97 Cobra Vortech supercharger with 12 psi load issue

[Denver_SVT]

Hello folks,

I have one of my friend with 97 Cobra blown and tuned properly as per data log reading and drivability of the car. The idle AF perfect, Partial throttle AF perfect and WOT AF 11.4 with 14 degrees of timing. After data log and with WOT test the cobra didn't go above 1.0 in load and it was actually 0.950 load. My question

Don't you think the load supposed to be higher than 1.0 as it is a blown car?
As for the MAF AD Count it was reading 676 at 6000 rpm, don't you think it supposed to be more up to 850?

I am trying to figure out if there is an issue?

 

[blownstang4.6]

I believe you're correct. My load is like 1.6-1.8 and maf counts in the 800's. Vortech auto Mach 1

 

[Denver_SVT]

I believe you're correct. My load is like 1.6-1.8 and maf counts in the 800's. Vortech auto Mach 1

So do you have an idea what was the issue of the load not exceeding 1.0 and MAF count not exceeding 656??
I am trying to figure out if there is an issue?

 

[blownstang4.6]

So do you have an idea what was the issue of the load not exceeding 1.0 and MAF count not exceeding 656??
I am trying to figure out if there is an issue?

I'm not a tuner but maybe something isn't scaled properly.

 

[Denver_SVT]

I'm not a tuner but maybe something isn't scaled properly.

I am an intermediate tuner and this thing 1st time happened to me. I asked another export tuner that i trust and he said thats fine “some of value is determined based off the air mass of one cylinder. You’ll find that setting in the software. Some vehicles don’t exceed a load value of one point no 1.0”

I am not sure if what he's saying is he 100% accurate and thats why i asked here to get some tuner opinions.
So i am trying to figuer out if something missing in the tune and found out on SCT Advantage software there is “Percent Load Switch” under Fuel was configured to #2 , i will try to set it to 1 and see if this will fix the issue or to 0 but hopefully one of the tuner here can elaborate more in this issue.

 

[decipha]

it sounds like your tuner did an excellent job

what your seeing is perfectly fine

load is just a number for spark control

maf counts is the physical voltage from the maf sensor, its number in itself is useless as a reference other than to be used as a set point for a given airflow. The maf voltage is a critical input to the ecu and the entire tune is based on that. From what you asked its obvious you have no idea how a maf sensor works. Read over this link and it will all become clear.
MAF / EFIDynoTuning

typically to get from 3.38 volts to 4.25 volts you usually have to double the horsepower. Does it feel like the engine is only making half the power it should?

its obvious you have no idea how fuel nor spark is controlled. Changing the prldsw from 2 to 1 will make the ecu stop using inferred load as perload from fn1036 and will instead use just load. Depending on how your tuner has perload referencing fuel, changing that one value will blow the engine just that easy. Read this fuel write up to understand how fuel functions.
Fuel / EFIDynoTuning

Its best you prob leave the tuning up to the experts. If you have issues get the tuner to resolve them or at the very least ask them for direction.

 

[Denver_SVT]

it sounds like your tuner did an excellent job

what your seeing is perfectly fine

load is just a number for spark control

maf counts is the physical voltage from the maf sensor, its number in itself is useless as a reference other than to be used as a set point for a given airflow. The maf voltage is a critical input to the ecu and the entire tune is based on that. From what you asked its obvious you have no idea how a maf sensor works. Read over this link and it will all become clear.
MAF / EFIDynoTuning

typically to get from 3.38 volts to 4.25 volts you usually have to double the horsepower. Does it feel like the engine is only making half the power it should?

its obvious you have no idea how fuel nor spark is controlled. Changing the prldsw from 2 to 1 will make the ecu stop using inferred load as perload from fn1036 and will instead use just load. Depending on how your tuner has perload referencing fuel, changing that one value will blow the engine just that easy. Read this fuel write up to understand how fuel functions.
Fuel / EFIDynoTuning

Its best you prob leave the tuning up to the experts. If you have issues get the tuner to resolve them or at the very least ask them for direction.

Thank you very much that was a good explanation to clear a lot of things on my mind. I already called the export tuner for direction and he clear something to me. He said as u said keep the percent load system as it is and go play with Engine Displacement by decreasing 10% and that should solve the issue. So, does it make sense to you too? He said sometimes if load exceeding 2 he play witg engine displacement to bring it down and for blown cars if load below 1 he did the same but the opposite way. So i think am starting to get his point and thats a good step to learn how to troubleshoot issues and learn from export tuner to be one day on of them.

Again thanks for the advice and valuable information.

 

[Denver_SVT]

it sounds like your tuner did an excellent job

what your seeing is perfectly fine

load is just a number for spark control

maf counts is the physical voltage from the maf sensor, its number in itself is useless as a reference other than to be used as a set point for a given airflow. The maf voltage is a critical input to the ecu and the entire tune is based on that. From what you asked its obvious you have no idea how a maf sensor works. Read over this link and it will all become clear.
MAF / EFIDynoTuning

typically to get from 3.38 volts to 4.25 volts you usually have to double the horsepower. Does it feel like the engine is only making half the power it should?

its obvious you have no idea how fuel nor spark is controlled. Changing the prldsw from 2 to 1 will make the ecu stop using inferred load as perload from fn1036 and will instead use just load. Depending on how your tuner has perload referencing fuel, changing that one value will blow the engine just that easy. Read this fuel write up to understand how fuel functions.
Fuel / EFIDynoTuning

Its best you prob leave the tuning up to the experts. If you have issues get the tuner to resolve them or at the very least ask them for direction.

Michael, regarding your question the car making around 65-70 % of the power. Just to let you know the MAF on it SCT 3000 and already loadded the maf value folder for that specific Mass Air.

So, my question for you, Do you think is good idea to make some changed by 10% in engine displasment settings? Your advice will be appreciated

 

[decipha]

no bad idea, increasing load by 10% will just bring all your spark down, if its tuned properly leave it alone

 

[Denver_SVT]

no bad idea, increasing load by 10% will just bring all your spark down, if its tuned properly leave it alone

so, what do you think will bring the load above 1.0 and MAF count more than 656 if the MAF entered correctly? you're valuable advice will be very appreciated.

 

[decipha]

why do u want to bring load up?

there is nothing you can do in the ecu to change the PHYSICAL maf voltage

the maf reads horsepower, the only way to get it to read more horsepower if to make more horsepower

read the links i posted and it will all make sense

 

[Denver_SVT]

why do u want to bring load up?

there is nothing you can do in the ecu to change the PHYSICAL maf voltage

the maf reads horsepower, the only way to get it to read more horsepower if to make more horsepower

read the links i posted and it will all make sense

I went through the links you posted and more. They are very valuable information and i am sure it takes you years to make such a reference for others will appreciat it to get the basic and more if EFI Tuning.
Let me give you an update of the issue, i tried what one of the export tuner suggest to make (+-10%) in engine displacement but issue still there and notice that the volta of the MAF don’t exceed 3.2v and the battery of the car reading 12.250v at wot around 5000 rpm. I am thincink he have an alternator issue or someting going on with his car electric. I advuce him to go to an expert shop to check the alternator and see from there.

Will a bad alternator will bring the voltage that low to 3.2v?

 

[decipha]

for the 3rd time no

if you would have read the maf link you would know that

 

[Denver_SVT]

for the 3rd time no

if you would have read the maf link you would know that

I went through the link couple of times and no help with my question!! Why my MAF count not exceeding 656 (3.2V)?? I am looking for answer here … either you have it or someone else will elaborate more on this specific issue that I am looking for answer to it.

The link you provided it gave an introduction of MAF how it works which I think clear to me. the rest it will explain of the frequency that some meters will operate on it and it will convert the voltage to frequency output, housing and pipe, stock & calibrated MAF's and how to work on some injectors from not having the exact file for it in the software that's it.

In the end I'm looking for help not to have me in a grey area.

 

[Denver_SVT]

From what I understand of your write up that Mass air flow sensor is used to determine how much air going to the engine so the ECU knows to tell the injectors how many fuel to inject to get a good air fuel ratio.

So, the current will pass through the hot-wires element and we want to keep this element in a constant temp and by doing this we will know how much air flow going to the engine.

let's say we step on the gas and we got more air going to the engine with more air is going to pass through the element and air flow inside and the temp in the element will get cooled.

As I know temp and resistance are related for this element so as temp drops the resistance will also drops.

Ohm's Low said that the Current is equal to the voltage divided by resistance so if we lower the resistance of this element, we will know the number will be bigger and that will bring the current up and the larger current will heat up the element and it will bring the temp where it was.

Now what ECU does will translate this current into voltage change and with that voltage change it knows there is difference in air flow.

So, in conclusion that what affects my voltage is the air flow and by that I will know that I might have restricted air flow not going right to the engine either by clogged Air filter of dirty MAF. correct?

 

[decipha]

If your having problems it would be best to give details as to the issues your having.

In the OP you simply asked if it was normal? yes what your seeing is perfect given the information you've provided

 

[01blckcobra]

I'm new to this... But what's the problem? A/f at WOT are good per OP.... your config can only pull in so much air.. Maf on my car "Flatlines" 825 count through a 4" at 20ish psi. turbocharged.

 

[Denver_SVT]

If your having problems it would be best to give details as to the issues your having.

In the OP you simply asked if it was normal? yes what your seeing is perfect given the information you've provided

Ok again we have 97 Cobra with Vortech supercharger (14 psi) after leak issue fixed. We upgraded to forged Pistons, rods and crankshaft, LT headers, SCT 3000 MAF, 60lb injectors, and return fuel system. We tuned the car for idle, partial throttle and WOT. For idle we got 14-15 AF, Partial throttle 14-15 AF, and WOT 11.4 AF and then we run the car at the dyno and only see 370 rwhp with 12 psi at 6100rpm when we face a leak from pipes and from datalog we only see 0.950 load and 656 MAF AD count with Air flow 27000. The MAF AD count bring question marks to my mind why it doesn't go higher to 850??
We did leak boost test and we found couple of leakage that we fixed and bring up the boost up to 14 psi but we didn't run it at the dyno because we want to make sure at the road when we did a quick test with datalog that we should see the MAF AD count go to 850 and during the run at the street we found out the Battery voltage drops from 13 to 12.2 volts. After more inspection to the car we found the red cable from the battery going to alternator half of it already eaten like half cut on it. I asked him to change the cable and change the alternator from factory to Power Master alternator 200amp. So, after fixing all issues hopefully things will be changed.

In the end I would like to know can a bad alternator affect the power that much as we supposed to see around 500 rwhp ? Do you think a MAF AD count 656 will make us to concern or that's fine?

 

[Denver_SVT]

I'm new to this... But what's the problem? A/f at WOT are good per OP.... your config can only pull in so much air.. Maf on my car "Flatlines" 825 count through a 4" at 20ish psi. turbocharged.

What about your load do you see higher than 1.0?

 

[01blckcobra]

Different ECU...

Not sure why you are worried about load and maf counts. if its fueling right, all that matters. Far as horsepower... all depends on the combo you are running.

MAf counts are affected by bigger housing. basically if you want more counts: reduce size or make the engine draw in more air.

14* of timing seems really low to me. Also if you changed compression (forged pistons) - lowering it- will effect your horsepower outcome. Also what fuel are you using? The spark plugs gapped right? Could be experiencing blow out. What size / model vortech. Lot of variables. Not just slap a kit on and expect 500rwhp.

Sounds like the car is tuned properly from info given. just normal characteristics of the setup

Stock engine with 16-17* 14psi 93gas might be 490-510rwhp.+/-