Do you really need a 'tune' or is it bs

Noobz347

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Timing set at 10 degrees
Fuel pressure set at 38psi
Idle at 950-1000
New IAC and O2 sensors

Car ran great idled perfectly prior to the new air box. Surged after. How come? A/F showed pig rich. Tuned to pull A/F back down. Problem solved. What logical and reasonable alternative was there?

The elephant in the room is turbulence over the mass air sensor.

Other possible solutions:

Change the shape of the intake tract
Screen the sensor
re-clock the sensor
change the sensor
change the housing
Scale the sensor and housing assembly
change the distance between the MAF and TB
etc..

There are a number of things that can induce and support a surging idle in a closed system.
 
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Habu135

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The elephant in the room is turbulence over the mass air sensor.

Other possible solutions:

Change the shape of the intake tract
Screen the sensor
re-clock the sensor
change the sensor
change the housing
Scale the sensor and housing assembly
change the distance between the MAF and TB
etc..

There are a number of things that can induce and support a surging idle in a closed system.
You're right. I'm wrong despite the tuner having fixed the surging and explaining to me what the issue was.
 

Noobz347

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You're right. I'm wrong despite the tuner having fixed the surging and explaining to me what the issue was.

Again, I don't think your tuner made a poor decision. The goal is consistency and reliability. If tuning was the most efficient tool available at the time to solve the issue then, sweet!

Some in these here parts think that digital tuning has [no place] or is voodoo or is used [only] to mask an issue on a malfunctioning vehicle (all on an initially computer-controlled vehicle that of course, was given a tune in order to operate).

I'm on the side of the fence where all of the mechanicals are combined, checked, and re-checked and the tune is used to bring those new components together.

The point being made with your post is that since the part you put in is a copy of the original that it alone, did not necessitate a tune.

In other words: Some combination of parts or actual mechanical defect allowing un-metered air in or out of the system is also possible as is an airflow over the meter that is different than OEM.


It goes back to my initial premise that you can either:

Change the tune in the computer to match the new parts that are given.

or

Fool the computer into thinking that the original parts are still there.

Of course, each of those assumes no other mechanical issue.
 

96pushrod

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The elephant in the room is turbulence over the mass air sensor.

Other possible solutions:

Change the shape of the intake tract
Screen the sensor
re-clock the sensor
change the sensor
change the housing
Scale the sensor and housing assembly
change the distance between the MAF and TB
etc..

There are a number of things that can induce and support a surging idle in a closed system.
Honesty, tuning seems like a far better option than working down that laundry list.
 
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2000xp8

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You clearly didn't read the part I wrote about air velocity through the MAF and how it was altered due to the new air box. But by all means flame away.
I read it.
But I've had so many meters and intakes i can't even remember them all at this point.
Not one quality meter, ever suffered from a velocity or turbulence issue.
Pretty much all have mine have been some iteration of Pro M (regardless of what name the company was at any point).
75's, 77's, 80's 90's etc.
I've also run a far far wilder tfs setup. Guess what? Idled and ran fine.
It's a stock intake, if a meter doesn't work with that, someone should just use a different one.

You suggested you have proven tuning works.
I feel like you have proven the opposite.
You made 300rwhp with a tfs top end (you can even get close to that with no meter or injectors), which is about the norm untuned, so i'm not sure there was any power there (especially with a valve job thrown in) and you fixed a mechanical problem with tuning which is fine, but IMO it makes no sense.
I don't know the software system tuning or costs you incurred, but i bet it was more than a better meter.

Noobz and i see eye to eye once in a while and i will concede that tuning may have it's place (that place being supercharged or turbo applications).
But fixing a surging idle with a TFS kit with a stock intake is not one of those places.

Personally what bugs me most is the "need a tune" comments or people who using tuning as a repair.

It's not personal, but your assessment that tuning works because your surging idle went away with what is one of the most basic setups is ill conceived.
 
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67coupe

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I think this boils down to just a few questions.

1). Mild build or pushing the limit
2). Stock displacement or stroker
3). N/A or boosted

If you’re engine is a mild build and near stock displacement. You probably don’t need one.

If max effort, increased displacement, or boosted. It’s almost mandatory.

For me personally, I’d want the peace of mind and improved cold start and drivability that a tune will offer.
 

a91what

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If the meter used was meant for instance a filter mounted directly to it, or if it was scaled for a tube with a sweep before it then the amount of air across the sensor will undoubtedly be altered with an intake box change.
Turbulent air and air velocity across a meter is a real world issue, it's not some fake news. No matter how high of quality the meter is this kind of issue will occur. Now where the air is turbulent matters a meter that reads from the center of the airstream vs the edge will not benefit from clocking and is more reliable overall.

Either way, I am always a fan of tuning.
 
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General karthief

wonder how much it would cost to ship you a pair
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Now we have a discussion!!!
Only 10 degrees timing? Bump it up to 12, hell 14*
Idle at 950-1000rpms kinda high I would think but not unheard of, don't remember what cam Habu is running, also don't know what size injectors, moot point though.
38 psi fuel pressure, back it down to say 32 psi.
What size maf, tb?
Now did 'tuning' this combo work? Apparently yes. Could it have been resolved without 'tuning' , well it depends on your definition of 'tuning' .
Manipulating timing and fuel pressure, setting idle would be considered 'tuning'. You just need basic eec tools.
I think no one is saying your tuner didn't fix your issue, I will say I think you could have 'tuned' it your self.
This is not factoring in a big assed tb, maf and/or cam which was not listed.
I feel nobody is right or wrong here, it's a discussion, bench racing.
And I prolly have the slowest bench here.
 

TOOLOW91

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Now we have a discussion!!!
Only 10 degrees timing? Bump it up to 12, hell 14*
Idle at 950-1000rpms kinda high I would think but not unheard of, don't remember what cam Habu is running, also don't know what size injectors, moot point though.
38 psi fuel pressure, back it down to say 32 psi.
What size maf, tb?
Now did 'tuning' this combo work? Apparently yes. Could it have been resolved without 'tuning' , well it depends on your definition of 'tuning' .
Manipulating timing and fuel pressure, setting idle would be considered 'tuning'. You just need basic eec tools.
I think no one is saying your tuner didn't fix your issue, I will say I think you could have 'tuned' it your self.
This is not factoring in a big assed tb, maf and/or cam which was not listed.
I feel nobody is right or wrong here, it's a discussion, bench racing.
And I prolly have the slowest bench here.
Cars with cams usually don’t idle well at the stock idle rpm even when I had the tfs1 cam mine liked the idle bump .

My car idles 980-1000rpm but for conversations sake it’s probably radical for a typical street car in here and this conversation. Oh and it has Holley efi in it
 

7991LXnSHO

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I think the question is where is that line is when a street/strip car needs a tune, so your combo is definitely relevant.

Old school reply-
I do not mind the lumpy idle the letter cam gives my 325-350 Hp (calculated from track time slips) 5.0. It also gets 21.5 mpg on the highway with the AC on. The surging idle checklist was all the tuning it really needed to be streetable, although installing the adjustable IAC spacer I have from an F-150 might still be a good idea.

When I upgrade to new aluminum heads and get the @tmoss ported intake on, I might as well pick a newer cam to match. I hope Rhodes has a set of roller lifters for a 5.0 roller block at that point. The other engine builds I have used them on have benefitted as advertised, but without excess noise. So a better idle with more vacuum should help move the limit at which a tune is needed. If so, they will definitely be worth the money. If not, a wider power band will still be worth it.


Cars with cams usually don’t idle well at the stock idle rpm even when I had the tfs1 cam mine liked the idle bump .

My car idles 980-1000rpm but for conversations sake it’s probably radical for a typical street car in here and this conversation. Oh and it has Holley efi in it
 
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Willybill32

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I think the question is where is that line is when a street/strip car needs a tune, so your combo is definitely relevant.

Old school reply-
I do not mind the lumpy idle the letter cam gives my 325-350 Hp (calculated from track time slips) 5.0. It also gets 21.5 mpg on the highway with the AC on. The surging idle checklist was all the tuning it really needed to be streetable, although installing the adjustable IAC spacer I have from an F-150 might still be a good idea.

When I upgrade to new aluminum heads and get the @tmoss ported intake on, I might as well pick a newer cam to match. I hope Rhodes has a set of roller lifters for a 5.0 roller block at that point. The other engine builds I have used them on have benefitted as advertised, but without excess noise. So a better idle with more vacuum should help move the limit at which a tune is needed. If so, they will definitely be worth the money. If not, a wider power band will still be worth it.
Mine makes over 300 HP, but my mileage is in the 16 mpg range...I'm envious!
 

7991LXnSHO

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The PO’s race team must have been wizards at porting snd not so good about electronics. I hate to mess with the combo more, but “More Power” is calling.

Mine makes over 300 HP, but my mileage is in the 16 mpg range...I'm envious!
 

TOOLOW91

If you're the village idiot what's that make me?
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I think the question is where is that line is when a street/strip car needs a tune, so your combo is definitely relevant.

Old school reply-
I do not mind the lumpy idle the letter cam gives my 325-350 Hp (calculated from track time slips) 5.0. It also gets 21.5 mpg on the highway with the AC on. The surging idle checklist was all the tuning it really needed to be streetable, although installing the adjustable IAC spacer I have from an F-150 might still be a good idea.

When I upgrade to new aluminum heads and get the @tmoss ported intake on, I might as well pick a newer cam to match. I hope Rhodes has a set of roller lifters for a 5.0 roller block at that point. The other engine builds I have used them on have benefitted as advertised, but without excess noise. So a better idle with more vacuum should help move the limit at which a tune is needed. If so, they will definitely be worth the money. If not, a wider power band will still be worth it.
Sounds like it’s a blast to drive still ! Tom and Matt did my intake , I think Matt does most of the porting now . I’m happy with it they did real nice work
 

Boostedpimp

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Exactly. I have an aftermarket BBK MAF. The car had been tuned with a 3" ID intake tube and open element air filter. If you look at photos of my car you'll see that. I swapped over to a stock style intake box and the outlet of the box is a smaller ID than the inlet side of the MAF. Apparently that caused some kind of velocity issue for the MAF and the car was highly rich.

I'll ad that the car dyno'd at 299/301 with that setup. Since then I had a valve job done and installed the new LMR stock intake box, but the idle surging didnt occur until I installed the intake box. Now, it's possible that the compression was raised slightly as a result of the valve job head milling, but I do believe the intake is good for a few hp. I was not told that my heads were milled at all. Overall I was surprised I gained 12/10.
So I may have misunderstood you so if I have please feel free to correct me but in this post are you saying that your car was tuned. You did the valve job and went back to the smaller factory airbox setup and picked up surging and required a tune? Further more you lay claim to yes a tune is necessary? Do I have that correct?
 

nelzfoxes

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I haven't read through the thread entirely but I have an opinion based on my mild engine build. I chose to swap in a 351 into my fox body. In order to compensate for the increased displacement I used gt40 tubular intake and 24 lb. injectors with a matching calibration MAF. The heads are gt40 cast iron. I am running a stock HO camshaft and the stock a9l computer with cobra 1.7 : 1 ratio roller rockers. It is my opinion that if you keep it mild even if you increase the displacement you do not necessarily need a tune. My car starts and idles like stock. It doesn't stall out or bog when I choose to drive it hard. Very enjoyable to just drive around all day.
 

90sickfox

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Back in the day this tune stuff didn't exist. A bunch of people did mods and installed camshafts ( alphabet cams were just about the only ones back then ). People did use ( what we called RV cams ). There were " work arounds " for most of the drivability issues. Bumping idle up...timing changes...plug gaps....indexing the MAF....larger injectors....all these things worked to a degree. Those cars ran but it was rare to see a fox mustang street car with EFI running faster than a 12 second quarter mile pass....breaking 11 seconds was just about unheard of in a street car.
 

Noobz347

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Back in the day this tune stuff didn't exist. A bunch of people did mods and installed camshafts ( alphabet cams were just about the only ones back then ). People did use ( what we called RV cams ). There were " work arounds " for most of the drivability issues. Bumping idle up...timing changes...plug gaps....indexing the MAF....larger injectors....all these things worked to a degree. Those cars ran but it was rare to see a fox mustang street car with EFI running faster than a 12 second quarter mile pass....breaking 11 seconds was just about unheard of in a street car.

I was one of those. I made an OEM SD computer work with an E-cam, FMS heads, and brass restrictor valve used to adjust the bubbles on a fish-tank. :D

I later installed a Kenne Bell over the top of it all still using the SD computer and FMU.

I didn't swap over to mass air until the Dart block went in. The extra cubes and custom cam were just too much for the SD computer and I wasn't aware of anyone that could/would tune the OEM SD.

I've seen folks that [can] tune the OEM SD computers pop up from time to time including very recently. I think I have one bookmarked somewhere. It's a consideration for a future project but not my next project. My next project will be a high compression, solid lifter, N/A build in a stripped-down 89 with a lot of sound deadening and undecided transmission. :chin