throttle surge on cruise control at light throttle

Thanks Mike,

That makes perfect sense.... Good thinkin! :thankyou2:

I will post the results of changing springs...

I tried to reply to your PM but could not cuz of forum rules of having less than 10 post... this is #10.... Yeeaah! I'm legal now :hehe:
 
Mine will do it ever so slightly when coming down the slightest hill with cruise. I'm 100% stock minus a muffler and BD Crazy Larry. I don't think it ever did it without BD CL. But mine is a very slight surge.

U said rail pressure surges with it. I would view this as a major hint. Surging rail pressure at idle causes engine surging, why couldn't it at cruise speeds with the TQ Conv. locked?
I'm not all up on the pump-hop-up kit and raised lift pump pressures, but I could see those either causing the problem themselves, or maybe you have a FCA beginning to get a harry spot in it where it can't hold a certain rail pressure perfectly. Often times this occurs at idle though, cause that's where the FCA hangs out a lot.
 
Changing the spring out for lower pressure (15 PSI SETTINGS) and it did not solve the problem of surging during cruzz control.. Changed smarty settings and it stopped/changed it for the better.. I believe higher RP on the Smarty TNT settings causes it to surge...
 
well, i have had the smarty (and the boost fooler) off the truck for about 2 weeks awaiting the EFI live to get here and it still surges. at first i would have told yall its not as bad but it just depends on the speed and the load of the engine v.s. the downhill slope.

right now im pointing twords either the FCA or the RP sensor. i hate to buy either of them without knowing but something's gatta change.

truck runs fine everywhere else but i can def. see the RP surge when cruising at slower speeds (less load on the motor). 55-60 on cruise is a bastard.... i can see it in the RP gauge before it starts... i will see a slight twitch and if i dont tap the brake within about 2 seconds it starts bucking like a rodeo bull. im surprised i havent lost a u joint because if it, seriously.


My plan as if right now is to wait till rob emails my tune back to me. i have often wondered if the post event is to blame at all but the truth will be told with i get this new tune with EFI live going because the post event will be gone.

other than that, im thinking RP sensor is in my near future.. its my second one already.....

any thoughts on RP sensor v.s. FCA being the cause??????

EDIT::: i also wanted to mention... when the surging happens bad/ long enough and i let it recover on its own. the ECU looses track of "set cruise speed" sometimes it will drop 4-6 mph before it recovers! i thought that was STRANGE. there's another marble in the mix to think about....
 
Update for those of you still wondering...


i have replaced the FCA, RP sensor and VSS. I have also changed several parameters with EFI live and it still exists. Only thing left is the Cp3 itself, which i know for a fact from data logging is on its way out.

Once shane gets done with my 10mm pump ill let you guys know if anything changes.
 
Subscribing, I'm having the same problem but it will also surge with cruise off if I maintain my speed around 50mph. What are your engine's RPMS at when it surges, just curios, mine are around 1500-1800 and with just a little throttle the surging goes away. Good luck I hope you find a cure!
 
I've got an 06' that does something similar. To me it just feels like its taking the slop out of the drive train and nothing more.
 
imfasterthanu82 said:
Subscribing, I'm having the same problem but it will also surge with cruise off if I maintain my speed around 50mph. What are your engine's RPMS at when it surges, just curios, mine are around 1500-1800 and with just a little throttle the surging goes away. Good luck I hope you find a cure!
Click to expand...

rpm's dont really seem to matter. it does it at 35 mph (just above idle) and it will do it around 70 (2000) if im going down hill. like i said, its only on cruise control and NEVER occurs other wise.

we are about to send a log with the rail surging to EFI live because they too are confident it is tunable if they can just see when its happening. in my case it could just be a commanded value that is trying to adapt to the speed sensor via cruise control, but once again, we can see what cruise control is trying to do yet so we are in the dark as of now.
 
We said to Marcus and his tuner Les that if they can send us some logs, we'll take a look at what is happening and see if we can find some new parameters for them to test with.

At the end of the day if Marcus is having this problems, others will be too, so lets see if we can work on a tuning solution to fix it. I can't promise we have a 'magic cure' but I can promise to investigate.

Cheers
Cindy
 
EFI Support said:
We said to Marcus and his tuner Les that if they can send us some logs, we'll take a look at what is happening and see if we can find some new parameters for them to test with.


Cheers
Cindy
Click to expand...

Would you believe that i drove around today for about 30 mins trying to MAKE it surge and of course... since i was data logging... it wouldn't skip a lick.:nail:

it was scurrrrrred bif its days are numbered!
 
SixOhh said:
Would you believe that i drove around today for about 30 mins trying to MAKE it surge and of course... since i was data logging... it wouldn't skip a lick.:nail:

it was scurrrrrred bif its days are numbered!
Click to expand...

argh; good old Murphy's Law at work hey!

Cheers
Cindy
 
have this same issue will want to run away on me on higher levels of the newest smarty tntr programming. it doesnt do it all them timebut when it does it only does it from like 50 to 65 mph for me though. have a stage 2 ii pump but i believe it did it before the pump was installed
would really like to know what it is it seems when i reset my apps it will work so maybe it is related to the tps or your tv motor possibly

hopefully it is a tuning issue and when efi comes out for the SCI trucks this will be rectified
 
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SixOhh said:
Would you believe that i drove around today for about 30 mins trying to MAKE it surge and of course... since i was data logging... it wouldn't skip a lick.:nail:

it was scurrrrrred bif its days are numbered!
Click to expand...

Any luck?
 
mine does it worst from 70to 75 i would have to say is related to tuning any luck six ohh
 
mine does this really bad with the smarty it will constantly give it throttle then let off then give it throttle and let off. very annoying It has done it when the truck was basically stock with just the smarty and up to what it is now with an LBZ CP3 and 120hp injectors. Im leaning towards the smarty on mine but I might try the cruise relearn
 
I have this on my 07, but to me it seems like it is in the transmission more than the engine surging. I do not have a smarty, but the truck does have an Edge J/A and it will do this on every setting when you crest a hill and the load is reduced. Could it be the VB acting up or converter trying to lock/unlock repeatedly?
 
^can't say for sure but I don't think so. My 07 does the same thing and it's a 6-spd.

Just like everyone else said its noticeable when the load goes away. Like going down hill with the cruise control on. Only mods are a 5" turbo back straight pipe and a smarty. I've got 145,000 miles on it and I've just decided to live with it.
 
Any more updates on this? Sorry for bringing up an old thread but my 2003 does this stock or with smarty with or without cruise on and when accelerating through my gears and really bad at 55-65 cruising. Rail pressure and fuel pressure surges...

Edit, this is on my scheid 150 injectors and stock 6.7 cp3. Exergy and ats aren't installed yet
 
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