PCM Tune

[Shaw520]

Just sent my info and payment to Lime-Swap for a pcm enhancement! (loaner swap) woohooo!,... fingers crossed
Heres a list of my request,.. am I forgetting anything ?

2005 Trailblazer 4.2 with 140k miles
Gear ratio is GU6 or 3.72
Tire size is 265/75/R16

Tunes:
Shift Management (shift delay) removal
Throttle delay removal
Torque Management removal
Evap system code removal
Secondary Air injection code removal
Misfire code removal
e-fan code removal
raise idle speed
eliminate speed limiter
eliminate rev limiter
(and any other DTC's or limiter's that you recommend)

 

[Mooseman]

For the shift, I think it's more the shift firmness to change. Stock, firm or firmest. Also get the torque converter PWM eliminated.

Why remove misfire codes? That's actually useful.

 

[Shaw520]

Also get the torque converter PWM eliminated. Why remove misfire codes? That's actually useful.

Is the PWM different than Torque Management ?
Im having the misfire code removed because I have what I believe to be a "lazy lifter" in cyl #4, causing just enough of a misfire at idle to through a code,...and in my State it wont pass inspection with a misfire code,

 

[Mooseman]

Torque Management is what you referred to as "throttle delay". PWM is what controls the torque converter clutch, making it slip on engagement.

I still don't think it's a good idea to disable misfire codes. If it's misfiring, it's for a reason and should be fixed. turning off the codes won't fix the underlying problem.

 

[Shaw520]

Torque Management is what you referred to as "throttle delay". PWM is what controls the torque converter clutch, making it slip on engagement.

I still don't think it's a good idea to disable misfire codes. If it's misfiring, it's for a reason and should be fixed. turning off the codes won't fix the underlying problem.

Ok I just sent him an email to remove PWM,..
Ive come to the conclusion that the only way around this misfire is to have the head rebuilt,...the misfire only occurs occasionally at an idle,..its really not a problem and I dont even feel it,.the only real problem is the CEL that will keep me from getting it inspected...so remove the code/remove the problem. I know this because: 1. Ive exhausted every other possible option and 2. when I change the oil and the oil is new the misfire does not occur, until the oil starts to break down. Also the idle is low at 550rpms, the misfire goes away at about 650 rpms,..so Im having the idle raised too. Ive been told by a gm mechanic that its not uncommon for these 4.2 to have a lazy or sticky lifter at real low idle.

 

[thebat]

Have you done a compression test? Sounds like that should be the next step.

 

[Mike534x]

Correct me if I'm wrong, but I thought the I6 didn't have lifters since its a DOHC? Its a long shot, but you haven't tried seafoaming your engine have you? I've seen a few threads in the past where random misfires went away with an engine cleaning. Maybe its just a coincidence that it goes away for a short while when the oil is changed.

 

[Mooseman]

Ive been told by a gm mechanic that its not uncommon for these 4.2 to have a lazy or sticky lifter at real low idle.

And you trust GM mechanics? I think I might have heard of ONE lifter failure. Have heard of way more valve failures (burnt). You do what you gotta do.

 

[Shaw520]

Burnt valve or a lazy lifter both equate to the same thing, head rebuild. This problem does not warrant that,..at least not yet,.. So yes i will "do what i gotta do" to get my sticker. Was going for the pcm tune anyways so no loss there. Hell the idle increase alone will probably cure the misfire.!

 

[Mooseman]

A lifter doesn't require a head rebuild.

 

[Shaw520]

True,..but once youre that far in,..be foolish not to right.

 

[Shaw520]

Update: I got my original oem pcm back from lime swap,.. Ive only put about 100 miles or so on it but much improvement is already noticeable. In the loaner swap he sent me he reduced the shift delay from 100% stock to 30%, I personally didnt feel much difference, so I asked Jeremy to eliminate the delay all together and oh what a difference, I love it ! The vehicle feels WAY more responsive to throttle and shift commands. Money well spent and I recommend to anyone owning this platform. Here is a copy of the original tune sheet before he eliminated the shift delay completely.