major fight
10-22-2008, 06:16 PM
#1
TECH Resident
Thread Starter
iTrader: (3)
Join Date: Oct 2006
Location: Northern NY
Posts: 868
Likes: 0
Received 0 Likes
on
0 Posts
major fight Alright guys I am about to kill my car. I have be trying to figure out a good tune for it and cant seem to get rid of one problem. I have based most of my tune off of a 05 gto that has similiar mods and was tuned by a pro and runs great. I have a 99 z28 and I can not get it to stop bucking and jerking. It is awful at 1500rpms and bucks and jerks when I give it gas. My only solution so far has been to just give it gas and keep it about 2k rpm.
What I am doing wrong here? Should I be looking at something in particular since it seems to be a issue with giving it gas? please any help or guidance on what I should look at changing to help tame this crazy car.
Also I am using hptuners.
What I am doing wrong here? Should I be looking at something in particular since it seems to be a issue with giving it gas? please any help or guidance on what I should look at changing to help tame this crazy car.
Also I am using hptuners.
10-22-2008, 07:40 PM
#2
Moderator
iTrader: (11)
Join Date: Mar 2002
Location: East Central Florida
Posts: 12,604
Likes: 0
Received 6 Likes
on
6 Posts
Look at the narrowband O2s and see if bucking is
coming on from a lean condition? If so then you have
something to chase down - why.
If you deleted EGR, take a look at the spark adder
for EGR; is bucking coming with a high advance?
Higher than the main spark table says for RPM and
g/cyl air mass?
GTO will have some differences from your motor
and you might want to spend some time getting a
list together. Different MAF? Different displacement?
Something has to account for suck vs great.
coming on from a lean condition? If so then you have
something to chase down - why.
If you deleted EGR, take a look at the spark adder
for EGR; is bucking coming with a high advance?
Higher than the main spark table says for RPM and
g/cyl air mass?
GTO will have some differences from your motor
and you might want to spend some time getting a
list together. Different MAF? Different displacement?
Something has to account for suck vs great.
10-23-2008, 01:22 AM
#4
TECH Resident
Thread Starter
iTrader: (3)
Join Date: Oct 2006
Location: Northern NY
Posts: 868
Likes: 0
Received 0 Likes
on
0 Posts
specs I believe are 226/237 110lsa at .550 lift.
Swaped on my aftermarket maf and it helped alittle. Seems like I am not getting enough air. Def gonna check into the egr thing.
Swaped on my aftermarket maf and it helped alittle. Seems like I am not getting enough air. Def gonna check into the egr thing.
10-23-2008, 12:13 PM
#5
Jedi Master
iTrader: (3)
Join Date: Apr 2007
Location: MN
Posts: 668
Likes: 0
Received 0 Likes
on
0 Posts
I hvae the same issue after I swapped cams. Bucking under 1500rpm...I think I might have too much timing, been too lazy to look at it lately. Will try tonight though to lower the timing in my HO timing table.
10-23-2008, 12:20 PM
#6
TECH Resident
Thread Starter
iTrader: (3)
Join Date: Oct 2006
Location: Northern NY
Posts: 868
Likes: 0
Received 0 Likes
on
0 Posts
When it is doing the bucking spark is going from around 22 to 29 and just bounces all over within that range. Just a jagged line on the tuners. Map pressure is usually around 45 also.
Trending Topics
10-23-2008, 03:27 PM
#8
TECH Resident
Thread Starter
iTrader: (3)
Join Date: Oct 2006
Location: Northern NY
Posts: 868
Likes: 0
Received 0 Likes
on
0 Posts
It does it when I dont have my foot on the throttle. Also when I give it gas such as in third gear doing 25mpg at 1300-1500 rpm it bucks like crazy untill I get around 2k rpm
10-24-2008, 07:31 AM
#11
Jedi Master
iTrader: (3)
Join Date: Apr 2007
Location: MN
Posts: 668
Likes: 0
Received 0 Likes
on
0 Posts
Fixed my problems last night by doing two things:
A. Adding advance in those cells
B. Reducing the transition of timing between cells in that area. I had a transition of 4 degrees between 1400 and 1600rpm.
A. Adding advance in those cells
B. Reducing the transition of timing between cells in that area. I had a transition of 4 degrees between 1400 and 1600rpm.
