VE tuning L67

[Ace25]

Vehicle: 2005 Monte SS 3.8 L67 with M90 blower; mods: stage 2 intercooler, xp hot cam, headers, catless downpipe, cat back exhaust, 3.0 pully, 42.5 injectors, cai...

I have an LC-1 wideband in place of the rear O2 sensor & the rear O2 codes disabled. EGR is disabled and Fuel injector data for 42.5 Lucas injectors provided by ZZperformance.

In closed loop, when the car is warmed up, it oscillates slightly at idle & typically dies. Running in open loop, I haven't experienced this yet. My initial thought was to tune the VE table and then move on to MAF tuning.
1-2-13 hour long mostly highway.hpl is my scan & LJL-05 Monte Carlo SS - Custom.hpt was the tune I was running.

I decided to attempt VE tuning by:

Fuel-> Open & closed loop, set coolant to 284 to enable open loop at all times
Open loop air to fuel ratio set all to 14.7
Fuel - power enrich - PE Enable TPS - HOT table set to 100% for all temps to disable PE mode.

I then started car, warmed it up & started scanning for a few minutes at idle, then did some mild & more moderate accelerations between 2,000 & 4,000 rpm, nothing with more than 50% throttle. My histogram populated initially with VE histogram.png ( a screen shot a took right after) however now when I open the scan file: 1-2-13 VE- run1.hpl the histogram doesn't seem to be populated??? Come to think of it, I think I forgot to click the "reset fuel trims" button. Is that why my LTFT are a constant 0 ??? (on my initial highway driving, they were pretty much 16.4 at cruising speed)

I'm sure there is something I don't have setup right... :-S

[Ace25]

help please do I need to bake some brownies and send on to y'all ??

[01abboud]

Okay, I'm no expert... but I DO know that the 01+ W-bodies dump fuel as a part of a catalyst efficiency test... and if they don't see a response from the rear O2 (which you've removed), it'll keep running the test in a loop for a ridiculously long time (my car was set to do it 18 times per trip). Your car appears to be doing the same thing. I'd be really surprised if you're not seeing a code for your front O2 not switching often enough.

You may also want to look at your vac lines... and consider blocking off your evap. Are you using the stock throttle body/maf?

There's a lot more to ask, but I'd start by putting the rear O2 back in place and see if the trims settle down. If that does the trick, add another bung and put your wideband back in. As far as I know, there is no way to disable the catalyst efficiency test with HPTuners. You can disable the rear O2 codes, but that's not the same thing.

[Ace25]

Thanks for the reply. I will temporarily remove my wideband and put the stock O2 back in the rear.

The question is, will this actually help matters? being I have no CAT the rear O2 is probably going to read the exact same thing that the front O2 is :-S

I'm not seeing a code for the front O2 (I did disable all rear O2 codes thought )

Here is what I did:
Engine error codes unchecked SES enable and set to no error reported:
P036 HO2S Heater Control Circuit Bank 1 Sensor 2
P0137 HO2S Circuit Low Voltage Bank 1 Sensor 2
P0138 HO2S Circuit High Voltage Bank 1 Sensor 2
P0139 HO2S Slow Response Bank 1 Sensor 2 (was already disabled / no error reported)
P0140 HO2S Circuit Insufficient Activity Bank 1 Sensor 2
P0141 HO2S Heater Performance Bank 1 Sensor 2
P0420 Catalyst System Low Efficiency
P0430 Catalyst System Low Efficiency Bank 2 (was already disabled)
P2A01 O2 Sensor Circuit Range/Performance Bank 1 Sensor 2

Also in the Engine, fuel -> COT (cat over temp) I set the engine coolant temp to 284. That should disable fuel being added to save the cats... ???

[01abboud]

No problem. My understanding is that the issue is that there's no response at all when the sensor is gone..... not that it doesn't like the answer. That, and it doesn't seem to matter what codes you disable, it still runs the test unless you can go deeper into the PCM and change the number of tests to zero (which isn't possible in HPT). I managed to borrow a DHP to do that with mine (well before I got the HPT), but your car isn't supported by a DHP even if you could get your hands on one. It seems like getting the rear O2 back in there may be your only option. It's certainly worth a shot.

On another note, you might get a little more traffic in the V6 Tuning section. I know there are some way more experienced people on here that might see it there. I'd imagine they know something I don't.

[Ace25]

I just removed my wideband and placed the factory O2 back in the rear... I was apparently mistaken that HPT could take care of it... On a side note, maybe I should contact them and engineer an aftermarket PCM that they are able to control all aspects of... One would think that would be easier then trying to reverse engineer each different PCM that comes out..