Super snake engine surging

[Hourigan218]

First of let me say my 2013 super snake is beautiful and I know, I know to most I could have done the same for less money but it's done so let's move on. The Car has 3500 mi. and did the 850 pkg with headers. I got it back about a week ago but had not been able to drive it much or get on it due to weather but last night took it out and noticed engine would surge in 2nd thru 4th gears rolling on the throttle slowly to little more than half ( felt like it wanted to take off and then would hesitate). I would let off and then clutch and the slowly come to a stop. The engine would then idle up to about 1500 at the stop for a few seconds and then idle down to about 900. Some times after rolling thru the gears and then clutch idle would stay at about 1500 to 2000 rpm then at the stop finally idle down. Power is great but the car is not running as it should. If I roll thru the gears in regular street driving the car is smooth but the idle is still off. Has anyone had this problem? Will be calling shelby tomorrow.

 

[stroked mach]

dk but get some pics up to help fig out whats going on,, lol jk

 

[Speedboosted]

Interesting. I talked to a guy locally to me with a '14 super snake, same 850 package with the long tubes and he was having the exact same surging issues you were. I wonder if SA needs to get a different tuner.

He just took it to another local shop and they retuned it, drives fine now.

 

[Hourigan218]

Interesting. I talked to a guy locally to me with a '14 super snake, same 850 package with the long tubes and he was having the exact same surging issues you were. I wonder if SA needs to get a different tuner.

He just took it to another local shop and they retuned it, drives fine now.

Yeah I'm thinking its a tuning issue as well.

 

[Mwynn]

Had the same problem, what kind of thottle body is on your car? Mine would hang around 2000 rpm then gradually come down to normal idle.

 

[2011 gtcs]

check for possible vacuum leaks, a small air leak will cause a surging issue, it's also possibly a tuning related issue, I would contact Shelby American and tell them about what's going on, you paid a shit load of money for the supersnake package it should run right.

 

[Hourigan218]

check for possible vacuum leaks, a small air leak will cause a surging issue, it's also possibly a tuning related issue, I would contact Shelby American and tell them about what's going on, you paid a shit load of money for the supersnake package it should run right.

First thing I checked when I got home. Nothing loose,and you can guarantee I'll be contacting shelby first thing tomorrow.

 

[Hourigan218]

Had the same problem, what kind of thottle body is on your car? Mine would hang around 2000 rpm then gradually come down to normal idle.

I have the k/b mono blade mammoth t/b.

 

[Hourigan218]

A little update. Still has the symptoms but no codes showing. A/f ratio is at about 14.0/1 at idle and when accelerating would fluctuate around 11.8/1 and after let off would shoot to 20.0/1

 

[93 347 Cobra]

A little update. Still has the symptoms but no codes showing. A/f ratio is at about 14.0/1 at idle and when accelerating would fluctuate around 11.8/1 and after let off would shoot to 20.0/1

14 at idle is similar to my factory tune 14. 11.8 isn't lean but is a tad on the hairy side of safe for longevity IMO but others can chime in with their experiences. 20:1 coasting sounds normal.

 

[Speedboosted]

A little update. Still has the symptoms but no codes showing. A/f ratio is at about 14.0/1 at idle and when accelerating would fluctuate around 11.8/1 and after let off would shoot to 20.0/1

Those are all fine ratios. The 11.8 is a tad leaner than most tuners would go on the car but it's not dangerous by any means. Low 11s seems to be the sweet spot for 5.4/5.8's

 

[Mainn]

A little update. Still has the symptoms but no codes showing. A/f ratio is at about 14.0/1 at idle and when accelerating would fluctuate around 11.8/1 and after let off would shoot to 20.0/1

Is that 11.8 AF/R at WOT, or just part-throttle acceleration?
Here is the general aim for AF/R's:

14.7 at idle and most areas under half throttle (this should be almost dead-on due to correction from O2 sensors).
11.2-11.8 at WOT.
You can interpolate between half throttle and WOT to get a very general idea of where AF/R should be at each throttle position. However, this is a very rough method of going about it.

 

[Van@RevanRacing]

You should check your O2's. If the headers were installed with O2 extensions you need to remove the extensions and re-route the stock wiring harness so that the stock wiring harness and 02's plug in directly to the collector.

Shelby uses the Kenne Bell throttle calibration. If it wasn't surging when you first got it back and it is suddenly surging it is more likely that you have an issue somewhere in the car because the tune didn't change.

Van

 

[Hourigan218]

You should check your O2's. If the headers were installed with O2 extensions you need to remove the extensions and re-route the stock wiring harness so that the stock wiring harness and 02's plug in directly to the collector.

Shelby uses the Kenne Bell throttle calibration. If it wasn't surging when you first got it back and it is suddenly surging it is more likely that you have an issue somewhere in the car because the tune didn't change.

Van

I'll check the O2 sensors but it has had the problem since the first time I was driving it when I got it back. I spoke the people at SA and they told me to run it a little so the tune can adjust it self , I've never heard of that but If it still does it after a day or so they said they to take it to a shop. Most likely ( maximum velocity) in San Antonio. To have the tune checked on.