5.3litre

iTrader: (6)

please tell me there is someone..i have been working to fix this problem the last 2 days and have had no luck at all..everytime i make a change it either gets worse or has no effect..i want to be able to cruise at low rpms without the car shaking me to death..i have added tons of timing and taken timing away and i have also played with the ve table..adding and taking fuel away..btw my cam is a 233/239..so what the hell can i do to fix this annoying *** problem?

02sierraz71_5.3

iTrader: (2)

thats a huge cam for a 5.3, the only other person I know with something that big is flyer. I would raise the tcc locking points to keep away from rpms below 1500 and raise idle rpms, what size stall? I would also open the throttle set screw around 270 degrees from the stock position and adjust idle air tables and iac. That should help in the parking lot at low speeds. But im sure you know a cam that big in a small V8 is not going to perform at rpms under 2000.

CAT3

iTrader: (9)

I cant say I agree. Yeah the difference in cubes is there, but not that damn much to my friends 5.7L with a TSP Torquer V2. It doesnt surge around. All I done for tuning is flipping the TB Set Screw and opening the blade some (reset the TPS), added idle timing, reduced VE at idle tables and finally raised the idle to 875 or 925. Now, if your just "playing around" with VE thats probably not the best answer. Once you can get it to idle, you should do the VE tuning which will establish a well tuned idle fueling, then work the timing. Some ppl have to change the RAF's, use the spreadsheet for this, posted in Marcins (RedHotSupra website). Good luck

Charlie

5.3litre

iTrader: (6)

sorry guys i need to make a sig..i used to own a truck now its a 2001 ws6 that i own..

CAT3

iTrader: (9)

Not sure how viewing of other years goes, but I posted in Horists .bin repository the TSP Tv2 tune I did for my buddies 2002 SS. under charlie trayer.

5.3litre

iTrader: (6)

ok cool i will take a look at it

Patrick G

iTrader: (14)

Are you still running a MAF? If so, the reversion of your cam is freaking out your MAF and giving you lots of low rpm bucking. A closed loop speed density tune will allow you to still rely on your O2 sensors and fuel trims, but you won't be having any more low rpm problems. My car runs baby smooth down to 900 rpm...pulls like a freight train above that.

5.3litre

iTrader: (6)

if i go to speed density will it change my idle stuff all up? cause i got it idling perfect pretty much and how do i get it to stay in closed loop constantly..

luv2spd

iTrader: (1)

The only way you can do this is if you have a wideband. Otherwise you won't be able to get your wot fueling right which will still be open loop using the ve and pe tables.

5.3litre

iTrader: (6)

welldoes anyone else have any suggestions..i really dont want to go SD..oh and cat3 i cant look at the bin cause it hasnt been approved yet

oange ss

iTrader: (50)

that .bin has been "unapproved' for awhile, i dont know what the deal is with it

WS6FirebirdTA00

iTrader: (33)

lots got to do with idle airflow. i still have issues but i think its because the injectors are too big. they get to a certain pulse width and wont go any lower than that. this makes me rich in some areas, although i should be getting lower pulse widths than i have. just something to think of. being rich will cause bucking. mine happens at very low load at about 1500 rpm, mostly only when im doing about 25 or 35

z06ufgrad2002

I've got this same problem; bucking at low load about 1500 rpms. The car did not do this unitl I added the FAST 90/90 setup.
I am very interested in the speed density tune but, can't find anyone that knows how to do it.

Ragtop 99

iTrader: (7)

I've noticed that too. I had an easier time tuning a bigger cam when I had an LS6 intake. Now I have a FAST 90/90 and a smaller cam but it is harder to get tuned right.

Patrick G

iTrader: (14)

Absolutely not true. I did a kickass razor sharp SD tune utilizing my narrow band sensors. The key to doing it right is by using fresh O2 sensors and making sure they're very warm before you start logging.

Do VE tuning by monitoring the S-Trims and do your WOT tuning by keeping your mv readings between .890-.910mv. I did this and the A/F ratio was perfect when we hooked up the wideband sensor on the dyno. My hp numbers are a result of using the narrowband sensors.

dgmiller

iTrader: (1)

I agree with PatrickG, the MAF sensorsensor cant handle the big changes in pressure due to the overlap in your cam. My son had the sam problem when he put a big cam in his Saturn, They solved it by putting a 10 microfarad capacitor to ground on the MAF output to the computer. This filters out the pulsations and the idle settled down.

97blkz

iTrader: (1)

My cam is a 238/242 and no issue like that, Jeremy Formato tuned it . It was bad before he played with the tune!

WS6FirebirdTA00

iTrader: (33)

WOT readings on narrowbands vary too much. 890-910 mV on my car is about a 13.7:1 to 13.4:1 AFR. 930 is about 13:1. My friends car 880 was 13:1

soundengineer

iTrader: (16)

I just tuned a 239/242 cam.. no surging...no idle issues..no stalling
just be sure to do a Running Air Fuel Idle tune and pay a little attention to spark timing at idle as well...and do some work on the throttle follower and cracker settings as well

Patrick G

iTrader: (14)

That's the reason why you choose fresh O2 sensors. When the sensors are new, they will not vary much at all. They can't. Otherwise, GM could never use them. In my experience, they are dead accurate when fully warmed up.

Also, keep in mind, sticking a wideband O2 sensor up the tailpipe is not very accurate either. It's been widely proven that A/F can be a much a 1 point leaner at the tailpipe vs taking the reading at the header. When you achieve 13.0 AFR with a wideband up the tailpipe, often you are really tuning a 12.0 AFR at the motor. That's one of the reasons why motors make more power with 13.5-14.0 AFRs. In actuality, they're really running 12.5-13.0 AFR at the motor. Another reason to put trust in the narrowbands.