Idle, interesting problem????
Thread Starter
Pro
Joined: Mar 1999
Posts: 678
Likes: 0
From: Oslo, Norway
Idle, interesting problem????
Hi I have an 85 z-51 4+3.
The problem is as follows.
Have modified the engine with among all larger cam 221/230@ .05 and LS112.
Have to open the butterflies quite alot to not stall the engine when releasing the throttle when towards a red light.
I have about 50-60 counts on the IAC at idle. The injector opening time is about 1.3 ms at idle.
The fuel pressure is about 44 psi without vacuum to the AFPR.
Do I have too high pressure so that there is too much fuel into the engine at idle so that I have to compensate with opening the throttle blades.
My logic tells me that too much fuel has to have much more air not to disturb the idle speed.
How small can the opening time of the injectors be adjusted to as a minimum?? If this is the smallest time the increased fuel pressure must give more fuel and then have to open up the blades to give a proper air fuel ratio.
This was the naive logic. There is surely some other mechanisms. Would very much apreciate comments and help,please.
Jan-erik
The problem is as follows.
Have modified the engine with among all larger cam 221/230@ .05 and LS112.
Have to open the butterflies quite alot to not stall the engine when releasing the throttle when towards a red light.
I have about 50-60 counts on the IAC at idle. The injector opening time is about 1.3 ms at idle.
The fuel pressure is about 44 psi without vacuum to the AFPR.
Do I have too high pressure so that there is too much fuel into the engine at idle so that I have to compensate with opening the throttle blades.
My logic tells me that too much fuel has to have much more air not to disturb the idle speed.
How small can the opening time of the injectors be adjusted to as a minimum?? If this is the smallest time the increased fuel pressure must give more fuel and then have to open up the blades to give a proper air fuel ratio.
This was the naive logic. There is surely some other mechanisms. Would very much apreciate comments and help,please.
Jan-erik
Burning Brakes
Joined: Apr 2000
Posts: 980
Likes: 2
From: Chandler AZ
Re: Idle, interesting problem???? (jan-erik)
My guess and only a guess would be to start the car and block the IAC inlet hole off. Open the throttle plates until proper idle speed is obtained using the idle stop screw. Shut off the motor reset computer and let it relearn. I try to get the idle count into the low 20's or high teens. See if that helps. The IAC is kind of a slow poke and that may be causing the issue. But this is just a guess.
Team Owner
Joined: Jan 2003
Posts: 20,316
Likes: 246
From: Summerland B.C. Canada
Re: Idle, interesting problem???? (jan-erik)
Have you properly set your minimun idle and TPS ?? https://www.corvetteforum.com/techti...D=55&TopicID=2
:cheers:
:cheers:
