Tuning Help?
Thread Starter
Cruising
Joined: Sep 2008
Posts: 11
Likes: 0
Tuning Help?
New corvette owner.... Recent mods, AFR 1031 Heads, GMPP LT4 Hotcam, harland sharp 1.6 rockers, AFPR, Headers, borla exhauest, 30lb injectors and stock intake port matched to heads. had the ecm tuned for new mods but having some driveability issues. When i'm cruising at constant speed low MPH seems like its loading up car tends to buck like it wants to run. At higher RPM or WOT shes great. Does anyone have any suggestions or similar symptoms. Could really use some help here
Racer
Joined: Jul 2007
Posts: 313
Likes: 0
From: Laurel MS
New corvette owner.... Recent mods, AFR 1031 Heads, GMPP LT4 Hotcam, harland sharp 1.6 rockers, AFPR, Headers, borla exhauest, 30lb injectors and stock intake port matched to heads. had the ecm tuned for new mods but having some driveability issues. When i'm cruising at constant speed low MPH seems like its loading up car tends to buck like it wants to run. At higher RPM or WOT shes great. Does anyone have any suggestions or similar symptoms. Could really use some help here
Smooths out @ higher RPM.
Thread Starter
Cruising
Joined: Sep 2008
Posts: 11
Likes: 0
thnx for the feedback... When i did the mods i installed a new opti, msd 6al,msd coil and wires i think it may be my tune... i've been driving the car monitoring engine data, when the car "breaks up" my timing reads 43 @65mph 9% tps. whenever the timing is over 39 she breaks up...
IS it the tune?
Ignition?
Any Ideas?
HELP!
IS it the tune?
Ignition?
Any Ideas?
HELP!
Racer
Joined: Aug 2001
Posts: 288
Likes: 1
My car did that after similar mods. We noticed the Short and Long
term Fuel trim was making one bank go super rich and the other super
lean. All boiled down to getting the LT header primary pipes to seal.
THis was not easy. The head are a d shape and most header
flanges are round, there is not a great amount of extra material
on stock LT4 heads at the flange face for a round pipe to seal too.
In the end I welded my flanges
to match the head, so there is more surface area for the gasket to seal
and used a Felpro 1406 gasket (EM's suggestion). I also used ball/seat
flanges at the header collector as the slip fit were not sealing and that
is right next to the 02 sensors. Once the leaks were fixed the LT counts
remained stable and the ST counts returned to normal and the car runs
as good as it did stock (just more power). It could be a lot of things
but I would start by capturing some data (DataMaster) and go from
there.
term Fuel trim was making one bank go super rich and the other super
lean. All boiled down to getting the LT header primary pipes to seal.
THis was not easy. The head are a d shape and most header
flanges are round, there is not a great amount of extra material
on stock LT4 heads at the flange face for a round pipe to seal too.
In the end I welded my flanges
to match the head, so there is more surface area for the gasket to seal
and used a Felpro 1406 gasket (EM's suggestion). I also used ball/seat
flanges at the header collector as the slip fit were not sealing and that
is right next to the 02 sensors. Once the leaks were fixed the LT counts
remained stable and the ST counts returned to normal and the car runs
as good as it did stock (just more power). It could be a lot of things
but I would start by capturing some data (DataMaster) and go from
there.
Thread Starter
Cruising
Joined: Sep 2008
Posts: 11
Likes: 0
I'm going thru that pain right now... i had the right bank header off twice already for leaks around the cylinder head flange. Afr heads and hooker headers not a happy fit. still have some small leaks i hope three times a charm cause its a pain in the @ss
