High LTFT's, Can not resolve, need help!
This is a discussion on High LTFT's, Can not resolve, need help! within the Computer & Tuning forums, part of the LSx Technical Help Section category; My Predator still shows very high LTFT's (~ 20) using factory tune loaded. I have pulled the intake and put ...
07-01-2011, 04:23 AM #1
High LTFT's, Can not resolve, need help!
My Predator still shows very high LTFT's (~ 20) using factory tune loaded. I have pulled the intake and put it back with new gaskets/seals, redone the complete pcv system, repaired the brake booster hose, and pretty confident that I do not have any vacuum leaks.
What else can cause the high LTFT's? Could a bad O2 sensor or cat casue this? Could the PCM itself have an issue?
Get a random P0174, P0101, and some Cat code, but infrequently.
Car has SLP lid, BBK 80mm TB, BBK SSI intake, and flowmaster welded into to stock SLP SS exhaust. Other than that, stock. Air systme removed, but did this before that was done.
This is getting frustrating.
07-01-2011, 04:27 AM #2
- Join Date
- Feb 2009
- Mansfield, PA
Black & Blue
- '02 WS.6 / '07 Suburban
Those mods would absolutely result in a higher than stock airflow through the engine. On a factory tune the PCM has to add fuel to maintain the correct air-fuel ratio. You probably just need a tune.
Assuming you have eliminated other potential issues, a MAF that is mis-reporting airflow could also add to the problem.
07-01-2011, 08:11 AM #3
I'm with Jeff, you've changed the entire intake setup including an aftermarket BBK intake manifold.
You really should get the car somewhere and have a tune done.
Little things like a lid or a muffler you can get by with,,,but changing that intake manifold is pretty major. If your 02's are old (50,000 miles or more) I'd swap them out anyway before a tune.
07-06-2011, 07:01 PM #4
+20 is a lot though generally speaking, even with the mods.
Unplug the MAF. Clear the LTFTs wither with your tuner (if it will do it) or unhook the battery for about 15 seconds. Start the car up and drive it and see what the LTFTs do. If they are significantly lower, your MAF may be on the way out. When they go, they don't quit, they report low.
07-07-2011, 09:44 AM #5
Will try the MAF thing after I see what the sensors do. I also have a Granatelli MAF I can throw in to see what changes that yields.
Jon35th Anniversary LE # 167 SLP # 1084
07-07-2011, 02:02 PM #6
If you are throwing the GMAF, throw it in the woods.
07-07-2011, 05:05 PM #7
08-11-2011, 06:47 AM #8
08-11-2011, 11:16 AM #9
Well, finally got around to trying this MAF disconnect, and the difference was dramatic. Bank 1 LTFT's stayed very close to zero all the time. Always low single digits if not. Bank 2 was another story. The STFT's hit +50 and LTFT's hit +25 at one point. The the LTFT's settled in around +11. Then close to coming home (about 20 miles later), the Bank 2 LTFT's were low single digits to zero.
I have had a fairly frequent (not every engine cycle, perhaps every 4th) P0174 code which is related to Bank 2. As I mentioned in earlier in this thread, I do have a GMAF I may put in just to see if it behaves better than this OEM one.
Should I be looking for a NEW OEM MAF now? Should I get an LS6 version?
Last edited by jfl330; 08-11-2011 at 11:19 AM.
08-11-2011, 09:48 PM #10
It took you a MONTH to try unplugging the MAF for SD? You need to not drive the car with this issue. If things are so far off that you have +30 trims, every single throttle transition will be lean and will want to knock at tip in.
So you sound to have a dead misfire or more than one on bank2 or a leak in the exhaust big enough to pollute the sensor's reading at low airflow such as idle. You really don't want to be driving the car with it flooding one side like this.
08-12-2011, 05:12 AM #11
Thanks for your support!
08-12-2011, 05:50 AM #12
Check your Fuel Pressure, my LT's were at 25% and it was because the hose on my Walbro FP had popped off.
08-12-2011, 06:10 AM #13
08-12-2011, 07:47 AM #14
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By Ed Blown Vert in forum General HelpReplies: 0Last Post: 06-29-2011, 01:00 PM
By Red 99 T/A in forum General HelpReplies: 5Last Post: 07-26-2010, 08:04 PM
By Ed Blown Vert in forum Almost Anything GoesReplies: 0Last Post: 01-21-2009, 06:00 PM
By SeVeReDiStOrTiOn in forum Computer & TuningReplies: 2Last Post: 04-06-2007, 06:14 PM