Thread: LTFT spikes to +16/other times perfectly fine

Results 1 to 15 of 15
  1. #1 LTFT spikes to +16/other times perfectly fine 
    GT Level Member PWNED's Avatar
    Join Date
    Jul 2008
    Location
    Hooksett,NH
    Posts
    399
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    Chats
    0
    I have been going in circles with this issue of my LTFT hitting +16 at times. Other times it is perfectly fine. I have sprayed brake clean and poured water on every vacuum line, gasket or rtv seal and trims will not change (usually -3-10 ltft at idle) Yes its rich but whatever. I even replaced my #1 o2 sensor with a genuine GM part. I have also replaced my BBV due to the findings of the orange diaphragm having a minor tear with no change. I have never kept an eye on my trims this much since my IC install at the beginning of this month. I want to say that I have watched my wideband dip into the 11's/12s (cruise/part throttle/idle) before my IC install so I believe this is an issue that has been on going. The car has no real issues with pulls. It does pull decent for what it is with no hesitation ever. At idle my fuel pressure is 45psi. At 2500 rpm it is at 44. When I got wot it will hit 62. Prime is 54 and will drop to 40 and rise back to 48. I have not tested fuel pressure when my issue happens due to the fact it is sporadic.

    Some screen shots but the actual logs are linked here to the hpt forum.

    http://www.hptuners.com/forum/showth...568#post383568





    02 Regal GS
    ZZP Headers/ 42#/ Intake/ S4 zzp sc/ Ported Lim/ LQ4/ HPT/ 3" to SuperTurbo/ Phenolic IC with 2.8 pulley/ XP/ Ported Heads
    PB-------12.3 @ 110.......312hp/350tq
    Reply With Quote  
     

  2. #2 Re: LTFT spikes to +16/other times perfectly fine 
    GT Level Member PWNED's Avatar
    Join Date
    Jul 2008
    Location
    Hooksett,NH
    Posts
    399
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    Chats
    0
    Today I removed the band clamp around my crossover and found a very minor leak (minor soot buildup) So I rtved the entire area where the pipe slips into and re installed the clamp. As well as rtving my map sensor just incase it was cracked and acted up due to heat. Nope.....nothing changed.

    I am at a loss to an extent. I am thinking there must be some table I don't know of that is making me lean. It will happen around 4000-5000hz at light throttle in cruise for the most part. But...not all the time. I even added 1% of fuel to 3500-5000hz and it didn't change.


    I am stock fuel pump. Maybe 100K on it? I am not sure as it was a used drop in. Maybe its getting hot and weak at cruise?? But it has no issue pumping out at WOT. When I first got the car 2 years ago it had an ebay 255 walboro and every now and then after driving and coming to a stop the car would die but would start right back up like nothing happened. Ended up being a bad pump so I ditched it for a stocker at the time.
    Last edited by PWNED; 05-18-2015 at 08:13 PM.
    02 Regal GS
    ZZP Headers/ 42#/ Intake/ S4 zzp sc/ Ported Lim/ LQ4/ HPT/ 3" to SuperTurbo/ Phenolic IC with 2.8 pulley/ XP/ Ported Heads
    PB-------12.3 @ 110.......312hp/350tq
    Reply With Quote  
     

  3. #3 Re: LTFT spikes to +16/other times perfectly fine 
    GT Level Member PWNED's Avatar
    Join Date
    Jul 2008
    Location
    Hooksett,NH
    Posts
    399
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    Chats
    0
    I did remember that the stochio was set to 14.1 by the pervious owner. I switched it back to 14.7 and no change.
    02 Regal GS
    ZZP Headers/ 42#/ Intake/ S4 zzp sc/ Ported Lim/ LQ4/ HPT/ 3" to SuperTurbo/ Phenolic IC with 2.8 pulley/ XP/ Ported Heads
    PB-------12.3 @ 110.......312hp/350tq
    Reply With Quote  
     

  4. #4 Re: LTFT spikes to +16/other times perfectly fine 
    Turbo is the way to go. BillBoost37's Avatar
    Join Date
    Jul 2009
    Location
    W Spfld
    Posts
    26,833
    Thanks (Received)
    53
    Likes (Received)
    90
    Dislikes (Received)
    1
    Chats
    98246
    We need two threads for this?
    I drink..so consider that when reading my posts.

    2010 Audi A6 Dual IC's
    Reply With Quote  
     

  5. #5 Re: LTFT spikes to +16/other times perfectly fine 
    GT Level Member PWNED's Avatar
    Join Date
    Jul 2008
    Location
    Hooksett,NH
    Posts
    399
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    Chats
    0
    Quote Originally Posted by BillBoost37 View Post
    We need two threads for this?
    Separate Issue it turns out now. That is why the new thread.

    Might have found something

    http://www.hptuners.com/forum/showth...568#post383568
    02 Regal GS
    ZZP Headers/ 42#/ Intake/ S4 zzp sc/ Ported Lim/ LQ4/ HPT/ 3" to SuperTurbo/ Phenolic IC with 2.8 pulley/ XP/ Ported Heads
    PB-------12.3 @ 110.......312hp/350tq
    Reply With Quote  
     

  6. #6 Re: LTFT spikes to +16/other times perfectly fine 
    GT Level Member PWNED's Avatar
    Join Date
    Jul 2008
    Location
    Hooksett,NH
    Posts
    399
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    Chats
    0
    Well unfortunately the IFR change did not help. The car decided to act up the other day and today. What am I missing? Could the maf be at fault? Or fuel pump? I did hear a noticeable tick from the engine area today only when standing in front of the car. The crossover pipe has been re sealed with rtv and band clamped weeks ago. I did not see any soot anywhere. It might just be the nature of the headers though. It does seem like the 02 got lazy or it saw something?



    02 Regal GS
    ZZP Headers/ 42#/ Intake/ S4 zzp sc/ Ported Lim/ LQ4/ HPT/ 3" to SuperTurbo/ Phenolic IC with 2.8 pulley/ XP/ Ported Heads
    PB-------12.3 @ 110.......312hp/350tq
    Reply With Quote  
     

  7. #7 Re: LTFT spikes to +16/other times perfectly fine 
    GXP Level Member Turbocharged400sbc's Avatar
    Join Date
    Jan 2008
    Location
    hangover park IL
    Posts
    2,714
    Thanks (Received)
    4
    Likes (Received)
    11
    Dislikes (Received)
    0
    Chats
    910
    welcome to the evap/purge emissions function.

    when the fuel vapor in the charcoal cannister is used up the purge is essentially a vac leak and trims go positive and the pcm can diagnose evap/purge and system integrity.

    99/00+ guys are ****ed with the more invasive tests of the eobd2. 04+ go full retard on the various tests and how many times its tested per drive cycle.

    block the purge line or unplug the purge valve. disabling the vent is harder
    ~James~ Psychotic Gearhead
    projects: 84 Cressida waGN~ 90 LN3 3800, equal length headers, T70, 89 700r4, misc parts,
    1994 Oldsmobile 442 (462ci-4wd-2 engines) L67/4t80e^2,
    00 Turbo Regal 608 fwhp 575ftlbs at 5500rpm, 98 WhippledRiv, 97 GTP
    Reply With Quote  
     

  8. #8 Re: LTFT spikes to +16/other times perfectly fine 
    GT Level Member PWNED's Avatar
    Join Date
    Jul 2008
    Location
    Hooksett,NH
    Posts
    399
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    Chats
    0
    Quote Originally Posted by Turbocharged400sbc View Post
    welcome to the evap/purge emissions function.

    when the fuel vapor in the charcoal cannister is used up the purge is essentially a vac leak and trims go positive and the pcm can diagnose evap/purge and system integrity.

    99/00+ guys are ****ed with the more invasive tests of the eobd2. 04+ go full retard on the various tests and how many times its tested per drive cycle.

    block the purge line or unplug the purge valve. disabling the vent is harder
    I have no evap on my car that's the issue on why I can't figure out why it does this. Where the purge line would go I have that capped off with a brand new plug.
    02 Regal GS
    ZZP Headers/ 42#/ Intake/ S4 zzp sc/ Ported Lim/ LQ4/ HPT/ 3" to SuperTurbo/ Phenolic IC with 2.8 pulley/ XP/ Ported Heads
    PB-------12.3 @ 110.......312hp/350tq
    Reply With Quote  
     

  9. #9 Re: LTFT spikes to +16/other times perfectly fine 
    GT Level Member PWNED's Avatar
    Join Date
    Jul 2008
    Location
    Hooksett,NH
    Posts
    399
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    Chats
    0
    Bringing back from the dead. Car has had a VE tune, new fuel pump, valve cover breather and will still act up.....at a total loss!! I even moved the 02 sensor close to the front header and no avail...at thos point I disconnect the 02 sensor to cut the BS out and am now tuning it as it should. What gives?!
    Reply With Quote  
     

  10. #10 Re: LTFT spikes to +16/other times perfectly fine 
    GXP Level Member GTPpower's Avatar
    Join Date
    May 2008
    Location
    Schuyler, NE
    Posts
    2,973
    Thanks (Received)
    8
    Likes (Received)
    23
    Dislikes (Received)
    0
    Chats
    265
    Your car is doing the cat diagnostic test. You need tiny tuner to shut it off.


    2001 GTP Drag Car - XPZ, Tischler heads, Upsidedown M90 IC'd, e85, Gen V, 2.3 w/ 5%OD
    2005 F350 6.0 - studded, deleted, tuned
    2001 GTP - cam, headers, nitrous, stock trans - 11.83 @ 116 <$2k in mods - sold
    Reply With Quote  
     

  11. #11 Re: LTFT spikes to +16/other times perfectly fine 
    GTX Level Member wstefan20's Avatar
    Join Date
    Aug 2017
    Location
    Raytown, MO
    Posts
    1,153
    Thanks (Received)
    33
    Likes (Received)
    63
    Dislikes (Received)
    1
    Chats
    34
    I fought this exact same issue for a few months. It ended up being a combo between the rear o2 sensor, and a tiny vacuum leak on the throttle body. I've got a great post on a diy smoke machine leak detector that works wonders. The rear o2 on 20+ cars can't 100% be tuned out. I had mine tuned out with hp tuners but left the rear o2 in place fully hooked up. That's enough to trick the test.
    Reply With Quote  
     

  12. #12 Re: LTFT spikes to +16/other times perfectly fine 
    Killa Bee Scottydoggs's Avatar
    Join Date
    Aug 2010
    Location
    new jersey
    Posts
    39,995
    Thanks (Received)
    63
    Likes (Received)
    166
    Dislikes (Received)
    5
    Chats
    243824
    the rear o2 can be turned off and kill the cat test with tiny tuner and a dhp only. or hack the vin in a bin and use old hpt to open the bin and save as a .hpt. this needs to be done if you dont have a cat, or run a hi flow cat on 01-03 cars.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, gen 5 N* 3.0 pulley, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW
    Reply With Quote  
     

  13. #13 Re: LTFT spikes to +16/other times perfectly fine 
    GT Level Member PWNED's Avatar
    Join Date
    Jul 2008
    Location
    Hooksett,NH
    Posts
    399
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    Chats
    0
    Quote Originally Posted by GTPpower View Post
    Your car is doing the cat diagnostic test. You need tiny tuner to shut it off.
    Is it still possible to download this? Using windows 10 now a days. Also unsure on how to go about deleting this diag test. Would I just bring in an hpt file or something?

    Quote Originally Posted by wstefan20 View Post
    I fought this exact same issue for a few months. It ended up being a combo between the rear o2 sensor, and a tiny vacuum leak on the throttle body. I've got a great post on a diy smoke machine leak detector that works wonders. The rear o2 on 20+ cars can't 100% be tuned out. I had mine tuned out with hp tuners but left the rear o2 in place fully hooked up. That's enough to trick the test.
    I have brake cleaned the entire engine bay. Trims would not budge meaning no leaks. I have yet to smoke it. But with it doing this +16ltft years a go I am sure it has noting to do with a vac leak as the IC has been off 4-5x. As I have had this happen on the highway a few times but more so in traffic at low speeds to the point that the car will stall out.....when its hot it will do it way more. I did some googling and people had the 02 simulator in and it still acted up. Hence there is noting for it to respond back to the pcm to say hey I see the fuel. I remember 1 particular day years ago. I was sitting at a light ready to go up a slight incline to my apartment and the car hated life. This might of been back when I just got the wideband hooked up to actually see that the car was in trouble. Now for my car as mentioned I did swap the #1 02 to where my wideband is (where the #2) should be and the wideband to where the #1 is. The car obviously still acted up. IT was just a test to see if it saw it on both banks just not one. Now lucky for me I can leave my wideband alone as I mentioned I moved the #1 02 sensor right under the throttle body so I have a 3rd hookup area in the location zzp made in their headers by the trans dipstick tube. I can re wire my #2 02 up as I had to cut the harness I had to make for the sensor swap and place my #2 02 in that spot so it can read. But even so the car will add fuel right? But maybe not as long? Just a split second thing that the car comes right out of it?

    I found this thread as well .

    Help with tuning a series 2 L67
    02 Regal GS
    ZZP Headers/ 42#/ Intake/ S4 zzp sc/ Ported Lim/ LQ4/ HPT/ 3" to SuperTurbo/ Phenolic IC with 2.8 pulley/ XP/ Ported Heads
    PB-------12.3 @ 110.......312hp/350tq
    Reply With Quote  
     

  14. #14 Re: LTFT spikes to +16/other times perfectly fine 
    GXP Level Member GTPpower's Avatar
    Join Date
    May 2008
    Location
    Schuyler, NE
    Posts
    2,973
    Thanks (Received)
    8
    Likes (Received)
    23
    Dislikes (Received)
    0
    Chats
    265
    Quote Originally Posted by PWNED View Post
    Is it still possible to download this? Using windows 10 now a days. Also unsure on how to go about deleting this diag test. Would I just bring in an hpt file or something?
    I think it can still be downloaded. I'm not sure if it works with windows 10 though.

    You need a bin file. Hpt does you no good. You need dhp to read the pcm as a bin file, then open the file with tiny tuner.


    2001 GTP Drag Car - XPZ, Tischler heads, Upsidedown M90 IC'd, e85, Gen V, 2.3 w/ 5%OD
    2005 F350 6.0 - studded, deleted, tuned
    2001 GTP - cam, headers, nitrous, stock trans - 11.83 @ 116 <$2k in mods - sold
    Reply With Quote  
     

  15. #15 Re: LTFT spikes to +16/other times perfectly fine 
    GT Level Member PWNED's Avatar
    Join Date
    Jul 2008
    Location
    Hooksett,NH
    Posts
    399
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    Chats
    0
    Thank you.....I have added the #2 02 sensor back and after a few weeks the car has not acted up!! As this was a daily thing basically.
    02 Regal GS
    ZZP Headers/ 42#/ Intake/ S4 zzp sc/ Ported Lim/ LQ4/ HPT/ 3" to SuperTurbo/ Phenolic IC with 2.8 pulley/ XP/ Ported Heads
    PB-------12.3 @ 110.......312hp/350tq
    Reply With Quote  
     

Similar Threads

  1. KR spikes under cruise
    By PWNED in forum PCM Tuning
    Replies: 0
    Last Post: 07-26-2014, 05:42 PM
  2. Random kr spikes during cruise control, wtf?
    By szalajka05 in forum 3.8L V6 Supercharged (L67)(L32)
    Replies: 2
    Last Post: 08-24-2013, 12:29 AM
  3. Replies: 1
    Last Post: 02-08-2012, 10:09 PM
  4. Sounded like a cracked flexplate, but it looks perfectly fine.
    By DanGTP in forum 1997-2007 4 speed Automatic (4T65E) (4T65E-HD)
    Replies: 10
    Last Post: 03-16-2010, 11:33 AM
  5. 96 gtp temp spikes
    By whiterider in forum Introductions/Noob Questions
    Replies: 4
    Last Post: 09-02-2009, 10:39 AM
Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •