Surging Base Idle (IAC Disconnected)
Thread Starter
Drifting
Joined: Jul 2014
Posts: 1,426
Likes: 46
From: Lynchburg, VA
Surging Base Idle (IAC Disconnected)
As I was setting my new engine's base idle (I'd done it before, but have been changing the tune so I gave it another go), I noticed that the idle was pretty unsteady--it was hard to hit the target of 450 RPM because the tach was varying from about 400 to 500 RPM pretty regularly, with occasional swings to 375 or 525.
I was datalogging the whole time, and the BLMs in that cell were passable at 124.
Is this behavior normal, is it a symptom of a bigger-than-stock cam (Lunati Voodoo 262/270, similar to LPE 219), or is it likely something else?
I was datalogging the whole time, and the BLMs in that cell were passable at 124.
Is this behavior normal, is it a symptom of a bigger-than-stock cam (Lunati Voodoo 262/270, similar to LPE 219), or is it likely something else?
Thread Starter
Drifting
Joined: Jul 2014
Posts: 1,426
Likes: 46
From: Lynchburg, VA
I hadn't really considered having it idle faster than stock, what would the advantage of that be? Every now and then at idle my engine will die like a switch was flipped--sometimes it will barely recover--which I had thought to be an electrical problem, but could this be because my idle is too low for my cam?
Oil Producer
Joined: Apr 2014
Posts: 9,372
Likes: 2,736
I was surprised too, back with the original engine and even the new one before I had the VE tables nailed down I had to feather the throttle and just guess at what the idle would be if I let off.
I hadn't really considered having it idle faster than stock, what would the advantage of that be? Every now and then at idle my engine will die like a switch was flipped--sometimes it will barely recover--which I had thought to be an electrical problem, but could this be because my idle is too low for my cam?
I hadn't really considered having it idle faster than stock, what would the advantage of that be? Every now and then at idle my engine will die like a switch was flipped--sometimes it will barely recover--which I had thought to be an electrical problem, but could this be because my idle is too low for my cam?
i assume your iac is set to fully closed.
Thread Starter
Drifting
Joined: Jul 2014
Posts: 1,426
Likes: 46
From: Lynchburg, VA
i concur with the base idle but for me its more like 550. i had an 85 (that bjank helped me with!) and it was definately happy at 550. There was a tsb issued for that year. but sounds like you are beyond stock setup anyway and doesn't look like you have a 85 buty maybe try a bit higheer and see if it will hold the idle.
i assume your iac is set to fully closed.
i assume your iac is set to fully closed.
Yep, jumped ALDL pins A and B, turned key to on, disconnected IAC.
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
I was surprised too, back with the original engine and even the new one before I had the VE tables nailed down I had to feather the throttle and just guess at what the idle would be if I let off.
I hadn't really considered having it idle faster than stock, what would the advantage of that be? Every now and then at idle my engine will die like a switch was flipped--sometimes it will barely recover--which I had thought to be an electrical problem, but could this be because my idle is too low for my cam?
I hadn't really considered having it idle faster than stock, what would the advantage of that be? Every now and then at idle my engine will die like a switch was flipped--sometimes it will barely recover--which I had thought to be an electrical problem, but could this be because my idle is too low for my cam?
