Finally got my turbo up and running and trying to do some data-logging to adjust the tune. Truck idles great with the exception of running a little rich (light black smoke). Took the truck for its first test drive today and it pulls out of the drive fine but as soon as I attempt to accelerate it pops and cuts out/dies until the accelerator is released. When the accelerator is released, the truck starts running again. This only happens when trying to drive down the road; when parked in my drive, the accelerator can be "punched/stabbed" and the engine will rev with no issues. Truck ran great prior to the turbo installation.

Anybody experience this before? I checked the 2-bar map sensor with KOEO; it measures 1.99 vdc. Your help is greatly appreciated.

Truck: 97 dakota, stroked from 318 to 390, alum heads, mopar 4bbl efi intake, 4bbl TB, KRC 210B cam, P.I.E turbo hot side,60lb injectors, Turbonetics 72 bb turbo, A/W intercooler, basic tune by P.I.E. and manual transmission.

 

Did PIE build the tune around the 2-bar map sensor?

 

Yes, the tune was built around the 2-bar map sensor.

 

It sounds like it either isn't seeing the TPS or the MAP sensor.
Lean pop?

Any idea on whether it's making boost before it pops or what the fuel pressure is doing?

 

The fuel pressure is set at 39psi. I didn't have my lap top hooked up to see the TPS or MAP sensor but will check it tomorrow or Tuesday.

 

Did PIE build the tune around just 39 psi of fuel pressure?
Generally these Dakotas run between 50-55 psi - and then we usually run a 1:1 regulator to up the fuel pressure when in boost to keep the math simpler.

What are you running for controls?
SCT or a standalone system?

 

The controls are via SCT and my fuel pressure regulator has a boost sense to adjust pressure as boost rises. I will have to verify the tune is set for a base fuel pressure of 39psi.

 

The fuel pressure is actually at 49 psi not 39psi as I listed above.

 

It sounds to me like the MAP sensor isn't functioning.

Black smoke at idle is too rich.
Pop when leaning into throttle under load is lean.
Make sure the wiring is good and the little vacuum line is hooked up.

 

Verified the wiring and have correct readings per GM diagram(5vdc, 1.99vdc and gnd). Verified vacuum line connection and made sure it was not plugged. Could the map sensor be dying as engine load increases?

 

The PCM doesn't seem to be seeing the MAP sensor. It sounds like the pins are mixed up as far as wiring order with the difference between a Mopar MAP sensor and the GM one.

 

If you are holding the map sensor in your hand with the electrical connection at the top of the sensor, the left pin is tied to violet/white wire (5vdc), middle pin is tied to grn/org (signal) wire and the right pin is tied to black/blue (ground) wire. Does that sound right?

 

#ad


This is the sensor I am using and the orientation mentioned.

#ad

 

Verify that your ground wire does in fact go to ground.
That sounds right according to mine.
I've destroyed a number of MAP sensors on mine.
It sounds like yours is acting the same way.

It sounds like you'll need to call Chris at PIE and see if he can help troubleshoot also.

 

The ground checks good to chassis ground. Chris has been great to help but was hoping to work through this without bothering him. May order another MAP sensor. Any suggestions on a quality part other than GM? Thanks for your help.

 

I'm afraid I haven't been much help.
I think I would in fact order another MAP sensor.
I don't really have any good info on a quality 2-bar MAP sensor.
And did you also verify that you were getting a good 5v for reference?
I found in the past that a failed O2 sensor caused problems with my 5v reference signal.... as wierd as THAT is.

I am running the onboard MAP sensor with my MS3X setup.

 

The reference voltage is 5.19v. The O2 sensors appear to be ok when viewed during data-logging but won't rule them out. Will be ordering another MAP sensor to see if it changes anything. How do you like the megasquirt system?

 

I've had great success with the MegaSquirt system, and really do like it. I enjoy having the ability to change anything I want at will. So far the only problems I have had were all self-inflicted, but that's how I learn stuff.... The hard way.

I used to run 24# injectors with an FMU and put 150 psi of fuel pressure to them. So this has been a much safer alternative.

 

Duner, I sent you a pm just so you know. I've been reading thru all your posts that date back to the early 2000's your the guy I'd really like to talk to about the 4.7. Thanks and sorry for the highjack))