Programming 99 Boosted Denali.

[solowma]

First off, this truck was programmed by Ed at Fastchips many years ago. Many modifications done since then I have been given the challenge of programming it.

I have been on this forum for a couple years now and a regular reader. I am currently helping a friend with his truck and it seems to be going fairly smoothly. It is a 99 denali with mild engine work and cam. Running about 14 lbs of boost at wot.
I have a couple of issues. 1st and this is a stupid one. I see people say "smooth out the ve table values". Does this mean round off the figures a little closer and make the curve a little more linear through the RPM range? That is what I have been doing and I have my stft and ltft at 0% through the entire range. But I have up and down areas in the table but it works great.
Second is; I have recently got into the wideband tuning for wot after I got my trims perfect and the maf good. Great throttle response, drivablility etc. Now when I go wot it goes extremely rich. I adjusted the VE tables again to make it a little more lean and it worked for the most part but not very linear. I want it to maintain a constant AFR in the higher rpm ranges. May not have my PE tabe right yet. Have you guys had this problem too?
Next and the most pressing issue. When we let off the throttle at any position or rpm, the AFR goes extremely rich and then backs off and goes stoich. How do I stop this or make it more bareable?
The issue is, we believe with all this WOT then off it has fauled the plugs and that is understandable. They are being changed on the weekend and we will try again. The truck will run great the first WOT run and then studder and hesitate on any of the runs after that. Plugs probably are the problem but if you drive a little more to clear out the fuel and then step on it again and same thing happens. Any help will be greatly appreciated.

Long post I know. I can provide JET program and data longs if needed.

[playtoy_18]

First off, this truck was programmed by Ed at Fastchips many years ago. Many modifications done since then I have been given the challenge of programming it.

I have been on this forum for a couple years now and a regular reader. I am currently helping a friend with his truck and it seems to be going fairly smoothly. It is a 99 denali with mild engine work and cam. Running about 14 lbs of boost at wot.
I have a couple of issues. 1st and this is a stupid one. I see people say "smooth out the ve table values". Does this mean round off the figures a little closer and make the curve a little more linear through the RPM range? That is what I have been doing and I have my stft and ltft at 0% through the entire range. But I have up and down areas in the table but it works great.
If it ain't broke don't fix it-yes smoothing the tables means to make it more linear and "pretty".
Second is; I have recently got into the wideband tuning for wot after I got my trims perfect and the maf good. Great throttle response, drivablility etc. Now when I go wot it goes extremely rich. I adjusted the VE tables again to make it a little more lean and it worked for the most part but not very linear. I want it to maintain a constant AFR in the higher rpm ranges. May not have my PE tabe right yet. Have you guys had this problem too?
Adjust PE table to the AFR values you want after you adjust VE,make sure when you adjust VE that PE is disabled and then all SHOULD be well-and make sure the wideband is before the cats
Next and the most pressing issue. When we let off the throttle at any position or rpm, the AFR goes extremely rich and then backs off and goes stoich. How do I stop this or make it more bareable? Have you tried playing with DFCO or throttle cracker?

[SubZero350]

Originally Posted by solowma

Next and the most pressing issue. When we let off the throttle at any position or rpm, the AFR goes extremely rich and then backs off and goes stoich. How do I stop this or make it more bareable?
The issue is, we believe with all this WOT then off it has fauled the plugs and that is understandable. They are being changed on the weekend and we will try again. The truck will run great the first WOT run and then studder and hesitate on any of the runs after that. Plugs probably are the problem but if you drive a little more to clear out the fuel and then step on it again and same thing happens. Any help will be greatly appreciated.

Long post I know. I can provide JET program and data longs if needed.

Are you still using the MAF sensor and if so, where do you have the MAF sensor located? If you have it far from the throttle body, what can be happening when you let off the throttle while under boost is all the pressure that builds up at the closed throttle bounces back out of the induction system past the MAF sensor which will register as airflow. I had this problem when I put a turbo on a 3800 years ago. The MAF sensor was mounted between the air filter and turbo inlet and it did the same thing yours is doing when I let off the throttle from a hard run. The fix was to mount the MAF sensor just before the throttle body (in the induction system between the throttle body and intercooler). Doing this fixed all fueling issues and also increased throttle response and the quality of drivability. Your Denali's stock MAF sensor should be good to about 400+ crank HP w/ boost; but keep tabs on its output frequency at full boost. If it is getting close to 11,500 hz or more, you are probably "outflowing" it and should get a bigger MAF.

[solowma]

Yes you are right. The big debate. To have the MAF on the intake of the charger or before the throttle body. We located the MAF between the airfilter and the charger. We keep going back and forth whether to locate after the charger or before. This also brings up the question of to resurculate the charged air back into the charger or to atmosphere.
You are also right on having it between the intercooler and the throttle body experience. I have a truck (see my sig) and had the maf on a push through design. Great driving, throttle response etc. After switching to multiport injection we decided to locate MAF on the intake side. After that intake backfires, bad drivability and throttle response. I just thought it had to be programmed out.
I will run this idea with my buddy and maybe relocate MAF.
Next would be, now bare with me. I will try to explain it clearly in routing of piping and charger. Air filter----> into intake of charger---> through intercooler----> through MAF----(Split) to throttle body and bypass valve. On the turbo setup I suppose you vented to atmosphere. On the charger do we vent or resurculate back to outlet of charger? I have seen both designs work on different vehicles but this is a denali with obd2 PCM!!!
Oh btw, I have been watching the MAF and it is not out flowing yet. Around 9 to 10 thousand HZ

[solowma]

Originally Posted by playtoy_18

Adjust PE table to the AFR values you want after you adjust VE,make sure when you adjust VE that PE is disabled and then all SHOULD be well-and make sure the wideband is before the cats
Next and the most pressing issue. When we let off the throttle at any position or rpm, the AFR goes extremely rich and then backs off and goes stoich. How do I stop this or make it more bareable? Have you tried playing with DFCO or throttle cracker?

I have been playing with the PE table to get the correct AFR. I guess I just need some more playing with it.
What does the DFCO and throttle cracker do? Little embarassed to ask this to but where do I find throttle cracker?

[solowma]

I went and read a little more on the DFCO and think I may have figured it out. I set my DFCO coolant temp to 150 deg C so it should work anytime.
Next is the enable RPM and that is set to 950. Makes sense when it should be enabled. The next few parameters are a little confusing. DFCO RPM hysterersis. What is this?
MAP DFCO Threshold is set to 33.99 kpa and the threshold hysterersis is set to 28.99. What are these?
The rest of the parameters are for a manual tranny. Don't have on the denali.

[Hog]

Setting the DFCO Enable Coolant temp to 150ºC will cause it to NOT work anytime.

I dont see any throttle cracker tables, just throttle follower tables.

peace
Hog

[SubZero350]

Originally Posted by solowma

Yes you are right. The big debate. To have the MAF on the intake of the charger or before the throttle body. We located the MAF between the airfilter and the charger. We keep going back and forth whether to locate after the charger or before. This also brings up the question of to resurculate the charged air back into the charger or to atmosphere.
You are also right on having it between the intercooler and the throttle body experience. I have a truck (see my sig) and had the maf on a push through design. Great driving, throttle response etc. After switching to multiport injection we decided to locate MAF on the intake side. After that intake backfires, bad drivability and throttle response. I just thought it had to be programmed out.
I will run this idea with my buddy and maybe relocate MAF.
Next would be, now bare with me. I will try to explain it clearly in routing of piping and charger. Air filter----> into intake of charger---> through intercooler----> through MAF----(Split) to throttle body and bypass valve. On the turbo setup I suppose you vented to atmosphere. On the charger do we vent or resurculate back to outlet of charger? I have seen both designs work on different vehicles but this is a denali with obd2 PCM!!!
Oh btw, I have been watching the MAF and it is not out flowing yet. Around 9 to 10 thousand HZ

If you are using a MAF sensor, the boost bypass valve should be located between the SC/Turbo and MAF sensor; then the MAF sensor should be mounted as close as possible to the TB. Here's the way I would hook it up...

Air Filter -> Charger -> To induction split that has 2 outlets; one leading to the boost bypass valve and the other to the Intercooler -> MAF sensor -> TB.

Of course you could also put the induction split point and boost bypass valve on the after side of the intercooler. I don't think it really matters that much. The main point is: when you let off the gas, air escaping out the bypass valve can't be allowed to be registered by the MAF sensor. If you have the bypass valve mounted between the MAF sensor and TB, then when the bypass valve opens, allowing air to flow out of it; this air flow will be registered by the MAF sensor -- which will cause problems.

[playtoy_18]

Originally Posted by solowma

On the turbo setup I suppose you vented to atmosphere. On the charger do we vent or resurculate back to outlet of charger? I have seen both designs work on different vehicles but this is a denali with obd2 PCM!!!

If the air has already been metered,and you allow it to vent to atmosphere than what's the point of metering the air for fuel control?

[solowma]

Originally Posted by Hog

Setting the DFCO Enable Coolant temp to 150ºC will cause it to NOT work anytime.

I dont see any throttle cracker tables, just throttle follower tables.

peace
Hog

I will change the DFCO enable coolant temp back to what it was. As for the other tables as I mentioned above, what are they used for?