PC Pro fueling in a 96

[bogey]

I have had the PCPro installed in my 96 for a couple weeks now. This is how it is currently have it configured. (winter temps 30-50 degrees F)

OFF Boost: 1 / 4 / 2.5

LOW RANGE
I have found that setting the low rpm range any higher than 1 results in jerky response at throttle tip in.

MID RANGE
Crusing mid rpm range without boost puts the A/F mixture dead center in the optimal range. If the optimal range runs form 1 to 10, the needle swings in the 4-7 range.

HIGH RANGE
I really do not have any high range off boost experience. (What fun is that?)

ON Boost: 4.5 / 6
The A/F gauge goes to rich under boost. It pulls strong all the way to redline.

I do experience some occasional knock at 6K+ and immediately back off. I think this may be heat related as it only happens if I push it hard for a extended periods. I have adjusted the high end under boost higher but it does not seem to make a difference.

It could also be the winter gas. I have been trying different brands of gas to see if there is a noticable difference.

I have wired up a LED light to one of the extra SS injector feeds to verify that the SS is sending a signal for eCool. It glows brightly under boost, so I assume it is working. One thing that surprised me is that there is constant current going to the injector. The light glows dimly off boost, and bright on boost.

Is there any harm to running so rich under boost if it runs stoich when cruising? Will this foul the cat?

[Tom @ Fast Forward]

Now I am curious as to the setting I used to force Open Loop on the ECU? There should be NO transition roughness at all. It should be smooth as glass. The fact that adding any GREEN fuel makes it worse leads me to that as well. GREEN fuel transitions at 2800-3000 RPM. Off boost the PC-Pro has no effect on the ECU at all. The only way off boost would be effected is if short term and/or long term fuel were effected. That would only happen if the signal to force Open Loop was incorrect. I had a 99/00 and an 01-05 to test on here but not a 94-97. The only setup difference between the years is that control signal.

You might have better control of the heat soak if you return the PC-Pro to the 'as shipped' settings and add the extra fuel as required with the SS. That would give more charge cooling and help the heat soak problem. I know the winter gas problem as well. We now add 10-15% corn liquer to our winter fuel. It gets real drunk on that and wants to knock on anybody's door. ;) I have to add just a little more E-Cool to correct the problem.

[bogey]

When I mean jerky transitions, it is the throttle that is so sensitive between off and on throttle. Transition from off boost to boost is fine.

The problem is off gas to on gas. The TPS is set to activate at the slightest pressure on the throttle plate. I think the engine is getting too much gas once the TPS indicates the butterfly is opening.

I will reset the PCPro back to original settings per your instructions and see how it goes.

Another possiblity I have considered is a broken motor mount. But I don't think this is the case.

[Tom @ Fast Forward]

The PC-Pro TPS setting is set to come on ~1PSI. You are making boost too easy. Maybe you need a much smaller pulley? ;) j/k

It should do nothing under 1PSI boost.

[bogey]

I don't doubt that I am imagining things. I have been playing with the PCPro settings and can't keep straight what works when. Like I said in my email, I have adjusted some slop out of the TPS and will see how it goes tomorrow.

I am pleased that the AF mixture is really jsut about perfect with the PCPro.

[Tom @ Fast Forward]

I doubt it is your imagination. It is the first 94-97 I have done with the PC-Pro and a setting may be off somewhere that needs to be different for it? You may be right about the TPS adjust. The 94-97 has a switch built into the TPS to tell the ECU that it is closed. If thatg is coming on too early, it may be confused about idle or go?

[bogey]

OK, I adjusted the TPS to remove the "slack" and reset the PCPro back to 1-1-1-4.5-6. What a difference!

The TPS was off enough that the butterfly valve was partially open (not by much) before the ECU would release fuel. If the butterfly is open slightly before fuel is provided, it is already getting a lot of air, and when fuel if provided, there is too much gas causing the abrupt power on transition.

It is much much smoother now at the cusp of on/off throttle. The TPS is now set to open if you breath on it.

This would explain the mid range "stumble". When I was holding at a given rpm, the ECU would cut fuel as the throttle would waver a the TPS cutoff.

Thank you Tom.

[Tom @ Fast Forward]

Wahoo. :)

Awesome. The thanks go to you for troubleshooting the problem to it's source. Now I will know what to tell other 94-97 owners if they have that problem. Thank you again.

:party: