Any idea what could cause this?

Fuel pressure with the vacuum unplugged is 52psi. New fuel filter, new high flow walbro 255lph fuel pump, new spark plugs.

It takes 3-4 seconds to crank, and after about 3 seconds of cranking, it will stumble into an idle. It starts up more quickly when the engine is warm, but cold it usually takes a while. Any idea what it could be?

Check engine coolant temp sensor, and check if the EGR valve is stuck open.

How do I check the engine coolant temp sensor? It seems to be working properly as hptuners reports the correct engine temperature.

How do I check if the EGR valve is stuck open?

Remember that time when I found that the EGR hose was cracked and I drove around with it blocked off for a day or two? I still had cranking problems during that time.

If it'* reading right then it should be OK, also check the MAF.

MAF just got calibrated in the tune. That'* working perfectly fine.

One thing I suspect may be of importance to mention is that I have an L36 PCM and a 2bar MAP sensor. That MAP sensor basically is set to report 160kPa at the same voltage that an L36 1bar MAP sensor reports 80kPa. Not sure if this has anything to do with it.

The MAP could be causing hard starts. When I get home I'll see what I can figure out.

Thanks. I'm going to work with hptuners support to see if they can enable the MAP calibration tables in the tune so that I can adjust the scaling of the MAP sensor. I know you can do it with tinytuner as a bin file, but I'd rather just have it right there in the tune so I could adjust it when I want to. My MAP readings right now are half what they should be.

Yep, that will throw things off. Those readings are used for setting your AFR

Bill@hptuners has offered to adjust the values for the MAP Sensor in my .hpt file after I sent it to him. I'll post the before and after numbers and whether or not it fixed the problem once I get the tune back from him.