BuickMike

This will be long, but bear with me. I got a bunch of stuff for my TBSS a few months ago all at once. I did TR6's, MSD wires, PCMforless trans cooler, 160 thermostat, 3 wire cable upgrade, LS1 E fans, PCMforless harness, & PCMforless tune. It also has a Vector intake that came on it when I bought it. I was going to get it tuned locally, but the guy I was going to use (STAGEUP) was incredibly busy. I got impatient and went with the canned tune. I regret that now.

After doing all this I gained some top end, but lost alot of bottom end. It bogs until 3500RPM's and pulls hard after that. Fuel economy also went way down. I ended up having STAGEUP log the truck for me and we found out that I was running super rich. I bought 2 HPT credits and he adjusted the fuel tables a little to see if that would help.

The truck still didn't feel right. I went through and put the stock wires back on. No difference. I checked all the plugs and regapped. No difference. I finally got a MSD Dashhawk so I could get an idea as to what was going on. I am still learning how to use it and didn't log anything, but here is what I observed. I'm hoping to get some insight on what I should be logging so I can get things sorted out. I am starting to read up all of the tuning FAQ's and keeping an eye out for a used HPT so I can do this myself. I really don't want to bother Rhett anymore because his time is short and I've already spent enough money on tune, HPT credits, and DH to have just bought HPT Standard suite.

My truck eats a ton of gas at idle. I can pull 18-19mpg with 100% flat fwy driving, but city drops down to 10.

Initially I checked vacuum at idle. Only 15Hg or around 43KPa. I get 22 if I rev it a little and it holds.

Timing at idle is 8-9 degrees. This seems a little low and would possibly explain the low vacuum and excessive fuel usage.

When I accelerate (WOT) timing is at 12 degrees until I hit 3500RPM's. After that it jumps to 16 and ramps up to 20 by the top of the RPM range. This is with 105 degree IAT's) Even mild acceleration below 3500 pulls the timing back to 12. I didn't see any spark retard st this point. I grabbed the general knock PID so I never got to see if I was getting alot of knock or not.

LTFT's were generally around -9% at idle and -14% to -17% while cruising. They would go down a little as I hit higher RPM's. They were around 10% at 65mph.

STFT's seemed to stay between -3% and -4% at all times.

I also looked for misfire counts as I was suspecting a faulty plug or wire for a long time. I accelerated and watched each cylinder. Counts and history. Nothing. Not cruising, WOT, light acceleration, or idle. There was one time where I was on a different screen that I put total misfires on and it hit 2 one time when I nailed it from a roll. I couldn't reproduce that.

At this point I'm trying to figure out what parameters to collect for logging so I can get it off to a tuner to review. I need to follow up with Alvin. Not sure if he'll still be willing to help me since I had someone do some minor tweaks after the fact. It was more of a convenience thing.

Old Geezer

iTrader: (3)

Vac leaks?
Exh leaks?
Why the 160* stat?
Try a bone stock tune, yet?
Lazy O2's?

BuickMike

No vac leaks

No exhaust leaks
--I'm sure the low vac at idle is directly related to 7-8 degrees of timing. I also
have plenty of vacuum if I have the RPM's up a little (more timing at that
point) and it holds, so I'm ruling out bad cats.

160 t-stat is a common mod that goes with replacing the belt driven fan with electric fans. The fans are set to start coming on around 180 or so an the truck stays around 190-200. Again, this is very common in the TBSS world.

I have not reverted to a stock tune, however when I did have the stock tune I was getting 15mpg city and had much more low end.

How can I tell if the o2's are lazy? What can I look for or log on the DH?

Old Geezer

iTrader: (3)

Next, I'd get either a EFILIVE or HP suite, do some logs, post the tune files...

MUSTANGBRKR02

iTrader: (91)

When you scan the o2's should be jumping from low to high ie 100-800 and form a peak and valley pattern.

jakes4321

iTrader: (7)

Start over!!!

Compare stock timing table to the table u have, I bet you have less timing down low...

What canned tune do you have? pm it if you prefer

BuickMike

I am still waiting to find a good deal on a used HPT so I can look at the tune. Until then, I have no way to look at the tables. Timing under acceleration is stuck at 12 until 3400 RPM's and it jumps up. Could this have anything to do with the VE table??

My original tune is from PCMforless. I didn't get back to them because I didn't have a way to reflash my PCM or even log it at the time. I couldn't have my TBSS down so I couldn't mail my PCM back to them either.

BuickMike

Front o2's jump around. Rear o2's do not. I'm guessing that's ok?

Frost

iTrader: (45)

Just don't waste the money on HPT standard; get the Pro up front. You need it to accurately log wideband, and that's what you need to fix your truck.

BuickMike

That's the plan. If I can't find a used one, I will probably wait for a friend of mine to find a G8 GT and split the cost with him.

Schwanke Engines

iTrader: (1)

So, you spent $250 on a dashhawk, just to see what was wrong? Dude, just get the tuning software and recover some of the cost by selling the dashhawk. Sounds like you are running into the TCS all the time. I would doubt that there would be a straight 12 deg. of timing in your tune, but, then again, I have seen worse.

BuickMike

I got it used for $80. In hindsight I should have just bought HPT Pro, but oh well.

BuickMike

A good friend of mine just bought an 09 G8 Gt, so we're going to go in on HPT Pro together within the next month. I definitely need to do some tuning on the low end for sure. I noticed that anything over 55mph the LTFT's stay very close to zero and timing is at 38-39 degrees at cruise. It's only when I hit a certain load that the timing falls off to 12 degrees. It jumps right back up to where it should be when under a load (24-28 degrees depending on IAT) once I hit 3500RPM's.