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First time tuning a FI car. I need some input.

 
Old 03-10-2016, 09:39 AM
  #1  
regorih
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Default First time tuning a FI car. I need some input.

Good morning,

So I been tuning bolt on and H/C car for the past two year and I now have my first FI C5 to tune. Everything looks good but I'm running into some stuff I'm not used to seeing. Can the more experience tuners give me some feedback?

Run down of the set up:

1999 C5, 243 Head & Arun cam, long tube headers, 60 lb. siemens deka injectors, P1SC Procharger with 3.5 pulley, walbro 225 pump.
Stock: short block, intake, throttle body, crank balancer-pinned

The issue:

I’m not getting the commanded AFR (12:0) I input when I go WOT. Also, when I’m driving and I clutch in and start coasting to a stop the engine dies. If I give it some gas before it shuts off the engine will catch itself and level out.

Two things I see as a problem but I need someone else to verify it or discredit it:


1. I don't have a hot wire kit for the fuel pump so maybe its not getting enough voltage from the factory harness? I figured the stock harness could handle a single 225 pump. I also don't have a way to monitor fuel pressure at this point. I might have to set something up.

2. As my RPMs and Dyn Air go up, it gets to a point where RPM's continue up and Dyn Air starts to level out or go down. Could this be a representation of belt slip?

Thanks for any input.



Roger


It's all good now. I have resolved all my issued above after some hard knocks learning ( no pun intended). Car feels really fast now, and I did it all by the making adjustments to the tune. No extra parts required. All I need to do know is start tuning with meth. Thanks to all that lend a hand.
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Last edited by regorih; 03-17-2016 at 12:18 PM.
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Old 03-11-2016, 03:26 PM
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Shoaf85
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Post up the tune file as well if you want and I will try to look it over if time allows.
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Old 03-11-2016, 03:43 PM
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TurboLX
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1) Do you have ALL of the correct injector data in there? (Hint: you will have to scale the tune to make SD60's work on a C5 PCM)
2a) Have you done steady state (and WOT) correction of the MAF curve?
2b) Are you sure you're not running out of MAF Hz at the top end? If so, you need a new MAF/housing.
2c) Are you sure you're not running out of MAF g/s (max is 512 in a C5 PCM) at the top end? If so, you'll need to restart with a greater scaling factor.
3) Have you done steady state (and WOT) correction of the VE surface?

Last edited by TurboLX; 03-11-2016 at 03:43 PM.
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Old 03-14-2016, 12:00 AM
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PhysicsDude55
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Gonna be honest here, you're unlikely to get good tuning advice on this forum.

Also, post a driving log if you can. Hard to diagnose a tune by itself.

All the good tuners charge for their service, so they won't give it out for free, but for a modest price plenty of guys can give you a good tune if you give them a few good log files, or can even tune your car live if you have a way to connect your laptap to internet while driving (phone tethering).

Do you have a wideband air/fuel gauge? Do you have the gauge hooked up to the HPTuners box to log AFR? Whats your AFR when idling? I have 80lb injectors and my C5 was idling really rich, even with the correct injector mapping. The fix is to change the minimum injector pulse, you have to lower it over the stock value because HPT scales it up. Not sure if this is your issue with the car dying at idle, but it might be. I think the stock value is 3.9ms?

Like TurboLx said, make sure you have the correct MAF settings, or disconnect the MAF entirely and go for a SD tune. My understanding is the stock MAF is only capable of supporting ~575 horsepower. After that you have to get a larger MAF or go SD. I personally went SD and never looked back.

Last edited by PhysicsDude55; 03-14-2016 at 12:03 AM.
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Old 03-15-2016, 12:25 PM
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Pekka_Perkeles
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Originally Posted by PhysicsDude55 View Post
Gonna be honest here, you're unlikely to get good tuning advice on this forum.
Probably so.

Originally Posted by PhysicsDude55 View Post
I have 80lb injectors and my C5 was idling really rich, even with the correct injector mapping.
Actually by halving "Min Fuel Milligrams" under "Transient Fuel Qualifications" (in HP Tuners) does the trick and I guess also "TurboLX" agrees with that. In other words, his 80 lb injector data just works!
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Old 03-17-2016, 01:45 PM
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Originally Posted by Pekka_Perkeles View Post
Actually by halving "Min Fuel Milligrams" under "Transient Fuel Qualifications" (in HP Tuners) does the trick and I guess also "TurboLX" agrees with that. In other words, his 80 lb injector data just works!
Yes on the min fuel mass clip. It has been my experience that even though I have data on the average 80# SD/FRPP injector, actual production part to part variability has been pretty big. This means that you could very likely end up with a set of injectors where one or two are far enough away from the average that it makes the car run poorly. IMHO, there are better 80# injector options out there (like the ID850) even though we have data for the SD/FRPP units.
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Old 03-18-2016, 02:43 PM
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Originally Posted by TurboLX View Post
Yes on the min fuel mass clip. It has been my experience that even though I have data on the average 80# SD/FRPP injector, actual production part to part variability has been pretty big. This means that you could very likely end up with a set of injectors where one or two are far enough away from the average that it makes the car run poorly.
Now that's interesting.

The (80 lb) injectors Ford is using are also a standard injectors in cars like some factory Mustangs, right?

Or am I wrong?

http://www.cjponyparts.com/ford-raci...3/p/M9593LU80/

Why would any car manufacturer use an injector that doesn't have ability to provide even a decent level of capability/variance?

Just asking.

Last edited by Pekka_Perkeles; 03-18-2016 at 02:45 PM.
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Old 02-22-2019, 11:38 PM
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1st I would make sure your injectors are properly scaled for the 42 lb injectors--- The injector slope is sclaed by MAN VAC-----this is an odd table --Typically a stock cam will idle at a higher man vac reading than a cammed car so you may need to adjust the injector slope to accomodate the changed idle IFR
2nd At EFILIVE we were taught with LT headers and a cam that you need to "trick the ECM " into a leaner mixture in open loop or start up fueling We often have to command MORE airflow at start up to compensate for the added airflow and the enrichment caused by the LT headrs--Not un common to command something as lean as a 16.0 in the "open loop normal" table ( only in the start up idle fueling areareas) to allow more start up airflow
3-- You can try adding like 20% to the "desired airflow" in P/N and IN DRIVE
4 We were also taught NOT to mess with the throttle cracker table UNLLESS you added a larger T Body-----------------To correct a dying or a hanging idle when stepping on the clutch we use the "throttle follower " table----- To correct a hanging idle you would ADD a % to the follower DECAY Rate table in gear
I would start with adding 20% If you get the opposite affect then you went to far simply back it off some %------
PS make sure if your fuel trims (LTFT's) are enabled that they are ALL slightly negative or "0"--
If you can't seem to clear up your LTFT's after a MAF adjustment then turn the LTFT corrections OFF ( often needed with large cams)--
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Old 02-23-2019, 12:04 AM
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I sure hope he's figured out his tune by now
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Old 02-23-2019, 01:07 PM
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Pekka_Perkeles
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Originally Posted by aaronc7 View Post
I sure hope he's figured out his tune by now
Could be dead as well.
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