volvo even gave their cars a Lambda Sond grill badge when they added O2 feedback to their Bosch K-Jetronic injection system. The older Volvos, like my 1973 145E, had no O2 feedback. My 1998 Honda VFR800Fi has no O2 sensor. My 2015 Nissan Frontier has a wideband front O2 sensor and a narrow-band rear.

I hope that I have dispelled any notion that I don't know the whys and where-fores of the systems I'm interacting with. Now, back to the point...

My point was that a MAF equipped system is much more flexible than a speed density system. Different companies have used different strategies at different times. We can see that GM changed strategies in 1994 and that is an advantage for the late C4s. Ford used MAF sensors a lot as a given engine combination didn't have to be retuned for every little chassis variation. But MAF sensors are more expensive than MAP sensors so if you can amortize the tuning cost of each chassis across enough units it saves money. Never fail to account for cost savings when assessing why something was done a particular way. Nor can market demands or government mandates be ignored.

 

You didn't. I didn't question if you knew the system. I will tell you that knowing the parts and components does not yield the ability to tune properly and certainly not expertly.

Maybe at a 100ft very basic explanation.

Yes they serve this function, but there is also more the computer uses them for to make decisions.



Not really sure how knowing this adds confidence to your ability to tune an entirely different system, but man that knowledge about the badge is sure going to come in handy. That is great for Cars & Coffee, but not sure that is going to help you at the lap top.


This is true, but incomplete. Even heated wide bands are still lambda sensors.... I don't know what you mean by really are... Oxygen sensors are lambda sensors in your car or anywhere else you are measuring oxygen content (divers use them to test gas as well, also termed a lambda sensor).


Lots of other cars didn't. And while it does help with emissions, there is also something about economy and proper operation. Do not look past the feedback system helping with emissions also extending the life of other parts of the engine by providing a clean burn. Also, the feedback loop helps dial in proper fueling for clean burn, economy, and safely making power. Sure beats listening to the engine, looking at exhaust and reading spark plugs. All though, I don't suggest abandoning those as tools in your tool box either unless you have the ability to get feedback from each cylinder individually.

The ability to operate doesn't mean it’s optimized. That car made all of 130hp with leaded fuel and no emissions. It was only an 8.5:1 Compression ratio engine leaving a lot of room for error in timing and fueling. Pales in comparison to today's engine abilities, while meeting emissions. No to mention it only got around 22mpg. Not exactly a "Worlds Best" bench mark to set.


Again, the ability to operate in open loop doesn't mean it is optimized. In 2000, Honda updated the fifth-generation VFR (RC46) with a catalytic converter, oxygen sensors, and an EFI system that would enter closed-loop mode under highway (cruising) operation. You will have to address both open and closed loop in your system. Obviously there was a need, because on 15 January 2004, EPA’s Control Of Emissions From Highway Motorcycles Rule (69 FR 2398)established 2 tiers of conventional pollutant exhaust emissions standards for highway motorcycles in the United States. Tier 1 came into effect in 2006, and remains in effect for Class I and II motorcycles.

Why add Cost 6 years ahead if there wasn't a performance increase to sell more units? I am not even sure I know where you are going with this. Are you planning to toss the oxygen sensor with the emissions and run Open Loop all the time? There are more advantages to having a feedback loop than just emissions. Hence -

Where now the wide band provides fueling information to the ECM and the rears are only there to provide catalyst information. They rears can be tuned out or simulators put it and they will do nothing to the function of the engine. While the wide band provides much more accurate and better resolution for the ECM to make adjustments.



It is to some degree, but it also creates limitations that are much easier to work around in a speed density system because of the VE tables. A 3 Bar MAP system can support way more HP and air flow than the MAF system. More of an issue on the TPIs due to being an 8 bit systems and being limited to 255gps. So yes, it is more flexible until you hit the wall. There are work arounds, but they are just that, you are not longer working with direct measurements.


Depends on who you talk to. The LS3/7 use a hybrid system of both due to some other limitations of MAF at low air speed and it's responsiveness at tip in. I see the advantage in flexibility to someone bolting on parts, but there are limitations and tradeoffs. MAF alone is not a perfect system.

Ford also used Speed Density. Sounds like you are very knowledgeable about the history of cars from 85-95. You're probably 40-45ish in age if I had to guess.

I am not saying you shouldn't start playing with the tune in your car. I am thinking about doing some playing with tuning as well. Especially to be able to turn a few things off. I do think you are setting yourself up for disaster being over confident in your knowledge and anticipated results. I would suggest keeping the original file so you can always go back. When I start playing with my IROC’s tune, I am going to get a complete new chip and keep my current bin on a chip ready to go. I know the components, I know what they read and how they function. I know what the ECM is supposed to do with them, but how it uses all the tables together… I feel I know very little and will approach accordingly. If you don’t humble yourself now, the process will later.

 

Fair enough. If he is after intangibles, I suppose. I'm looking at it from a "spreadsheet view" and I absolutely hate having a car that I am constantly having to test it and see how it goes. More annoying to have to put it on a dyno and all the hookups to see what is happening each time while learning.

 

KyleF,

All true. What's also true is that the forums are necessarily limiting in scope and I further limit myself on how much time I'm willing to devote to these discussions.

We have a history of Otto engine fueling from surface carburetors, float and pressure carburetors, a huge variety of mechanical injection methods, moving into analog computer-controlled solenoid fuel injection, some mechanical injection added back in which later added electronic feedback, feedback carburetors, and digital computer-controlled injection. All the electronic systems have used with increasingly advanced sensors, controls, processors and memory. More recently we have electronic direct injection, dual injection and on the fringe, HCCI. The history is important. As we are in the C4 Tech/Performance what's most relevant is digital EFI with 2 to 8 (+1 for early TPI) injectors, the various control strategies and the hardware required to implement them. Not once have I held myself out as a tuning expert. In fact, if you go back you'll see where I state what I've learned about my '94 as a novice using cheap hardware and free software. I have yet to make one edit to the PCM.

 

you guys scared away the OP

 

This one just took a turn to tuning. I was wrong, the LS swap guy didn't show up.