MSefi.com read only forum (Jan.15,2018)

Hello, I am new to megasquirt and have finished my MSII install on a AMC 360 with a chevy 454 tbi controlling fuel only. I believe that I may be having a MAP issue. When I free rev the engine about 2800 rpm the engine MAP reads low down in the deceleration range of the tables and the AFR is lean to the point that the engine stumbles. This issue follows when driving down the road.
This is what I have done so far to troubleshoot. The map read 98kpa unhooked. When a syringe is hooked up I am able to get the gauge to peg per the manual. I have verified that the MAP is installed correctly. I have new hose installed and verified no kinks. I verified that there are no other leaks at the TBI or the spacer. I have tried three different ports on the intake with the same results. I have done a little tuning to the VE and AFR tables with no positive results.
I am using the stock TBI fuel regulator and the stock Jeep in tank fuel pump. The engine is an AMC360 board .60 over with a RV cam.
I am running a MS2 ECU V2.90. Attached are two data logs. The short one is a free rev. The long one is driving down the road.
Sorry if I gave to much information or not enough. Thank you taking the time to read this.

It is perfectly normal for the manifold pressure to decrease on deceleration, both free reving and otherwise. You could bump your fuel map up in those areas if you are concerned about lean deceleration. I, personally, keep my decel bins pretty lean in lieu of using decel fuel cut.

Ken

Thanks for the reply Ken. My engine is running low map (30-35-kPa) even at a constant 2800 RPM. Driving it down the road it is still noticeable at the 2800 RPM range but the map is not riding down in the deceleration range.

savage2506 wrote:My engine is running low map (30-35-kPa) even at a constant 2800 RPM

Not particularly unusual either, IMO. In fact, Your numbers are similar to mine (36-38 kPa) at the same rpm at cruise.

but the map is not riding down in the deceleration range.

That is not indicated in your log. I am seeing ~15 kPa during deceleration.

Ken

Ok thank you Ken. It looks like I just need to do some tuning.
Thanks again.
Kirk