Lateley as its been warming up ive been getting detonation on tip in. Its kind of annoying because it kills the throttle response for a second or so untill the timing recovers. To be precise, heres what I have: The car has a 2 in 2bbl tbi on top of a goodwrench 350 with 8.5:1 CR with a mild stone age 204/214 cam in it. The tbi is a bit large for the engine and by around 45-50 % WOT, the MAP will rise up to around 90 kpa and sometimes at WOT itll go as high as 101 kPa. Its also not lean. The stock 02 shows voltages around .98 volts while the TPS adn then MAP AE are in effect. Now that I got rid of some WOT tps compensation stuff, this is also accompanied by a trail of black smoke while AE is in effect so im at least quasi-sure its not going lean. When there is no detonation the throttle response is very good. The timing tables where done at cooler temps over the winter but I still only added as much timing as necessary to get it to run acceptably.

What should I do to remedy it? Doesnt seem like it has too much timing as I only really get detonation on tip in, everywhere else, itll show maybe one or two counts. The 8063 has the option to use the IAT instead of the CTS for the coolant comp SA table (as well as others), so should I try to compensate for the temp increase and see if I can get anywhere with that?

It sort of seems like maybe I dont have enough TPS AE and it goes momentarily lean on tip in but at night with cars behind me, after a fast start I can see a trail of black smoke leading back to a hovering cloud where I started off at. Seems like I may have too much already.

 

Heres my timing table. There isnt any WOT added SA or any added cool. comp. SA and the base time is set to what the base time on the motor is set to, which is two degrees. Assuming my chinesium balancer + timing pointer are correct, the values there should be the advance at teh dist.

 

You might try ramping the timing out faster.
If your cruise timing is say 32d at 55 K/Pa, then you want to drop to like 30 at 60, 28 and 65, and then be almost flat going toward 100 K/Pa. Fuel will always lag timing, and the pedal, in the 3rd gens. So you have to yank a lil timing out, to allow for that, IMO.

And you can have too much AE. Take a close look at your VE tables, sometimes people use AE to cover for the VE being off. And sometimes you have to use VE since there are filters on the AE stuff. So you in some apps. just have to use the VE tables, in the ~70-80 area as fuel adders, and then go back down at 90-100 K/Pa, so that the PE AFR is right.

Make sense?.

 

What Doc said and... the AE from delta TPS tables in the car f-body code is crap. Unless you can move your foot at the speed of light (I know I can't) you have only one real useful value in that table. For some reason it's like this, RBob pointed it out to me and I've noticed that adjusting the tables at 12.5% do nothing, ever! So adjust the AE using the MAP until source code .

 

The deltaTPS AE works. Its the large initial black cloud while the deltaMAP AE is the black trail of smoke. I wonder why the guys over at GM chose to make the TPS AE so fast acting? On the bench its gone almost as soon as its added. Ive also noticed that itll cause the motor to bog real bad on sudden throttle application if I add too much. I really wish I had a WB-O2 so I could get it a little leaner w/o having to guess.


Ok, so I should try to ramp the timing down a little faster as the MAP increases? Ill give that a try.

 

'8063 (dimented24x7) vs. '8746 (JP), probable differences.

RBob.

 

For figuring out AE they become cost effective, at a $1.90 a gal, the $350 for an Innovative WB ain't bad.

 

Ok, I had the timing ramp down a little faster toward WOT and it seems to help. Also seems to feel a little better under load, maybe too much timing at the higher map values. Will know for sure tommorow when I hook up the laptop while I drive.

 

I assume hes probably done alot to his calibration? On a side note, Ive been going through the 8063 code. Hanvnt done any side by side comparisons but glossing over it the 8746 looks like a cut and paste version of the 8063 with some minor stuff taken out and some minor stuff added in.

 

Yeah, I know, one of these days im going to get one.

 

How is the delta TPS% term for AE is created (on the '8063, of which I have no idea how it is done)?

On the '8746 it is the difference in TPS% within 12.5 milli-seconds. Very difficult to get a delta TPS% of more then a few percent.

Check at how it is created on the '7747 ECM. It is derived from lag filtering the TPS% term. Very much programmable and much more useable. Uses a lag filter coefficient that is CTS based. Not only can the magnitude be changed, but also the duration of delta TPS% AE.

RBob.

 

Its identicle to the 8746, it uses the delayed tps term to calculate it. Opps... forgot about this. After I did up the linkages for the holley, my gas pedal only had about 1/3 the travel that it did stock, which means I can snap the throttle open in a hurry. Dont know why, but it does. Makes the car a bit of a pain to drive. That explains why I can get to those upper values when I hit the gas.

 

Thats pretty cool. Ill have to take a look at that. Is there any reason they chose to have the tps AE the way it was in the f-body ecms?

 

I think that there may be two reasons, or two that I've come up with:

The first being fuel mileage and emissions (I guess that is two reasons, so I have three). Cars had more stringent emissions and fuel mileage constrants then trucks do.

Second would be vehicle weight and required AE. A heavy truck is going to need more AE for a longer period of time (over a lighter car such as the f-body).

The '747 was used in trucks from the light Astro van to 1/2 and 3/4 ton trucks.

There may be an easy way to increase the delta TPS% for AE on the '8063/'8746. Just never looked at it.

What is also interesting is that the '747 has an option bit to select the delta TPS% creation. One method is the lag filtering, the other is the 12.5 milli-second delayed term, just like the '8746.

Even with that option available I've yet to see a '747 calibration use it (doesn't mean there isn't one).

RBob.