I asked this question on the ECU part of this forum, but it looks like nobody posts over there or something. It's been a week and not one response.

All I want to know is How accurate is the reading from the PFS PMS using keypad?

The reason i'm asking this question is When i look at the MP (boost) it shows at idle like -18,-19. But my autometer gauges show 15 and 16. Which is more correct. I know ECU get's reading from map sensor, and i tapped the gauges in to the UIM on that nipple next to bov hose.

Thanks a lot.

Amel

 

I couldn't help but to post because this is like asking what is worse, a rock hitting you in the head or the nads. The PFS computer in my opinion is complete trash however autometer gauges are notoriously inaccurate. To answer your question trust the rock hitting you in the... err I mean the PFS key pad. Despite the opinion about the PFS computer it shouldn't have any problems reading boost. Also the computer does take it's reading from a different location so the two will probably never match up.

My suggestion, take that rock and bash that gauge

 

I had pfs for 2 years and no problems with it, but Thanks anyway.

 

Not that it really matters... Try T-ing the gauge line into the MAP sensor line and see whatcha get.

 

 

ummmm Bump!

 

Ahh, just try getting the gauge calibrated or try somebody else's gauge.
cvs

 

I did try someone else's gauge, autometer again, and it showed 14

 

mine is the same way....i never worried about it

 

But still doesn't answer my question really. What is more accurate, the readin from pfs which comes from the map sensor i believe or reading from that nipple on the UIM that goes to boost gauge?

Amel

 

I have my Autometer boost guage T'd into the MAP sensor line and I have been using the EFI/PFS unit for quite a while. I see the same thing that you do. I think that the MAP sensor via keypad reading is the one you should pay the most attention to when tuning. Good news is that you have more vacume at idle than the Autometer guage shows. My experience is that when the Autometer gets down around 10-12 at idle you will start to get the stalling and hard starting that means its time to shop for a reman. People that have not personly used the "pink" version of the EFI unit shouldn't bash it. The early versions had problems and the three position switch shold be disabled since there is only one boost control setting but for a lightly moded car they work just fine.

 

Sorry, I got confused.

 

Here's part of an email from a friend in regards to the PFS boost reading:

 

The only way that this could be true is if the PFS/EFI unit has an incorrect conversion of the MAP sensor reading.

I can't believe that this would not have been addressed when the units software was updated in '99 by EFI since this difference in readings has existed for since the early "purple" boxes were sold by PFS.