Hello


I rebuilt my 1989 Iroc 305 TPI last winter and now i have problems with the idle quality. Most of the time the idle is to high (~ 1000U/min) and the engine runs rough below 1200U/min. I used xr264hr cam with ported stock 081 heads.


It can be a problem with the MAF or a vaccum leak. Is there a possibility to check the MAF values ? What is a normal MAF value at idle speed ? My MAF values at idle are constant and do not change.


The Timing is set to 6 in bypass mode. Is it normal that the timing jumps to more advance when i go above 1500U/min (in bypass mode) ???


Thanks for your help.

 

What i allready did.:


-Set Timing to 6 Degree (in bypass mode)
-Set minimum Air Screw to 650 U/min (below 650 is not possible and engine stalls)
-Set TPS Sensor to 0.54 V at Idle

 

New engine might be tight. I had a hard time getting a freshly rebuilt LB9 to idle at first. Drove it around a bit to loosen it up and slowly the idle got better and better. Your going to have to reset the minimum idle and TPS after it smooths out.


Also, that cam is about max for a 305 TPI.