MAF transfer with Tweecer

[jruppert]

This is for anyone who has tweecer or a tuner and is familiar with it. I have a pro m 77mm meter calibrated for 24lb injectors. If I tell tweecer to run this meter with the tweecer file and tell it to run 30lb injectors it wants to lean out horribly under any sort of load. It is so bad that the exhaust muffles out and has no acceleration. This also shows up on my wideband between 19 - 20. Now, If I load up a file for pro m 30lb injectors then it runs. It doesnt run perfectly but I dont get the lean condition. What is the deal with this? Does this mean that my meter is out of wack?

 

[Michael Yount]

Have you downloaded the detailed transfer function of the maf into the ecu via tweecer?

 

[Daggar]

What size injectors do you actually have?

Where did you get the meter's transfer function?

You can not choose a generic .bin file, slap it in there, and expect everything to be happy about it.

 

[90Notch]

Find the spreadsheet (one created by Raymond B) that calculates what the MAF transfer should be with new size injectors and download this. This is a great starting point, from here though you will need to fine tune the values down near idle. BE VERY VERY CAREFUL WITH ANY CHANGES TO MAF TABLE AS A LITTLE GOES A LONG WAY!

Here's the website:

http://www.iwantperformance.net/cgi-bin/ultimatebb.cgi

Here's another site that will be very helpful:

http://autos.groups.yahoo.com/group/EECTuner/files/

and on this page has the MAF calculating spreadsheets:

http://autos.groups.yahoo.com/group/EECTuner/files/Tools/

 

[Daggar]

Find the spreadsheet (one created by Raymond B) that calculates what the MAF transfer should be with new size injectors and download this. This is a great starting point, from here though you will need to fine tune the values down near idle. BE VERY VERY CAREFUL WITH ANY CHANGES TO MAF TABLE AS A LITTLE GOES A LONG WAY!

Here's the website:

http://www.iwantperformance.net/cgi-bin/ultimatebb.cgi

Belay that suggestion. It may be necessary to perform some monkey business like that on the EEC tuner but that's not how TwEECer works. Trying to input an interpretive tranfer function will inevtiably lead you to problems with other function variables available with the TwEECer. At this point (if I'm reading your problem correctly) you need to first find the CORRECT transfer function for you specific meter. Once you've verified that those are correct, then you will need to tell TwEECer what size your injectors are and set the injector break points. Once complete you'll need to move on to the load tables and ensure that the ECU knows when you're on the gas, when you're off of it and down the line. If you're not already a member of the TwEECer forums then you need to be. As great as this board is for a lot of things, TwEECing the EEC is not one of them. Drop BlackFox5.0 (SP) a line and he can probably get you started. I believe he's running a TwEECer on a normally aspirated motor and might be able to help you out.

 

[90Notch]

"As great as this board is for a lot of things, TwEECing the EEC is not one of them."

My apologies!!

 

[Michael Yount]

"At this point (if I'm reading your problem correctly) you need to first find the CORRECT transfer function for you specific meter. Once you've verified that those are correct, then you will need to tell TwEECer what size your injectors are and set the injector break points."

I think this is pointing in the right direction. The maf's ACTUAL transfer function (sometimes hard to get your hands on) can be loaded into the ecu via tweecer so there's a match between transfer functions of the maf and the ecu. Once that's done simply select the size injector you want to run -- oh -- and then install that size injector. That last piece is key.

 

[Daggar]

"As great as this board is for a lot of things, TwEECing the EEC is not one of them."

My apologies!!

Not a problem... I didn't want to see the guy go down a road that would lead to having trouble with the other (unerlying) tuning functions in the TwEECer. You can compound trouble very quickly/easily when modifications to the EEC DEPEND on the correct settings for things as basic and important as injector size and transfer function.

To the original poster:

Here's a link for the TwEECer forums:
http://eectuning.org/forums/index.php

 

[jruppert]

The reason I posted here is because I get feedback much faster then the tweecer forum. I have already received 8 or so replies and I will not see anything in tweecer for at least the day. Anyway, the car ran great last year with this same meter and the same transfer function. I understand its generic but it works. This time around it will not work. Like I said, I have to load up a 30lb transfer instead of the 24lb which is what I have always used and has always worked. The meter is calibrated for 24's and I have told tweecer I am using 30's. Thanks for the replies

 

[Daggar]

Loading up a transfer function for a meter calibrated for 30s will not solve your problem. Your tuning issues lay in other areas if you already have a transfer function that works correctly. You haven't by chance done anything to or with the meter recently that might have had the potential to mess it up have you? Say.... cleaning it?

 

[Daggar]

Click here:

http://forums.stangnet.com/private.php?do=newpm&userid=11088

and give BlackFox a shout. He's got quite a bit of practical knowledge in this area and might be able to give you specific help.

 

[jruppert]

No I havent done anything to the meter. I wouldnt think that uploading a file for 30lb injectors would work but its the only thing that made it run. I will message him and ask. THanks

btw, I have forgotten to mention that I upgraded to a larger throttle and long tube headers. Could this have an issue with mass air?

 

[BlackFox5.0]

You have a PM.