What does it matter?

 

You could drive Doc up a wall with a nice cheat: change the code to enable the delta TPS AE while the engine is not running. . . Think of it as a double-pumper and wet the manifold before cranking. . . Not that I'd ever do this, nope wasn't me.

RBob.

 

Bruce and Bob, I will try and email u my bin later t-nite when i get home from work and u can comment all u wish :-)

Will check the 100kpa area out when i get home and have my laptop bruce(im at work)

If i barely touch the pedal and crank it over it will start instantly, even at roughly -8deg F this morning.....just frustrating lol

thanks again
Jeremy

 

In this case I would data log each episode and look for differences. Remember to take into account that the throttle is slightly open in the one for more airflow.

Check things like injector PW, IAC steps, SA, a side by side comparsion should reveal something. Maybe AE when you touch the throttle? (slim chance though).

If nothing shows up try more IAC.

RBob.

 

Because your going from a ton of fuel running on the ign module, at 100 RPM, to 900, at a commanded AFR, and an active EST. All in a little less then .2 sec.. Change enough things far enough, fast enough and the engine will bulk, hot or cold. Adding lots of cold just makes it all the worse, and even more of an extreme.

 

Or use the TPS vs Crank enrichment as an anti-theft.

 

Bruce,
Gonna try a couple things in A.M.
after that i might give u a call , u gonna be around?
thanks
Jeremy

 

If anyone knows where in the code the enrichment routine is (crank with pedal depressed) you could turn it off and then try cranking with the pedal depressed and see if it still starts and stumbles. If it starts easier and doesn't stumble afterwards, then you'd know you need more IAC (more air) during start. If it still stumbles after start then you probably need more fuel during crank.

 

Could you just not open throttle blades a little more?
Long as you have room with IAC to allow.

 

Gotta watch the TPS voltage when trying that, you can't go too far or you'll hit max voltage before reaching WOT.

 

If you turn off the TPS crank enrichment, the car won't start. Er, some cars won't and I believe the 8D is one of those.

 

In the calibrations that I've done, it's a matter of too much IAC. Which means closing the throttle, and too often running out of IAC.

 

I'm in for the day now.
I was out working on the cold AE correction stuff.

Wow, I'm glad you brought this up. Got me motivated to redo and double check some stuff, the truck is so much nicer now. Instant startups (down to -12dF), and great cold drivibility.

 

Its adjustable.

 

Not all are and even the ones that are only go so far.

 

And you can set it anyway you want, once you know what your doing since it's adjustable, at least in all the GM code I've seen. ie the limits, and rates of progession.

 

Enlighten me. The slots only allow for so much adjustment, if you open the throttle blades far enough you'll bottom out in the slots...how do you compensate for this? And from what I understand, even the non-adjustable systems can only "zero out" the TPS so far...how do you overcome these limitations?

 

You would need to open throttle a heck of alot to run out of adjustment.. Even on my car with the healthy cam and 400 cubes I have way more than I will ever need.

On the ones that are not you just elongate the holes.

 

But from what some people are saying they are having to crack the throttle pretty good to get it to start.

 

It's in the code.
there are rates of progression for the TPS.
Depending on what code your running they do an auto reset for idle everytime you start the car. But, not all do that. On the ones that don't you have to either adjust the TPS, or adjust the code settings.

For WOT you can set 100% to be lower then 2.8v on some of the codes. Just a matter of reading the hac for what your working on.

 

I just cracked the blades open then adjust the tps. 87 t/a is right on the money. It would take aprox 25% throttle opening to max the tps slots. Grumpy mention the rate of progression. That is why I prefer an adjustable tps(if it matters).

 

Ok, so you can reset the values in the code to basically whatever you need to be the min and max values?
So if you are having COLD starting problems you could say set the min TPS value at say 1.0VDC and the max to 3.0VDC....If you do this what happens to the resolution in between? I mean you are going to have less seperation between min and max so won't this affect the throttle response? Make it very touchy?

Just trying to understand the "cause and effect" of tinkering with the code when it was devloped for a specific spread in values.

 

I'm having the same problem with the '89 tpi 350ci that i just bought. I originally guess the IAC valve but that didnt seem to do the trick and i'm gonna try playing with the timing tomorrow.

Is it better just to bring the car to the shop and have them fix it up? Think this could cost too much?