LS7 engine variations

My car has a crate LS7 and a GM controller kit. It's never really run right, with a weird idle hanging problem -- it would hang at about 2000-2500 RPM on decel, then slowly lower itself to a normal idle of 800 in a minute or so. That made it hard to heel-and-toe and didn't make me look like the smooth driver I know I am. :)

It also seemed really low on power. Though the car was relatively snappy, it never had the power I thought it should have.

I finally took the car to a local shop that had experience with an SLC they had prepped for race duty, and that also had a hub dyno (Dynapack). They discovered that I had a pre-2009 engine (I knew that) and a post 2009 controller (I knew that too, but...).

It turns out that is a problem, as there were running changes in the specification for the LS7s that included a different MAP sensor (1-bar in the early engines, and 2.5 or 3-bar in the new ones), as well as a different throttle body.

While the car still ran, it didn't make much power, and of course, had the driveability problems. When the shop swapped out the TB and MAP sensor, and adjusted the mechanical linkage at the ETC, the car lost it's driveability problems. It also made more power!

At the end of the cycle, after a dyno tune, the car made 491 HP at the hub, which is pretty stout for a stock LS7.

I took it to a car show today, and on the way back made a WOT run in first and second gear. The results were dramatic- the car now is a beast, and makes incredible power. Redline came up so fast I wasn't able to shift quickly enough- I just wasn't expecting it to hit redline again so quickly. It's really what I thought the car would be like so many years ago when I was building it.

I'm posting this in case other SLC builders have the same or similar problems. I wish now that I'd done this long ago. Thanks to the crew at Agile Auto, who did a great job diagnosing and correcting the problems!

Here's a link to the dyno run: Agile Automotive Performance LLC - Home | Facebook You might have to scroll down to get to the dyno vid- it looks like it's only posted on the FB page.
 
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