Just swapped Injectors, now lean AFR

[CLRD4TO]

Edit: If you're having issues tuning 42# SVO "Green Tops", skip ahead to my last post.

Hi all, you guys have been a help this spring. Now I just installed a set of 42# SVO Green Tops (M-9593-f302 FRPP, 0 280 150 558 Bosch). I have the Greg Banish DVD and with the injector data spreadsheet. I had the stock 28# inj (GM 12561462) and had the inj data in the tune from the DVD.

I should be just fine bolting the new injectors in and flashing in the new injector data, right? Thats what I did and its VERY lean. I let it warm up (in closed loop) until the LTFT stabilized. Which was 25% (IIRC that is maxed out) to hold 14.7 ish on the WB. I restarted the car, turned off CL with the scanner and reset fuel trims. AFR jumps to 18 and with small revs it will completely lean out the WB (21.9).

Attached is the current tune file. I didnt save the short data log but I can record another one if need be.

Im thinking I need to completely retune my VE and MAF tables now. I should work on the VE anyways since I had issues with the 2200 rpm range previously. I am trying to get ready to run my 100 dry shot but not until this is fixed.

Thanks in advance

[CarsonTech]

What does the AFR look like with a load on the engine other than at idle?

[CLRD4TO]

Unfortunately I didnt drive it. A storm was blowing into my neighborhood just as I finished. I plan on spending some time on this tonight after work.

[schnellTTZ06]

You will need to work on your maf and ve for sure. Resetting your fuel trims wont reset the idle trims, so its running off of old trims for your idle. Mine did the same thing but went back to normal after driving it a couple days.

[KLUG'S SS]

Go for a drive when you can and get a log for us to look at.

[nmcqueen469]

Yes, you should re-check your VE and MAF tables. Did you just copy/paste the Banish data into your file, or did you actually watch the process on the DVD?

[KLUG'S SS]

If your ve and or maf tables were calibrated correctly before based on stock injectors and the factory injector calibration and then you go and change injectors in any car you should not need to go back and redo the airflow tables, that is the completely WRONG way to go about it and you are just creating more of a mess in the tune.


I cant see your tune from the computer I am at right now but I would go back thru and double check to make sure that all of the injector data is correct in your tune.

[Frost]

Remember, Greg didn't promise the holy grail here and it's not so much HIS data. He tells you what he did. He used mathematics to interpolate the GM data from the data that Ford had provided.

I tried the data for multiple injectors on a bone stock car that had OEM injectors and would trim to +/- 2 to 3% with it's OEM injectors. I tired 42s and 60s in the car. The 60's would not idle clean and both sets had some serious trimming show up. I went back to my own tried and true values that I can plug in on the same car and have pretty much the same trimming all over that the OEM units produce. If your injector data is solid, you should have little VE/MAF tuning to do, since that is becoming a catch-all for the injector error anyway.

[CLRD4TO]

I entered the data just like he shows in the DVD. I went over it again last night and found that I did not copy/pasted the offset v volts v kpa table with the interpolate for the 5's columns, but the new changes were very close to what I had.

I did forget about idle trims. I will also scan them tonight.

I agree with klugs ss, the fuel injectors dont change airflow so I shouldnt have to change any MAF or VE. But if thats what it takes to get this right oh well.

Frost, how do you determine your own values for injectors? I found a pdf page with ford values on these injectors but not sure how to use them.

[KLUG'S SS]

I entered the data just like he shows in the DVD. I went over it again last night and found that I did not copy/pasted the offset v volts v kpa table with the interpolate for the 5's columns, but the new changes were very close to what I had.

I did forget about idle trims. I will also scan them tonight.

I agree with klugs ss, the fuel injectors dont change airflow so I shouldnt have to change any MAF or VE. But if thats what it takes to get this right oh well.

Frost, how do you determine your own values for injectors? I found a pdf page with ford values on these injectors but not sure how to use them.

Well that's the problem, it gets complicated converting the Ford values to work in the GMs (wish like hell I knew how to do it!) as they are figured differently between GM and Ford, well for one thing Ford doesnt use a short pulse adder among other things. This is where Greg spent alot of time converting all the values over.

[CLRD4TO]

Attached a couple logs with the configs I used. I only used idle config for the cold start file.

[KLUG'S SS]

Definately went lean on you. How much in check was your fueling before the inj swap? Trims within the 1%-3% range??

[CLRD4TO]

I searched through my logs and can only find some prior to getting the greg dvd. The STFT ranged from +-3%, LTFT ranged from +2% through 7%.

I did some digging. My guess is the flow rate numbers are off. I found bosch info, Flow at 3 bar is 326.8 grams/min. Which equates to 43.228 lbs/hr @ 43.5 psi. (3 bar = 43.511321319 psi. 326.8 grams = 0.720470625169 lbs. 0.720470625169 x 60 mins = 43.22823751014 lbs/hr)

Then I found this site http://injectorrx.com/sizing.html with a calculator. Which gives me 60 psi flow rate: 50.8 lbs/hr. Id like a more accurate number, then how do I slope it for the table?

My current table is
52.20857 52.51860 52.82862 53.20066 53.51068 53.82071 54.13074 54.44076 54.75079 55.06082 55.37085 55.68087 55.99090 56.30093 56.61095 56.92098 57.16900

Nowhere near 50.8

[KLUG'S SS]

Here ya go read this from redhardsupra's blog.

http://redhardsupra.blogspot.com/201...-and-4bar.html

[CLRD4TO]

Good verification that I did my math right. I figured out the multiplier from that calculator and entered the new (smaller) nominal value. That populated the excel sheet (close to the 50.8) and I copy/pasted the info into my tune. I still had 40%+ AFR error with LTFT commanding 25%.

Im confident I have the best info availible for these injectors. So I just went out and started retuning VE. I multiplied the whole table by 12% to start, then the usual "areas" of the VE table. On the drive home, the bulk of the VE AFR error table is already less than 5%. I think the VE was a mess to begin with and the new injectors exaggerated it. Hopefully tomorrow night I'll have the re-tune all done and one big step closer to spray!

[69lt1bird]

Greg's 52 lb number is correct in the first cell. The Green Tops are rated at 39.15 lbs by Ford, not 43.5.

I think your short pulse adder looks wrong. The section goes a long ways before it starts to step. Just a thought.

[CLRD4TO]

The first cell in Greg's spreadsheet is 0.609783385. Im not sure what to do for the the short pulse adder cells prior to the .609 cell.

[69lt1bird]

I see what you mean, I just tried it on a stock 99 file and its just like yours.

[Frost]

...
Frost, how do you determine your own values for injectors? I found a pdf page with ford values on these injectors but not sure how to use them.

Use a 100% stock car with stock injectors. Calibrate the VE and MAF. Now swap injectors and tune only injector tables until you get the same results that the stock injectors had.

The thing to keep in mind though, is that offset can be very difficult to plot outside of a controlled environment.

[KLUG'S SS]

Greg's 52 lb number is correct in the first cell. The Green Tops are rated at 39.15 lbs by Ford, not 43.5.

I think your short pulse adder looks wrong. The section goes a long ways before it starts to step. Just a thought.

Yes that has been the theory but if you read the link that I posted those green tops were tested at 4 bar/58 psi and the results are right there plain as day they flowed at a little over 50 lb/hr.

I am sending out my set as well soon to get flow tested at the 4 bar pressure and we'll just have to wait and see the results from those too.