for anyone who has done the 3.1 conversion, does the idle run a little rough but smooths out once you give it some gas not sure if it would do this with all the parts from the previous 2.8 engine installed on it, this was a new crate motor for a chevy lumina, I have pulled each plug wire one at a time and the idle does not change, this was installed on my 86 GT, any suggestions would be helpful TIA Donald
You don't detect any change in RPM because your IAC compensates for the loss of RPM when you unplug each plug wire, if you really want to see a difference unplug the IAC. You say it's a new crate engine, let it run a bit, you have to break it in and the ECM is to learned the new engine. Go do some KM.
I took it for a small drive today it has great power response trying also to get the TV cable set right I had to let off the gas each time for it to shift to the next gear, I think also the tach might be off some roller at 60 MPH and the tach is at 3200 rpm sucks I only have one day each week to get to work on it now so I got to take my time with working out the bugs, just happy it runs after working on this project for the last year and a half.
If you used a pre-88 flex plate, you can have issues. The 3.1 engine is internally balanced and needs a neutral balanced flexplate or flywheel. You might find some roughness at idle. In the case of a 3.1 with a manual transmission externally balanced flywheel, it can do damage to the crankshaft bearings and seal.