BUILD THREAD 86 GP 2+2~Blown 6.0

[Northernregal]

 

[motorheadmike]

Well I spent Saturday organizing the garage and doing trim work in the house so I procrastinated until Sunday night to deal with my idle RPM sag when the AC is on.

Since I am doing HR power tour in a few weeks the car is going to sit in traffic a lot and I want my AC to work. The AC works but it doesn't like to idle when the pump is on, and it always dies when I am coasting to a stop and the pump is on.

I did the hook the Red 17 request pin on the ECM to 12V when the compressor turns on to try to bump the idle RPM but it didn't work. I found out it needs to see ground on red 55 but that still didn't work.

When I did hook up both pins it started idling worse and pulling timing. So I went full on HPT forum archaeologist and had to find like 6 tables to change to get the idle to actually bump when the AC compressor is commanded.

First, the ECM is allowed to pull timing when the AC is on. That happened sporadically to me. I zeroed that out and it helped the dying due to way low timing but still surged and didn't bump idle.
View attachment 181278


Then I learned about Long an Short term idle trims (STIT, LTIT). I also turned on the AC active vs AC request to see when the AC was being requested vs when the ECM determined the conditions were met that it allowed it to turn on an thus bump the idle.

I found out if the idle adapt STIT and LTIT are really toward their limit, even if the car idles OK with the AC off, it won't allow itself to enter AC enable mode.
View attachment 181279


So I had about 0.6lb./min of combined short and long term error so I added 0.7lb/min to the idle airflow table
View attachment 181280


THEN it finally allowed the AC idle to bump when it was commanded. I noticed I had about 0.2lb/min of STIT error when the AC was on and the ECM was only commanding 0.2lb/min of airflow to compensate for the AC comp when it was bumping the idle so I had to increase the AC inertia torque by 50% and it commanded 0.3lb/min and got me a little less on the error.

View attachment 181281


SO the result. When I request AC and the STIT and LTIT are NOT maxed out, it idles 975
View attachment 181282
And when I dont want AC it idles 775. Cool!
View attachment 181283

It only took 2 hours of HPTuners forum digging and about 8 different posts to piece together the timing thing, the wiring, the airflow, what tables to adjust and all that jazz.

And that's the difference between a tune, and tuning. Awesome work.

 

[81cutlass]

I need to do Task A on a holley, change table, Done!

I need to do Task A on a stock ECM with HPTuners
Subtask 1, 2, 3, 4a, 4b, go back to 2b, log the result of 3, paste values into 4b, review 1 results.

HPtuners is for people that deserve pain...

 

[64nailhead]

From the looks of this post ^^^^youll have an HP or Dominator for Christmas

 

[Supercharged111]

GM makes 3D tables for things that can easily be corrected with 2D or a single value. And yes, the domino effect is a nightmare. Just hope you never have to deal with transient fueling on a GenIII PCM.

 

[81cutlass]

Well I have been doing everything for the last month in anticipation to go race tomorrow night at the street drags and dial in my launch and test my new timing.

Looked online to find what time they start and the event disappeared. WTF!?! I am 100% confident it was scheduled 2 weeks ago. Sneaky SOB's must have pulled it.

If I would have known I would have found a track last weekend since I had diddly squat going on.

So I'm kinda stuck. Every track in a 3hr radius minus BIR has a race this or next weekend. I'm booked this weekend and next weekend is right before power tour, and I don't want to risk breaking the car 2 days before power tour. Past that it looks like Sept 11th weekend is the next opportunity.

Then drag weekend is 2 weeks after that. Cordova Il, Byron IL (where I blew my rear end the last 2 times) and Earlville IA. T

he owner of Byron started his own drag weekend style event last year due to HRDW being cancelled and he is good freinds with my buddy/ the promoter of the drag weekend gone to for the last 4 years.

So they combined forces and the classes got changed. Instead of an 11.50 class it's a 10.0 and slower bracket class. The remaining all steel all glass street class with 78mm turbo limit or bolt on blowers with exhaust past the rear tires, the late model 17" tire ctsv, zr1 and bolt on coyote class, the sorta street 94mm turbo class and unlimited class stays the same.

So I impulse bought some VP track bite on my summit order tonight. Also got a linelock so I can try 2nd gear burnouts and stocked up on some fuel filters. My buddy that bought my wagon and promotes drag weekend has a short asphalt test driveway so I need to bug him and see if I can do some test launches on his pad.

I also ordered up a gauge pod for a TJ to relocate my AFR gauge and boost gauge to free up some space for an on/off switch for the line lock.

 

[64nailhead]

Ah, you're in a time crunch - I'm feeling that pain as well.

 

[motorheadmike]

Ah, you're in a time crunch - I'm feeling that pain as well.

Both of you...

 

[81cutlass]

Ordered up some parts and am getting my line lock installed, redoing some of my gauges and wiring a second pump switch.

I had issues with what looked like my second pump kicking out. I found the issue was that the plastic relay harness plug fractured and the ground wire on the relay was loose and not making contact so the time. Easy fix but odd problem.

Pulled a second wire from the ecm to the second fuel pump and put a green light switch in the cab. I can turn the second pump on with that switch so on long cruise I'll turn it off and at the track I'll flip it on.

Also pulled wires for my line lock.

Working on fixing the mess that was my boost and afr gauge mounting and finally connected my boost gauge backlight. Hopefully mount the line lock switch near the shifter so I can flip the line lock on/off without moving my hand from the shifter.

Car is due for an oil change before power tour and a fuel filter change too.

 

[81cutlass]

Diddly squat interior update #173.67

The TJ gauge pillar pod arrived and got to work modifying it.

The GP's have arguably the best dash and console of all G bodies but they are really hard to find places to mount additional gauges. There's no place under the dash and on top of the console like montes, cutlasses or regals. There's no place under the gauges and I don't like A pillar pods, they look bulky and kinda ruin the stock appearance im going for.

The TJ pod was the only one I found that faced up and towards my eyes. I had to cut a flange off for the screw that holds it in but otherwise it's a good fit.

I used 2 of the fake ash tray bolt head holes to fasten the pod down. I might try to look for some button head Allen screws so it matches the rest of the trim but overall it didn't turn out too tacky with some black head Phillips head screws. It's far from stock appearing but not awful.

Also mounted the line lock and 2nd fuel pump toggles in the left side. I can flip the line lock on and off with my finger when I'm in 1st and my hands in the shifter.

Bonus is I have a place to toss my phone and wallet in without it escaping too easy. It looks way better than my bent piece of sheet metal holding the 2 gauges in those cheap stamped steel brackets they come with.

I've got a few cleanup things to do but otherwise I should be ready to go with Power Tour. The only thing I'm missing is cruise which is hooked up but doesn't work due to t56 gear ratio mismatch in the computer with it having a 60e segment.