Sai Li System Help

[venumous]

Guys who have done this system install would appreciate your review of my situation here. So I had the system with twin GT350 pumps installed by a professional mustang shop because I didn't want to mess with it. Loaded 93 Tune from Lund, first logs - good, told to do 2500 to 5500 - good, told to do pull to 7200 - good, final 93 tune sent with base tune for E85. Ran car down to E on 93, car took 15.9 gallons of E85 (tested to exactly E85) to fill up, change tune, did idle log, cruise log and short pull to 5500, going lean at WOT. AFR looks fine but STFT is adding 15 to 18%, this did not happen on pump gas.

I guess I can pull the seat and check the pumps by pulling 1 fuse at a time to see if both pumps are firing properly/bad fuse? Any other thoughts? Lund seems to think it must be a pump issue. Sai Li says he has not had a pump this new be bad, though the Fuel Pressure Gauge he sent me was bad and had to be swapped by shop.

Log 93
http://www.datazap.me/u/venumous/50...16-17-18-19-20&trim=0&tmin=169.65&tmax=180.27


Log E85
http://www.datazap.me/u/venumous/50...16-17-18-19-20&trim=0&tmin=303.07&tmax=314.10

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[Jn2]

The beginning of your pull is a little lean, you are seeing .84-.85 λ, how ever it looks like they left your timing pretty conservative so this lean spot isn't causing any pre-detonation, most likely due to e85's increase knock resistance. If this is the first log you sent them I would expect your next revision to no longer have that lean spot and for them to give you more timing up front with out relying on the knock system to do most the work.

bout the pump, if you look at your top end, when fuel demand is at it's greatest, you are seeing .80 lambda at WOT, which means your fuel system is keeping up with demand just fine. Normally when you have pump problems you will see a drop in fuel pressure and a spike in injector duty cycle as they try and compensate for the pressure loss.

Here is a example of what happens when pump is acting up, fuel pressure will drop, in this case it dropped to 27psi, this caused injectors to ramp up to 96% duty cycle to compensate for the drop in pressure and car was not able to reach desired lambda at all...I do not believe your pump is the issue

 

[markmurfie]

Your STFT and LTFT are opposite of each other in the E85 log. They cancel out and are not as bad as it seems.

In your 93 tune LTFT seem to be disabled.

I have seen a few tunes like this now where it has learned to add a bunch of fuel and now the STFT are having to pull that fuel out as the tune gets closer. Just a guess, they may have left the LTFT on when they sent you the E85 tune and not compensated for it when dialing in the fuel causing them to command more fuel than necessary. Its usually tuned back on with the final tune. Compare lambse and actual lambda to see where the lambda would be if the trims were not compensating. It would be rich. Actual lambda is not spiking lean so I don't think its a pump issue.

 

[Jn2]

Your STFT and LTFT are opposite of each other in the E85 log. They cancel out and are not as bad as it seems.

In your 93 tune LTFT seem to be disabled.

I have seen a few tunes like this now where it has learned to add a bunch of fuel and now the STFT are having to pull that fuel out as the tune gets closer. Just a guess, they may have left the LTFT on when they sent you the E85 tune and not compensated for it when dialing in the fuel causing them to command more fuel than necessary. Its usually tuned back on with the final tune. Compare lambse and actual lambda to see where the lambda would be if the trims were not compensating. It would be rich. Actual lambda is not spiking lean so I don't think its a pump issue.

Good call on the LTFT, I didn't even look at that one since Lund tends to always disable it in their tunes. How ever it does look like he has a lean spot when he initially goes WOT, it does settle down to .79-.80 lambda though once he revs up higher...so def doesn't look like pump issue

 

[venumous]

You guys are awesome. I will ask Lund about the LTFT. Appreciate you both!!!

 

[markmurfie]

Good call on the LTFT, I didn't even look at that one since Lund tends to always disable it in their tunes. How ever it does look like he has a lean spot when he initially goes WOT, it does settle down to .79-.80 lambda though once he revs up higher...so def doesn't look like pump issue

Yeah tip-in is lean. Takes 500-600 RPMs for the trims to fix it. I think it wouldn't be so bad once they actually get the fuel dialed in.

 

[venumous]

Lund says LTFT is not used WOT. He enabled it going to E85 tune since trims looked fine. He says that is not the problem.

 

[Jn2]

Lund says LTFT is not used WOT. He enabled it going to E85 tune since trims looked fine. He says that is not the problem.

LTFT are enabled and working during WOT...attached is a screenshot of your e85 pull showing STFT and LTFT are working during WOT. When LTFT are disabled they will display a value of 1 the entire time.

 

[markmurfie]

Then disable them in E85 tune and get a new log with E85. Compare STFTs before and after.

 

[venumous]

Yeah looks on to me!

 

[markmurfie]

Here's a history lesson on Fuel trims.

Back when cars had narrow bands O2 sensors open loop was used to obtain a rich wot lambda. Open loop eliminated the fuel trims to do this as narrow bands were limited to swinging rich or lean of lambda and that's it. So STFT and LTFT not being used at wot is or dated information.

Modern day cars come with wide band O2 sensors. The ECU quirks with them directly. This gives the ecu the ability to target a rich wot lambda and apply error corrections while doing it. So while it's still called open loop, it's really not.

 

[venumous]

With the denial that it's the problem do you see an issue with providing a log to 6500? In terms of motor reacting poorly to it?

 

[markmurfie]

If Lund is right, LTFT are doing nothing at Wot, your STFT are taking care of it. Disabling will make no difference.

If they are working at WOT and they disable them. The STFT should need to compensate less and look more like your 93 log.

Either way I see no problem in doing a 6500rpm pull with them disabled. Just to see if it is the problem.

 

[venumous]

Sorry the log he wants is with original e85 tune like above log.

 

[markmurfie]

No problem with that its safe. Give him what he wants.

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