Tuning Help! New blower, HPX....

[03Steve]

The PW issue may very well be with the crappy SD #80 (that are also used, I never flow benched).

So once I input those values into the MTF, would I still correct certain cells in #mass/tic in open loop for commanded lambda? Or should I be changing BFT now?

Just want to make sure I have the right process now.

I think you have quantified the PW issue very well.

-560-600 inj pw with the MAF plugged in
-260 inj pw with the MAF unplugged
-210 A/D counts from the MAF at idle
-~1VDC output from the MAF at idle (1VDC * 204.6 = 204.6 A/D counts)


It seems that the PCM is telling the injectors what to do. That is quantified with the unplugging of the MAF. The SD 80s aren't at fault when the PCM is cutting injector pulsewidth by over 50% when the MAF is unplugged.

One thing to consider...the minimum pulsewidth scalar. I don't have the source code for the AOL3, so I cannot verify if injector minimum pulsewidth only applies with a MAF that is in an operational state. But you can lower it. To zero. Just to test. Nice having the software to test, isn't it?

You can put up a screen shot of your base fuel table if you like. Low load and low RPM (bottom left part of table) values are typically 1.00. You can also verify that your Stoich Air/Fuel ratio scalar is set to 14.64 (100% gasoline) or 14.08 (90/10 gasoline/ethanol).

To answer your question, yes...you can still correct the transfer function. As long as there is nothing radical going on in the base fuel table, that is a good place to typically start.

Curious, have a photo of the location of the sensor and bypass valve? Centri setups can be touchy with hardware placement...

 

[Don 95Vert]

Actually, I have had quite a few EEC IVs and early Cobras/GTs that are #mass/tic PCMs that hit a hard airflow limit. Greg B. told me years ago he seems to think it may be a fuel flow limit, but I disagree. I was credited as 'discovering' this on the SCT Dealer's forum. We had a number of higher HP vehicles in the 500ish RWHP area that just went lean for no reason. Scaling the tunes made this go away. Jerry W. also confirmed this way back when. So, if a vehicle is going to be one of the ones that MAY be over the limit, because you never know power at the end of the tune, I just go ahead and scale them because it stops issues on down the road and it does no harm at all. Certainly it would not result in a vehicle being rich with adjustments to the MTF doing nothing. I have probably done >100 vehicles #mass/tic vehicles like this with no issues whatsoever. Don't know what the airflow limit is, I just know it is there. This has saved many a headache among tuners who frequent the dealer's forum.

Don

 

[03Steve]

Understood Don. I'm not going to argue with your experience. I haven't done anywhere near that many cars and I have not experienced an airflow limit on a #mass/tic PCM. The AOL3 PCM I last worked with was up there in airflow, but it was also scaled due to the injector size. The 1999 CHH3 #mass/tic in my own car is 106#/min unscaled.

I understand your point that it can vary from one #mass/tic PCM to the next. With that in mind it certainly makes sense to scale. Thank you for the information.

 

[03Steve]

Values from screenshot above, scaled to 63#/min range...

#mass/tic (21MHz processor)

0.0000047985
0.0000040316
0.0000032600
0.0000027743
0.0000022784
0.0000020492
0.0000018075
0.0000015723
0.0000013217
0.0000011844
0.0000010877
0.0000009010
0.0000007064
0.0000006112
0.0000005260
0.0000004343
0.0000003510
0.0000003081
0.0000002239
0.0000001811
0.0000001619
0.0000001228
0.0000001037
0.0000000832
0.0000000632
0.0000000455
0.0000000390
0.0000000292
0.0000000238
0.0000000000

 

[Senator]

Thanks for the help guys.
Let me get back at it this weekend, and we'll just go from there.

 

[Senator]

New Rule:
Don't ever take previous owner, tuner, or shop mechanic's word for 100%.

"There's no previous tune on this car."
"Your MAF, BOV, and injectors are definitely not allowing me to tune the car."

Decided to start breaking down some of the mechanical stuff myself, and then this........
That'll hinder the SCT from making tune changes....

 

[Stanger00]

Wow! That'll screw things up for sure.

 

[04sleeper]

Doh!

 

[03Steve]

Ugh, the J3 port. *smacks head*

 

[Don 95Vert]

Glad you figured it out! I think someone may have mentioned this as a possibility... Lol!

 

[Senator]

I feel bad that I didn't check myself, but when you first start out and you know nothing about the mystical world of tuning, you can only take people's advice until you learn the lessons yourself.

Glad you figured it out! I think someone may have mentioned this as a possibility... Lol!

I went down the checklist that "someone" helped me put together. :thumbsup:

The PCM is responding to every change I make now, so that part is good.
I'm tuning off my wideband (MTX-L), in OL still, and the only thing I'm not sure is normal is that the AFR bounces around a bit.
Let's say idle for example, the range is 14.2-14.6.
Is that normal?
Do I need to go back and fine tune <5% increments on the MTF table to get this constant?

Just want to make sure before I WOT tune, then go back into closed loop and the STFTs are way off.

 

[Don 95Vert]

It is normal for the A/F to bounce a bit in OL. When you put it back in CL to fine tune it, it will be closer, but the trims will still move around mirroring how the O2 sensors switch. If you give it any bias because it is a moving target go for it being a hair rich rather than on the lean side.