47 replies to this topic

[marcusmazza]

No no no, I was saying MY post was somewhat self-serving because I DO sell tuned AFMs.  Sorry for the miscomm!

 

Oh, got it.

 

 

Your wrong about the 99's not spending as much time on the dyno, I can personally promise you that. My whole fleet hits the rollers before every race, and usually right after every race to see if anything is going soft. The year model of the car doesn't matter either. If its at the top of the heap, it's getting 110% attention, ALL the time. 

 

I get that the '99s spend a lot of time on the dyno as well. I was more refering to the 100's or 1000's of dyno pulls needed to figure out the initial tuning for the 1.6L AFM. After the AFM is correctly tuned, I can imagine that dyno time for the 1.6's and 99's are probably close. I guess it's really not an issue, since the 1.6L guys can just buy a tuned AFM. I wanted to figure it out on my own, but I think I'm going to cave in and buy one.

 

Marc

[Mike Collins]

You need to go back and read Saul's (Mark's) post.

 

With the restrictor plate on 99's the absolute "matching" of flow tested parts is not AS necessary...it is still a requirement and you see some cars that it makes a noticeable difference on but it is in fact easier to do on the '99 because of the restricted flow...  flow matching parts on  1.6 is imperative to get the penultimate performance.  Notice I say flow matching...In my experience the best flowing exhaust and best flowing downtube matched together did not make the best power...  It was almost a witch doctor science to get the desired result...

[Panic Motorsports]

What Mike said. Tune YOUR car, for what it likes. I have moved parts between cars that one car loved, next was indifferent to. Advantage to those that own a dyno for the convenience of doing a lot of part swapping, but my point is, go to the dyno with a pile of stuff to try, and a plan/order in which to do so. Quality dyno time > than quantity. 

[Bruce Wilson]

You need to go back and read Saul's (Mark's) post.

 

With the restrictor plate on 99's the absolute "matching" of flow tested parts is not AS necessary...it is still a requirement and you see some cars that it makes a noticeable difference on but it is in fact easier to do on the '99 because of the restricted flow...  flow matching parts on  1.6 is imperative to get the penultimate performance.  Notice I say flow matching...In my experience the best flowing exhaust and best flowing downtube matched together did not make the best power...  It was almost a witch doctor science to get the desired result...

 

That sums it up pretty nicely.  Although having owned a top 1.6 for a long time, it's not as hard as it sounds.  Most of the work was done in the early years, and then doing everything you can to maintain the status quo...  The worst part is worrying about an overheat or thrown rod.  If that ever happens, pretty sure I'll move to a 99 or a gen3 SRF unless I get lucky with a rebuild.  It's happened before, it could happen again!

[Sphinx]

I've probably learned more than a few nuances of these of these cars in this thread than I have in any other.  So, thanks to everyone who gave input.  I've got some work to do.

[Sphinx]

A couple of followup questions.  Your point about the idle and WOT stops?  What happens when they aren't properly adjusted?  I'm not sure I understand the relationship to timing.  Is there some black magic to setting these stops?  Or just set it to factory specs?

 

As for the AFM installation, 45 degrees, got it.  Are the physics of that as simple as 45 degrees?  Or does it need to be adjusted depending on track conditions (banking, direction of the track (clockwise v. counterclockwise))?

 

 

<snip>

 

Get your throttle plate right so that the car idles where it should, and make sure the idle and WOT stops are doing their job - otherwise, your timing light will trick you, plus you'll fight the engine under braking, and your fail throttle shafts.  Do it once, do it right. 

 

<snip>

 

 

If you swapped ECUs and made power, it is almost certainly because the timing and A/F are different due to tolerances in the ECU hardware.  All ECUs are "equally good" if you reset the timing and A/F.

 

<snip>

 

AFMs installed "flat" tend to change A/F when cornering.  Mod your setup so the connector can point about 45 degrees down.

[marcusmazza]

A couple of followup questions.  Your point about the idle and WOT stops?  What happens when they aren't properly adjusted?  I'm not sure I understand the relationship to timing.  Is there some black magic to setting these stops?  Or just set it to factory specs?

 

I was curious about that myself. Not the stops, but the TPS. The TPS on the 1.6 is just a contact switch that tells the computer if the throttle is at idle or WOT. If the WOT switch makes contact, does that change the spark map? Does the spark map go to some predefined WOT map in that case (in which case the AFM would get trumped?). My guess is this isn't the case, otherwise the AFM tuning wouldn't really matter as far as the spark map is concerned. So what does the computer do if it sees WOT at the TPS?

 

 

As far as the stops, and I don't want to put words in Mark's mouth, but I think you want to make sure the butterfly valve is truly 100% open when your gas pedal hits its stop, otherwise it can restrict airflow. The pedal stop needs to hit just after the butterfly is at 100%,  otherwise you can overstress and break the throttle body.

 

 

Marc

[SaulSpeedwell]

A couple of followup questions.  Your point about the idle and WOT stops?  What happens when they aren't properly adjusted?  I'm not sure I understand the relationship to timing.  Is there some black magic to setting these stops?  Or just set it to factory specs?

 

As for the AFM installation, 45 degrees, got it.  Are the physics of that as simple as 45 degrees?  Or does it need to be adjusted depending on track conditions (banking, direction of the track (clockwise v. counterclockwise))?

 

The idle and WOT stops won't affect your dyno numbers.

 

The idle stop being right is more about:

1.  Not tricking yourself, your mechanic, your dyno operator, your future owner, into making botched ignition timing adjustments. 

2.  Not fighting an 1000-1200 rpm idle when you are on track and trying to brake and shift.

3.  Not asking the IAC valve to work too hard (i.e. same as #2).

 

A "tuned" AFM will tend to raise the idle speed - you want to adjust the idle stop to get it back down.

 

The WOT stop is more about not "overtwisting" the throttle shaft, which will then screw up the idle, and/or cause a throttle shaft failure.  The throttle body flows plenty on the unrestricted 1.6 - you don't need it to be the last 1 degree open.  So, when your helper has the pedal floored, you want to be out under the hood and find that the throttle plate has NOT hit its stop.  As you stomp on the gas repeatedly, you want the hard "tapping" to be under your foot on the floorpan, NOT happening out at the throttle body.  If the latter is happening, you are "twisting" the throttle shaft every time you floor it.

 

The TPS switch adjustment should NOT affect your dyno numbers.  If it does, something is "weird" (either on accident or on purpose).  Whether you have the TPS full counterclockwise, or full clockwise, it will still read idle at idle, and WOT at WOT.  The purpose of the adjustment is to determine at what % the car goes open loop for street driving.  It is a street fuel economy calibration.

 

 

Re: the 45 degrees:  If you have it simply flat, you will see the A/F ratio swing around dramatically in LH versus RH turns.  At 45 degrees, this is largely minimized - it is just a matter of how lateral forces are acting about the AFM door axis.  So yes, banking will matter, peak "Gs" of corners when you are at WOT will matter.  At vertical (connector down), the effect is almost eliminated, but now flow is fighting the AFM door "gravity", and the shape of the curve tends to change.  Vertical tuning can work if you can shut your hood and retune "around" it.