Ok, I checked the FAQ sections for the code my truck started throwing with the new MAP, But the 78 code is blank in the list. Any help, idea's, thoughts welcomed.

Wastegate Solenoid Fault

Thanks TDG Now to figure out why it showed up now. I will start UN doing things I just did. I think I know whats causing it.
Also got another question Of the 2 hoses plugged in the the waste gate solenoid, which one goes forward and which one aft. I ask cause my color coded hose were burnt off during the fire and not sure I reconnected them right. I did switch them yesterday and boost sure did hold up better but the light came on, I switched them back and light still comes on at 60 MPH @ 2000 RPM's curising. So still playing with it. Boost now stays up better than with the new MAP installed, 15 psi peak drop to 12-14 then back to 10 at 70 MPH @ 2300 RPM.

The one from the pump goes forward and the one to the turbo goes after. But with the 3 bar map you can just put the vac direct as the wg solenoid is not required anymore. What ultimatly controls the boost is how hard you throttle it.

hum I'll try that tomorrow cause tonight
LET's GO RACIN' is the theme for me.

The one from the pump goes forward and the one to the turbo goes after. But with the 3 bar map you can just put the vac direct as the wg solenoid is not required anymore. What ultimatly controls the boost is how hard you throttle it.
Hey QM I tried this and still get a light, WHen I have the solenoid in control and the light comes on I lose all boost for the few seconds the light is on. LIght goes out and boost comes back. Happens alot while cruising around 60 MPH @ 2000 RPM's in 5th gear and no load. It will also ligth up at 65 and 70 mph. Seems if that while pulling my race car this weekend I never saw the light or boost drop off. I am currently running vaccum direct to the actuator and the solenoid is unplugged as well. I have ran different combos but still get a light. The new MAP sensor is installed in the intake position, anyone got any ideas about swapping it to the baro position on the firewall??

I'd read the volt signal off the new 3 bar MAP, It sounds like a one bar MAP, that is an unresisted one. Contact summit and explaine it's not working and you wish to exchange it but MAP volts would seal it.
Getting DTC 78 and loosing all boost for a sec. is overboost detected. The 3bar is not working correctly and the PCM can "see" the higher boost levels.

Cool What should the voltage reading be, where at , when ???
Also reconnected everything vacuum line correctly and plug solenoid back in and drove around this morning and no light and boost held at 5-6 PSI at 60 and 70 MPH and would peck at 14 before dropping back. Heck guess I'll watch it and chase some voltage issues down.

Take a reading Green B (center) MAP wire with the key on, stock MAP should read barometric ~14.5 psi or 1.5v
3 bar map should show a lesser value ~1.35v key on engine off.

If you remember the 3bar MAP vs. Stock chart you could look at it as well to see what you should see at 15+ psi where you're getting the overboost code.

ok will do