Fuel pressure?

Ron

Sam, can you pm or email me info on what you are using to monitor knock? I sent you an email on that, specifically about the J&S Safeguard. Thank you Sam and phunk. I think this thread has turned into a VERY informative one.

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phunk

Ron, you should scan through the UpRev website. They have on there detailed information to building a dual channel knock amplifier so that you can build a little circuit that allows you to plug in headphones and listen to the knock sensors with one sensor per ear. I bought all the components but I havent put it together yet... not much to listen to with E85 from what I hear.

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SAM@GTM

Of course it is...we're using a rising fuel pressure regulator, which has made it a ************ to tune. Keep in mind that the VVEL vacuum variation has a negligible affect on fuel pressure under vacuum, since the difference is only a few psi between low vacuum and high vacuum. Once you're in boost, that is no longer a concern and the rising rate fuel pressure regulator does what it needs to do.

BTW, your Twin Pump setup is doing its job very well.

Sam

phunk

^^^^ http://uprev.com/documentation/Knock...n%20Device.pdf

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phunk

Yes under boost it will surely work consistently. But its the low load cruising that made me decide not to follow through with building external regulator 1:1 ratio based fuel system kits for these cars.

What about under this circumstance as an example. And yes, I understand closed loop fueling SHOULD be able to handle this situation, but it still feels improper to me.

Say you are cruising down the tollway, and the VVEL is maintaining a 0/0 vacuum environment in the intake manifold. If you simply tap on the brake but do not lift throttle. The system instantly switches to throttle control and generates vacuum to operate the brake booster. But instead of holding on the brake, it was just a mere tap (for whatever reason). Now I know this test circumstance is more like searching for a inherent flaw than it is an actual driving condition... But, we have now created a situation where we have gone from no vacuum to engine load specific vacuum. The fuel pressure will instally drop due to vacuum, and then within a few moments it switches back to VVEL load control and fuel pressure will raise.

Like I said, I know thats a strange set of conditions and not very likely to occur in regular driving... but that set of circumstances alone was what told me that I cannot depend on the VVEL system to give me a consistent connection between actual engine load and manifold vacuum. I stopped trying to theorize other conditions where this could occur... but I certain there has to be some others.

But if the car seems to drive and cruise without issue regardless, then I suppose my concerns are exaggerated for the situation.

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phunk

That is good news. I figured it should work out as its based on the 350z twin design.

Build more crazy cars! I have a handful of those twin pumps with your name on them!!

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Neo187H

Awesome information in here guys, I'm glad this has turned into such a discussion. Despite the fact that I'm now more confused than when I began .

My tuner is an experienced tuner, mainly with Hondas, but they have no experience at all tuning Nissans or Uprev at all. They have been on the phone with Uprev throughout the day so I'm ASSUMING that they have stuff like the K factor (not that I have any idea what it is) covered but I'll talk to them further tomorrow.

Would stuff like the K factor affect the cars running throughout the entire RPM range? It currently runs great on the dyno up until the point where it starts to lean out up top.

A rather basic question but, what should the target AFR be? Years of fixing cars and I'm totally incompetent on the tuning side of things.

Jordo!

The K multiplier is a constant value that models injector size and pulsewidth -- it affects injector ontime throughout the tune. To the best of my knowledge, the value typically needs to be chaged if you change injectors.

Target AFR is whatever makes best power with no evidence of detonation, and varies from engine to engine. Something on the rich side, most likely, as the extra fueling (i.e., running a mixture higher than stoich) is used to cool in-cylinder temps. Probably something around 11 - 12, but could be a bit richer (or leaner) depending on load, octane, ignition advance, CR, boost pressure, etc, etc.

If your guys have good general knowledge with tuning FI'd cars, they should be able to figure it out, at least to dial in a basic tune. Eventually somebody who has more experience with uprev and with this engine should be tracked down for fine tuning if possible.

The guys with more experience using uprev in particular and on tuning this motor in particular can probably give you more specific info...

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Neo187H

To bump a now old thread, I now have larger 725cc injectors as well as a 300lph pump installed in the car and I'm still running into this same lean issue above 7000RPM.

Any thoughts or ideas?

I know the tuner is currently reading over this specific thread so I'm hoping maybe someone knows something thats way above my head that will give them some insight.

Vince@R/T

Sounds like the MAF values or the K fuel Multiplier is way off. You need to have a happy medium of the two. If one is way out and you try and compensate with the other it will throw BFS way out. Also a F/I 370z is a tricky car to learn UPREV on. Probaly the hardest actually. PM me if interested in maybe some E Tuning or coming down here...

toner123

you can check the k or even have the tuner load a different uprev map but I think you are having the same issue that I did. My fuel pump assy(housing where you put your fuel pump in and holds the regulator) was bad. We suspected it had a crack or a clog in it, so we replaced it, and no more issues.

Neo187H

After they were able to dive into it they finally found that the MAF is pegging out at 4.99v at about 7100RPM, something I worried might be happening after reading about Mr. Squeeze saying his car was getting close to maxing it out with the upgrades he did to the Stillen kit as well. At this point I'm just waiting for Sam to get back to me about some questions I had with their upgraded MAF and will likely be ordering that shortly.

So for futur reference, on a Stillen SC kit Motordyne ART pipes, 9psi pulley and the 928 motorsports impeller will have 725cc injectors running at close to 80% duty cycle and max out the stock MAF at around 7000RPM

phunk

Is that both MAFs hitting the same voltage?

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Neo187H

yes, both are hitting 4.99 volts at about 7100 RPM according to the tuner. I'm not sure how they didn't notice this earlier but they have now and it seems I needed the injectors one way or another anyways.