High rail pressure at idle

[The Highwayman]

Hey everyone. I am new to the forum/EFI so please forgive any poor etiquette.

I am getting code P0089, i believe as a result of high rail pressure at idle in park. FRP goes to 10-12k and DES FRP is 6k. When I go into Drive FRP comes down and is close to desired. MIL comes on roughly 15 seconds after start up, while still in park.

The truck is an '01. Items of potential interest: 75HP injectors, air dog, new LBZ CP3 (B1010 has been rescaled), new aftermarket FRP sensor (the one in the block), modded FP Regulator, IIS Dual Feed line (so no relief valve in the system).

I am attaching a log file (I think). It shows start up, idle in park, and idle in drive (you can tell when the FRP more closely matches the DESFRP. ANY HELP IS GREATLY APPRECIATED!


12436

[THEFERMANATOR]

You neeed to tweak the B1010 table some more to bring the rail pressure down. There is a limiter table that will only allow the ECM to go so far from the B1010 table. If it is to far out then the ECM cannot bring it down under an idle condition. Try raising it up some i nthe bottom 2 cells, and smooth it some in the 3rd cell and see if you can bring it closer. When you add in bigger injectors, a different CP3, and a modded regulator, you have to custom tune the B1010 table to your application(not just a generic table swap).

[killerbee]

You have a big MAF issue, probably not related to your question.

[The Highwayman]

THANKS! That did the trick.

I increased the first two cells by 10% and smoothed cells 3-5. The FRP and DESFRP now match closely, around 6k, and the P0089 stayed away. It does have a slight lope when not in park but I can deal with that.

[The Highwayman]

I did notice that the MAF number was pretty high, around 43. I logged it again after making the B1010 adjustment and it is now staying at 40 at an idle in park. See attached log file. What should a normal value be here? Any thoughts on what its deal is? Thanks again!

12440

[THEFERMANATOR]

You should be sitting around 38-45 grams/sec which I believe is around 5-7 pounds per minute.