14.49 ET @96mph. HELP!
This is a discussion on 14.49 ET @96mph. HELP! within the Firebird / WS6 forums, part of the Vehicle Specific category; Originally Posted by 0rion To the K&N debate.....that's been ongoing for years. Personally I've ran the same one for about ...
09-22-2015, 09:11 PM #41
Last edited by Naaman; 09-22-2015 at 09:15 PM.
09-23-2015, 03:57 AM #42
- Join Date
- Feb 2009
- Mansfield, PA
Black & Blue
- '02 WS.6 / '07 Suburban
Just a heads up - manually shifting the car you may experience a delayed shift. It is a common issue with the 4L60E and there are some threads on here about it. Also, I am one of the anti-K&N advocates based on personal experience. They simply allow way too much dirt into an engine as compared to a quality paper or dry nanofiber style air filter.
09-23-2015, 04:10 AM #43
With that kind of mileage, I would think the cats are probably clogged up. When your on the highway and floor it, does it seem to pull up to the redline decent? It will be a little difficult, but you can test the clogged cats theory by disconnecting the exhaust where the cats meet with the headers and make a pass down the track with no exhaust. IMO, I would just upgrade to some stainless steel long tube headers, with no cats. Then stop by and see FROST and have him give ya a tune. Your lucky to live so close to him. He's located in Richmond VA.1998 Pontiac TA, stock heads, FAST 90, FAST 90 TB, FLP LT, off road y-pipe with cat delete, flow master muffler, comp cams 54-457-11 223/231-610/617-112 LSA, Pro charger D1SC with FMIC @ 8psi, FROST tune, VIG 3200 stall, built 4l60e, snow meth kit, MOSER 12 bolt 373 gears, Derale 13900 trans cooler.
09-23-2015, 04:17 AM #44
I had a 1984 Pontiac TA given to me on time. The previous owner was told he had a bad transmission, cause the car wouldnt go over 60 mph on the highway. When I got the car, the 1st thing I did was have my girlfriend hop in the car and give it some gas a few times, revving it up to 4000-5000 rpm's, while I was at the tailpipe checking to see what kind of exhaust flow I was getting. Turns out, hardly any exhaust was coming out. So I just dropped the cat out with a few bolts. Took my trusty screwdriver and hammer and smashed all the guts out of the converter. Reinstalled the body of the cat onto the car, then went for a blast down the highway. Problem is solved. Car ran like never before. Cost of repairs, zero dollars.
09-23-2015, 04:37 AM #45
My experience with K&N is much like Orions, never an issue with any car. I've been running them since the 1980's on various things. I honestly don't believe that's what is going on here.
I also think Orion was on to something when he mentioned your gear ratio, as if hinting the rear gear has been changed and it might not match the RPO code.....
If that's the case, it would explain your odd shifting issues because at least 2 things have to happen in the computer to command shift points, one of which is MPH, which would be off if the gear was changed from stock. The other is commanded RPM. The 2 just won't pair up properly with a rear gear change if the computer tune hasn't been corrected for it.
That thing should be shifting on it's own up near 6,000. However my bone stock 2002 SS was very similar. It shifted on it's own on the 1-2 at about 5500, but held the 2-3 shift to 6,000 with it's stock tune. The low rpms on the 1-2 shift doesn't help things because of the horrible gear spread the 4L60 has (3.06 drops to 1.62) I found when doing my tuning that if I commanded the 1-2 to hold as high as I could get away with (stock cam and valvetrain) my ET's improved. So I commanded the 1-2 at 6100-6125 while logging which helped the huge rpm drop in 2nd gear, left the 2-3 at 6,000.
It's quite possible that a simple tune would help this car tremendously.
The stock tune on my 02 SS was absolutely horrible in my opinion, with the shift points not where they should have been, plus my fuel trims were + or - 10-12 and always hunting. After I tuned it the fuel trims came into a more acceptable + or - 2 to 3 and shift points where they worked best, the car picked up 3 tenths and almost 3 mph, still a bone stock car otherwise.
Last edited by Firebirdjones; 09-23-2015 at 04:43 AM.
09-23-2015, 11:25 AM #46
09-23-2015, 11:27 AM #47
I went ahead and swapped in a Fram paper filter today.... While it was off, I couldn't help but do the Free Ram Air and EGR tube mods :-) please forgive me for changing several variables at once. At any rate, I took the car round the block and did not register anything different on the butt dyno :-(
09-23-2015, 11:43 AM #48
Thanks for asking the question. That's even worse!
So let me tell about how we came up with the 3.23 ratio. I went to replace my outer wheel bearing about a year ago. Before doing so I watched a ton of YouTube vids about it because I have never worked on a diff before. So all vids I watched showed a clutch type carrier.
When I opened mine up, there was a helical gear type carrier, Torsen came to my mind. We then looked at the stamped numbers and came up with the 3.23 number, knowing nothing of the RPO codes at the time.
So question 1- does a gear type posi diff belong in this car stock? If so, any idea why none of the YouTube fbodies had it? Rare?
Question 2- if it does not belong as a factory option maybe my 3.23 calculation was correct?
Question 3- if this all does sound normal, what gear set is recommended? I do put a lot of highway miles on it.
09-23-2015, 11:53 AM #49
Last edited by Whamhammer; 09-23-2015 at 11:55 AM.
09-23-2015, 12:01 PM #50
So we are getting somewhere.
RPO code shows the car as a factory 2.73 geared car, which means that's what the tune is setup for from the factory.
If you in fact have 3.23's, someone has swapped the rearend with another most likely and that would explain funky full throttle shifting. It would also mean your speedometer is off and reading too fast.
Torsen diff came about around 1999 or so, so that would be correct for your car.
09-23-2015, 12:06 PM #51
Anything is possible, the previous owner could have killed the original diff and put another one in that did have a set of 3.23's in it, couldve swapped the gears too. Does the vin o. The door match the vin on the windshield, could be a different door too. Best thing to do is to recount the teeth on the gearsets, or count the turns of the driveshat to the turns of the tire.
As far as the best gear to have depends on you future plans for the car. 2.73's on a 4L60 make a final drive of 1.91, which is great for highway cruising, bad for fun with the loud pedal.
09-23-2015, 03:18 PM #52
Excellent detective work! So the crappiest gearset available with larger OD wheels compounding the issue might explain the ET/MPH differences I have versus a stock performance optioned car.
I think I see there is likely no components failing, I just have a bad combo for top acceleration.
Well that's good. I don't need to try to find a bad part... I can instead use my time and resources to start hoping this thing up. :-)
PS- the door and windshield vin do match
Thanks for all your help guys!
09-23-2015, 03:33 PM #53
Speedo says 50mph.... Gps says 52mph
09-23-2015, 04:38 PM #54
09-23-2015, 04:50 PM #55
09-24-2015, 12:32 AM #56
09-24-2015, 12:44 AM #57
Hedderz!!!!!!Lid, Throttle Body, LS6 Intake, Stage 1 Heads, Mild Cam, Magnaflow Cat-Back, LS7 Clutch, SFCs, STB, Panhard Bar, Strano Springs, Strano Sway Bars, LCAs, Konis (F), Bilstiens (R), MGW Shifter
09-24-2015, 08:54 AM #58
09-24-2015, 11:48 AM #59
09-24-2015, 05:28 PM #60
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