Closed loop Lean cruise and idle and cruise timing

General Tuning Questions And Discussions
immortality
Posts: 3416
Joined: Thu Apr 09, 2009 12:31 pm
cars: VH, VN, VS, VX

Re: Closed loop Lean cruise and idle and cruise timing

Post by immortality »

Ours is a VX with the factory twin cat system but it still merges into a single 2.5" after the diff. I upgraded to a full twin V8 system which allowed the engine to rev out better and it wasn't pulling timing anymore either.
vp304
Posts: 451
Joined: Wed May 19, 2010 2:21 pm

Re: Closed loop Lean cruise and idle and cruise timing

Post by vp304 »

I done a back pressure test on a old Holden v8 I had many moons ago. Will let you guys know how I go over the next couple of weeks
Thanks for the info again
vp304
Posts: 451
Joined: Wed May 19, 2010 2:21 pm

Re: Closed loop Lean cruise and idle and cruise timing

Post by vp304 »

Small update cat was welded on chopped it of Today and was half collapsed inside.
Only gave car a couple of full throttle runs today looks like boost has dropped 2 psi or so and top end were it died over before has picked up heaps :)
'quipt4it
Posts: 675
Joined: Sun Oct 28, 2012 12:57 pm

Re: Closed loop Lean cruise and idle and cruise timing

Post by 'quipt4it »

'quipt4it wrote:That exhaust would have to be really restrictive to be almost doubling the boost pressure.
I would guess that the cat is either blocked or partially melted. Or the muffler has collapsed.
Not a bad guess eh... :lol:
Muffler next?
vp304
Posts: 451
Joined: Wed May 19, 2010 2:21 pm

Re: Closed loop Lean cruise and idle and cruise timing

Post by vp304 »

Lol
Il drive it for now probably wideband it just to see what the a/f is like on top end and worry about rest of exhaust down the track. Once i finish the 50 other projects i have going on at the moment :)
vp304
Posts: 451
Joined: Wed May 19, 2010 2:21 pm

Re: Closed loop Lean cruise and idle and cruise timing

Post by vp304 »

Follow up on this has been 2 weeks of daily driving now car has picked up heaps more all round.
I wideband it other day and has gone lean (fuel wise) on the top end but pulls way harder up top.
Just cruising for now will have to richen it up a bit more on the top end when i get time
vp304
Posts: 451
Joined: Wed May 19, 2010 2:21 pm

Re: Closed loop Lean cruise and idle and cruise timing

Post by vp304 »

For anyone else in similar situation.
On the weekend i done some more wideband tuning. Car required 3% more fuel and dropped boost from 11psi to 8.5 psi when i logged some full throttle runs :)
So win win
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