PTE 50trim + 650s + 255/afpr, need AFC help

[Spidey]

Posting this for a friend. I did quite a bit of searching this morning and did find some useful info, but I'm looking for more.

The car is a Galant VR4 with the following setup:

PTE 50trim
Holley 650s(what the previous owner told him anyway)
Walbro 255lph
Aeromotive AFPR set to 43psi w/ vac hose disconnected
Spearco 2-216 FMIC w/ short route piping
3" turbo-back exhaust
GM MAF w/ translator in draw-through
SAFC-II

He just put the AFPR on yesterday, and obviously it needs to be retuned. Previously we tuned out all the knock @ 15psi on 93 octane, and it ran fairly well. With the AFPR and bumped fuel pressure, we decided to up the boost to 18psi.

The problem now is, the car seems to knock no matter what once the turbo is pushing 10psi or more. The MAFT is 0'd out for now, we're trying to tune with the AFC only. His Th points are 40/60, should these be changed(I have seen differing opinions with searching)? The AFC is also set to around -15 LOW across the board, and -20 HIGH for 3500-5000rpm. o2 sensor voltages are around .82-.84 99% of the time, and it will get anywhere from 20-40 counts of knock rolling into the throttle and going WOT for a very short period of time, say 5 seconds. Before the AFPR, the car was seeing 0 knock with .76-.78 o2s and low EGTs, barely over 800c with a full 3rd and some of 4th gear pull.

Now, last night, we kept on leaning it out, -20 max from 3500-5000rpm, and nothing seemed to change. o2s stayed around .84 and the car was still seeing tons of knock. When we tried -25, o2s showed .82-84 once again, and then out of nowhere dropped to .02.

I realize he should be somewhere around -30 across, but we're both a little skittish about doing this. I'm mainly looking for someone with a similar, if not identical setup, for some baseline AFC settings at around 18-20psi on 93 octane. If anyone is willing to help out we would greatly appreciate it. I did search, and did not find any SPECIFIC information, just some general stuff that may or may not help, but we will try.

Thanks in advance,
Shannon

[edit]I will also post some logs when I get the chance to, we have a few small ones and one giant one that needs to be split up[/edit]

 

[44pirate]

On the MAF T was is your base set at. Should be 6 or 7 with 650 injectors. Dial in the idle and set teh mid and wot to 0. Zero out your SAFC and make some runs.

 

[kpt4321]

First of all, zero out the SAFC and base tune with the MAFT.

First, reset the ECU. This will make tuning MUCH easier. Also zero out the SAFC.

Cruise at 45-70 mph in fifth, and watch the O2 trim. The hi fuel trim should be 100%, so you can disregard it. Tune the BASE knob on the MAFT such that the O2 trim cycles around 100% during steady-state cruise on the highway.

Once that is done, you can stop and let the car idle, and use the idle knob on the MAFT to get the lo fuel trim in line.

With that set up, you have a good base tune and you can tune WOT on the MAFT, or on the SAFC if you wish.

The throttle points on the SAFC should be more like 25% and 60%, maybe plus or minus a little bit here and there. That would be a good starting point.

Go and read my tuing guide and the tuning worksheet in the tech files section. It'll help you.

I think it's time for me to make a MAFT tuning guide.

 

[Spidey]

Thanks Kyle, I knew you'd chime in. I did read your tuning guides already, tonight we will give everything another try. His fuel trims seemed to be in order last night, but I agree that the MAFT should be set first and fine tuned with the AFC, it only makes sense. With the MAFT dialed in, and fuel trims proper, the AFC should be somewhere around -20 to -30 for 18psi, correct? Baseline settings for the AFC once everything else is in order would be the biggest help, we just want to make sure that is a general range to set the AFC to, though we realize it will vary from car to car and other variables.

 

[kpt4321]

No. The base knob on the MAFT will do a general airflow correction all the time.

So, if the base knob is set so that you have -20%, you will have 20% airflow reduction everywhere. If you were to also set the SAFC to -20%, then you would end up with -40%. Not good.

The MAFT can be used to set up injector compensation, and then you can do little changes on the SAFC from there.


Not to sound like a salesman, but the new version of the MAFT has been released. If your friend wants to sell his SAFC and buy the upgrade for 30 dollars or so, it may be something to consider.

 

[Spidey]

Originally posted by kpt4321
No. The base knob on the MAFT will do a general airflow correction all the time.

So, if the base knob is set so that you have -20%, you will have 20% airflow reduction everywhere. If you were to also set the SAFC to -20%, then you would end up with -40%. Not good.

The MAFT can be used to set up injector compensation, and then you can do little changes on the SAFC from there.


Not to sound like a salesman, but the new version of the MAFT has been released. If your friend wants to sell his SAFC and buy the upgrade for 30 dollars or so, it may be something to consider.

He ordered the supposed bolt-on Aeromotive as well as the new chip 4 weeks, ago, he just received the AFPR monday with no chip, and is not very happy to say the least. We will start by 0'ing out the AFC and re-setting the MAFT tonight or tomorrow I think, get the fuel trims back in order, and go from there. I'll post back with results and hopefully, logs.

 

[kpt4321]

The new chip didn't go on sale until yesterday, so I don't know what you are talking about.

Any other customer service problems, I am not going to get into. It's not the right place for them, nor does it really matter.

Let me know how the tuning goes.