EFIDynoTuning Forum

I just upgraded from 42lb lightning injectors to deka 60lb injectors, and entered all the injector data from the references pages. When I updated the AHISL, all values in the FN036 MAF curves scaled up around 30%. I dialed in the MAF and now they are around 8% higher than they were on the 42lb injectors. This means the RAW MAF is about 25% lower than it was.

Fuelling is great, I have no errors over 5% and most within 1-2%, but the load is now less than 1.10 under boost, where it used to be in the 1.45ish range. Have I made a mistake somehwere, or is this normal with larger injectors?

If it's normal, what should I do to compensate for load to get into the area of FN2200 borderline Knock where I should be in while in boost?

Thanks for your help

Paul

Oh, that's actually good news, I have a fresh set of 60's to put in when I get a second.

Thanks for your help

Yeah it spins in 1st and slips in 2nd, it definitely runs through the rpm quickly. It still reads nearly the same air mass and load though so I was I little worried about being on the lean side of 0.80.

And temperature wise, on that pull it only went from 94 to 104. I just wasn't sure how much temperature affected it. It's a stock cobra intake sucking from the fender, and a fairly big heat exchanger. The only time it gets out of hand is when it's heat soaked I'll see 160s IAT

Been thinking and reading...

Is there a modifier to the MAF transfer for IAT?

It would make sense to me that the MAF would read slightly less voltage for the same air mass as temperature increases. however with only one IAT input and the sensor located after the blower, it would be incorrectly inferring that correction during a pull as IAT goes up.

Am I on the right track? Is there a way to give the ECU IAT1 input from the MAF temperature sensor? Or to give the IAT less effect on air mass calculation?

I put a bigger MAF in it, since I was close to pegging the 90mm Ford one. Made a new log, still seeing the same puzzling pattern. Lean in 1st and then richer in the higher gears. I don't quite have my head wrapped around the injector Pulse width, but it seems like it's shorter at the same RPM when the Wideband is reading leaner, so I don't really think it's an exhaust leak. It looks to my uneducated eye like it's reading less Mass Air in lower gears, and calculating less load and fuel required at the same RPM at WOT.

if anyone can see anything I'm missing in this log or the other one, I'd love to hear theories or suggestions.

Thanks,

If you're using a decent base tune with your injector slopes entered correctly, and cranking pw scaled for your injectors, it's more likely an installation problem from the new motor. Have you checked base timing and verified plug wires are in the right order? Are you getting rpm signal when cranking? Is your fuel pressure regulator getting vacuum to the right port?

It should start and die at least unless you have mechanical problems

sounds like a problem in your O2 circuit.

If Lambse is less than 1 it's waiting for the O2 to switch rich. If Lambse and your Wideband are that close, your fuel is pretty near dialed in. The only thing I can think of that would cause this is your front O2 sensors aren't responding. Watch IEGO11 and IEGO21. they should be switching rapidly around .4V or so.

I'm trying to see how much injector I've got left. I'm logging FuelPW1_21MHz and INJDC_21MHz, but I'm not getting credible values. I've got a few questions:

1) How do I identify my ECU clock speed? In the table in the Fuel Write up, all 1998 ECUs are 21MHz. Is that correct for my BAI1 box code? (98 mustang GT 5 speed)

2) If that is correct, is INJDC_21MHz the correct payload to be watching for injector duty cycle?

3) if both of those are correct, is there anything else I'm doing wrong?

FUELPW1 is about 3500 at 6000RPM WOT, which is the same as I'm logging in Livelink, however FUELPW1_21MHZ is returning 0.07 and INJDC_21MHz is returning 0.00. Using the conversions in the ADX file (if I'm referencing the variables correctly) I calculate INJDC_21MHz is 0.0015.

I don't mind creating my own calculated item if I know what the forumla is.

Is it as simple as 3500 ticks / 0.0000045 ticks/sec = 0.01575second PW?

then at 6000RPM 100% DC is 0.02 seconds, so INJDC_21MHZ is .01575/.02 = 0.7875?

I just want to make sure I'm on the right track before I go up the boost and especially before we get into colder weather and denser air.

Thanks for your help,

The AFR it asks for is stoichiometric AFR for the fuel you're using. There's a table at the top of the fuel write up

http://www.efidynotuning.com/fuel.htm#stoich

I don't know how EA records it, but STFT is probably Lambse, or commanded AFR as lambda. It should be between 0.75 and 1.25

If it's between -0.25 and +0.25, It might be actual fuel trim (Lambse - 1)

There's tables explaining fuel trims and lambda AFR values for different fuels in the fuel write up on the home page