new cam and trouble cranking

[chipper05]

A friend of mine put a tr220/224 cam in his 2009 5.3l sierra. He did a DOD delete and i turned off his afm. The truck wont start unless you give it a little gas. Can anyone give me a few pointers that will help get rid of this problem? Thanks for help

[swingtan]

Hi chipper05,

It'd be worth logging the start (including WB data) to see what's going on and then posting the tune and log file. It's possibly just insufficient cranking air, or it may be too rich when cranking. a little hard to tell without the log and tune though.

Simon

[Tre-Cool]

i would bet he was supplied the wrong 3 bolt cam gear. when the car finally starts up, does it run like sh*t?

if so, that's the problem.

[chipper05]

Simon, it doesn't have a wide band sensor on it but i will try to post the tune later, along with a log. I'm thinking that the vacuum is wrong but I'm new at tuning gas burners.

Tre-Cool, it starts off sounding decent but after a minute it idling sporadic and almost sounds like it wants to shut off. I did some minor tinkering with some fuel tables and ve correction and he told me it was running great, but a week later he says it is running like sh*t and "feels like it is choking itself" when he lets off to turn or slow down.

[chipper05]

The cam is actually a thunder racing 219/224 .609/.604 115 lsa. The truck is a 2009 crew cab sierra with a stock tranny, stock gears, and riding on 33x12.50 17s

[swingtan]

Log and Tune...... it'll all be in there.

That cam is not too huge and I would have thought it'd run with stock cranking and idle settings, however the tune will be a little different than the E38 ones we see in Aus. To give you an idea, here's the first start of a 224/224 Comp cam in a 6.0 Gen IV

http://youtu.be/g7IyXw0ZU6I

Post the log and tune.

[chipper05]

1357013571

[chipper05]

I posted the tune and a log.

[swingtan]

Well, there's not a lot in that log file, certainly no start up data anyway.

What I can see is that at points, the ECM is pulling 20% fuel out with the LTFT, but it's a very short log. It may be that the ECM has some bad data in for some reason and is messing with the fuel trims. The LTFT's are applied all the time ( including OL mode and PE mode ) so if they are off, they can impact the idle fueling even just after a cold start.

Log a cold start and post that up.

Simon