Changed my IFR...AFR Is erratic

[zapp168]

When my car was tuned previously, the tuner used the following values for the IFR
0 7.7656
5 7.7891
10 7.8438
etc

Using the spread sheet listed here I get:

0 8.7295
5 8.7839
10 8.8380

I plugged those numbers in and according to the gauge the AFR went Real lean, I switched it back.
Which set of numbers would be considered correct? Is it wrong to put an incorrect number in the IFR tables and tune around it? I understand that changing the flow rate would change the AFR, but if my commanded AFR is matching my gauge with the original numbers, does that mean those numbers are correct?:Eyecrazy:

[SSpdDmon]

Sounds like he tuned your AFR using the IFR table. This is a common method of tuning as most pro's don't follow the VE/MAF tuning process that we do. Entering realistic flow numbers into your IFR table will require you to tune the MAF and VE accordingly.

An IFR tune can still achieve commanded AFR=actual AFR. It just does so using the stock MAF curve and a bogus injector flow rate table instead of an accurate IFR table and modified MAF curve.

[zapp168]

Hmmm No MAF here, I bet that really messed things up. I hate to ask this, but would it be better to plug in correct IFR numbers and start over on the VE table? I am assuming that is all I would need to change. Is the IFR tune just faster? Sorry I am asking so much, as I start to see how things interact, I think myself into a corner....damn ADD.....I am going to do a search on IFR tunes and see where that logic is. Thanks

[joecar]

Hmmm No MAF here, I bet that really messed things up. I hate to ask this, but would it be better to plug in correct IFR numbers and start over on the VE table? I am assuming that is all I would need to change. Is the IFR tune just faster? Sorry I am asking so much, as I start to see how things interact, I think myself into a corner....damn ADD.....I am going to do a search on IFR tunes and see where that logic is. ThanksThat's what we do... recompute the IFR and then do Auto VE.

IFR tune is much quicker than VE tune, but the PCM is being tricked under most conditions
(actual AFR not equal to commanded AFR).

Important: if you change IFR and/or VE, monitor what is happening with your wideband.

[zapp168]

OH YA.... when I changed the IFR table I went real lean real quick! If just re-calculating the VE table with the correct IFR will make the tune "more correct" I would rather go that route. Again...Joe...Jeff...Thanks.....you guys work for EFIlive or something :)?

[joecar]

Zapp, you're welcome. :cheers:

Jeff and I are EFILive users, and I'm one of the forum moderators ("In charge of lost bolts").

[zapp168]

Funny....you always seem to help me when I've lost my marbles...:Eyecrazy:

[SSpdDmon]

One of the perks of using EFI Live I guess. :)

[5.7ute]

Zapp, if you look on redhardsupras blog he has a method of unscrewing a bad tune. Give that a read.

[zapp168]

I will take a peek....Thanks...I think / hope this is just going to be some more VE tuning. The car does not run bad now, just rather have the correct numbers in there.....How did he pick those IFR numbers?

[SSpdDmon]

I will take a peek....Thanks...I think / hope this is just going to be some more VE tuning. The car does not run bad now, just rather have the correct numbers in there.....How did he pick those IFR numbers?
A 5% reduction in the IFR table is pretty much a 5% increase in fuel delivered (richer). Increase the IFR 5%, and AFR should lean out 5%.

Keep in mind, the IFR table references MANVAC and not MAP.

BARO-MAP=MANVAC (if I remember right)

[zapp168]

That Was It!!!!!! :jump:
I added 15 percent to the VE table and plugged in the corrected numbers into the IFR table......NEW CAR!!!! Since I had it tuned the car just felt sluggish, like I was towing something. When I started auto VE I could not seem to get the AFR right. Now the car woke right up, the pedal is responsive and it pulls HARD! :) BEN is showing close to all 1.00 and the AFR is correct....NICE.
The other issue that I never had before the injectors were installed is this harsh bucking at 1500 RPM (which is actually less now also), I think a better direction is to work on the injector settings (minimum pulse ...etc.) other that throttle cracker / follower since the motor and the low end tune were unchanged, just adding the injectors made it buck. What ya think?

[SSpdDmon]

If AFR is close, I find that bucking/surging is related to the other two remaining factors: spark and airflow.

[zapp168]

but but but.......it was Otayyyyy before the injectors??? The spark and airflow did not change. Do you mean that the spark and airflow need to be adjusted because of the larger injectors? I tried before following your example but had no luck....maybe now I will....I am just happy it runs so much better now....