the.jack

Wow... I feel stupid that I didn't notice this myself. I had the talk with the dude, looked at the peak numbers and that was that... This doesn't make sense to me either.

Well played! Doesn't clear up a thing!

the.jack

HOLD IT... Different scales. That's all:
At 5252 they are both at ~220.

It's all good.

DrLoch

Where's the other scale? Just curious, where/how did they get the AFR numbers?

2005HHRauto

I just wonder if Trifecta even changes the "torque-curve" on their 'tunes'.
Click the following link, post #15, to see what I'm talking about:
https://www.chevyhhr.net/forums/hhr-...e2/#post794620

Also, Trifecta tunes are on the 'rich' side, our DI 'buggys' like 'lean' PEs...
An air/fuel ratio of 12.5:1 equals a lambda value of 0.85, and is a typical value for a naturally aspirated engine under full load.

Our DI LNF runs best with a PE of .885 , which = 13.0 AFR...
So, with a PE of .85, you will be losing maybe 30HP....

the.jack

Hahn got back to me quickly, and on the weekend Said step 1 is to replace the plugs. They are original with 82k mi on them, so even if it doesn't help with my "problem" it is not going to hurt to do so.

But I'm intrigued after reading the threads on self-tuning. I've always figured this was a Dark Art that was best left to the magicians who have time and patience for a lot of trial and error, but with all this "desired torque"-based engine management, I'm wondering if it's really within grasp.

Of course I'd have to get the tuner which is no small investment in a 6 year old car with over 80,000 miles

DrLoch

Changing the plugs is certainly a step in the right direction. The investment for HPTuners will depend on whether you intend to keep the car around or not since it is an investment, in some cases no more than you have invested in bolt on parts now. What 2005HHRauto has said about the PE numbers is correct, a DI likes to be run lean. In fact running them to rich will make them knock at which point the ECM will pull timing and make the numbers worse.

If you decide to go with HPT and you go back to a dyno your going to want to log what the ECM is doing during the run. There are other ways of accomplishing the same thing without spending money on dyno's. A number of people will log the car and look at the time it takes to go from one speed to another, if that time increases you've obviously made changes in the wrong direction. Once you get the results you're looking for then go back to a dyno if you want. Don't be fixated on the high numbers since those numbers can be different from dyno to dyno and the correction factored dialed in. Try to use the same dyno and make sure the correction factors are the same for each pull.

If you are considering HPT go over the the HPT forum, register and read the L4 LNF posts, there are a number of sharp individuals that have tried a lot of thing and found what does and what doesn't work and are willing to point you in a correct direction.

HPT can be used to tune a number of other cars as well even if you decide to sell your HHR.

Just my .02 cents.

2005HHRauto

You already have a 'tune' that is better than the GMPP 'tune', so really, no need to go farther with HPtuner, unless "racecar"...

Also, everyone that has E85 available, should be running E22 in their 'buggy".
No tuning needed for E22
1 gallon of E85 + 5 gallons of E10 93 octane gasoline = E22

RJ_RS_SS_350

Interesting thought. With the high octane of e85 mixed in, couldn't we downgrade to 5 gals of midgrade?

EDIT: maybe not. Wiki says the true octane of e85 may be only 95

The Renewable Fuels Foundation states in its Changes in Gasoline IV manual, "There is no requirement to post octane on an E85 dispenser. If a retailer chooses to post octane, they should be aware that the often cited 105 octane is incorrect. This number was derived by using ethanol’s blending octane value in gasoline. This is not the proper way to calculate the octane of E85. Ethanol’s true octane value should be used to calculate E85’s octane value. This results in an octane range of 94-96 (R+M)/2. These calculations have been confirmed by actual-octane engine tests." [12]

the.jack

If I can come up to where it "should be", then I'm fine with leave a small percentage on the table.

I did change the plugs. The suggestion was non-standard so before commuting to work, I took it around the block. It's night, so I didn't bang on it, but things seemed OK so far.

I did notice on the stock plugs there was a "puddle" on the ground electrode... Now whether there is a sort of bump across from center electrode on the ground strap originally I don't know. It was a decidedly different color so I took note. I'll try to take a macro picture of one if that sounds like something strange to the general wisdom of the board.

the.jack

It ran well today. I'm trying to ignore the ever-optimistic butt-dyno (which is happy) but I have some more objective metrics I can point to that something wasn't before.

1. The surging is mostly gone. That's been consistent so far.
2. The turbo (and torque) comes on more quickly than before. Before the pedal felt like I was pressing on a big rubber band and there was a noticeable lag between when I'd apply x% throttle and I'd get x% torque.
3. Torque is more available now. Along the lines of my last comment, but I'm basically having trouble testing WOT because I'm well past acceptable public speeds. So I've been using higher gears and bringing the boost up that way. I had the tires screaming in 3rd today. Skinny winter tires had something to do with that, but I was starting from 30 MPH (and these tires are done this year so I'm not trying to save them).

I'll get a fresh air filter while I'm doing maintenance items. But since I missed a fairly simple maintenance hole, any other obvious, simple items I could work? Oil is coming up soon but I don't expect to see more than 15-20 hp from that job

In short, I'm cautiously optimistic.