This is a LT1 conversion in a mid 80s Chevy Pickup. Owner built so I don't know every detail. Has a custom harness and a 95 PCM and a 95 F-body bin. Won't start unless a little starting fluid is shot into it. Once started, runs and drives fine. Injectors are stock 24.9 and have been flowed and ultrasonic cleaned. Fuel pressure while cranking has been verified. Scanner shows a 2 ms pulse width while cranking and 4 ms pulse with when idling. All the crank and prime pulse tables in the PCM are stock values. Any ideas of what we should be looking at? Any more information needed just ask and I'll try to provide it.

 

If you have Datamaster or freescan withh key on engine off start logging RPM s/b 50 , desired RPM 3188 , voltage to PCM 12 v min. Then start cranking it.. Voltage should drop to 9v or lower, RPM should move up starting at 75 and increase to 400. And you should see basic pulse width at 10-20 Ms depending on coolant temp. At 85* it will be about 13 MS. After it catches BPW drops to what you are seeing at idle. Make sure your IAC is at parked position when cranking so it gets air the count s/b 100 or better.

 

We are using an OTC genisys. All parameters look within your guidelines but we don't drop battery voltage below 9v, voltage only falls to around 10.9v. Cranking RPM is in the mid to high 200's.

 

I can use my datamaster on it tomorrow. NEokcTerror and I are working on this together.

 

Is the fuel system priming for ~2 seconds when you turn the key to ON?

 

Honestly haven't noticed just has correct fuel pressure and does maintain with key off / pump not running. Where are you leading with the prime test?

 

If there is no prime, the rails may not have enough pressure for startup. Will it immediately restart after it has been running (you say it maintains pressure with key off).

 

It can be sitting with 40-45 psi in the rail and no start hot or cold.

 

I implied but did not specifically mention that the engine coolant sensor controls the injector duration during start up. Make sure it's reading correctly in your scans a way-out hot erroneous reading would decrease the BPW. 10.9 V at cranking is fine, your battery has more guts than what I had at the time when I recorded the starting sequence. Again your 2 Ms injector pulses at crank are low, make sure the readings are correct. Also I assume you do not have any DTC's set since they were not mentioned.
If you can get Datamaster running post up a log on a file sharing site.. Start the trace with key on engine off then hit start for a few seconds. Additionally if you could then spray starter fluid in there and get it running. It would be good to see a trace of it idling until it switches from open to closed loop. That would show us how all your sensors are performing.

 

I was unable to get to NEokcTERROR's shop today with my Datamaster. I will be there tomorrow morning and get that log posted. In the mean time here is the bin that is in the truck. I've gone over every table comparing to a stock bin with Tunercat and can't see anything that would be causing this.

http://www.mediafire.com/file/2f26vr...T1Truck_01.bin

 

FIXED!!! Bad MAP sensor. MAP read 16.6 KPA all the time. Apparently it doesn't use the Cranking VE table at start up which is TPS vs RPM as much as it uses the Main VE table which is MAP vs RPM. At 16.6 KPA the VE airflow is so much less than at 100 KPA that is what was keeping the cranking IPW at 2 ms.

 

Here are the log files. Maybe someone can use them for future reference.

1. Actually started up first try even with the bad MAP sensor. Then repeatedly would not start again.
http://www.mediafire.com/file/gua20afk418xs7a/1.uni

2. Here is cranking then hitting it with the starting fluid then running to closed loop.
http://www.mediafire.com/file/bzktzxdwg21aggx/2.uni

3. Here is cranking with no start.
http://www.mediafire.com/file/p9pi749dip8jd8i/3.uni

 

Glad you got it resolved.. The MAP and Baro sensor readings of 16.6 Kpa stick out in the logs. Strange thing is you would of thrown a DTC 34 if the MAP was 16 with RPM below 700, but yours was just a tad above the error threshold. Also see you have no SES light on your conversion and are running a manual fan control (DTC 11 and DTC 77 ). Good luck with your project..