ShellDude

iTrader: (12)

now might be a good time to grab some Injector Dynamics ID1000s I have all the AP latency data for them if you're interested... based on a cool spreadsheet I threw together that allows for interpolation.

9krpmrx8

iTrader: (46)

As it is I have too much fuel, I see no need for larger injectors. The yellows in the p1 and blues in the P2 should be plenty.

Sifu

iTrader: (34)

Makes me wonder how much fuel I am getting with my injectors.

Can't wait till you sort out the tune and get this beast running 100%

Want to help me with a base tune in December haha?

9krpmrx8

iTrader: (46)

You really should have them tested at 60psi so you really know what they are flowing for your application. It's a learning process and I learn more everyday. I would be glad to help you man, we have been having group tuning meets so that we can correct each other and compare our notes against our research, etc. The biggest problem in learning how to tune is understanding the terms used because they vary depending on what tuner you talk too.

I have a good book for you to read if you want to go into super nerd mode. But honestly Kane is the man and without him and Brettus to speak with I would be way lost. I'm so close I can taste it.

The car actually ran great today, my injectors were behaving I guess because of the really cool weather and now that I think of it, they seem to act up even more when it's hot.


If you ever need to ask questions or talk to someone the guys and gal at home. They are local for me.

TeamRX8

iTrader: (25)

breaking out the broken record player again .... remember that for most Renesis FI applications that don't have a boost compensated fuel pressure system the true injector flow rate will be defined @ fuel pressure minus boost pressure

9krpmrx8

iTrader: (46)

Resolving that issue sounds really, really complicated.

dannobre

iTrader: (3)

Understanding it is most important. Then a strategy can be developed to deal with it

9krpmrx8

iTrader: (46)

I understand Boost tries to push fuel back into the injector and I guess a return style setup would be ideal. I have some research to do.

Brettus

iTrader: (2)

it really isn't such a big issue as is being suggested here . Just understand that it exists as an issue but won't actually make that much difference at the boost level you are likely to run at and you will be fine.

9krpmrx8

iTrader: (46)

I just read Dan's return fuel system thread, I think I'll save that project for the next engine replacement.

Kane

iTrader: (1)

Good lord guys, asked and answered like years ago.....

You don't need a return system, you just have to compensate for it. If you don't have a RISING rate regulator, then use the Fuel VE% Table. For lower boost applications it's fine.

olddragger

iTrader: (3)

it is not like we are pushing 15-30 psi of boost...not yet anyway.

TeamRX8

iTrader: (25)

I'm not saying its an overriding issue. As long as the injectors are large enough then its easily compensated for. When you discuss/determine injector flow then its something to consider. If you intend to maintain 55 psig fuel pressure, yet not exceed 15 psig boost the you might consider requesting your injectors to be flow tested at 40 psig (55-15=40).

I recall a certain somebody railing on about a set of modified yellow secondary injectors don't flow up to their rating. Well they do actually under the NA pressure condition for which they were tested. It just wasn't the same as his actual fuel vs boost pressure setup.

There are other reasons to make the feed/return/regulated fuel system changes, but this is mostly for competition reasons. The typical street/play car doesn't really require it.

As usual, typical forum twisting a comment or two into something that wasn't meant or intended

dannobre

iTrader: (3)

I would tend to bump up the static fp to the higher end of the scale..say 65psi..and tune there...modify the latency change due to that increase .....and then have flow closer to what should be expected at normal boost levels. Ending up with 40psi after baro changes isn't ideal

TeamRX8

iTrader: (25)

It was just an example using the OE fuel pressure figure

olddragger

iTrader: (3)

agreed in principle. It is just another factor that has to be considered when modifying an engine.
Thats all.

Brettus

iTrader: (2)

Interestingly ......... It was under NA conditions that the lack of flow from uncapped yellows became apparent to me.I would still disagree with the second sentence above.

ShellDude

iTrader: (12)

This recent fuel pressure tangent has done nothing but hurt my brain. If you've got the basic latency values plugged in for "static" pressure and +/- range provided then shouldn't it just be a matter of making adjustments via the VE table?

Does it really matter that much if the final VE % is a little higher or lower than the "true" value? No matter how hard you try to polish a hardened pile of ****, it will always be ****

9krpmrx8

iTrader: (46)

It's always the little things. So today I pulled the UIM to install the new injectors and everything went smooth. But as I was putting the UIM back on, I noticed that the vacuum check valve on the brake booster hose looked different on mine than it did on other 8's I have worked on. Mine was covered in thick black tape (that was falling off and nasty) and when I looked at another 8 that is in my garage I noticed the valve on it was not covered in tape. So I removed the tape and found this:

http://www.flickr.com/photos/9krpmrx8/8194026321/
It looks melted, not sure how the dealer would have done this but no one else besides me and the dealer has ever worked on it.

I have never messed with it so the god damn dealer must have done it at some point during the couple of engine replacements or something. When you blow thru it air goes thru regardless of what side you blow on and air comes out of the crack. It explains my whacky idle at times I guess.

dannobre

iTrader: (3)

Basically the final result is what is important

You can get there in a few different directions....with the fuel tables, MAF, injectors and the Ve table....

Ideally it would be best to have rock solid fuel pressure with a rising rate regulator that would adjust for manifold pressure....injectors that you knew the perfect latency values...and a perfectly adjusted MAF.....then you could type in your "wanted" Lamba value and it could do it perfectly every time. And great adjustability for different ambient and engine conditions

The reality is you get a MAF that is fickle..injectors that change for a multitude of reasons, a regulator that isn't perfect.....you get the picture

and then we fudge stuff till we get out of it what we want

It ain't pretty...but it works 99% of the time.

The trick is knowing which variable is causeing strange little glitches in the Lamba that move around for no apparent reason despite trying to adjust for them. That is when having better values for the sensors and injectors etc will make them easier to figure out

TeamRX8

iTrader: (25)

I suppose that would come down to who tested them and how it was done then. If done properly then the results just don't magically not add up.

9krpmrx8

iTrader: (46)

Giggity, Giggity.

http://www.flickr.com/photos/9krpmrx8/8198264231/

dannobre

iTrader: (3)

Good choice..now get some good pads and hit the track

9krpmrx8

iTrader: (46)

I have a full set of ET300's and ET500's. Not track pads I know, but a start. Track time will be soon, the tune is almost there. I also have a broken (wasn't me this time) rear sway bar bracket bolt that needs to be drilled out, yay.

TeamRX8

iTrader: (25)