It's not just the regulator, but also the entire return side of the fuel system. I've found that I can get away with using a high volume/pressure pump as long as I have at least a 5/16" return line with no restrictions. If it's a 1/4" return line (like on an early Mustang tank with an EFI sending unit), then the restriction is too much for a low pressure TBI fuel system, yet is fine with a higher pressure multiport system.Originally Posted by kevinvinv
If it really is set at 14psi (not all pressure gauges are accurate) then something else is wrong, however like 1 project said, the only thing changed was the fuel pump ( mine is a 38psi tpi pump that delivers a solid 13 at the throttle body). I would start to data log to look at what the computer thinks your fueling looks like. Guessing doesn't work. 14 psi versus a stock delivery of about 11 psi is a 27 % increase in fuel. Your fuel maps would be way off. Over time it will lean out, however I would turn down your fuel pressure to about 12 and see how that responds.
Last edited by jim_in_dorris; 08-04-2014 at 08:10 PM.
Square body stepsides forever!!!
no, it's not. the change in injector flow due to pressure change is not a percentage change. 1% more pressure is NOT 1% more injector flow, it uses square root. going from 40lb of flow @ 11psi and moving to 14psi bumps you to 45lb of flow. that's more like 12%, not 27%.
I realized that later steveo, but 12% more fuel will also drive it rich. 128 BLM + 12% more fuel should drive you to 113 BLM, that is fairly rich. It will correct itself over time, but just turn down the pressuire and solve it quickly. (TBI 350- injectors are 61 # injectors not 40, but the difference isn't much 12.7% as opposed to 12%). Still I would just turn down the pressure, it would be the easiest fix. Then again, I would data log instead of guessing.
Last edited by jim_in_dorris; 08-05-2014 at 04:22 AM.
Square body stepsides forever!!!
Kevin, while doing the research on the pressure manual adjustment screw conversion, I do remember coming across a company making the same thing on a marine application. I got my whole setup through rv machine (that's not recreational vehicle, guys name is Roy something). He gets the kits (I later found out) though cfm tech. Stuff seems to be pretty well made, I'd reccomend them.
As far as the rough start idle, I have resolved the issue. You guys all had me convinced that 14 psi was just too high. So I went out there to adjust it and noticed that SOMEONE (or something...) must have disconnected the vacuum line coming out the back of the throttle body. I know I wouldn't make such a rookie mistake as to not reconnect it in the first place....
Anywho, problem is solved and it runs fine on 14 psi. Thanks for all the help. My original question was answered. I will keep focused on MY stuff and worry about learning about all the other things until the situations present themselves.
TJ
I still don't understand what a mask is exactly. I think 1projects comment here is leading to helping me understand this. What kind of specific features or performance are you referring to? Do diffrent masks provide you with a bunch of diffrent tables you can make adjustments too?
Glad you found a simple fix!!! The adjustable fuel pressure regulator I got is actually STOCK GM. No modifications and no special anything- it is just a stock adjustable FPR from a GM Marine application. It even has a little spout on it to dump fuel into the TBI instead of on the ground if the regulator diaphragm leaks. These things are a little rare I guess but still way cheaper than any custom AFPR's I've seen AND… they are factory GM :) Of course YMMV. :)
Hum...that's pretty cool. Wish I'd know about this thing. Sounds pretty cool. I'm all about keeping original equipment...unless it's a performance of course. It makes sense that it dumps leaked fuel into the tbi for marine applications. Beats dumping it into the boat, or the water for that matter.
marine mechanical pumps do that too, vac line from the fuel pump diaphram to suck leaked fuel into the intake.
in terms of tunerpro, you can think of a 'mask' as a specification of where the various tables/constants/switches in your bin file (the calibration that runs your ECM) are located, and how they work.I still don't understand what a mask is exactly. I think 1projects comment here is leading to helping me understand this. What kind of specific features or performance are you referring to? Do diffrent masks provide you with a bunch of diffrent tables you can make adjustments too?
so yes. different masks provide different tables.
the mask tunerpro is editing must match the mask that your ECM's software is using, or horrible things may happen (like you'll edit a chunk of code when you think you're editing your idle speed target)
does that make more sense?
When I was young, we used to take standardized tests. Maybe you've done the same thing. You read a question and several answers then on a separate page you fill in a circle that represents your chosen answer. Back then the teacher would grade the test by placing a special master sheet over your answer page. The teacher's sheet had holes for all the right answers. If your answer didn't have the circle filled in where the master sheet had a hole, it was wrong.
The "mask" is a code to identify where the variables are laid out in the calibration. You can think of it like the test master sheet. The calibration is like an answer sheet. If you pick the wrong mask for the calibration, nothing lines up and everything is wrong. The mask doesn't mean anything performance wise. It's just a way to identify a master sheet and the calibrations that match it. Tuning software definition files are written to match a particular mask. Definition files for a one mask will not give desired results with a different mask. The tuning software will allow you to change the variables, but the variable's function will not match what is in the definition. The software might say you're changing cylinder displacement, but really you're changing spark advance reference angle.
In most cases the only reason to know your code mask is so your tuning software "fits" your calibration. But sometimes people have some specific requirements that will need features not offered in all calibrations. They will need to pick a specific mask that does what they want. For example, someone has a turbo and wants the ecm to have wastegate control and the ability to back off boost and add fuel if knock can't be stopped with spark reduction. They need code written just for this. The community has figured out that those features were available in factory code from the turbo Sunbird and Syclone, identified as $58, and in code from the turbo Grand Prix, identified as $8F. This would be a case where picking a mask is based on performance.
Ok I'm finally starting to understand. So let's try a for instance. My ecu has a specific program written for it that reads the mask $OD. Let's say I build a 383 for it and the turbo it. Does that mean that I need to get a different ecu that can read the mask that has all the tables and such to run this setup? Or can you just reprogram them to read whatever mask you want to use. Or am I still completely lost??
lets describe it another way.
i write a program for your ECM that makes your car run.
keep in mind a particular ECM can run various different programs that are designed for that hardware.
the program has instructions like
- look up information in table x to squirt fuel.
- look up information in table y to adjust spark timing.
- check a bit z to see if.. i dunno.. your idle increases when cold.
the MASK defines the locations of where x y and z are located in the bin file, how they work, and how to view that data so it makes sense, so you can tune it.
a slightly different program that uses the exact same tables could use the same mask.
if a drastically different program uses different tables in different places, that'd be a different mask.
does that make more sense?
Please don't get hung up on this. The importance of this value to a beginner is small. Match the ID of your chip to the tuning software, definition file, and ALDL definition and you're ready to start learning how to tune.
That means you'll want to consider the tradeoffs between giving up a highly capable pcm which can control electronic transmissions but does not have a factory program for a turbocharger against the compromises you would make switching to an older ecm which cannot control the electronic transmission but has code written to work with the load generated boost of a turbocharger. You don't need to know anything about the mask, other than what the ID's are for the two most common versions of factory code designed for a turbo.My ecu has a specific program written for it that reads the mask $OD. Let's say I build a 383 for it and the turbo it. Does that mean that I need to get a different ecu that can read the mask that has all the tables and such to run this setup? Or can you just reprogram them to read whatever mask you want to use. Or am I still completely lost??
And to rephrase your question in a more accurate manner using the context generally applied to GM ECM's:
"My 16197427 PCM has a specific program written for it. The one currently in use is $0D. Let's say I build a 383 and then turbo it. Does that mean that I need to get a different ecm to use $58? Or can I run $58 on the 7427?"
Ans: $58 will not run correctly on the 7427 pcm. The program expects inputs and outputs to be at different addresses than that pcm uses. Additionally, $58 cannot control an electronic transmission so you will lose that feature. Your options are to use a piggyback ecm configuration, where the 7427 controls the trans and a different ecm running $58 controls the engine, or to use the 7427 code with a 2 BAR MAP & scaling MAP readings and doing your best to tune around the lack of turbo specific code, or to get really hard core and learn to write your own code for the 7427.
Moates.net seems to call the mask "the operating system" -- from my understanding this is not the best term but it did help me understand what "mask_id" meant just a little bit.
I would say two things (based on my novice understanding)…
1) The EPROM contains a bunch of tables, the mask_id is a way of keeping track of which tables it contains and WHERE they are located in the EPROM
2) The EPROM ALSO contains actual microprocessor code (a program that uses the data in the tables). The code in different "mask_id's" is different.
So the mask_id is like a "model number" for the data in the EPROM… which is both code and tables.
Correct.
Correct, although there is no requirement that the code be different. Custom code with different functions could also use the same tables and the same locations.2) The EPROM ALSO contains actual microprocessor code (a program that uses the data in the tables). The code in different "mask_id's" is different.
This is not an unreasonable association.So the mask_id is like a "model number" for the data in the EPROM… which is both code and tables.
Posting Permissions
Reply With Quote
Bookmarks