Ragtop 99

iTrader: (7)

Eliminating cam surge from off-idle to 2000 rpm will vary by set-up and cam size, but it would be helpful to post a summary description of the tuning tweaks made to reduce or eliminate it. Please post a general description of:

mods (i.e. cam only or H&C)
cam duration and LSA
tweaks to timing between 1200 - 2000 rpm
tweaks to VE table
changes to Idle Air in gear
Anything else you did specifically to solve non-idle cam surge.

I'd like to see if we get a tuning pattern depending upon cam size or overlap.

samz28

what do you mean surge off idle? I only get surge when at 0% tps and that can be cured im sure, but i just reset the in gear IDLE higher than average which solved that problem in a meathead kind of way.

you get surging while your on the gas? if i touch the pedal 1% TPS the surging goes to nill at 900rpm locked up in 4th or 3rd but as soon as i go to 0% tps surging occurs locked up.

There is also a surge at cold/warm start and right when you hit the 1mph (set low) point. (ie going from 0mph to 1mph) which is where the ecm is set for movement.

Tuner did work to get the surge completely away at 1% tps and moving, but theres some bugs that still need to be worked out. Meanwhile (new house) i just turned up the IDLE higher (like 1200) in gear and 0% tps surging is gone. I'm guessing if i get a wideband on her she's running too rich. Keep in mind when i say i set the idle at 1200 desired, the car may be at 0% Tps 900rpm's locked up in 4th but not surge. However if i set the idle desired to 900 it would surge. I'm guessing the IAC counts are letting more air in which is similar to 1% Tps.

might just have to open the TPS blade a little more and turn the idle back down but no time

Ragtop 99

iTrader: (7)

By off idle, I mean at low TPS, say like enough TPS to hold the car at 40 mph in OD on a level surface. If I'm going up a slight grade so that I'm into the throttle (e.g. TPS >10%), I don't have much problem.

I had used a similar solution to what you suggested (opened up the TB, more idle air) when I had my 232/236 cam and that pretty much cured it, but it also caused a cruise control effect. The car would want to pull along 1600 rpm with my foot off the gas. I now have a 228/228 114 and I think this should be easily cured, I just need to be pointed in the right direction.

furiouSS99

iTrader: (-1)

He means from (wherever your idle is set) to about 2000 rpm-in that range where surging is most prevalent.


I have a fairly small cam (220 on a 114lsa) and I have no low speed driveability problems or idle issues (I went through about 15 flashes until I was happy). I cruise along in 5th around 1050 rpm and 40mph very smoothly-none of that bucking bronco surge feel Oh yes, my idle is a steady 800rpm.

Here is what I did for part throttle:

In the VE tables from 400 and 800 I reduced by 60 and 70 % respectively, going any higher in rpm didn't do me any good (I believe the pcm is splitting the difference in table values between rpm ranges so this worked out just right for me).

High octane timing map: added 1 degree of timing from 400-800 rpm range and .08 to .32 g/cyl engine load.

Idle airflow tables: like everybody else, I tried the nogo suggestions and they seem to work fine as-is for me, so I haven't played with them anyfurther to see if I can improve

idle speed: recurved the rate at which it drops versus temp, so when its hot outside(and the car is fairly warm) the idle dosen't immediately drop down to 800-it helped my hot start idle from fluctuating in that first minute until it settles into a steady 800...I know, I can probably tweak the airflow tables but this was easier and faster.

I have no idle issues with decel or snapping the throttle shut and coming to a stop-so I didn't mess with decay rates.

This is just my .02 cents-It works for ME, and my particular combination-I'm not saying anyone should do exactly what I did.

samz28

yah cruise control effect is a side effect. i'll have to read up on others suggestions. I wonder if you turned off the closed loop mode if it would help or hurt. I did notice that less timing increased the effect.

Ragtop 99

iTrader: (7)

Furiou:

Thanks for the suggestions. When I had a 224/224 114 I had no issues past 1400 rpm (with almost no tuning) and zero issues with a 218/218. I know that with the right changes to either the VE or timing tables I should be able to get this cam to do as well as my 224 cam which had no real tweaks beyond idle air and idle rpm.

samz28

I tried the nogo suggestions and they seem to work fine as-is for me, so I haven't played with them anyfurther to see if I can improve

^^ what are these suggestions.

My only problem is warm restart surging, and cold start (10 seconds warmup) to gear surge/stall.

What do you guys have your idle follower mph set to? 1mph/2mph? (low/hi)

Slowhawk

iTrader: (12)

It really matters what Cam you use since each Cam is different.Some Cams up to 224's I don't really touch the VE tables.Some I do..
For idle and surge these are the main tables I work with.

idle speed
IAC
Idle follower
idle timing,park,gear
High octain timing table
crank VE
Secondary VE
Main VE
Decel follower

Ragtop 99

iTrader: (7)

Slowhawk:
I know different cams will be different, that is why I was hoping that people would post what cam they had and what tweaks they made. Anyways, I have a 228/228 114 +4 if you have more specific thoughts.

BTW, when does the secondary VE table come into play?

Cheatin' Chad

iTrader: (3)

to the top

WS6snake-eater

to the top again...this is an excellent question.

JNorris

iTrader: (4)

One more time.

Sunset01

I have TR224 on 114. The Nogo basics worked pretty well, but I had an annoying cold startup surge/difficulty in idling. I finally did the open the throttle blade up (with TPS disconnected to make sure it resets to zero)- that worked pretty good and absolutely no cruise control.

Only remaining issue is 4th gear cruise w/ lockup .. ie. where I'm only around 1000rpm, the car flutters a bit and it feels like it is rattling the play in the rear sometimes... wish I could find a way around that one.. usually is to grab 3rd gear manually!

Another_User

I have been tinkering some more...I think it comes down to more idle air, throttle cracker, and pulling some low-rpm timing. I'll post when I am done testing.

SMOKIN01TA

iTrader: (10)

id like to get some answers to this question also, i have a baby 243/249 cam and above 2500 is fine but cruising in any gear below that with little load on the motor, well i fell like im riding in a rodeo. it happens just randomly. i know at wot im pulling 30* of timing but not sure what it looks like in low rpm range. do you thing pulling some out in the lower range would help, or i remember a mention of opening up the tb a lil more.

Sunset01

After just taking the car out, I'm changing my mind. 4th gear, more like 1100-1300 rpm, around 40mph is my issue-- but the engine rpm doesn't vary when fluttering happens- the fluttering is all in the rear. It's just like the backlash in the rear gears is exacerbated.

samz28

most tuners just unlock at those speeds.

Sunset01

Thanks. I'll try pushing it up a little further. My car locks much earlier than where I tell ls1edit to do so.

samz28

ttt lets figure this out. I'd try increasing DFCO MAP entry/exit each +5 (try 4 successive variants).

disable closed loop mode during those rpm times (for ORY folks only)

1fastWS6

iTrader: (3)

Good topic. I've just finished getting rid of the idle surge and now need to work on the part throttle cruise. I think I'm going to play with the timing a bit first and see if that helps.