2003 5.3 with flat tops/ Truck Norris Cam Idle Surge

[Galbatorix]

I must start off by saying very new to the tuning game. I've been trying to work with my tuner or about two weeks now regarding this issue. Vehicle runs perfectly otherwise. Vehicle those great at idle with air on or with the air off does great at speed. Just trying to find these gremlins at low speed.

I've got a 2003 Chevrolet Suburban that has a fresh rebuild with 4.8 flattop pistons and a BTR Truck Norris camshaft. I have the truck tuned at a local shop and it runs well other than when at idle in gear. Whenever in gear the truck surges and act like it wants to die whenever you're backing out of a parking spot or whenever you're trying to cruise at low speeds. Occasionally when coming to a stop idle will drop/surge and occasionally turn off. That is intermittent regardless of whether the air is on or off. I have tried to increase the base idle airflow which helped a little bit but now feels like the car wants to run about 20 with your foot off the brake. Any thoughts on how to fix these surge at idle would be greatly appreciated.


2003 Chevrolet Suburban with flattop pistons, a Truck Norris cam, Shorty headers, cold air intake, and high flow cats. Stock intake, stock injectors, and stock exhaust.

2003 Suburban cam tune 93 with e-fans 190.hpt
Here is the tune file

[SiriusC1024]

Here you go.

Main thing is the idle to base spark transition was abrupt. Adjusted idle spark tables.

Idle being a little high will make it feel like it's pulling in drive with your foot on the brake. Try to bring in down further to 750 at temp if you can. Small touchup is rolling idle matches base now, too.

[Galbatorix]

Here you go.

Main thing is the idle to base spark transition was abrupt. Adjusted idle spark tables.

Idle being a little high will make it feel like it's pulling in drive with your foot on the brake. Try to bring in down further to 750 at temp if you can. Small touchup is rolling idle matches base now, too.

I will try it tomorrow after I get off work and ill let you know. Appreciate it .

[Alvin]

Look up a good article for speed density tuning. This needs work on the VE table. This will make a huge difference downstream on the idle so much so that you might find yourself undoing things that you did to get a decent idle with a bad VE table.

Also this has a ton of idle air in it. Can you get a log with STIT and LTIT ? I'll bet timing is super low at an idle with airflow that high.

[Galbatorix]

Here you go.

Main thing is the idle to base spark transition was abrupt. Adjusted idle spark tables.

Idle being a little high will make it feel like it's pulling in drive with your foot on the brake. Try to bring in down further to 750 at temp if you can. Small touchup is rolling idle matches base now, too.

It helped a little but it still surges at idle. I dropped the idle airflow from 2.5 to 2.3 which ended up helping the feeling of trying to power over the brakes. I drove it red light to red light to try and get the computer populated at the low speed and idle for about 30 minutes and it didn't really surge/try to die at the red lights. Pretty much the only time that the car surges was backing out of my driveway and parking lots when you are off the gas and just letting the vehicle creep.

[reubone]

try this
2003 Suburban cam tune 93 with e-fans 190try.hpt

[Galbatorix]

I logged some data of what it was doing when it dies and some driving but im not really sure how to post it off the app.

[reubone]

Screenshot (104).png
Click the insert image and you can search for the tune file or log file that you want to post

[Galbatorix]

I'm using the TDN app off my phone and it just keeps saying sync but has no way to upload