Need help with part throttle boost AFR

[mike72678]

I feel that I've tried everything and I probably just missed something little but I am stumped and don't have the time to keep chasing this issue . This is on a 08 Trailblazer SS with 60 lb injectors and a sts turbo kit . at 45-50% throttle it will make 5 psi under 2000 rpms and the AFR stays right at 14.7 , to me I don't care and I can just drive the truck a little differently so this doesn't happen , but my wife also drives it too so I have to make it safe at part throttle . But it is driving me crazy that I can not make it work correctly . I need it to go into PE or Open Loop when it sees 103 kpa so the afr richens up and the short term fuel trims stop trying to correct to 14.7 part throttle cruising . Thanks in advance for the help!

[John_D.]

On my Camaro, I reduced the PE Enable TPS.

Mine tapers from 50% at 2000 rpms to 30% by 4000 rpms.

Stock was 64% until 2800, tapering to 36% at 4000.

[mike72678]

If you look at the edit file , you will see it is reduced to 40% which below this tps % it never sees part throttle boost , gen 3 and gen 4 especially on the 08 model are very little alike , thanks for trying to help though !

[mike72678]

The tune currently in there which is posted here is really close , but as you can see in the log it isn't right .

[RomansDesigns]

Log your commanded afr next to actual afr. Reduce your PE enable down until it's always in PE if necc to figure out why it won't go into PE. There has to be a reason. Turn off Closed loop until you figure out why it won't go into PE. Mark

[EC_Tune]

You need to log some proper parameters for the ECM first. Get the E38_E67_08.cfg config and histograms from the stickies at the top of this forum.

You may be in Differential TPS mode for PE enable below 50% TPS. Try setting it at 12-15% and see if it goes into PE more readily. MAP for PE Enable should be 100 Kpa though. No higher, especially on a 1 bar MAP sensor.

[John_D.]

If you look at the edit file , you will see it is reduced to 40% which below this tps % it never sees part throttle boost , gen 3 and gen 4 especially on the 08 model are very little alike , thanks for trying to help though !

Ahhhh... Ok, so you're covered there. I wasn't on a computer with hptuners on it at the time, so I couldn't open the files... :-)

From memory, there are some other PE enable factors. KPA, delay, etc. Might be one of those hanging you up, since they all have to be met ("and" vs. "or"). I still am not on a computer with hptuners on it, so I can't spot check you. If you're in boost, KPA is probably not an issue. I remember folks saying on slightly older trucks there was a huge PE time delay though.

[5_Liter_Eater]

Is this a custom OS? Maybe the beta one? Because I can't seem to open it.

I was going to tell you to look at the PE Enable RPM. The Tahoes have this set to 5000 RPM so it won't enter PE until then even if the TPS requirement has been met.

[streetcar]

I would look at PE ENABLE RPM and DELAY as others have stated. I know trucks tend to have crazy delay.

[mike72678]

It's not going into PE , PE enable rpm is set to 0 , tps enable is set to 40 % , Map enable is set to 70 kpa . I will try setting the tps enable at 15% on the way home from work tonight and let you know , thank you for all the replies , I appreciate the help .

[mike72678]

OK , I changed the PE enable to 15% tps, now it goes into PE at 47% tps instead of around 60% tps, but I still get part throttle boost as low as 43-44% tps , I am thinking that if I make the PE tps enable to 11% and the MAP enable to 100kpa , it will go into PE when I have part throttle boost fairly accurately and I can start retuning the afr because I got it all over the place trying to sort through this issue . Thanks guys , it looks like EC Tune hit it right on !

[RomansDesigns]

Many Forced Induction setups have the PE Enable TPS set to 19%. You want to be in PE before you go into Boost.
Mark

[Bill@HPTuners]

The ETC vehicles TPS position is a bit complex in how its calculated, usually setting the tps enable to 20-30 % less then what you actually want it at will give you the desired results, ie if you want pe to enable at 40% set the enable setting to 10% and it should enable at about 40-50%.

[mike72678]

I have it set at 0% and using the MAP enable appears to be doing the trick , what bothers me still is that I can't make sense of this because of what I am doing and commanding is different ?