MAFT tuning and timing

[Clipse]

So I've had a blow through MAFT on my car for a while now and had it running great with my 14b and 450s. Just yesterday I put in my new Evo III 16g and FIC 650s and set everything back to 0 with the base and aux set up for 650s. First the car wouldn't idle because it was too lean... fixed that kinda, but still only reading 30-31 hz at a 950rpm idle. Anyways the car is pig ass rich up top. AND I'm getting 25-40 counts of knock!!! Mind you the car is so rich that it bogs out at about 4500-5000 rpm, but still knocking. This morning I watched my logger as I began a 3rd gear pull from about 2500rpm. Once I nailed the throttle to the floor my timing only retarded to 27...? Shouldn't it drop down to about 11 or 12?

I havn't checked my base timing but I never changed it from the last setup. So why would it be different? I'm really confused by this and am not what you would call a tuning god, so any help would be appreciated. Thanks,

 

[sleepyvr4]

I'm going to setup my car w/ 680's and 14b today, w/ all other supporting mods. Does aux have to be dialed in according to the chart to reach the right injector size?

 

[Clipse]

Off subject.. but yes, and if they're FIC or PTE they're actually 650cc.

 

[BOBS90TURBO]

My setup is very close to yours except I have 550's and when I first installed them I could not get my car to run right so I put the 450's back in and have been learing to tune with these first, they are a lot easier to get the hang of, and at this point I am very impressed with how shes runnin, I get almost zero knock, timing advances from 16-22 like it should and o2's are around 82-92. and feels so strong and smooth now with the 450's back in, with the 550's I was bogging down and cutting out, blowing black smoke under boost in the upper rpm's. I will put the 550's back in after I really know what I am doing.

BTW, did you do that 1/4 mile time in your profile with the 16g and injectors or with the 14b and 450"s?????

 

[Clipse]

Well, I did already learn how to tune the MAFT with my 14b and 450s. I had them tuned perfectly as a matter of fact. I don't know WTF is wrong with my new setup...

The time you see was on my 14b and 450s @ 16psi on pump gas. I had every other mod that I have right now aside from the 16g and 650s though.

Danny

My setup is very close to yours except I have 550's and when I first installed them I could not get my car to run right so I put the 450's back in and have been learing to tune with these first, they are a lot easier to get the hang of, and at this point I am very impressed with how shes runnin, I get almost zero knock, timing advances from 16-22 like it should and o2's are around 82-92. and feels so strong and smooth now with the 450's back in, with the 550's I was bogging down and cutting out, blowing black smoke under boost in the upper rpm's. I will put the 550's back in after I really know what I am doing.

BTW, did you do that 1/4 mile time in your profile with the 16g and injectors or with the 14b and 450"s?????

 

[kpt4321]

You changed your setup, so you need to retune the car. You can't just expect to use base settings and have everything work beautifully.

 

[Clipse]

You changed your setup, so you need to retune the car. You can't just expect to use base settings and have everything work beautifully.

Did I say I expected the base settings to work? No, I said I can't figure out why my car is knocking no matter what I do. I've been adjusting the settings non stop and can't figure out how to tune the knock out.

 

[kpt4321]

Why is it that you are posting entirely different information in the different places you have posted this problem? That's why you shouldn't ask a question at more than one forum at a time.

On NABR-Public, you said:

Just to clarify, which I appearantly haven't done. I have my base set for 650s and my WOT knob is leaned out -30% plus and additional -13% on my SAFC. I got there from tuning the o2v and injector DC and have had a shit load of knock ever since the MAFT was zeroed out.

And I replied:

Well, don't tune with injector duty cycle and O2 voltage, that's your first problem.

Tune the base knob first with the hi fuel trim at a highway cruise. This will set up the MAFT's global correction.

From there, you can do the rest of the tuning with the SAFC, if you want. However, what version of the MAFT do you have?

With the base knob set for 650s, you're taking out about 40% of the airflow going to the ECU. Then, you have an additional -30% on the WOT knob, AND -13% MORE on the SAFC? And you're wondering why the car is lean? Your total correction is something like -60%, or more. That's probably too much, don't you think?

 

[Clipse]

Why is it that you are posting entirely different information in the different places you have posted this problem? That's why you shouldn't ask a question at more than one forum at a time.

On NABR-Public, you said:



And I replied:

Well I hadn't seen your reply on the NABR board and my original post on NABR was after the post on Tuners and I had made changes in that time. I posted in 2 boards for more advice/help.

Just to update, I zeroed out the MAFT (left it setup for 650s though), lowered my base fuel pressure to 30 and tuned with the SAFC. I also retarded the base timing to 0 btdc and it helped A LOT. Still working on fine tuning, but I managed to get it down to only 15 counts for the time being. Thanks for the help

 

[sleepyvr4]

holy sh*t - base fuel pressure at 30psi. that's heroin. I just got my setup dialed in today. Set the maft to 680cc injectors. base fuel pressure at 37/38 psi. idle knob on 2. Low fuel trims fluctuate between 135 and 139, so hopefully I'll be seeing decent mileage. 3rd gear run produced 3 counts of knock as soon as I floored it, which disappeared right away. No knock at all high in rpms. 17psi. timing climbed from 22 to 28. o2 values stuck at .84 - so I'm pretty happy right now. I think I need to add/subtract fuel from my mid to get rid of the bit of knock I had. other than that, what a setup. Idles great, smooth throttle, no bogging, no black smoke. Simple stuff really.

 

[sleepyvr4]

clipse - set your injectors accordingly, and drive you car normally. Drive it so the ecu can figure out what's going on. changing the settings constantly is not going to get you anywhere. make the car driveable, and go from there. I had tons of knock when I first went out (30 counts) and just taking my time and getting the small things out of the way made it much easier. READ THE MAFT MANUAL. Pay attention to the little details. It pays to discover.

 

[98spydert]

The manuals BS. It gives you a starting point and that's about it. I've got a 3" blow thru set up with a keydiver comp. for my 650s. I ended up having to set the dip switch for a 3.5" MAF, lean out the base 2 clicks from 450 settings, then the other knobs are like +2 -1 -2... just all jacked up but it runs smooth and strong, trims are happy, and knocks gone away except for sometimes out of know where my knock gauge shoots through the roof when I'm cruising at like 30 mph and give it just a tiny bit of gas. I'm not sure what that means since it only happens like 1 out of 10 times.

The one thing to remember when figuring out the MAFT is make small adjustments and let the ecu adjust to them over a long period of time, especially the mid range. I made the mistake of trying to get it to run perfect in one sitting. I ended up starting over, making one small adjustment for every 30min of drive time, sometimes only once a day.

 

[sleepyvr4]

well, since your are chipped for 650 injectors than I'd say you're going to dial in quite different than us, aren't you? The manual seems to contradict itself when I read it, but it's the fine details that help you get setup. I have 2.01, which from those I've spoken too is pretty different than the earlier mafts. 98spydert is right, though. take your time.

 

[Clipse]

Well, my MAFT is set up for my injector size. As far as base fuel pressure goes, it's a good way to lean out your fuel curve without more timing advance from compensation.

Bottom line, I've found tuning with the MAFT sucks my ass so I'm just going to use the AFC from here on out.

 

[kpt4321]

and knocks gone away except for sometimes out of know where my knock gauge shoots through the roof when I'm cruising at like 30 mph and give it just a tiny bit of gas. I'm not sure what that means since it only happens like 1 out of 10 times.

How much knock retard is "shoots up?" Could be phantom.

 

[kpt4321]

Bottom line, I've found tuning with the MAFT sucks my ass so I'm just going to use the AFC from here on out.

You had the base knob at about -40% and then you were taking an ADDITIONAL 30% out at WOT, and then you were taking 13% MORE out with the SAFC. I don't think you have the hang of this tuning thing good enough to judge how well different devices work.

Not to mention that the two devices do the same thing anyway, percentage based airflow adjustments...

 

[Clipse]

You had the base knob at about -40% and then you were taking an ADDITIONAL 30% out at WOT, and then you were taking 13% MORE out with the SAFC. I don't think you have the hang of this tuning thing good enough to judge how well different devices work.

Not to mention that the two devices do the same thing anyway, percentage based airflow adjustments...

Well, your right about me not having the hang of this tuning thing as I am still learning. I do know some people that are tuning geniuses who don't like this thing either. It's really more of a personal preference thing though really.

 

[98spydert]

How much knock retard is "shoots up?" Could be phantom.

I'm not sure how much knock retard there it is. When it happens I can feel the car "hit the brakes" for no apparent reason. Then I look down at the keydiver knock gauge and it's maxing out. All I have to do is take my foot off the gas really quick and get back on it and it's gone.

 

[98spydert]

well, since your are chipped for 650 injectors than I'd say you're going to dial in quite different than us, aren't you? The manual seems to contradict itself when I read it, but it's the fine details that help you get setup. I have 2.01, which from those I've spoken too is pretty different than the earlier mafts. 98spydert is right, though. take your time.

You're right, I should be set up differently than the rest of you with 650s. I just thought it was wierd I should be set up for 450s, a 3" MAF, and base fuel pressure, yet I ended up with 3.5" MAF settings and aux/base for 470 or 480 injectors... I just through the instructions away after that crap.

 

[kpt4321]

Well, your right about me not having the hang of this tuning thing as I am still learning. I do know some people that are tuning geniuses who don't like this thing either. It's really more of a personal preference thing though really.

I have never understood why people don't like it. It does the exact same thing as a SAFC, except without the bling screen. In terms of tuning adjustments, it does things the same way, except with a better system (airflow per rev and airflow based, rather than throttle based).

 

[Clipse]

I'm not knocking the MAFT, so I apologize for saying it sucks my ass I'm sure it is a great tuning tool for some people, I just don't prefer it. I don't want to offend the creator of this device.

 

[WTNGST]

I'm not knocking the MAFT, so I apologize for saying it sucks my ass I'm sure it is a great tuning tool for some people, I just don't prefer it. I don't want to offend the creator of this device.

It's not just you buddy. I am running the EVO III Big 16 and FIC 650s and have the same problem you do. I've tuned the MAFT for my 450s prior to purchasing 650s and the MAFT did a great job. Part throttle knock is crazy with 650s no matter how I have tuned. I'll be watching this thread for the solution and hoping someone comes up with one.

 

[98spydert]

You must be the same guy on the FTS tech forum who posted about this. Same boat, E316G, FIC 650s(but I'm running a chip), and blow thru. Tons of low-mid throttle knock in lower rpms... Somebody shed some light on this.

 

[BobTurbo]

It's not the MAFT, its 'piggyback syndrome'. Sometimes these are worse with the MAFT over an SAFC due to the much easier spooling and increased part throttle power.

There are 2 things that happen when you make a big injector shift with a piggyback. 1 is increased timing because the ECU believes there is less air flowing. The other is delayed WOT or Open Loop mode. Sometimes this is called part throttle lean-out. It's fairly common.

The timing can be handled somewhat by reducing the base timing setting.

The delayed WOT mode is something that can be corrected externally, we are working on that.

Another solution is to run an chip in the ECU set up for those injectors. It handles both problems and has other benefits as well. Then you have the good spool benefit of the MAFT and extra's from the upgraded chip.

Bob

 

[WTNGST]

What's the down side of reduced base timing? In other words, how much would you recommend reducing it in a effort to control knock and what's the trade off, if any.
I've read that virtually no 92 model ECUs were EPROM. I haven't opened mine but am reasonably sure that it is not. I wouldn't mind having a chip - I just have to find/buy the appropriate ECU and have it socketed. I was working on more basic mods first and didn't anticipate a need for another ECU yet. I appreciate your description of the syndrome. I only wish I had read about it somewhere prior to buying injectors - I would have bought 550s in an attempt to minimize the problem. This might be a dumb question but I'm not a MAFT expert so bear with me: Since I didn't have problems with the MAFT set for 450s the airflow the MAFT was reporting to the ECU worked O.K. for my setup and normal base timing. If I set the MAFT to as small an injector size as the ECU can adjust the mid fuel trim for, am I helping my situation any?