Starts and dies immediately; runs briefly if MAP hose disconnected

**wanderingturtle** · 10-20-2017

Originally Posted by dave w

I have an unconventional and potentially dangerous way to help figure why the engine starts and dies.

I'd pour about 4 oz of fuel down the throttle body and start the engine and see how long the engine will run with the map sensor connected. If the engine keeps running for more than a second, I'd pour another 4 oz of fuel down the throttle body to keep the engine running. If the engine keeps running by being bottle feed fuel, I'd be thinking there is a fuel problem to figure out.

If the engine still starts and dies after being bottle feed fuel, I'd be thinking there is a spark or ignition problem.

Fuel is very flammable and potentially explosive, proceed at your own risk!

dave w

I can keep it running on starting fluid ;)

First thing I did was get a fuel pressure gauge. Fuel pressure and supply is good.

**dave w** · 10-20-2017

Originally Posted by wanderingturtle

I can keep it running on starting fluid ;)

First thing I did was get a fuel pressure gauge. Fuel pressure and supply is good.

What happens when a noid light is connected to the injector connectors?

dave w

**Nasty-Z** · 10-20-2017

Does the engine still have an EGR valve ? If so is it operational and closed fully at idle ?

TOM

**wanderingturtle** · 10-21-2017

I appreciate the replies. This situation is saddening and stressful. My boys and I have put a lot of hours into this van with the interior and upgrades, and now it seems like maybe we made the wrong choice. I really hope I can get this fixed.

I got the other van today. The computer from that van put into this van yields the exact same results. The computer from this van into the new van runs just fine. So computer issues are not the problem.

It does have EGR and it is closed.

W

**wanderingturtle** · 10-21-2017

Here is what it looks like with a noid light on the injector connector. The part where i fiddled with the tube was because I've had a few beers and I thought I needed to be clear that the tube was disconnected, lol.

https://www.youtube.com/watch?v=86qn...ature=youtu.be

It is dieing because of a lean condition.

**wanderingturtle** · 10-21-2017

So here's where I'm at. Fuel supply is fine, judging by the fuel pressure gauge and the fact that by teasing the MAp tube off and on it can run indefinitely.

It runs with the MAP tube being disconnected because apparently that triggers AE. I don't know why.

So what remains is why is fuel being cut? All ignition parts are verified good. All fuel parts are verified good.

I have not touched knock sensor or oil pressure sensor yet.

I did try running with the O2 sensor disconnected. No difference.

What is telling the PCM to cut fuel?

**dave w** · 10-21-2017

Originally Posted by wanderingturtle

What is telling the PCM to cut fuel?

The PCM sends ground pulses to the injectors to trigger the injectors on / off. With ignition key on, in either start or run the injectors will have 12 volts.

dave w

**wanderingturtle** · 10-21-2017

Can someone tell me what a normal injector base pulse width is for idle on a similar engine? From my logs it appears that it will idle with the bpw above 2 but dies from the lean condition when it is below 2. I am trying to determine if the lean condition is being commanded by the pcm or if it is due to a mechanical or electrical fault.

**delcowizzid** · 10-21-2017

I would try swapping the ignition module from the good runner into it or the whole dizzy .it may have good spark and an rpm trace on the ecu but not enough current to make the ecu trigger the injectors properly.i had a test bench that wouldn't fire the injectors but would show rpm in datalogs fine just my rpm trigger circuit wasn't supplying enough grunt to get the ecu to actually fire the injectors.