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2004 chevy trailblazer_ls_ext
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Discussion Starter #1
I have been tuning on my WS6 for a while, and thought I'd do some logging on the TB to see what it looked like after I added my K&N. I was quite surprised to see IATs of 150-160 (around town, 120-130 hwy), lean LTFTs (10-19) and knock retard of 5-7 degrees initially on hard acceleration?! :eek: The KR and lean LTFT exist even before the IATs jump, so I don't think the IATs are the whole problem.

I have one of the TBs that needs the GM calibration update, and intend to have my PCM updated before making any changes and having to relicense it again and waste the credits. I'm hoping that the GM update will help somewhat.

I'm looking for a way to get my IATs back down in the meantime. I added the K&N CAI, which improved airflow, but it is sealed horribly from K&N and sucks in mostly hot engine compartment air. The K&N 'cold air' actually raised my IATs. I'm going to try and fabricate a better heat shield and some type of fresh air scoop...
 

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2006 chevy
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What Octane gas are you running??

0 KR would be Ideal. But I have seen up to 6 degrees of burst knock.

Things that help with KR - Exhaust, CAI, Plugs, Thermostat, Headers (If we ever get one)
 

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2004 chevy trailblazer_ls_ext
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Discussion Starter #3
I'm currently running 87 octane. I guess I could run this tank out and relog with 93 octane to see what changes.

My TB is garage kept with 30k miles and has stock exhaust, plugs, & thermostat. It came with the 3.73 posi, automatic transmission, and is an EXT 4x4. The only modifications are the K&N FIPKII (with the plastic tube) and a set of 20" wheels with 275/40 Toyo performance tires (which were tuned in the PCM to correct speedo/tranny calculations).

The KR only appears when accelerating hard, and just for a few seconds. It doesn't matter whether I'm kicking it down on the highway or from a stoplight, it shows KR initially at WOT then it goes away. Light throttle seems fine. I can't detect any pinging, have no heat problems or any mechanical issues, just have the KR showing on the log.
 

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That is burst Knock, it is the hardest to get rid of. I would try higher octane and see what happens..

You may loose a degree or two. But I would look into exhaust, and PCM programmer and all should be good.
 

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Discussion Starter #5
I have HPTuners, which is what I logged the KR with. I guess I'll try a few different things:

First, since my truck is one that is covered under the GM service bulletin that needs a PCM calibration, I'll get my PCM updated.

Second, as my gas runs out I'll fill up on 93 octane.

Third, I'm going to try and get my IATs down by fabbing up some type of CAI to quit pulling in the hot engine compartment air.

I'll post any progress here, so that anyone else with this problem might be able to find it.
 

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2002 gmc envoy_slt
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The factory air-box seals out hot engine compartment air pretty well, try taking the stock box and opening up the front end. You can also cut out the lining or inside wall to allow more air to reach the filter from all sides a little better. That's what I did with a cheap e-Bay intake tube, keeping the resonator, and I've never seen much more than around 110-115 IAT readings around town and I'm sure they're lower at highway speeds. (You end up pulling in most of your air from around the headlamp assembly. With a TB, you can actually open up the trim cover immediately in front, like on the SS, and pull air through there as well).
 

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Discussion Starter #7 (Edited)
I thought about hollowing out a factory type airbox like that after I got the K&N. Seems like it would have to be better than sucking hot engine compartment air, and maybe it will reduce some of the annoying noise the K&N makes. Do you have any pictures of what you did?
 

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2004 gmc envoy_slt_xuv
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My IAT's are around those numbers as well. I see about 1-2 degrees of burst knock even with 93 octane.
 

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Discussion Starter #9
I got the plexiglass fabbed up to seal off the K&N better. It slightly reduced the K&N noise level and dropped by IATs by 40-45 degrees :woot:. My IATs run within 5-10 degrees of the outside temp now in motion (20-30+mph) and in heavy traffic at they dropped from 150-160 to 110-115 (mostly stopped, and <20mph). That should provide me with a little bit better mileage and power. Fixing the high IATs did not affect the KR though :(. I did notice that my TB runs really lean, like -10 to -22 on the LTFTs. I'm thinking adding a bit more fuel could help somewhat...

I'm getting low on fuel now, will fill up on 93 octane and see what difference that makes later today or tomorrow.
 

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Discussion Starter #10
I let it run almost dry, refilled with 93 octane, waited 2 days of driving to let it get well into the system and relogged a couple runs. The KR was reduced somewhat, but still there. I dropped from 5-7 (and as high as 8) KR to 2-3 (and as high as 4). 93 octane definitely helped, :( but there's still some knock there. Next comes the GM calibration update, then tuning...
 

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Discussion Starter #11
I had my calibration updated this week. It's definitely an improvement. The new calibration helped my A/C at idle, improved the shifting (especially 1-2), fixed the erratic idling, gave me more power off the line, and reduced my burst KR. The burst knock is now 1-2, with a max of 3-4. Now starts the HPTuning. I've read that the torque management causes some of the burst KR. We'll see...
 

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Jag if you get the KR figured out let me know how you did it. I have been battleing with mine since I got the HPTuners and started playng around. I have tried all you have, and read on the HPT forum in a post to watch the log and mark where the KR is and go into the spark tables and adjust acordingly. The only problem is the KR is not always consistent in my logs. And the spark adjustments didnt seem to do much either.

Chris
 

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Discussion Starter #14
This is my temporary setup. It took me about an hour and half or so, using a $15 butane soldering iron with a plastic cutter, and heating it with the heat bit to bend on a scrap piece of plexiglass I had in the garage. I intend to make a better box in the future with some type of cold air input, possibly using the stock airbox top or a homemade setup from all plexiglass. Still trying to figure out something. These mods to the K&N shield were quite effective though, dropping my IATs by about 45 degrees or so on average.




 

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Discussion Starter #15
Just as an update (for anyone searching with this problem), tuning removed almost all of my KR. I think a lot of it was torque management. I still get 1-2 degrees on occaision, but not nearly as often. It went from an every time I accelerate thing to a only every now and then thing.
 

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Glad to hear it man, I might have to enter the dead zone and get the stealer to update my PCM to the latest cal to see if I can get some more KR under control. Ive fixed the LTFTs for the most part, but unfortunately Im just messing with the low VE table to get them close to 0 ( at -3 to +4 now, were closer to like -20 to +10). I need a WBO2 but dont have the cash to get one.
 
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