Surging Problem

[TooCoolHemi]

Guy's the Hemi truck community has a problem that i would like to make you aware of.Most of us with a bigger than 260ish cam have a surging problem.This surge varies in intensity from truck to truck.The surge is prominete usually below 2,000 rpm's.This surging happen's on take off and stopping.It will also do it under lite throttle while crusing.I have watched the rpm's dance and felt the truck surging. Sometime's it won't stop till you change the amount of throttle.Some have just learned to live with it.It seem's i have one of the worse case's of it.(so it bother's me more)On a lite take off you can hear the motor surging and with each surge the rpm's slowly rise.This is annoying and i know it's hurting performance in this rpm range.The stopping surge can be more dangerous though.At it's worse when stopping the rpm's will dip down to below 400 rpm and then jump up as high as 1100/1200 rpm.(idle set at 700rpm)When the rpm's jump back up this will sometime's cause the truck to luge forward.(Try this one when trying to park between 2 parked car's at your local Wal Mart) It was doing this the other day when i went to do a quick take off to get in traffic.I caught it in the dip and the truck hesitated when i went to accelerate.This caused me to hit the brake and left the nose of the truck in the highway.(Glad the oncoming driver was paying attention) Thankfully i was the only one in the truck at the time.This surge seem's to not care about what cam or the tuner (hand held) being used.If you have a bigger cam you have this problem to some degree.My tuner has tried to resolve this problem and has effected it,but can't seem to get it gone.My new tuner believe's it's a combination of the cam and the long tube hedder's we all run.He think's he can solve the problem but dosen't have the adjustment he need's to make in the cmr software for the truck's.He is requesting that Exhaust Transport Delay be added to the software.I'm requesting to add this to the software so we can try to solve this wide spread problem.(not for our sake's but for our family's who are riding with us and other's on the road.) Any help you guy's can give will be deeply appriciated.Not to say make us all much happier and safer.Thank's guy's for listening.

[mikel]

Does he know if that table exists in some other software, or is he assuming that because that may work in a Ford, it should work here??

I have to say, this clearly sounds like a tuning issue, and this is not something I see in the LX world, and those guys are running HUGE cams compared to that 260.

[TooCoolHemi]

Mike he is one of the best LX tuner's.He dosen't tune the truck's but is tuning my truck to try help me solve this problem.I'm quessing this is one of the adjustment's he is using to tune the LX's.I just sent the link to this thread to him.I'm sure he will post up once he see's it.

[mikel]

Cool, if he can get logs and a copy of the tune we can help

[TooCoolHemi]

Awesome Bro!!! If you guy's solve this your going to make a lot of us very happy.

[whitehemi]

Joe and I talked for a long time yesterday and it appears he has the worse case of this I have heard of, Maybe if Joe could get Mike the tuner to call Diablo Sport they could collaborate and come up with a solution for Joe.

The other part of this surge is when your driving in 5th gear at about 45 mph/1500 to 1800 rpms it appears that the TC is trying to lock up. It appears to lock then un lock and if you speed up ever so slightly it locks and the surge disappears too.....

[392stu]

The log looks as such: As the short term fuel trims get real rich, the rpm starts to fall. when they finally figure out there is too much fuel in the exhaust stream, they pull a bunch of fuel, and the rpms jump back on target, overshoot lean, and start to fall again. It then repeats.





On the LX cars, if you have a 5.7 thats gets a set of SRT shorty headers and has a *slight* surge even with a solid tune, it is FULLY remedied by a move of the Exhaust Transport Delay tables from an SRT to the 5.7 tune. Things with Long tubes usually like a LARGE bump in the transport delay table before the lean/rich surge goes away....

[392stu]

Attaching files...

[FAhemiST]

this is good. hopefully a remedy for this is around the corner. and hopefully it can be applied to SCT as well

[TooCoolHemi]

Mike do you think it's possible to give this log a look at today and let us know what you think?

[johan]

Give this one a shot.....

[TooCoolHemi]

Thank's Johan.I'll get it loaded into the truck and report back.

[TooCoolHemi]

Just got back from a 50 mile test drive.The stopping surge is not happening anymore.It hold's the rpm's up when stopping now.There's a slight rpm swing in the higher rpm when stopping.But if you don't look at the rpm gauge you would'nt know it's there.(i can live with that and would like to see what the adaptive's do with more mile's on the tune) In the base tune of 104 (I know it as Stu's tune 10) once the adaptive's learned the stopping surge was lite.)On your tune the rpm's have not dropped below the set 700rpm idle and seem's there was no learning curve.The tune had no effect on the take off surge though.You can still hear and see the motor surging on lite take off.It will do this when trying to maintain a 45 mph or lower with a lite throttle.(Which the truck see's alot of with the speed limit's around here.) Johan this is where the problem begin's so to speak.Usually the adjutment's made to help this,usually make the stopping surge get worse.On a side note: the take off surge got a little better when i updated from crom 3 to the last temporary crom before crom 9.(just thought i'd mention that) I was playing with adjustment's on the DSP at that time so not sure what happened.The improvement has seemed to have stayed though.(all setting's are back where i had them and this surge was as bad as the stopping surge at one time.) Also noticed Mike's throttle adjustment in that tune is gone.Look's like 1 down 1 to go.(If you need a log just let me know.)

[johan]

Ok, yeah a log will help of that scenario you describe.

[TooCoolHemi]

Johan i have 3 log's of that tune already would you like the other 2 or you want a new one of your tune?