mauimoon

Not getting any replies in the PowerFC forum so I thought I'd post my problem/questions to a wider audience.

New injectors (850x1300) against a previous PowerFC and the whole thing is running way too rich, especially at idle and low-rpm. This is despite my performing what I believe are the necessary adjustments to the injector settings in the PowerFC.

Please go to the thread below for more details.

https://www.rx7club.com/forum/showth...hreadid=147081

Jon

Lost Time

Well, without reading your other thread let me take a gander at this for you. I'm hoping you changed the injectors settings to 850/1300cc respectively. Assuming you did that, you just need to lean out some of your low rpm, 500/1000 vacuum cells. The 850's are too large for the computer to properly meter out small amounts of fuel, so it's probably having issues. Just pull out some fuel either via the PIM volts at 1000rpms, or just pull it out of the individual cells. Hope that helps.

fdracer

stick the stock primaries back in and set the pfc back to the 550's. that should work. leaning it out any more really won't help if in fact the pfc can't open and close the 850's fast enough.

Tim Benton

iTrader: (1)

A search of the PFC forum will yield some info dealing with the 850 primaries, the setting some have used with good results. I'll be doing that search myself since I'm dropping 850's in pretty soon.

Tim

mauimoon

To be sure, I applied the following inectors settings on the PFC per the accumulated recommendations in the forum:

Loc Pulse LagTime
Fr-Pr 64.5% +0.04ms
Fr-Sc +0.20ms
Rr-Pr 64.5% +0.04ms
Rf-Sc +0.20ms
Q-Pr 850cc
Q-Sc 1300cc

However, one piece of feedback I've received indicates I may have made a rookie mistake and ended up with a leaking primaries in that stock 850's (new in this case) are NOT a direct one-to-one fit into the primary injector fuel rail. Supposedly there's some subtle difference (which I didn't notice, not that I looked very closely) where the lower o-ring will leak if not modified in some manner. Can anyone verify this and what your supposed to do about it?

The worst part is, if I did a Homer here, then I'm facing about 10 hours of labor plus other factors to tear things back down to get at the primaries. The way my schedule looks that translates into two more months of down time.

Jon

Tim Benton

iTrader: (1)

You do indeed need a very small o-ring along with the stock one on the 850 to fit correctly in the primary spot, or you can shave some off the top to make it fit. Wade Lanham's web site, let me try to find his url, has some great info on it concerning the o-ring, installation, etc.

www.newwave.net/~flanham/wlanham/

in the fuel section is write up on it.

Tim

Wade

iTrader: (1)

Try the additional o-ring and see if it helps, you might be leaking fuel around your 850's. I haven't personally used 850's primaries with a Power FC so I can't vouch for the settings you entered.

Wade

mauimoon

The additional o-ring seems to be the way to go. However, it's been strongly suggested I also take the lower intake manifold off and verify the seal from the 'inside'. I'm not going to race this thing so I may just go back and have RC Engineering bore out my original 550 primaries.

Any further thoughts?

Anyone interested in a set of slightly used 850's?

Jon