I've been doing some street tuning this week (tuning from 2k-5.5k on the street in 3rd gear, within legal speed limit on service roads) and have noticed some interesting things.

1st: I have an RTek 2.0 and I noticed in my logs that the MAP sometimes shows boost. Obviously not a lot, but throughout the rpm range it goes from vacuum to boost. Most of the time it ranges from 0 to -4 in-hg, and every once in a while it goes as high as 0.4 psi(very briefly). I first thought it was a glitch, then I noticed the AFR's spiked up slightly at those points. This is causing a slight problem as it's harder to smoothn out the afr curve at that point.

Advice on how to tune for it since it seems kind of random? Or eliminate it from happening? Or is it just something that happens in our motors?

Also, anyone else have issues with tuning at 2600 and 3200 rpm? It's becoming annoying as at 2600 is "spikes" rich, and at 3200 is spikes lean. So when I tune to accommodate this it affects the rest of the numbers within that cell range.

 

You will see positive pressure at certain points. This is from the tuning in the intake manifold so it actually forces more air into the motor.

As far as tuning, you will have to be on a dyno to see the difference in power from tuning for this extra air or letting it be. You will more than likely have to find a happy medium.

 

underachiever! you want to eliminate positive pressure from an N/A?

a couple of questions: (1) what do your logs say about the timing at those points that you specified? (2) where do your secondary injectors open?

 

I should have thought twice about asking about eliminating the positive pressure haha. How about, how do I get more of it without turbo?


Stock timing settings. I'll have to goto the car to get the actual timing at those points.

I open my 2ndaries at ~3600. Reason: damn hesitation. I've gone through all the grounds I could and fixed them. I've read all the archives and searched a ton on this matter and nothing has fixed the hesitation.

Anyways I brought it a bit lower to ~3600rpm so I could "band-aid" the hesitation at WOT and splash some fuel to even out the AFR curve.

 

How does the RTEK measure pressure, as an absolute or relative to barometric?

I wouldn't think that a "good" resonance would result in positive manifold pressure (gut feeling is that when it goes higher than ambient, then it is due to reversion) but then, if it runs leaner at that point then that proves it's getting more air...

 

well if the timing doesn't reveal any possible solutions at those points, then maybe you could have the secondaries open 400 RPM sooner? it would coincide with your lean spot. as peejay said, you're clearly moving enough air.

 

just wondering how is your Rtek 2.0 working out for you?


thanks

 

RTek measures pressure the same as the stock ecu. The boost sensor readings I see on the logger are relative and measure the boost seen in the manifold.



The RTEK is working great. They have a small piece of software that allows you to see your datalogs on your laptop. So when I'm street tuning, I will load the log onto the laptop and make my fuel corrections based on what I see in the logs (takes 2 seconds to sync the pda to the laptop). The RTek has a couple RPM outputs,and has an input for a wideband O2. It has everything I need as a beginner. Not to mention it's the stock ecu so it truly is plug and play.

Also, the support at Digital Tuning has been amazing since my RTEK first arrived.