Cammed ls1 surging

[tunnagrunt]

Hi guys,
I'm pretty sure I know what the answer will be but I just want some confirmation. I have a C4b with 224/234 cam, shaved heads, under drive and the usual supporting mods. Recently did a manual conversion and therefore a retune. This thing is a pig to drive under about 1800 rpm which makes it very hard in stop go , speed bumps etc. I took the missus for a drive today and she thought it was gonna rip the gearbox out!

At revs under 1800 it surges badly and gets worse if I don't push the clutch in, to the point that it is smashing the input shaft of the gear box back and forth pretty violently. There is very minimal slop in the shaft though.
I've done some googling and it seems it is in the tune as people claim to have bigger cams than mine putting along with no probs.
Do people on here with cams have surging troubles or should it be tuned out of it?
I need the tune tweaked anyway due to revs hanging with the air con running. It's a bugger that the tuner is 2 hrs away too.

 

[07GTS]

yea some tuners say to just keep the revs over 2k and it will be fine, but what they should be doing is spending more time tuning the under 2k area more, some cams will just have a bit still there but most of it should be controllable just takes more time to get better

 

[Darcon666]

Leaning towards the tune as well.

One of my toys has a 228/228 cam +Heads +Springs +Lifters(301rwkw) LS1 and its Manual and drives live stock... However, it did take 3 stabs @ the tune.

 

[tunnagrunt]

Thanks guys.
Coming from auto to manual I wasnt too sure. I spoke to a mate with a similar size cam than mine and he said his drives perfect right from idle.
I got the tune done at a shop with a good rep but just goes to show that everybody can't get it 100% right every time. I sure hope he gets it right the second time cause its a real pain taking it 2 hrs away for him to look at it

 

[Red LS1 V8]

Cam surge is an interesting one, I have a manual LS1 with a baby cam tuned by a well known Sydney workshop and mine still does it, I was told all the LS1 Manual do it with anything but the smallest cams although the newer engined cars don't. Its most noticeable at ultra low revs like car parks etc. I just adapted my driving style which I think most people do as I am pretty sure I can get in and make most cammed and tuned cars do it, even for mates who tell me their car drives like stock but it may be a tuner thing too and I haven't experienced a car that has had this dealt with.

 

[bozodos]

Cam surge is an interesting one, I have a manual LS1 with a baby cam tuned by a well known Sydney workshop and mine still does it, I was told all the LS1 Manual do it with anything but the smallest cams although the newer engined cars don't. Its most noticeable at ultra low revs like car parks etc. I just adapted my driving style which I think most people do as I am pretty sure I can get in and make most cammed and tuned cars do it, even for mates who tell me their car drives like stock but it may be a tuner thing too and I haven't experienced a car that has had this dealt with.

My VZ L76 was doing this with a small cam, the tuner was able to tune it all out with some extra data logging that I did for him. I didn't like how it carried on at pretty much walking pace in car parks.

 

[07GTS]

surging and bucking are two different issues, surging (rpm going up and down like a wave) should not happen with basicly any cam and if it does it can be tuned smooth again, bucking (jerking around at low speed low rpm) is a little more to deal with and does depend on the cam most should be tunable to get to a normal state but some can still have a bit of it left over its basicly the ecu trying with what it has to control the poor air flow at low speeds with the cam, its few timing and related tables and fueling few tables can all be adjusted to help and some extra tables thats too many to go into, u can easily spend hours getting it dialed in especially when alot of tables affect other areas also so it all has to work together for it to be good

 

[Red LS1 V8]

Yes, by surge I was referring to "bucking". I was told with the newer, larger 6L + motors most normal sized cams can have this pretty much tuned out, especially in an auto but in a manual 5.7 any cam with a decent amount of intake and tight LSA will see bucking at really low speeds.

I would have thought a 216 or 218 on the intake would be small enough but apparently even that's too large without going to something with lots of negative overlap, wide LSA etc

 

[tunnagrunt]

I'm booked in to have it looked at tomorrow so I'll see if it improves. Mine is bucking but it's really full on for a mild cam. It does it at any revs under about 1800. I can't have the clutch out when going around corners, roundabouts etc. With 3.7 diff gears it always seems to be in that spot where one gear is revving a bit high and the next bucks like a bitch.
60km/hr in 3rd gear attracts to much attention but 4th gear is just on the limit of the bucking.
I expect a bit of it but it's a real pain when I can't go around corners properly.
Hopefully after tomorrow it is a bit more street friendly
My mate has a 228/228 112 cam in his and it drives nice and smooth where mine is a 224/234 112 and is a pig.

 

[tunnagrunt]

OK so I had the tune looked at again on Saturday which has made a huge improvement. After more than two hours of tweaking, driving, logging and retweaking, the driveability improved by about 70%.
It turned out that the mechanic originally "turned off" all the original auto parts of the tune and then retuned it. There was hidden auto stiff in the background that was playing up. Once he wiped my tune completely, flashed a manual tune from another car and then copied all my tables across to that tune....huge improvement. The hanging revs with the ac on disappeared and the bucking was cut by at least half. My Tps was giving slightly inconsistent voltage at heavy throttle, which affected the idle a bit afterwards.
Today I installed a new Tps and wound the throttle bump stop open a smidgen and the bucking is about 90% gone.
It idles a bit higher now at around 820-850 but is heaps more street friendly.
It seems I can make it buck at one particular throttle position but a bees dick either side and it's sweet. I can live with that
Thought I'd update the thread for anybody having the same issues in the future.

On another note, had a close call worth the local constabulary the other day. Turns out their automatic number plate checking software can be wrong. Two female cops pulled up beside me at a stop light and said my rego had expired. Lucky they were in a good mood and gave me a warning. I went home and checked it out, it's paid up to November 2017.
Rang the cop shop and they checked their system, finding that I was right. So lucky that those ladies didn't pull me up to push the subject, as there are just a few things that would warrant a yellow sticker. ...tinting, otr, cam, exhaust, non load rated 18's on a tonner. I would have been up **** creek all because of a computer glitch!