Modified FPDM Causin some idling issues

[beastmar]

So I am getting ready to install new improved GT pumps into my car and I also purchased a used modified (Black306) FPDM. Before I switched my pumps out, I wanted to make sure the FPDM worked. I installed the modified FPDM and now I am having some slight idling issue. Upon first start up, my idle bounces in between 2,000 and 900 rpm. Could this just be the computer adjusting to the new FPDM? Do I have any concerns I'd need to worry about?

I will be getting a new tune, and could the tune fix this problem?

 

[Midnight_Cobra]

As far as I know the FPDM just supplies voltage to the pumps depending on the need for fuel. It MAY be possible it's bad, however if you put the stock one back in and idle and rev it up to see if the problem persists. If it does, you know the problem is somewhere else. If the problem goes away, put the modified one back in to double check. I have dual FPDM's so I don't have to worry about the single setup.

I went from the stock pumps with BAP and single FPDM to GT Pumps and dual FPDM's without the BAP. I had my tuner install everything and check the tune afterwards. As far as I can remember, he didn't change anything in the tune, just double checked the A/F and timing on a few runs.