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06-15-2020 #1Registered User
- Join Date
- Feb 2009
- Posts
- 54
minimum engine vacuum needed for EFI
Hi
have a 70 Firebird with a 30 over 455. The car produces 5 - 7" of vacuum at idle. Butler is telling me that that is too low for EFI systems to self tune and that I will need an expert with a lap top to get it to run properly. Can anybody comment on this...what is the lowest engine vacuum anyone has run on a street system that was able to self tune? What brand system was that?
Thanks for any help/suggestions.
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06-16-2020 #2Registered User- Join Date
- Sep 2004
- Location
- Kettering, OH
- Posts
- 537
My EFI 462 ci Pontiac pulls about 10" at idle and is very streetable. The car idles fine at 700 rpm and while I'm not an expert, I did tune it myself versus relying on the self-tuning. 5-7" at idle sounds very low, but 10ish is definitely not a problem. Finally, I think self tuning is over rated, but it shouldn't be a problem at higher rpms. Also know that it doesn't set your afr or timing, only your ve, so you'll need to do some tuning anyways.
1967 Firebird Convert, Fuel Injected 462 ci, TKO 600
http://1967firebird.atwebpages.com
06-16-2020 #3Registered User- Join Date
- Feb 2009
- Posts
- 54
Thanks for the feedback. Did a bit more reading and found the link to the Comp site where the definite opinion is that my vac is a bit on the low side and will need some manual intervention.