Starts and dies immediately; runs briefly if MAP hose disconnected

**wanderingturtle** · 10-10-2017

I am in troubleshooting hell, but I think I see the light. Maybe.

Randomly died one morning 30 seconds after starting. For troubleshooting background, the Only thing that changed was it had idled the day before for an hour to charge the battery. My wife went and turned it off, reported that it seemed hot. No signs of mechanical problems.

Now it will start, run for a second and die. I can see the fuel stop spraying from the injectors.

Went back to a known good bin. Tried different PROM and PCM. Troubleshot fuel pressure, 14 psi steady. Tried spare injectors. Tried new ICM and ignition coil. Verified EGR valve is closed. Oil pressure is good. Tach reads seemingly accurate. O2 sensor output seems inline with what the wide band says. TPS voltage accurate.

MAP pressure seems weird, but I don't know what normal is. Tried new MAP sensor, same problems. But, if I start it with the MAP hose disconnected, it runs for several seconds, then revs for half a second then dies. Watching the datastream, I can see that with the MAP disconnected, it runs rich for a few seconds, then tries to lean it out, and dies. If at any point I open the throttle at all it dies.

I can make it idle if I tease the MAP hose on and off of the fitting. I will attach a log file where I was making it idle like that for a few seconds before I let it die.

What in the ever loving hell is going on?

The other wild card is that I found some mouse turds on the intake manifold. No chewed wires found, but I haven't taken off the dash or probed any wires yet.

I'll buy a six pack for whoever can solve this damn thing.

**wanderingturtle** · 10-10-2017

As someone pointed out in a private message, I should clarify that it is the vehicle in my signature. 16197427 pcm.

**wanderingturtle** · 10-16-2017

No ideas?

I've now replaced the distributor pickup coil. Same thing. Will idle for 5-10 seconds with the MAP sensor vacuum hose is disconnected. Starts and dies in uner a second if the MAP sensor is connected.

**wanderingturtle** · 10-17-2017

I guess I should have said that it uses the OE xdf.

Here is a log I took today. I alternated between starting it with the MAP hose connected and disconnected. You can see which is which because with it disconnected the MAP stays at 100 the whole time.

If you can look at the log and give ANY feedback at all it would be appreciated.

**Turbo Nasty** · 10-17-2017

I had a similar issue when I built my setup but it sounds like your car was already running fine as is. My car had the map wires reversed. It was also doing strange things before I made the switch in the KPA rows. I also had a map sensor before that looked good but tested bad. Replaced it and that fixed the issue. How long have you ran it in closed loop? correct injector offsets? Is your battery dead again or low voltage?