ULTM8Z

I did a search on this and didn't find a whole lot of discussion about it.

In neutral, when I "blip" the throttle from being at 0% TPS, I get about a 1/4 to 1/2 second "whoosh" as the throttle blades open, and then the engine revs up. If I'm already slightly open on the throttle blades even a little, and then blip the throttle, I don't get that hesitation.

No amount of playing with AE (vs delta TPS, vs delta MAP, vs %TPS etc) seems to have any effect.

I notice on my wife's car and my daily driver that the throttle response is immediate. Is there any way to speed up the reaction time?

Set up is a miniram with a 52 mm throttle body. Cam is pretty mild at 212 deg intake duration. Vacuum line to map sensor is only about 1.5 inches long. TPS voltage reacts smoothly and immediately to throttle movement. Idle speed is set at 725 rpm.

It appears to be something to do with calibration, but I don't know what.

Thanks.

Dr.E

Have you tried increasing the TPS voltage at idle (o%)? ie.from .5 to .6 at idle closed throttle.

gp90gta

iTrader: (1)

I had the same problem with my setup, seem that only way I was able to resolve the problem was to raise the idle from 700 to 850, seem like my cam just didn't like the lower idle (@.50 226/234 112lsa), I also think my Miniram has a lot to do with it, on my little ol 350 with the Miniram, velocity in the intake is slowed down much more then with the tpi, that why so many people say that when they switch to the Miniram the throttle feels spongy, the theory goes something like this, on an intake with a plenum you need 40-50% volume of the given engine, so a 350 of 5.7l would need a plenum of at least 2.28l, on an intake without a plenum 20-30%, this is why samller throttle blades have a much better throttle response then the lager ones on a manifold with to much volume, it reduces the available amount of air between the throttle blades and runners. Also one other thing to note it that air that touches any serface in the intake moves a lot slower then the air in the center and the rear cylinder will alwasy be richer because of the less available air (only when that TB is in the front).

I have made many changes this year to my car and was thinking that I wanted to go back to the lower idle to see if I can nail down the AE tables but feel that the pressure difference in the intake to the MAP sensor with my cam might not workout because ofthe lag with the less vacuum.

ULTM8Z

I didn't think this had any effect on an $8D car. ECM relearns 0 on every start up??

ULTM8Z

Do the LT1s have the same issue then?

gp90gta

iTrader: (1)

Not sure, maybe my problem is not the same as yours, for me its not an AE problem, its more of just a delay in the rpm to raise, it gets much better with the stock smaller TB but still noticeable in in park or neutral, the LT1 intake might have a smaller cavity then my Miniram. I just want to play with it some more to see if I can get it down to 650-700 without losing throttle response. Oh and I see TPS relearn at every startup also so I dont think that has anything to do with it.

dimented24x7

iTrader: (2)

This is an issue, especially with the older batch fire systems. They take longer to update. A fast throttle opening can take maybe 6 or 7 cylinder firings to take the engine from idle to 50 or 75% throttle. With older systems, there will be no updates to the fueling, so the engine leans out momentarily. With later SFI systems, each cylinder has its fueling delivered in real time, so its much easier to compensate for the throttle opening. OEMs also use smaller throttle bodies and/or e-throttle to limit how fast the load can change.

With my 1000 CFM TB, I can get the engine to pop out the intake if I stomp on it just the right time, right after the current cylinder has had its injector firing. Nothing can be done to stop it.

If it ONLY does it in neutral, and the rest of the time its fine, then I wouldnt worry about it. Ive found that you can compensate for it by dumping in lots of fuel, but then the engine is pig rich during accel under load. Hard revving under no load results in the fastest change in required fueling.

RBob

iTrader: (1)

Correct, it is constantly re-learning the 0% TPS setting (not just at start up).

Another item to check is the closed throttle SA table. Make sure that it transitions to the main SA smoothly. Not enough SA in the closed throttle table will cause a delay in acceleration.

RBob.

ULTM8Z

Interesting... I hadn't considered that. Thanks! I'll check that.

BTW, what would be considered "smooth"? Having the same value in the closed throttle table vs what's in the main table? Or is it better to have a little more or less? Or maybe I should just go try it and see

Ronny

iTrader: (1)

Is there not a TPS-MAP "filter" in def file that will allow a change in delay/onset of of AE event ?

DeathStarr89

iTrader: (1)

I'm running ITB's and have the same problem, i just deal with it.. No amount of AE or Spark helped.


When I was running the Holley 950 the problem went away so i figured it was just the '7730's fault.

ULTM8Z

Are you talking about the TPS filter coefficient?

RBob

iTrader: (1)

Basically the same SA value in the closed throttle table as the area of idle in the main SA table. Or even a little more so that it matches when transitioning between the two tables.

RBob.

RBob

iTrader: (1)

I wonder if it is the AE PW limiting in the $8D code that contributes/causes this issue.

RBob.

Ronny

iTrader: (1)

Not sure. I would need to search to find the definition. In my EBL def file I have two AE filers TPS and MAP. Changing them affect the duration and onset of AE event.

There are also AE throttle follower. That may come into play. Not sure.

DeathStarr89

iTrader: (1)

I run $A1 but if so it's probably the same issue. I'll have to log it again and see how high the PW goes. The wideband does show a lean condition though.

JP86SS

iTrader: (1)

I also feel that it could be the hydraulic lifters take a bit of time to react.
Mushy at low oil pressure possibly bleeding down a bit.
Once the motor revs good, then its repeatable. Would be nice to have it respond like a solid lifter motor right away.
Jp

ULTM8Z

Shoot, I'm pretty much already there. And adding a degree or two didn't seem to help.

ULTM8Z

Is that not a modifiable parameter?

Dr.E

Maybe it's just the air flow characteristics of the mini ram and the AFR heads. Since the TPS zeros at start up in $8D, you may be able to decrease the lag with a slightly higher idle. The more I learn here, the more humbling this tuning thing becomes. I just have to fight the urge to try to make the program do everything that it wasn't designed to do...just the things I can trick it into!
Which AFR heads are you using? Any TB mods?

ULTM8Z

I'm using the 180 street heads and a 52 mm throttle body.

RBob

iTrader: (1)

I don't believe that it is, but I can't find it in the code at this time. Maybe the limiter is just for the MAP based AE. I have to look further.

I did find some interesting items for the TPS based AE that affect the AE. These appear to have calibration parameters for them.

RBob.

JP86SS

iTrader: (1)

I've always had this issue too and just lived with it but if the 950 was able to manage it than there must be a way to correct for it.
RBob,
Why would there be limiting if AE hasn't started yet?

Ultim8Z,
Are you reading the lean out like Deathstar has?
Maybe a tweak in the filters for RPM based tables/constant for MAP would bring the change values sooner, but that would also make the dwell shorter.
You may have tried that already.

RBob

iTrader: (1)

I found the TPS AE fuel limiting routine. Never really went through that code until now. It appears that when TPS AE is active the main fueling injector PW is reduced. Since TPS AE is async it is delivered rather quickly.

As such the ECM then limits, or reduces, the injector PW for the next regular firing. See the table at $8563 to find the section of code.

There is a bunch of other parameters and limits on the TPS AE PW. TPS AE is delivered async, with MAP AE being delivered sync (added to the main injector PW).

RBob.

ULTM8Z

There's a switch in Tunercat that I posted about a while ago where the INT resets during the AE event. That helped the throttle response TREMENDOUSLY during driving. Not sure if this is what you're referring to.

ULTM8Z

JP, no not really. I don't have a wideband to detect that.

I haven't played around with the filter coefficients. that's the only AE parameter I know of that's RPM related. Which is unfortunate, because it would be great to tailor AE to certain RPMs rather than have to deal with global changes that may improve one area but degrade another.

RBob

iTrader: (1)

Yes, but not what I am referring too.

Also, there is a maximum limit to the TPS% AE PW:

L8532: FDB 0364 ; 5.6 MSEC MAX Accel ENR PW LIMIT

RBob.

ULTM8Z

I think somehow I need to alter the AE so that it reacts sooner to throttle opening.

One thing I just noticed during scanning, the TPS voltage increases prior to the scanner registering a % change in throttle position. That is, the TPS voltage will increase from .64 volts all the way up to 1.03 volts before the %TPS reaches 1%. From there, the %TPS changes much more closely with throttle movement. The voltage itself changes as soon as the throttle is moved at all.

Does the ECM pay any attention to %TPS? Or is strictly operating off of the TPS voltage? If it's looking at %TPS at all, then there's a brief period where change in airflow is not reacted to by the ECM with additional fuel. Given how sensitive the Minirams are to off-idle transition, that would seem to be likely big contributor.

This discrepancy between % and voltage is independent of ECM's and TPS sensor as I've swapped both out for others and get the same results.

gp90gta

iTrader: (1)

Would the AE mult. VS TPS% at L859F help? Table starts a 00% then 12% TPS, maybe add to the multiplier at 00%. Also maybe change the max limit that Rbob is talking about.

RBob

iTrader: (1)

The ECM uses TPS% for the table look ups.

> That is, the TPS voltage will increase from .64 volts all the
> way up to 1.03 volts before the %TPS reaches 1%.

I wonder if the scan tool is reporting the TPS% properly. As this makes no sense. The code for the conversion from ADC value to a TPS% value is straight forward. It takes the lowest seen TPS AD value and subtracts it from the current AD value. Multiplies by 105 (calibration dependent gain term), and divides by 64. The multiply & divide is 16 bit math.

The result being the TPS% value as an 8-bit variable.

Using the above values of .64 volts and 1.03 volts, first convert back to AD values:

0.64 / 0.01961 = 33
1.03 / 0.01961 = 53

53 - 33 = 20 AD counts

20 * 105 / 64 = 33 AD counts, 33 / 2.56 = 12.9% TPS

Seems to be time to start looking at the raw ALDL data values.

RBob.

ULTM8Z

The scanner is an Autoxray. What I can do is hook up the laptop with Tuner pro and see what I get.

BTW, how does one go about looking at raw ALDL output.

RBob

iTrader: (1)

If using TP set the conversion to: N * 1

Which will display the raw value.

RBob.

JP86SS

iTrader: (1)

Or word 10 of the default datastream is TPS volts

ULTM8Z

It's doing the same thing in TP.

However, being the dork that I am, I'm not sure what you mean by set the conversion to N * 1. Where in TP do I go to do that.

Below is a plot of TPS voltage vs TPS %

Dominic Sorresso

RBob,

Would the discrepancy between Closed Throttle or Idle SA and the SA in the Main Spark table at idle params be the cause of a surging in decel from speed?
Surging stops when I hit the defined mph for idle SA.

RBob

iTrader: (1)

It can if there is enough difference between the tables, and the TPS% is on the edge and causing the ECM to switch between the two tables.

Usually on decel it is due to either/or the VE being too low causing the engine to be lean. Or the ECM stays in closed loop and the proportional gains cause it to surge.

RBob.

RBob

iTrader: (1)

The change is made with the ADL or ADX file. It has been a long time since I've worked with one in TP, so don't recall how it is done. It will be the data stream definition file. For the TPS in AD counts the conversion to volts will be similar to:

volts = N * (5 / 255) = N * 0.01961

Change it to:

volts = N * 1

This will show the raw ECM value, not the converted value. Do the same for the TPS% to show the raw AD value.

The TPS idle setting looks to be high, about 0.92 volts is right on the edge of the upper boundary.

RBob.

ULTM8Z

Ok, so here's what I did... it didn't look exactly as how you're describing, but it pointed me in the right direction. In my ADS file, there were the following. I changed the dFactors to 1. The original dFactors corresponded to the values you described.

Below are the exceprts from the ADS file which I'm showing what I modified. Only the items in red were modified. Everything else was left as-is.

For TPS %:

Was

btByteNumber =24;
btMessageNumber =1;
dwItemSizeBits =8;
dwOperation =0;
dFactor =0.390625;
dOffset =0.000000;
strItemTitle =TPS %;
strUnitLabel =%;
dwAlarmHigh =255;
bAlarmHighENable =0;
dwAlarmLow =0;
bAlarmLowEnable =0;
iRangeHigh =255;
iRangeLow =0;
iLookupTableIndex =-1;

Changed to

btByteNumber =24;
btMessageNumber =1;
dwItemSizeBits =8;
dwOperation =0;
dFactor =1;
dOffset =0.000000;
strItemTitle =TPS %;
strUnitLabel =%;
dwAlarmHigh =255;
bAlarmHighENable =0;
dwAlarmLow =0;
bAlarmLowEnable =0;
iRangeHigh =255;
iRangeLow =0;
iLookupTableIndex =-1;

For TPS voltage

Was

btByteNumber =10;
btMessageNumber =1;
dwItemSizeBits =8;
dwOperation =0;
dFactor =0.019608;
dOffset =0.000000;
strItemTitle =Throttle Position;
strUnitLabel =Volts;
dwAlarmHigh =255;
bAlarmHighENable =0;
dwAlarmLow =0;
bAlarmLowEnable =0;
iRangeHigh =220;
iRangeLow =28;
iLookupTableIndex =-1;

Changed to

btByteNumber =10;
btMessageNumber =1;
dwItemSizeBits =8;
dwOperation =0;
dFactor =1;
dOffset =0.000000;
strItemTitle =Throttle Position;
strUnitLabel =Volts;
dwAlarmHigh =255;
bAlarmHighENable =0;
dwAlarmLow =0;
bAlarmLowEnable =0;
iRangeHigh =220;
iRangeLow =28;
iLookupTableIndex =-1;


Results

TPS voltage readout is now 33 volts at idle, 200 at WOT.

TPS % readout is 0 at idle, 253 at WOT.

TPS voltage will now increase from 33 volts to 48 volts with no corresponding increase in %. At 49 volts, I get 2% throttle and it increases fairly linearly from there (which is pretty much a function of how smoothly I can manually open the throttle).

So it appears that the raw data corresponds with the converted data?

Is there any way someone else can independently verify these results on another 7730 vehicle?

RBob

iTrader: (1)

The changes you made to the ADS file are correct. So now we are looking at the raw ADC counts for the TPS voltage. And the raw TPS% for that (it is a scaled ADC value).

> TPS voltage readout is now 33 at idle, 200 at WOT.

Converting these to voltage (*= 0.01961) we get: 0.65 volts at idle, and 3.92 volts at WOT.

> TPS % readout is 0 at idle, 253 at WOT.

This scaled ADC values for TPS% is OK: 0 at idle will be 0%, 253 at WOT is 98.8%. Note that I used the gain term of 105 for this calc, same as AUJP & AXCN.

Now for the relationship between TPS volts & TPS%, here something is wrong.

> TPS voltage will now increase from 33 to 48 with no corresponding
> increase in %. At 49, I get 2% throttle and it increases fairly linearly from there.

With the ADC of 33 at idle, and then at 49 counts when the TPS% actually increases. It should be:

49 - 33 = 16 counts, convert to a %: 16 * 105 / 64 / 2.56 = 10.25 %

One thing to try is doing this with the engine running. It shouldn't make a difference but want to be sure to cover all bases. If the above was with the engine running no need to do it again.

So what is going on? There may be a TPS soft error. The default idle TPS ADC counts is 48 (look familiar), which is likely what is being used, not the real ADC idle count of 33.

To check if there is a soft error, place RAM location $40 into the data stream (change the ALDL data stream table). Then convert and display that with the N * 1 so it too is raw. Convert the decimal to hex in the Windows calculator and check bits 5 and 2 ($20, $04), if either is set this is the problem.

RBob.

ULTM8Z

Ok, mystery solved. It doesn't do this when it's running. %TPS changes immediately with TPS volts when the engine is running.

Very strange that there'd be a discrepancy between running and not running.

Saar

if i had to guess(since i'm not as well versed in 8D), i'd say it's the ECM constantly relearning the TPS 0% value with the engine off? so it allows a large gap before it starts to actually change the TPS% value.

RBob

iTrader: (1)

I'm a bit surprised by that. Looking at the code it appeared that it would learn the lowest setting whether the engine was running or not. But at least that is solved and isn't an issue with the blip.

RBob.

ULTM8Z

RBob, thanks for working with me on this.

BTW, I'm still not clear on how the TPS filter coefficient works. As of now, every RPM has the same value: .063. What's the significance of that number and how does the engine theoretically respond to increases or decreases in those values?

RBob

iTrader: (1)

This table?

If so it sets the duration and magnitude of the delta TPS% AE. Best used as the duration, and use the "ASYNC FACTOR vs DIFF TPS" table for the magnitude. This latter table won't affect the duration.

Where the first table (TPS filter) affects both.

As for the values, not sure what the .063 represents. The raw values in the table can be converted by using: N / 2.56 or N * 0.390625. To a number from 0 to 100.

The higher the number (after conversion) the shorter the duration & PW.

RBob.

34blazer

this table? if so, i can plug in the equation into the xdf parameter to get a whole number? that would make things easier lol

RBob

iTrader: (1)

Yes, you can use the equation that I posted. For filter coefficients it is usually what I use. Easy to understand. In general it then becomes a percentage value, with 50 being 50% of the old and the new to form the filtered (or lagged) value.

RBob.

JP86SS

iTrader: (1)

Looking at this, most of the filter coefficients are just N/256, I like the idea of shifting the decimal to get a more meaningful value.
You may possibly know without digging into it, is 255 basically equal to 100% (no lag) on the filter or is there some other factor involved?

ULTM8Z

I came across this old thread of mine during a search on another topic. So I figured I'd update it with the solution I found- for the benefit of anyone searching on the subject (and seeing as how ~1300 people have viewed the thread!

So, what I did was go to the fueling constant AE Delta TPS Scale Factor (NOT the PW Scale factor!), and set the value to 1 (factory ANHT is .125). I think this constant is how fast the ECM reacts to changes in TPS. The response to a throttle blip now is literally instantaneous- complete night and day difference.

For the PW scale factor, I actually lowered it to .09. As a result of the AE responsiveness, it seemed the engine wanted a little less fuel. I wanted to keep all my AE tables exactly set at the LT1 values (BDZL- A4 Trans Am), so I simply modified this constant.

Anyway, that's the resolution.