Carl Fausett

I would go to the Vortech website and get their instructions for adjusting the Vortech Super-FMU.

In my world, an FMU works with the stock fuel pressure regulator, and a Super-FMU replaces the stock fuel pressure regulator as it performs both the static fuel pressure regulation and the enrichment under boost. So check. Your kind of off the page now - I don't know what the PO has done.

Did they install a Super-FMU AND also leave the stock fuel pressure regulators? Or did they remove them. Don't know. Send me some pictures of the install, especially back top of the motor and I can tell you.

Again - get the instructions for adjusting the Vortech FMU from the Vortech website.

blau928

There can be a large variance between the gauge reading depending on the wideband sensor you are using, as well as the wideband controller being used.
I think the Innovate kits come with NTK L1H1 or Bosch LSU 4.9 sensors. The controller is important and affects the speed or the data as well as the frequency of the data sampling. The best sensors I know of are lab grade NTK and Bosch, and two of the best controllers are Motec and Horiba.

If you want professional grade results, use a Motec PLM or a Horiba unit, but for most scenarios, the Innovate will be fine. Motec is expensive, but Horiba is really expensive...! (I have a spare Motec PLM if you wish to buy it and go off the deep end with tools, send me a PM. It lists for $2K, I will sell it for 50% or $1K, or you can buy one on EBay etc.)

I believe the Sharktuner also can log the wideband data, and not only the narrowband data, which will be more helpful in the analysis. The logged data will tell you a great deal if you log all those variables and compare like for like. Especially so, if the logging is in the same tool/logger. You can make a simple excel spreadsheet and do a comparison on selected data points if the data logs are in the same tool/logger etc.. This alone is an important reason to get the Sharktuner to properly baseline and also setup the car once the SC is added.

I have no relation to JDS and the Sharktuner, other than I have met John Speake in person in the UK, and he is a great guy.! I am running all Motec electronics in my 928, and have an integrated Datalogger as well as a dash logger with lots of other capabilities. I also have nothing to gain being for or against Carl and his business.

Tuning tip: Set the fail condition to fail rich.. That way, the ECU is trimming fuel out in closed Loop. If the thing goes boom, it will not be from too little fuel and melt your pistons, break a ring land etc. etc. If you hear detonation, it's already too late, as the motor has already suffered. You have to control the detonation, or it will kill your engine..!!

Here is a thought: If you don't know where the baseline is on that motor, How do you know how much fuel to add, and to which cylinder? Even if it's batch fire, you will have to tune the entire bank of cylinders to the leanest running cylinder on that bank, or that cylinder will break something once it goes too lean. (I think you can see which cylinder has a tendency to run lean if you look at the knock logs in the Sharktuner..) With sequential injection, it's easier, as you can tune the specific cylinders based on how they run..!!

Another thought: If you use the FMU, you will have a linear fuel map relationship (1/1, 1/2 etc. for X rise in manifold pressure = Y rise in fuel pressure), and if the FMU fails, or vac line breaks, the engine will fail lean. If you remap the fuel table in the LH, the fuel map is tunable to any organic shape it needs.

I have never seen a linear fuel map that didn't put either too much fuel, or too little fuel in an engine at part throttle, roll on, or tip in. This bit is essential at part throttle. Because, idle and WOT are the easy part of the fuel map to tune. Part throttle, tip-in, and roll on acceleration are much more difficult.

Why do manufacturers now use a chip with an organic map if they could use an FMU with a linear function on OEM supercharged or turbocharged cars?

Best of luck, whichever way you decide, have fun tuning and enjoying your SC'd 928 !

Rob Edwards

For about $1000 all in, you can own a Sharktuner 2/Sharkplotter,, a pair of PEMs, and the AFR gauge you already own (it is a WBO2 gauge, yes?) that will allow you to properly tune the entire fuel map and make the car run optimally and safely.

And you will be able to share data logs here. The benefit of that is that there is a built-in group of users who cannot help but analyze your data and help with dialing you in.

jwyatt8171

Thanks Carl. I have contacted vortech and downloaded the instructions. I think they installed with the factory fuel pressure regulator. Per Vortechs instructions you can use it in series with the factory FPR, or replace the factory FPR. I will post some images for verification, in not 100% sure on this.

I did connect a fuel rail pressure gauge. Per another thread I started it was recommended to drill and tap the existing cap to install the gauge, but use this temporarily. I will order a new cap on Monday.

It would seem my FMU is not doing as I would expect. idle 49-50psi. Adjusting the static screw does nothing.
I have some calibration eqipment I use in the field, so I dug out my low pressure hand pump. Plumbed it to the boost gauge and the FMU. At idle eased up the pressure from 0 to 10 psi. Still no movement on the fuel rail gauge.
A couple of questions on my testing. Can I run the fuel pump without the engine running without any negative side effects? If so, is it as simple as a jumper(maybe a toggle as well) at the fuel pump relay?


I appreciate all the help and responses. My plans are to try to get the system working as Carl designed, but using the SFMU if I can. If the FMU needs to be replaced I may bite the bullet and buy the bigger injectors and sharktuner since this is the direction im going anyways.

jwyatt8171

super fmu connections.

jwyatt8171

Pulled the FMU. Broke it down, and found it looks good inside. Nothing broke, busted, cracked or seized. The FMU looks to be in good condition. Both diaphrams look good. Spring in good shape. The O-ring looks good. I think this part is good.

A couple of questions. How much pressure should i have on my fuel rail @ idle, and under load? Im showing 49-50 psi at idle. Im reading different numbers here on Renn from 32-58psi. Does the factory FPR increase fuel pressure as the vacuum decreases? What range should this be?

One thing i noticed. After idle for a few minutes last night to check things. When i turned the engine off the Fuel rail pressure stayed high. It actually rose to 55PSI, and stayed there for at least 20 minutes until i was called away. When i returned it was down to zero. I wondered if the FMU was holding the pressure. So i disconnected the fuel line on the exit side of the FMU. A little fuel came out, but pressure stayed. Then i carefully disconnected the fuel line entry side of the FMU, same story. The fuel pressure stayed at 55ish.
Is this normal? Does the factory FPR hold the pressure? Does it seem i have issues with the factory FPR? Could it be a vacuum issue feeding the FPR?

Tested the vacuum lines going to the 5 way splitter under the MAF. Its hard to reach. I pulled the vacuum from the fuel damper on the front driver side. Couldn't get vacuum to pull down. Keeping my pump on the front damper, I pulled the vacuum line off the rear damper, and capped the line. Same, still would not pull down. I then pulled the vacuum line off the FPR, capped the line. Same results. The 2 lines I could not get to are the line going to the transmission, and the line going under the intake. That being said, did i waste my time here. The line going under the intake i assume is the supply. Should i be able to pull a vacuum on this line?

Thanks for any help or input.

jwyatt8171

So tonight I bypassed the fuel pump. With no vacuum I measured 62psi. Pulled vacuum on the FPR and the pressure dropped to 50 psi. Im wondering if those pressures are normal. In the previous post at idle I was around 49psi. I have WSM on the way. Hopefully I can figure something out with that help.

Any help is appreciated.

jwyatt8171

More digging has proven to me the fuel system is working as designed.

Im going to pull the FMU off again. After looking at the pictures i took, i did not inspect one of the O-Rings. The center oring in the image below looks like i may be flattened. That is the return port for the fuel. Fingers crossed.





The center O-Ring may be flattened.

Hilton

They sound resonable for an AFPR set on an S4 to provide more fuel.

However, just cranking up the fuel pressure isn't really a substitute for actual tuning (candykibort candykibort candykibort... ). The previous advice to get stock fuel pressure reg, bigger injectors, and get the car sharktuned, is pretty unbeatable.

You can download the workshop manuals here if you're waiting on shipping of a dvd.. from memory, volume 1a has the fuel pressure test values etc.

http://www.ligeti.com/928/

SeanR

Why have you disassembled the entire fuel delivery system?

jwyatt8171

I agree that cranking the fuel pressure is not the best that can be done for tuning. I am trying to get this system working as Carl designed without having to buy another FMU.
My goal is to follow the advise given earlier, but only after I make sure it's working as designed. You mentioned stock FPR, it is still being used, and appears to be working.

Thanks for the hint of where to find the fuel test values. It appears 3.8 bar is what I should expect. I'm seeing around 4 bar with the fuel pump jumped out.

jwyatt8171

Sean, what makes you think I have disassembled the entire fuel delivery system? The super fmu is the only part I have removed. It's 2 fuel lines, and a vacuum line. Oh, I have removed the vacuum lines for the fuel dampers for testing(checking for vacuum leaks). Have I done something wrong? Seriously I'm learning, so tell me if I'm screwing up here.

I'm trying to figure out what is going in so I don't destroy this engine.

FredR

The whole point of having ST2 and Sharkplotter is to be able to see/understand what is going on.

It is only a relative few years ago that a piggy back external FMU was just about the only thing you could do with these cars to support boost- but not any more. I dare say that someone like Carl who knows what he is doing with supercharger engine management can get credible results but the simple fact is the FMU does not pull any timing.

The auxiliary boost adjusted FMU by today's standards is a somewhat crude tool and leaves you with little clue as to what is really going on never mind having to transiently raise the fuel pressure which personally I do not view as a "good thing". I do not know the actual numbers but I dare say you will likely need to get around 10% more fuel into the mix - the pressure in the rail has to be increased by 21% to achieve that.

You need PEMs in your LH & EZ control units, probably wise to fit 30 lb injectors [the stock 19lb units can deliver a bit more but not an awful lot at stock rail pressure], an Innovate [or equivalent] wideband kit and access to ST2.

Your choice of course- "Chance favours the prepared mind".

Rgds

Fred

blau928

The FMU is a precision assembly, and you will need to get the specifications to re-torque the bolts... Maybe Vortech has an assembly procedure posted.

In any event, it appears that you are deciding to go your own path with a hammer instead of a scalpel to slice an egg.

After all the benefits of a Sharktuner with pems have been explained to you, it is still perplexing that you are asking about the fuel pressure. Especially when all of your headache symptoms can be cured and you will also get additional benefits for about $1000.

You might want to get a book on supercharged engines for $25 before you break something. Then again, maybe your decision to use the FMU is not affected by boiling the fuel, not adjusting timing, and lack of experience with supercharged engines.

Again, either way, best of luck.

Carl Fausett

Our Stage II kits are shipped with larger injectors.... I'm wondering whether the PO put them in...