BAD IDLE UP AND DOWN UP AND DOWN

[mike7581]

I just finished my 2.3 - 5.0 swap and first went carbed but it pissed me off so i finished installing the EFI last night and started her up. she started right up but my idle is all messed up. it goes up and down up and down from aroun 500- 1500 constantly and enetually if i idle long enough it dies. my previous car was carbed so i am not to good with this efi thing what should i check for, where could my problem be

 

[HISSIN50]

any codes? did you set the idle? quickly, it is disconnecting the IAC connector, setting the screw and then the TPS accordingly. attach IAC connector and disconnect battery to discharge the KAM.

it can be a finicky thing - which is why im asking.
also, how is your vac? any leaks?
good luck and congrats on the swap.

 

[mustangdaren]

I just finished my 2.3 - 5.0 swap and first went carbed but it pissed me off so i finished installing the EFI last night and started her up. she started right up but my idle is all messed up. it goes up and down up and down from aroun 500- 1500 constantly and enetually if i idle long enough it dies. my previous car was carbed so i am not to good with this efi thing what should i check for, where could my problem be

Adjust your throttle position screw so that the throttle is in the correct position using a feeler gauge. I forgot exactly what it is suppose to be but I am sure someone on here knows. After you have that set you will have to set your TPS voltage to .998v. I had the same problem that was about to drive me crazy after changing intake and throttle bodies. I would have never thought something so simple would have made it idle so smooth.