running rich

fasterthanyou

Registered User
motor: 93 SC, ported big valve heads, mild .550 lift cam, ported late model with MP plenum, PP 75mm tb, stock intercooler/piping, stock exhaust manifolds, 60lb injectors, 4r70w trans, stock FPR.

issue: runs rich at all times.

**injector slopes are set at about 57.xx for the high slope and 64.xx for the low slope with .000014 injector breakpoint. (only huge changes in these slopes seem to affect my AFR) if i leave it at the stock injector settings it runs rich at around 11.4AFR at idle. the slopes i listed have the car idling at 13.4AFR at idle and very very rich while cruising and wot. anything above 70 for the high and low slopes dont do ANYTHING towards the AFR.

**Injector offset vs voltage. I cut the stock values in half, this seemed to help a little...but sometimes it wouldn't help at all. it would run stoich for about 2 seconds after cutting the injector offsets in half but then would go rich again. I set the offsets to .10 for anything above 12 volts and it still ran rich. about 13.5 at idle.

I'm running the stock maf, the only way I can get the AFR near perfect is by subtracting 15% to the entire curve. If its at all possible, I'd like to keep the maf curve stock since its a big factor in accurate load calculations(correct?). My short term fuel trims are way off base. when I go WOT they are at 20%, somtimes 18% but pretty much stuck at 20%

can anyone offer any advice?
 
Several things.... and keep the KISS rule in mind.

1. Setup the injectors as follows, Hi slope @ 60.2669, Lo slope @ 63.1868, breakpoint to 0.00003363

2. Leave the Battery offset at stock for now. The values I'm using are not far from the stock values anyway.

3. Set the cranking pulsewidth vs ECT by multiplying the stock values by 0.60 for now

If you have to lower the MAF curve by 20% to dial in the AFR, then do it... you'll never get an accurate LOAD value once you have started modding the car because you don't have the equipment and financial resources to bring that back in line again. Load values are "subjective" so to speak, and you are moving alot more air than a stock setup. I would also highly recommend you step up to a bigger MAF.

Fraser
 
I'm running the stock maf, the only way I can get the AFR near perfect is by subtracting 15% to the entire curve. If its at all possible, I'd like to keep the maf curve stock since its a big factor in accurate load calculations(correct?). can anyone offer any advice?

I am by NO MEANS even CLOSELY knowledgable about TUNING the electronics on these cars.
BUT from what I have read, been told, warned and cautioned about...
this seams fairly simple to me...

Stock MAF and big injectors= NO GO/BAD JUJU!
Aren't we supposed to have the MAF calibrated to the injectors?
Thats why I bought a MAF with the calibration tube and the injectors the tube is calibrated for!

Correct me if I am wrong, I am TRYING to understand the electronics on these!
To me, that explains why with a change to the MAF stuff it runs fine??

Standing by to be schooled!
 
To put it simply.... if you are "tuning" the car by a chip or QH or something, then the word "calibration" no longer applies to the MAF. It was only done in the old days where it wasn't so easy to tune the car, so the idea was to use a sample tube to alter the flow of air over the MAF sensor to read lower than reality so bigger injectors could be used. It worked somewhat, and worked better on some cars than others.

It still was not a good thing to do because the LOAD values etc would all be scewed enough to possibly hurt things.

Today, the tube you put into the C&L will set up its flow range, so the idea is to put a tube in that will cover the full range of the MAF from 0 to 5 volts so you can tune more accurately. For eg, I'm running an 85mm C&L, but I'm using a purple sample tube in it so I can tune using the biggest range possible. I am running 60# injectors. Thinking of it this way, essentually the injector size is no longer used to size the tube, but how much air you estimate the engine will flow.

What will have to be monitored in this case with using the stock MAF, is if air flow exceeds the capacity of the stock MAF, which will be close to 4.75 volts..... other than that, its not really an issue until then.

Fraser
 
Frit, can exceeding 4.75 cause problems, Ive hit 5v on my maf a few times datalogging, AFR seems to be ok. I know I need to upgrade, but once the maf peggs what exactly happens?
 
Theoritically, as more air goes in the motor, no more fuel is being delivered so you lean out. In the real world, it'll be more erratic and start bouncing fuel delivery all over the place, which is also not good.

Get a bigger MAF and stop fooling around before you blow something up again :rolleyes:.


BTW the 4.75 volts was the older cars limit in the MAF transfer, the newer cars went to 5 volts.

Fraser
 
I have just about the biggest draw thru I plan to mess with, once the funds are in Ill go blow thru. Sux that I cant turn my go fast knob up until I get a new maf:(
 
my cranking pulsewidth is fine. I divided the stock values by half and it starts on the first crank every time. i should touch up my cranking pulse around 120 degrees F though. i have to tap the throttle to get it to fire.

I can get this car running great by adjusting the maf curve. BUT my curve looks a little screwey. I have anything over 60% load set for 11.7 on my fuel stabilized table and anything under 60% is set to 14.7. instead of having a nice smooth curve, it looks like slanted stair steps in order to keep my AFR around 11.7 from 2.5 maf volts to 5 maf volts in 3rd gear. I have good vacuum 15" at idle and 13psi of boost. I don't think I'm losing any air, so I'm not sure what would cause the funky curve. as for spark. I left it stock except I pulled 4 degrees of timing from up top because it was dogging/feeling sluggish above 3k in 3rd gear(high load)

so to simplify things. I can't get leaner by adjusting slopes or injector offsets, the only way i can lean it out is with the maf curve..should I do this and just leave it alone? or is there something I'm over-looking or missing?

also, I set my fuel adders to zero for ect/act to see if that would help, didn't change anything.

thanks guys, I'm all out of ideas
 
speaking of maf volts, my maf is just on the verge of maxing out. I log 4.96 volts when going wot. I have an 80mm Lmaf ready to install, but I was trying to get my fuel slopes dialed in so swapping the maf would be easier.

if I have a known constant which is a stock maf, and an unknown slope/offset. i thought it would be simple to figure out the offsets/slopes to adjust for fuel, but I was wrong :eek:

edit: I replaced my FPR with a new motorcraft FPR, I dont remember exactly what my fuel pressure was reading, this was a couple months ago, but it was 32 I believe at idle and in the 40's with no vacuum supply.
 
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the maf transfer correlates airflow to voltage, the maf transfer and sarchg are the primary means of load calculation which is the single most significant factor for tuning

since you are using the stock maf, DO NOT ADJUST THE MAF TRANSFER ANY MORE THAN YOU NEED TO, MINIMAL CHANGES ARE BEST

since your obviously hitting some kind of clip limit on your injectors, i recommend you cut your injector slopes and breakpoint in half as well as cut your maf transfer in half and your sarchg in half

this keeps everything mathematically equal

don't forget the injector min pw scalar

now, since you've gained 150% more headroom, you can adjust your slopes to get your fuel where you need it, that is the CORRECT way to bring your fueling where it needs to be, with a known maf transfer you can bring your fuel in to within 2% by changing just the injector values, I do it everyday.

adjusting the maf transfer to alter fuel is just wrong and is the SCT way of doing things, not ideal at all, especially with a KNOWN maf transfer
once again, the maf transfer just means for x amount of air the maf is reporting x amount of voltage, that is it nothing more nothing less

also don't forget you'll need to update the PCT_Load "inferred load" table so your alpha-n fail safe are accurate if your maf ever craps out, once you get it dialed in, disconnect the maf and make a WOT pull, should be the exact same with maf disconnected if you got it dialed in good
 
the maf transfer correlates airflow to voltage, the maf transfer and sarchg are the primary means of load calculation which is the single most significant factor for tuning

since you are using the stock maf, DO NOT ADJUST THE MAF TRANSFER ANY MORE THAN YOU NEED TO, MINIMAL CHANGES ARE BEST

since your obviously hitting some kind of clip limit on your injectors, i recommend you cut your injector slopes and breakpoint in half as well as cut your maf transfer in half and your sarchg in half

this keeps everything mathematically equal

don't forget the injector min pw scalar

now, since you've gained 150% more headroom, you can adjust your slopes to get your fuel where you need it, that is the CORRECT way to bring your fueling where it needs to be, with a known maf transfer you can bring your fuel in to within 2% by changing just the injector values, I do it everyday.

adjusting the maf transfer to alter fuel is just wrong and is the SCT way of doing things, not ideal at all, especially with a KNOWN maf transfer
once again, the maf transfer just means for x amount of air the maf is reporting x amount of voltage, that is it nothing more nothing less

also don't forget you'll need to update the PCT_Load "inferred load" table so your alpha-n fail safe are accurate if your maf ever craps out, once you get it dialed in, disconnect the maf and make a WOT pull, should be the exact same with maf disconnected if you got it dialed in good

thanks for the information, ill give that a try during my lunch break today
 
I'm not going to get too involved here because forum tuning is not my specialty, but I have to say a couple things to *maybe* get you guys pointed in the right direction.

1) There is absolutely no reason to scale values on his car.

2) I see no mention here of what type of intake or filter setup he has affecting his MAF. You all should know that this is extremely important and simply cannot be accounted for in the stock MAF function. The stock MAF function is generated using the stock airbox and filter. Changing that will change the transfer function. This isn't an opinion, it's fact.

3) Of all the components in the air/fuel system of the SC, assuming accurate fuel pressure, the injectors are the most defined and accurate of all parameters. Changing injector values from the known good values is a mistake used to cover up other mistakes.

4) Load calculations are important, but for someone just learning to tune, sticking to the proper injector sizes and allowing the MAF/load to fall where it may is a MUCH preferred way to approach tuning.

5) Changing cams will change the engine's VE, and there are other things that will impact VE as well. Exactly how and at what RPM these changes take effect are anybody's guess right now. The Ford EEC has no way to compensate for changes in VE other than through manipulation of the MAF curve and proper functionality of the adaptive table.

6) The MAF curve cannot be a stair step. If you have this, you are not tuning correctly. I suspect your understanding of how Lambse and Kamrf work may be flawed. You also did not state how you were determining AFR.

I won't be providing direct tuning advice online, I'll leave that to others but I think most of your issues are pretty simple tuning mistakes.
 
I'm not going to get too involved here because forum tuning is not my specialty, but I have to say a couple things to *maybe* get you guys pointed in the right direction.

1) There is absolutely no reason to scale values on his car.

2) I see no mention here of what type of intake or filter setup he has affecting his MAF. You all should know that this is extremely important and simply cannot be accounted for in the stock MAF function. The stock MAF function is generated using the stock airbox and filter. Changing that will change the transfer function. This isn't an opinion, it's fact.

3) Of all the components in the air/fuel system of the SC, assuming accurate fuel pressure, the injectors are the most defined and accurate of all parameters. Changing injector values from the known good values is a mistake used to cover up other mistakes.

4) Load calculations are important, but for someone just learning to tune, sticking to the proper injector sizes and allowing the MAF/load to fall where it may is a MUCH preferred way to approach tuning.

5) Changing cams will change the engine's VE, and there are other things that will impact VE as well. Exactly how and at what RPM these changes take effect are anybody's guess right now. The Ford EEC has no way to compensate for changes in VE other than through manipulation of the MAF curve and proper functionality of the adaptive table.

6) The MAF curve cannot be a stair step. If you have this, you are not tuning correctly. I suspect your understanding of how Lambse and Kamrf work may be flawed. You also did not state how you were determining AFR.

I won't be providing direct tuning advice online, I'll leave that to others but I think most of your issues are pretty simple tuning mistakes.

#1, what do you mean no one needs to scale values?

2, 75mm professional products group buy throttle body with a 45* 22" intercooler pipe is used as an intake pipe. NO PCV HOOKED UP. the maf is at the end of that pipe with a conical air filter at the end. (i set unmeasured air to ZERO)

3: why shouldn't I change my injector values? I'm running 60lb siemens with stock fuel pressure

4: im a little iffy with agreeing on that one

5: makes sense, I guess without a vast knowledge of engineering and physics I will never get the VE tables correct.

6: I realize my maf curve is not supposed to be a stair step, which is one of the reasons for starting this thread. I'm datalogging lambse1 & 2 and they show 16-18.xx while idle and cruising. and when I go wot they both stay at 11.67 without varying. both kamfr's are at 1.0 and NEVER change.

I never read a tuning manual or faq, everything I've done has been trial and error over the past 4 or 5 months. with all of my mechanical issues fixed, tuning this thing has become a LOT easier, yet I'm still a little off. Thanks again guys, i'll keep on truckin'.
 
#1, what do you mean no one needs to scale values?
It was suggested to you above to scale values to which you replied that you would try it. I am telling you that there is no need or benefit in scaling values for your application. That is what I mean.

2, 75mm professional products group buy throttle body with a 45* 22" intercooler pipe is used as an intake pipe. NO PCV HOOKED UP. the maf is at the end of that pipe with a conical air filter at the end. (i set unmeasured air to ZERO)
If you don't have a pcv hooked up and routed to the intake tube, then you have leakage. I'm not saying the setup isn't tunable, just that you definitely have leakage. Your intake as described will most definitely require adjustment to the MAF curve. This is fact, not an opinion.

3: why shouldn't I change my injector values? I'm running 60lb siemens with stock fuel pressure
I didn't mean not to change your injector values to the proper 60lb settings as Fraser stated above, what I meant was do not use injector value adjustments to alter AFR. This is the wrong approach, plain and simple. Injector values should be set according to the published data for the injectors you are using.

4: im a little iffy with agreeing on that one
Being iffy on this doesn't change the facts. I've been doing this a long time and I am giving you invaluable advice. If it doesn't agree with what you think, then that's hint you need to do some more thinking. ;) Load calculations are relative. There are ways to check the accuracy of your EEC's calculations, but with your limited knowledge of tuning, you should be worried about other things. You are straining on a gnat and swallowing a camel. Trust the injector parameters published for the injectors and work backwards from there. I highly doubt that your Seimens 60lb injectors are really 45lb injectors. ;) Don't lie to the computer when it is not necessary to do so. Your life will be easier.

5: makes sense, I guess without a vast knowledge of engineering and physics I will never get the VE tables correct.
You didn't understand what I said. Ford tuning software does not use VE tables for normal running operations so there is nothing to be done in this area. MAF function and adaptive tables are used instead of VE tables.

6: I realize my maf curve is not supposed to be a stair step, which is one of the reasons for starting this thread. I'm datalogging lambse1 & 2 and they show 16-18.xx while idle and cruising. and when I go wot they both stay at 11.67 without varying. both kamfr's are at 1.0 and NEVER change.
The MAF curve is never a stair step. If it looks like a stair step that simply reflects errors in your tuning. Keep your MAF curve closely resembling a curve.

I never read a tuning manual or faq, everything I've done has been trial and error over the past 4 or 5 months. with all of my mechanical issues fixed, tuning this thing has become a LOT easier, yet I'm still a little off. Thanks again guys, i'll keep on truckin'.
I realize you probably want to learn on your own (for the fun of it) and maybe even save some $$ in the process, but for something like this purchasing a base tune that sets up the important stuff and then tweaking it on your own from there makes things much easier and faster. But there's nothing wrong with the school of hard knocks!
 
dave, i set the injector offsets to stock, set the injector slopes to what they should be for 60's, set the maf curve to stock and went for a drive. i immediately needed to reduce the curve by 30%. once i did that it was pretty good. 11.8-12.0 afr wot and 14.5 at idle. Buuttt i popped a head gasket during the process. i went high dollar on everything when building this motor except for the head gaskets and TTY bolts. ive gotta pull it apart send the heads out to get resurfaced and get mls gaskets with arp studs next time around. im not blaming the tuning process or anything like that, just letting you know that i wont have any more tuning updates for a week or two
 
that sux man, drain the coolant and run the engine a minute (60 seconds) when cold to clean out the cylinders, don't need any pitted walls

30% is huge, as for correct/accurate injector data, your injector values not only depend on the actual injector, but many factors effect slopes and what not, the fuel your burning, the fuel pressure, etc... comes in to play
 
30% is huge, as for correct/accurate injector data, your injector values not only depend on the actual injector, but many factors effect slopes and what not, the fuel your burning, the fuel pressure, etc... comes in to play

This is true, but there are no absolutes in tuning. He is using the proper fuel pressure and still running rich. Due to oxygenation and additives, fuel sometimes ends up lighter, meaning less fuel energy per unit of volume, not more. Unless he unknowingly has high fuel pressure, the factors normally affecting fuel injector slopes would tend to reduce flow, not increase it. If he indeed does have high fuel pressure for some reason (possible) then that is a mechanical issue that should not be tuned around.

MAF data is the most inconsistent sensor data in the whole system. Any time intake systems are altered MAF data is absolutely impacted by it. You have to tune for any intake system modification, particularly anything in front of the meter. Now as for 30% - that's enough to cause definite pause. My first step would be to verify that the sensor housing has not been modified, then verify that the sensor wires are clean (very important!). If this is the case then I would substitute a known good sensor to see if there is a sensor issue (not common but it does happen). If everything appears fine then I would start comparing load and boost to see if indicated load is consistent with manifold pressure. This is the first test to determine if your sensor is reading wrong or if something else is amiss.
 
oh dave, honestly, how often do you load known values for injector/maf and everything falls right into place?

it just doesn't work that way, i ALWAYS adjust my slopes to get my fuel as close as possible then adjust the maf transfer to nail my lambse's

usually with a known maf transfer i can get my fuel almost perfect just by messing with the slopes then possibly make very slight changes to the transfer
 
oh dave, honestly, how often do you load known values for injector/maf and everything falls right into place?

it just doesn't work that way, i ALWAYS adjust my slopes to get my fuel as close as possible then adjust the maf transfer to nail my lambse's

usually with a known maf transfer i can get my fuel almost perfect just by messing with the slopes then possibly make very slight changes to the transfer

Of course things need adjusting, but adjusting injector sizes is the incorrect approach. Fluid dynamics are much more predictable than airflow and in this case we have very good data with respect to the fluid properties of the injectors. The Ford strategies all force you to assume certain things and to rely on derived data for other things. There is no absolute, but the most reliable set of data you have to build your assumptions off of are the injector parameters.

I am well aware of the entire school of thought that surrounds manipulation of injector values to suit a given situation and I am also aware of where that school of thought originated from, but that doesn't make it right.

If you are adjusting injector parameters to cover up a mechanical problem (incorrect fuel pressure, for example) then that is mistake #1. If you are adjusting fuel injector parameters to compensate for an inaccurate MAF sensor, then that is mistake #2.

If after tuning the MAF curve to dial in commanded AFR's you are convinced that your load calculations are still off, then there are other things to look at for answers. But neither in my professional training or in my tuning experience, has it been necessary to adjust fuel injector sizes to reconcile load calculations.

MAF values should always be considered the most flexible sensor data in the entire system. With respect to MAF sensor output, all data is inferred. The MAF sensor does not directly measure airflow and as such it is the most susceptible to being fooled by any number of things. It is ironic that the most important and central sensor for the Ford system is also the most susceptible to generating false data. Just removing a factory air box and installing a cone filter will change both the range and curve of a sensor. The style of filter will have further impact on sensor performance as will transitions and couplers on either side of the sensor housing.

To better illustrate my point for yourself, try taking a stock car (something basically new, not an SC for heaven's sake! lol), check the tune using stock injectors and then install 60lb injectors using the parameters listed making no other changes to the tune. Compare fuel trims before and after and you will find that the injector parameters are basically dead nuts accurate.
 
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