New User-- Unhappy with professional dyno tune. Low speed bucking BTR2 Cam

[MustGoFast]

Hello,

First time poster who is very new to HPTuners and LS1 tuning in general. Be nice!

1999 Camaro 6spd 4.30 gears
BTR2 Cam Kit .613 .576, 227-234 113+3
Ls6 Intake 60lb injectors (i know kinda big)
1 7/8 headers 3.5" exhaust

Car made 421whp and runs great above 2500rpms.

My complaint is low speed driveablity 1200-1800 the car likes to (buck, surge, trailer hitch, (lean misfire?)) during low load low speed applications. Car seems to be better when cold and the complaint is the worst when the car is hot siting in traffic.

I uploaded my Tune File and an Marathon Data Log (the last 4 minutes I was cruising back home and it was surging the entire time).

I tried taking my car to the tuner twice and they said that's how these cars run and they did the best they could.

Thoughts? I'm learning and reading as I go.
low load bucking.hpl
Camaro 421whp tune.hpt

[Ben Charles]

I can make that rig in 6th gear cruise at 40 with no buck...

[podium]

I can make that rig in 6th gear cruise at 40 with no buck...

So throw the guy a bone!



I agree, thats any easy cam to tune. The VE table has a lot of fuel taken out of it for that cam in some spots but that could be due to injectors. Are they 60 pounds at 3 (43psi) or 4 bar (59psi)? Do you have a wideband? Would really help to see where your fueling is at.

You can also copy your High octane spark table to your low octane. I also like to copy the rpms my car likes to idle from the idle table to the main spark table. An example would be I would copy the 0,400, 800 and 1200 column and rows from the IDLE SPARK ADVANCE and paste it to the same rows and columons in the MAIN SPARK ADVANCE HIGH OCTANE table, then copy the whole HIGH OCTANE TABLE to the LOW OCTANE TABLE. The timing seems high in certain places (idle and off idle transition) for that small of a cam.

[DrLoch]

Sure is a pretty VE table though

[lukearmstrong1990]

Hello,

First time poster who is very new to HPTuners and LS1 tuning in general. Be nice!

1999 Camaro 6spd 4.30 gears
BTR2 Cam Kit .613 .576, 227-234 113+3
Ls6 Intake 60lb injectors (i know kinda big)
1 7/8 headers 3.5" exhaust

Car made 421whp and runs great above 2500rpms.

My complaint is low speed driveablity 1200-1800 the car likes to (buck, surge, trailer hitch, (lean misfire?)) during low load low speed applications. Car seems to be better when cold and the complaint is the worst when the car is hot siting in traffic.

I uploaded my Tune File and an Marathon Data Log (the last 4 minutes I was cruising back home and it was surging the entire time).

I tried taking my car to the tuner twice and they said that's how these cars run and they did the best they could.

Thoughts? I'm learning and reading as I go.
low load bucking.hpl
Camaro 421whp tune.hpt

few things I would recommend.

set your clutch activated DFCO coolant temp to 141c and MAP value to 0KPA to rule out unwanted fuel shutoff.

set all your throttle follower, cracker and rolling idle tables to factory. then disable rolling idle by setting top value to 410kmh and bottom to 0kmh

disable your bust knock by maxing airlow table and fill spark table with 0

make your idle and main spark tables identical from 0-1200rpm.

set rolling idle target at 0kmh to 875.

then you need to set your throttle blade to where the car will comfortable idle at target speed when warm on 8-11degrees advance. if you have adjustable stop screw that in and reset the 0% TPS position. if you cant adjust it then drill a 5/32-3/16 hole in the blade to allow the required air in.

set your idle spark in the main tables to between 8-11* at 800 rpm. then use ETC multipler to add spark to help it when its cold. then use idle table to remove or add timing if it rev hangs or tries to stall respectively. your logger will tell you which areas. generally 0.08-0.24 g/cyl in the 0-2000rpm area.

see attached example 232/234 .598.598 112 in 5.7 manual. drives like factory with a 3/16" hole in the throttle blade

final 395rwhp.hpt

[Chrome_Rust]

few things I would recommend.

STUFF

then you need to set your throttle blade to where the car will comfortable idle at target speed when warm on 8-11degrees advance. if you have adjustable stop screw that in and reset the 0% TPS position. if you cant adjust it then drill a 5/32-3/16 hole in the blade to allow the required air in.

STUFF

final 395rwhp.hpt

I have been chastised for this on many other forums and facebook groups. I have been told that this isn't the correct way to make the vehicle idle. I don't mean to hijack, but this has been the only time I have ever seen someone mention this and also seems to know WTF they are talking about.

[Ben Charles]

It?s all about iac and fueling... sometimes you have to (normally larger camshafts)

[tbrtuning]

I think most act like drilling is being done instead of tuning properly but they don't realize tuners that know what they are doing check to see if the IAC has enough range before drilling.

[kingtal0n]

Many engines have throttle blade adjustment screws to open or close the blade at idle.

Drilling a hole is the same as that: you are opening the blade at idle.

As a mechanic with 15 years of exp (including tuning various cars) I never like to drill anything unless there is no other way. I hate putting extra holes in things.

Not saying it doesn't work, or that it isn't "correct". Some folks do and its fine.

however, I always look for other way to correct the issue without drilling holes.
The engine simply needs more idle airflow. The piston sucks on the intake manifold; not the throttle body. If the intake manifold needed "more air at idle" all you need to do is create a small 'vacuum leak'. For example the PCV valve is a 'vacuum leak' that sucks on the crankcase. The brake booster hose is a 'vacuum leak' that sucks on the brake booster. If you pump the brake pedal at a stop light the idle will increase slightly and the a/f ratio will lean out slightly because of this leak. there are lots of little 'leaks' all around the intake manifold and together they represent the "drilled hole in the throttle body" i.e. 'extra airflow that the IACV doesn't need to know about'.

With this in mind, feel free to create any number of 'new leaks' for the intake. yeah you can drill one into the throttle body, but thats a permanent hole. Instead, why not add a vacuum hose with a filter that sucks air. This way you can easily close it off/delete it anytime you wanted to. instead of having a hole in a place that you can't easily close.

Its all the same though; tuning to get the engine to do what you want.

Most of the time low speed bucking is erratic timing and fuel related. Smooth the VE map, get proper a/f ratio, and a add stable timing digit (check the 0.00X's place in the tune file for decimals that make sense)

[1364838952]

EOIT? If I'm not mistaken those are stock #'s in the tune. Also, what kind of fuel are you running? I've heard that if you are on E10 that you should change your stoich AFR to 14.08 in the tune. Yours is currently set at 14.63 (stock?). Thats all I saw that the other guys did not cover. Very nicely blended VE table!

[lukearmstrong1990]

as I have said every time I have offered some methods for trial to guys having idle and return to idle with LS1 PCM and DBC throttle fitted with large camshafts, the way I do it isn't technically "correct".

with significantly greater amounts of time spend logging and idle tuning could be altered so the mechanical changes (air bleeds) have little to no effect. however sometimes there are time restrictions and an IAC motor can only physically add or take so much air. sometimes the engine requires more than that with big cams. in my opinion I believe that if the IAC is constantly operating on its limits, then its beyond a resolution that can reliably operate repeatedly and provide idle that never stalls, including when parasitic load like A/C or P/Steer relief is applied while the car is already trying to add airflow to maintain idle.

the way I have suggested and the way in attached files are what I finds to work best for me. I find I can achieve reliable idle and return to idle characteristics in all operating conditions.

but I'll take the criticism from anyone onboard as there is ALWAYS room to improve and I still learn with every car.

[SultanHassanMasTuning]

Camaro 421whp tune VE.hpt


i never do MAF on these platforms especially cammed