Chevelles.com banner

1 - 18 of 18 Posts

·
Registered
Joined
·
1,533 Posts
Discussion Starter #1 (Edited)
FiTech 4 600HP and SBC test and tune

Motor
Low compression 350 SBC with about 15K miles on it
Cam specs with 1.5 ratio rockers:
lift .450 intake, .460 exhaust, duration at .050 222 degrees int/ext, lobe centerline 114, 10-12" vacuum in park 800 RPM, 8-10" in gear.
The motor runs 1.6 ratio full roller rockers, so the cam specs are different. Some say add .040, some say add .030 with 1.6 ratio rockers. I don't have the tools to measure it, so it is what it is.
Dart SHP intake, 3 inch open air cleaner
ProMaxx 185cc runner heads, 72cc combustion chambers, 2.02 intake valve, 1.60 exhaust.
Headman Elite shorty headers 1 5/8 tubes, 3-inch collector to 2.5.
Pypes x-pipe exhaust 2.5 inches to the oval tips at the rear bumper.
MSD 6AL, Summit pro-billet mechanical small cap distributor, MSD adjustable rotor, timing control
Walbro 255lph 60psi external pump, 6AN 3/8ths lines, return to tank and fuel filler neck from throttle body.

Back story
The FiTech self learning software couldn't figure out how to make a warm blooded motor run right when cold. I had occasional lean hesitation off idle and on off/on throttle transitions. This was not a rich condition the system was trying to lean out. Making it leaner made it a lot worse. I only had to change things a little bit to make it work. Having to make a few changes in my opinion does not make the FiTech system faulty. However, people can spin it anyway they like.

I have no trouble with starting cold or warm, or putting my foot on the floor. My motor works everywhere as far as I can tell. It doesn't misfire or nose over. It's no race car by a long shot though.

The Tune
Below is the cal file tune I ended up with as written by the ECU and read by the ProCal software. The ProCal software uses different nomenclature from the handheld, but it's close enough to figure out. The changes are subtle. A lot of it is defaults. Maybe it will work on another bolt-on modified low compression SBC that hesitates a little, maybe not. My idle exhaust does not smell like roses, it smells like a pre-smog exhaust.

AFR Control
Idle 14.40 (as lean as it will go without hiccups somewhere)
1100 13.65 (1100 is 1175 in breakpoints, ditto on the hiccups)
3000 14.75 (3000 is 2600 in breakpoints)
6000 13.40 (6000 is 5800 in breakpoints)
WOT 1100 12.70
WOT 3000 12.70
WOT 6000 12.70
WOT TPS Position 99.5
WOT Max AFR 12.50

Spark Map with Timing Control (2-wire VR+Coil)
Base Timing 16.5
VR Advance 17.6
Idle Advance 17.3
1100 22.1
3000 39.4
6000 39.4
WOT 1100 19.9
WOT 3000 32.3
WOT 6000 32.3

Fuel Transients
Accel Pump 20F -0.8
Accel Pump 65F 1.6
Accel Pump 170F 1.6
Accel Decay 20F -9.4
Accel Decay 65F -10.2
Accel Decay 170F -29.7
Fast Accel 20F 0.0
Fast Accel 65F 1.6
Fast Accel 170F 1.6
Fast Decay 20F 0.0
Fast Decay 65F -17.2
Fast Decay 170F -43.8
dTPS Acc Gain 111.3
dTPS Acc Max 139.8
Tipout -20F -62
Tipout 0F -62
Tipout 40F -60
Tipout 70F -60
Tipout 120F -57
Tipout 150F -44
Tipout 185F -42
Tipout 215F -48
Trans Enable DMAP 4.00

Fuel Control
Fuel -20F Cyl -3.1
Fuel 5F Cyl -1.6
Fuel 32F Cyl 3.1
Fuel 70F Cyl 6.3
Fuel 85F Cyl 9.4
Fuel 105F Cyl 10.9
Fuel 130F Cyl 12.5
Fuel 195F Cyl 12.5
Rev Limit RPM 6250
DFCO Enable Min ECT 68
DFCO Cut Fuel MAP 28
DFCO Return Fuel MAP 30
Fault Rev Limit 7575
DFCO dRPM Drop max -220
dTPS Fast Acc Gain 111.3
dTPS Fast Acc Lim 139.8
DFCO Time Drying 1175
Ring Fill PW Max 4.19

Cranking and Choke Fuel
Prime Fuel Multi 200
Crank Fuel Multi -0
Crank Open TPS Fuel Multi 114
Prime Shot Delay 1.5
Prime Shot Cranking Revs 2
Crank Mult 20F ECT -0.8
Crank Mult 65F ECT -23.4
Crank Mult 170F ECT -37.5
Choke 20F Fuel -2.3
Choke 65F Fuel -2.3
Choke 170F Fuel -3.1
Overall 20F Fuel -2.3
Overall 65F Fuel 0.0

PWM Pump Control
Fuel Pump Prime 4.0
Pump On RPM Low 30
Flow for Pump On 75
MAP for Pump On 95
TPS for Pump On 23.2
RPM for Pump On 2400
Volts for Pump On 9.0
Fuel Pump PWM Tbase 10
Pump Duty Low Flow 75.7
Pump Duty Mid Flow 95.3
Pump Duty High Flow 97.6
Low Fuel Flow 12
Mid Fuel Flow 26
High Fuel Flow 52

Settings (looks like a combination of breakpoints and other stuff)
Preheat O2 STALL 248
2Wire VR+Coil 8
Pump Volt PWM 248
Skip Injection 4
DFCO Return Fuel 40.6
Low MAP 45
WOT MAP 95
Low RPM 1175
Mid RPM 2600
High RPM 5800
Low Temp 21
Mid Temp 70
High Temp 162
Low Fuel Flow 12
Mid Fuel Flow 26
High Fuel Flow 52
Dwell Max Duty 56
Min Coil Fire Time 689

That's enough.
 

·
Registered
Joined
·
1,533 Posts
Discussion Starter #2
Changed 14.4 to 14.3 on idle AFR.
Changed 17.6 to 17.3 on idle timing

Starts easier and runs a little better of the bottom on the street.

Every motor is different. YMMV
 

·
Registered
Joined
·
1,533 Posts
Discussion Starter #3
Tom Mobley, or any other admin looking in here.

Can you delete this darn long useless post? I never tested what it would be like to use it. I tried using it today and got stuck on the parameter names being too far off from those on the handheld. I really didn't think it was as far off as it is. Quality control issue.
 

·
Registered
Joined
·
1,533 Posts
Discussion Starter #4
What I meant to convey was the names as listed are harder to map to the names on the handheld device than I had originally thought.

The values I actually am using, and they do work for my motor combo. I just wanted to test using the list as is, and it was near impossible.

Since nobody that can delete this long thing is reading it, I'll get up on my soapbox.

You guys that know how to tune carburetors and are convinced the EFI computer is smarter than you, need to realize the computer is only doing what it has been programmed to do by another guy, or gal. It isn't really smart at all in and of itself (if it has a self), and the programming wont always work out of the box for everyone. Especially if you want to get performance and a little bit of improved mileage out of the thing. I encourage you to experiment a little. It's real easy to set it back to a known good state.
 

·
Registered
Joined
·
46 Posts
Well Schwany, I see you have posted quite a few times for Fitech related stuff in other threads and you have a lot more experience on the fitech topic then I do. I find this thread very helpful as reference to see what kinds of changes you made and why. They are giving me some ideas on my setup. My SB355 is not too far off from your setup.

In fact, I'm going to use like 10 pages of paper in the printer and print this list, and then cross reference the default settings currently in my ECU. However, I'm going to take the advice given by many on several threads, make small changes and review the results before making additional changes.
 

·
Premium Member
Joined
·
3,657 Posts
To do a rough calculation of your cam lift, take your lift numbers (the lift WITH rocker arms, not the cam card lift), divide them by 1.5, then multiply them by 1.6. That will get you pretty darn close. I come up with .480 and .490 with 1.6 rockers.
 

·
Premium Member
Joined
·
6,262 Posts
small changes can make the difference some times.
 

·
Registered
Joined
·
1,533 Posts
Discussion Starter #8
Well Schwany, I see you have posted quite a few times for Fitech related stuff in other threads and you have a lot more experience on the fitech topic then I do. I find this thread very helpful as reference to see what kinds of changes you made and why. They are giving me some ideas on my setup. My SB355 is not too far off from your setup.

In fact, I'm going to use like 10 pages of paper in the printer and print this list, and then cross reference the default settings currently in my ECU. However, I'm going to take the advice given by many on several threads, make small changes and review the results before making additional changes.
Posting a lot about the FiTech EFI means I probably need my head examined more than anything else.

The list below uses the Handheld names, if you want to use up some more printer ink and paper.

AFR Targets
Idle 14.35
1100 13.65 (1100 is 1175 in my breakpoints)
3000 14.75 (3000 is 2600 in my breakpoints)
6000 13.40 (6000 is 5800 in my breakpoints)
WOT 1100 12.70
WOT 3000 12.70
WOT 6000 12.70
WOT TPS Position 99.5
WOT Max AFR 12.50

Spark Map with Timing Control (2-wire VR+Coil)
Distrib Base deg 16.5
VR Advance4000 17.6
Idle Advance 18.00
1100 45kPa 22.1
3000 45kPa 39.4
6000 45kPa 39.4
WOT 1100 95kPa 19.9
WOT 3000 95kPa 32.3
WOT 6000 95kPa 32.3

Accel Pump
Accel Pump 20F -0.8
Accel Pump 65F 1.6
Accel Pump 170F 1.6
Accel Decay 20F -9.4
Accel Decay 65F -10.2
Accel Decay 170F -29.7
Fast Accel 20F 0.0
Fast Accel 65F 1.6
Fast Accel 170F 1.6
Fast Decay 20F 0.0
Fast Decay 65F -17.2
Fast Decay 170F -43.8
dTPS Acc Gain 111.3
dTPS Acc Max 139.8
Tipout -20F -62
Tipout 0F -62
Tipout 40F -60
Tipout 70F -60
Tipout 120F -57
Tipout 150F -44
Tipout 185F -42
Tipout 215F -48
Trans Enable DMAP 4.00

Fuel Control
Afterstart 20F -2.3
Afterstart 65F -2.3
Afterstart 170F -3.1
Warmup 20F -2.3
Warmup 65F 0.0

Rev Limit Decel Cut
Rev Limit RPM 6250
DFCO Enable Temp 68
DFCO Cut Fuel MAP 27.50
DFCO Return MAP 30.00
DFCO Return Fuel 40.00
Dry Ring Fill PW 4.19
Max drpm Drop rate -220
Fault Rev Limit 7500

Cranking Fuel
Prime Fuel Multi 200
Crank Open TPS Multi 11.8
Prime Shot Delay 1.5
Prime Crank Revs 2.
Crank IAC Multi -21.9
Crank Fuel 20F -0.8
Crank Fuel 65F -23.4
Crank Fuel 170F -37.5
Afterstart 20F -2.3
Afterstart 65F -2.3
Afterstart 170F -3.1
Warmup 20F -2.3
Warmup 65F 0.0

AFR Closed Loop
Fuel Trim Max 45.3
Fuel trim Min -33.6
AFR Loop Speed 44.5
Idle Trim Rate Pos 38.
Idle Trim Rate Neg 10.
Idle Trim Jump Pos 29.
Idle Trim Jump Neg 6.
Fuel Learn Rate 29.7
Idle Fuel Learn Rate 9.0
Fuel Learn Max 29.7
Fuel Learn Min -35.2
Fuel Learn OFF 1 0
Fuel Loop OFF 1 0
Reset Fuel Learn 0

Idle Control
Warm Idle Speed 800
Rest Idle Learn 0
Idel Learn Max 40
Idle Learn Min 1
Loop aRate Up 35
Loop Rate Down 33
Fan RPM Addr 30
Fan Idle Steps 11
Decel Open IAC -40.6
Decel RPM Decay 9.4
Decel IAC Decay 0.7
Crank IAC 78.1

Fuel Pump Control
Pump Prime Time 4.0
Flow for Pump On 75
MAP for Pump On 95
TPS for Pump On 23.2
RPM for Pump On 2400
Volts for Pump On 9.0
PWM Low Flow 75.7
 

·
Registered
Joined
·
1,533 Posts
Discussion Starter #9
To do a rough calculation of your cam lift, take your lift numbers (the lift WITH rocker arms, not the cam card lift), divide them by 1.5, then multiply them by 1.6. That will get you pretty darn close. I come up with .480 and .490 with 1.6 rockers.
That works out to adding .030 to both numbers. Good enough or me.

Thanks
 

·
Premium Member
Joined
·
3,657 Posts
That works out to adding .030 to both numbers. Good enough or me.

Thanks
It will come out different with other cams. My cam has .510 .520 with 1.5 rockers, but it comes out to .544 .555 with 1.6 rockers. But the math is easy enough to do on it.
 

·
Registered
Joined
·
1,533 Posts
Discussion Starter #11
It will come out different with other cams. My cam has .510 .520 with 1.5 rockers, but it comes out to .544 .555 with 1.6 rockers. But the math is easy enough to do on it.
Yeah I noticed one of the numbers on mine came out with a weird fraction. It makes complete sense to do it your way. Not sure why I didn't run into that equation when doing a brief search on rocker ratio a while back

Thanks
 

·
Registered
Joined
·
46 Posts
Schwany, I finally got time to play with settings but had no idea what I was doing.

Since my engine is close to yours, I used your settings below:
Accel Pump 20F -0.8
Accel Pump 65F 1.6
Accel Pump 170F 1.6
Accel Decay 20F -9.4
Accel Decay 65F -10.2
Accel Decay 170F -29.7
Fast Accel 20F 0.0
Fast Accel 65F 1.6
Fast Accel 170F 1.6
Fast Decay 20F 0.0
Fast Decay 65F -17.2
Fast Decay 170F -43.8

I had to start somewhere as all of the above were ZERO on my system. When I say I used the numbers, I'm saying I got close to your numbers as I couldn't do 1.6, I could only do a 1 or 2, so I chose the numeral closest. Noticeable difference for the good.
 

·
Registered
Joined
·
1,533 Posts
Discussion Starter #13
Schwany, I finally got time to play with settings but had no idea what I was doing.

Since my engine is close to yours, I used your settings below:
Accel Pump 20F -0.8
Accel Pump 65F 1.6
Accel Pump 170F 1.6
Accel Decay 20F -9.4
Accel Decay 65F -10.2
Accel Decay 170F -29.7
Fast Accel 20F 0.0
Fast Accel 65F 1.6
Fast Accel 170F 1.6
Fast Decay 20F 0.0
Fast Decay 65F -17.2
Fast Decay 170F -43.8

I had to start somewhere as all of the above were ZERO on my system. When I say I used the numbers, I'm saying I got close to your numbers as I couldn't do 1.6, I could only do a 1 or 2, so I chose the numeral closest. Noticeable difference for the good.
I agree you gotta start somewhere. I read a lot before I started farting around with it. Even though FiTech doesn't go into a lot of detail regarding the functions, there is a enough info spread around on their site and in the docs they provide to get somebody up an running if they've tinkered with cars for a long time.

The factory tune works for some, not for others. My changes are really minimal. By the way, I went up on the accel pump numbers up for 65F and 170F, since my motor just happens to like more fuel when not fully warmed up. The shift from 1st to 2nd with a 700R4 and higher (3:36?) rear end gears is the problem. It's a big gear change and can make the car nose over a little if there's not more fuel there when it's cold and I'm crawling around on neighborhood streets. Flooring it that doesn't happen though. I tend to tune for how I normally drive though.

If you just use the joystick to make your adjustments the system picks the numbers for you. It's pretty smart about it. I usually edit the ones I really only want to go up or down a little on. With that said, sometimes it works and sometimes it changes the values anyway after a key off/on.

One thing I don't care for when tuning with the handheld is it is a PITA to change several values in different tuning menus on the handheld without turning the key off and back on again. I know what I want to change and am not afraid to change a lot of things at once. It slows me down on testing ideas. Boo hoo.. On the other hand, I like the FiTech because it is tuner friendly.
 

·
Registered
Joined
·
46 Posts
The factory tune works for some, not for others. My changes are really minimal. By the way, I went up on the accel pump numbers up for 65F and 170F, since my motor just happens to like more fuel when not fully warmed up.
I was just logging-in to post my findings and see you already suggested going up on these numbers. I've been adjusting the Fast Accel 170F setting. I'm already up to 8. I had a pretty good hesitation at 3, I went to 1 and it got worse so I went in the other direction with 5. Had improvement. Went to 6, better. Just set it to 8 but will need to wait till tomorrow to do more testing. I'm looking for a good snappy throttle response when I slap my foot on the peddle, TPS to 100 for 1 second and back down to 0.
 

·
Registered
Joined
·
46 Posts
I haven't been driving much to do the kind of testing I had hoped but I just had a nice update to throttle response on this thread. This was a discovery moment for me so I'm bumping this thread.

I went from only seeing around 2500rpm on a crack of the throttle to now upwards of 4500rpm on a throttle wack.

After watching the infamous "Nabors" Fitech tuning videos on youtube where he mentioned starting at 20 or 30 on the "Fast Accel 170F" setting, I had to wonder what the heck. My motor was falling on itself if I had anything above 3 on that setting -- way too much fuel. If you really dig into Nabor's videos and all the various messages in these forums, the Fast Accel is directly tied to the "dTPS Acc Max" setting which translates into the percentage on how fast fuel is squirting that "Fast Accel 170F" fuel shot. Out of the box, my unit had the "dTPS Acc Max" at 198. Turns out that is way too fast of a squirt for my motor. Every time I punched the pedal I had good throttle response but the RPM rarely went above 2500rpm. Fast Accel at 3 was barely enough fuel to get me a big RPM hit.

So here I was getting ready for my annual Wildwood NJ trip and I started to try different settings. I set the "Fast Accel 170F" to 20 and naturally it was killing my motor. However, I backed off on that "dTPS Acc Max" setting from 198 to 120. Pow! I now have the larger fuel shot to get me a nice load of fuel for quick 4,000+rpm burp. Backing off on the dTPS Acc Max was a major turning point in how I'm seeing these configurations work. Reminds of the all the different pump cams on a holley carb. I added a load more fuel but backed off on how fast all the fuel squirts. Still have more trial and error to do. My goal is to blow the wig off granny in the car next to me kind of throttle wacks.

I did also try adjusting the "dTPS Acc Gain" setting which is pedal sensitivity, I had it up to 190 but wow, I couldn't drive my car. Way too sensitive. Very wicked throttle response but it made me look like I never drove a stick car before. I left it at 111 which is where it was out of the box.
 

·
Registered
Joined
·
1,533 Posts
Discussion Starter #16
Mike,

My numbers may have been based on an engine with a cam, lifter, or both on it's way out. The backfiring up through the throttle body the day I first put the FiTech on was a symptom that went away with more fuel and timing. I'm investigating the flat cam right now, since it finally started making a lot of rocker noise on the odd bank side of the motor, and I had no power when putting the gas pedal on the floor before that happened. Might be time to upgrade my engine to something designed in this century. >:)

Good info on dTPS acc max and the accel pump relationship. :thumbsup:

Thanks for the update.
 

·
Registered
Joined
·
1,533 Posts
Discussion Starter #18
You can thank Nabors for posting a video on youtube:

The info I gathered started with that video.
OK

I tried fooling with those settings and the throttle responds better. Gas gauge moves faster toward empty as well. >:)
 
1 - 18 of 18 Posts
Top