VP 5.0GI running better but still not right

[BarryTurano]

Rebuilt the entire fuel system (high and low fuel pumps Throttle Body and VST cleaned, injectors replaced. Rebuilt the entire ignition system Distributor, wires, rotor had the ECU looked at and fixed, replaced the MAP Sensor, Temp Sensor. TPI Sensor working fine 0 to100%. Timing curve is correct IAC working properly. All voltages are within spec. Everything seems perfect but.....Motor runs better with the MAP sensor disconnected. With the old MAP sensor motor ran terrible. Drew a 5" vacuum and it ran normal so we changed the MAP Sensor. Still running very rich plugs are all full of soot. Showing 22# of back pressure in the manifolds (both sides) Scoped the exhaust from the drive up past the Y pipe and found no blockage. If I go up on the throttle slowly it will get up and run. It will not go past 4200 RPMs I have about 3 inches of throttle left. At 4200 RPMs it starts to bog down slightly but then steadies out. But nothing changes. If I disconnect the MAP sensor I can throttle up hard with no issue. Still can't get beyond 4200 RPMs and still have the same 3" of throttle left. I contacted Albemarle. They said when they built her she topped out at 4900 RPMs with the same D5 props that are om the drive. So that is where I am at.
Anyone have any ideas?

 

[Tail_Gunner]

The injector's what exact model number or part did you use. They are very spefic and uncommon injector's. Notice the how the pressure regulator works.

 

[kmarine]

I have a similar situation with my boss gt 40 multiport efi. I have been working with a ford expert and we have tracked it to a temp sensor grounding out throwing the computer into some type of limp mode. We now have to wait for spring to test the theory. I recommend checking all sensor connections and harness clips.

 

[BarryTurano]

Does 22# of back pressure in both manifolds at 4000 RPMs seem high??

 

[Tail_Gunner]

"
If I disconnect the MAP sensor I can throttle up hard with no issue."


When you drop the map sensor you enrich the fuel and retard the timing (no vacuum heavy load) so when you drop the map do you unhook the vacuum line or unplug the electrical circuit. And again to the tbi injectors they are 454 injectors not 5.7 or 5.0 they are very spefic injector's below is fairly decent mefi pdf.


https://drive.google.com/file/d/0B3w...Z2s/edit?pli=1

 

[BarryTurano]

News flash.....This just in BAD Pressure gauge shows false reading.

New pressure gauge shows 3# of back pressure.

Going to try disconnecting the TPI. If at 4200 rpms it is telling the ECU that it's at WOT, that is really 85% of WOT based on 4900 rpms at Albemarle Sea Trial.
Up to 4200 rpms timing curve is correct to RPM. After 4200 rpms timing retards instead of advancing. With MAP sensor connected after 2200 rpms you need to step up in increments. With MAP disconnected (electrically you can go straight up to 4200 rpms. After that it starts to bog down because timing is retarding. Thinking that the TPI is causing the issue.

I think (HOPE PLEASE) we are getting closer. Will keep everyone updated.

 

[Tail_Gunner]

1.Up to 4200 rpms timing curve is correct to RPM. After 4200 rpms timing retards instead of advancing.....
( The system is automated here its responding to some input)


2.With MAP disconnected (electrically you can go straight up to 4200 rpms. After that it starts to bog down because timing is retarding. Thinking that the TPI is causing the issue. (Here the system is in default or heavy load enriched and retatred timing)

Think detonation knock sensor's that will retard the system (point 1.) Knock sensor's pickup harmonic's in the engine coolant....when they do that it would be far ahead of what you could ever hear. It would seem at high rpm or advanced timing your engine is knocking and no mefi will not alway's store knock code's...Just how did you set your base timing...timing tool or shunt.