Here's my last tuned WOT run.



I would have suspected the HPOP was tanking at that point, but it *does* look like the RPM is dropping first.

Is this a RPM-based defueling?

 

And the one just prior to that.

 

I see the ICP/IPR start to get back in line at the higher RPMs, but everything goes sideways at the lower RPMs. The shift is nothing more than losing the RPMs that drive the HPOP, but the FIPW crossed the line of death... so any evaluation of the HPOP is in the wind. You might email your guy and ask him to back off the FIPW a little bit. Hooray for Hydra.

*EDIT* For those reading this an not used to my style - "line of death" is just my own little expression. It is not an overly-harmful thing in this particular case, but it does lead to undesirable results.

 

OK, so my truck does seem to be behaving like a stock one with the exception of max boost, EBP and EGTs.

 

That's what I'm seeing.

 

That's my seat of pants feel when towing, good to know it's typical.
I share the low boost so will curiously follow along

 

One thing I discovered was that my EGTs can rise FAST above about 2200 RPMS. This is most obvious and problematic when pulling hills with the ~8,000 lb trailer. In order to make a long 6-7 percent grade in Vermont I needed to back down to 2nd gear with RPMS below 2200. Eastern PA hills like those on I-78 were doable. They might have required 3rd gear with the lower RPMs.


I'm giving you all this background to let you know that an EGT gauge might be a good investment. The common knowledge is that a stock truck won't make excessive EGTS. However, if you're not making 17PSI of boost there there may be something going on that could cause the to rise above the 1250 "red line". If you're towing while trying to track down a boost issue a EGT gauge can be considered an insurance policy.

 

Yea, debunked both the stock truck egt and the press tow button and let her eat mentality.
I don't have an egt gauge but do realize their importance, it's been on the to do list but nothing on that list seems to get done
However in my head theres more to your egt's than just a lb or two of boost
We will know when you get to the end of this chapter

 

Going to add a little info here about tuned defuels (mine anyways). This discussion seems to involve folks who will not have any problem following multiple data points

Had a discussion with my tuner today. Not someone in the office, a "Tuner" this time. Big difference

1) No low boost defuel in this tune. 27-28psi should be quite okay.

2) My heavy tow does have a boost defuel about 22-23psi. It isn't the one I logged, but it might make for an interesting comparison

3) These non-aggressive tunes... have a torque-reducing/limiting feature for shift points. Still good, but well below 100%. That could account for the rapid drops that I thought looked like a defuel.

The more aggressive tunes remove this.

4) I had an adjustment made and emailed to me (before I got off the phone ) that changes the TC engage/disengage timing or strategy or whatever to a more improved setting. I'll test it out in the next few days and see what happens.

5) My first "aggressive" tune should stay under 1000F if not towing, so I should be fine playing with it a bit.

6) I definitely need to open up my intake a bit (my assertion, with agreement)

So I don't know what other tuners/tunes may be doing a torque limiting shift strategy, or if the STOCK programs have a similar feature If so, this could account for some of the "Rev limiting" or "Defueling" we seem to see cropping up in different scenarios...

Just when we needed ANOTHER variable to throw into the analyses

 

Hello, I'm back. To summarize the issues here.


1) Can't really make good boost - get 14.5-15 or so completely stock.
2) did lots of leak tests, found leaky up pipes, replaced - no real change
3) Black fuel in filter - did injector o-rings.
4) Unable to produce black smoke - indicates there's not a lack of air?
4) "Bouncy" EBP readings - I was never able to tame this either - the may imply an still unfound leak....

I never figured out what to try next without going after big ticket items (Turbo/Injectors)....

I finally was able to get a good towing test with the the only change being the red wastegate hose was disconnected. To my surprise this seems to have made a huge improvement with respect to EGTs. The boost seems to peak out around 20.5 (and Exhaust pressure about 33 psi) but more importantly, I never had to get off the throttle due to egts getting above 1250.

So now the questions.

My EGT problem seems to have gone away by supplying more air by disabling the waste gate. Could my issue be simple that the waste gate is misbehaving and leaving the red tube off can be a long term fix?

Is there a max Exhaust pressure I should be trying to avoid?

Any other issues with running with the red tube disconnected?