2000 T&C sparks 2x and won't start
 

Vehicle: 2000 Chrysler Town and Country Limited
Engine: V-6 3.8L
Miles: 206,452

Problem: Engine will crank and fire 2 to 3 times then shut down and only crank unless I turn the key off and try to start again then fires 2 to 3 times and shuts down. Engine will not fire up and stay running.

Symptoms: The van has been experiencing a lack of power and a reduction in MPG. Down to 18 – 19mpg from mid-20’s. The oil pressure was in the low acceptable range. The serpentine belt began to whine so I replaced it. After the whine was gone you could hear a “worble” sound.

History: I took the belt back off and started the van in effort to discover if the “worble” was coming from any of the accessory equipment. The “worble” sound was still present which to me indicated a possible timing chain or oil pump issue. Upon investigation I found the timing chain had approx. 1.25’ total play from side to side on the rear portion of the chain. The oil pump was also out of tolerance. I replaced the timing chain complete with cam and crank sprockets and the oil pump. I made sure to line up the TDC arrows on both cam and crank sprockets as well as installing the chain so the colored links are in line with the dots at 3 o’clock on each sprocket. Since I was doing this work I also replaced the cam shaft position sensor, water pump, tensioner pulley and idle pulley.
Now the van will not start

What I have investigated:
Battery is fully charged and at 12.4 volts.
Battery terminals are tight, clean and corrosion free.
Checked the wiring harness as best I could for chaffing and/or breaks.
Checked all electrical connections and grounds
The fuel injectors are grounded.
The ASD relay is good.
Fuel pump is working and fuel rail is pressurized.
All fuses are ok.
The cam shaft position sensor is good. It is getting power and signals 5v
The coil pack test out at 12,500 ohms across the contacts on the secondary side and .9 to 1 ohm on the primary side.
Cylinder compression for cylinders 2, 4, and 6 is 185, 180, 190 psi.

Question:
The coil pack resistance is out of tolerance on the primary side by approximately 0.3 ohms. Is this enough to cause the PCM to trigger the ASD? If so why is it doing it now when the van started right up and ran before doing this work?

What about the crank position sensor. Good fault for not starting. EGR for lacking in performance. Any fault codes.

Googs
Thanks for the input. Yes I did think of the crank sensor and tested it. It was sporadic so I replaced it. The problem persists.

I decided to test for crank and cam signal back as close to the PCM as possible and got a solid 5v signal. I tested all the contacts at the coil pack and all are firing 2x before the PCM shuts them down and all I have is a crank. When I was retesting the cam and crank sensors I noted a "cycling" sound coming from the PCM every time the cam sensor triggered the 5v signal. I am now beginning to lean towards the PCM being bad though it is allowing the engine to fire 2x before something is shutting it down.

Regarding the 5v signal. Is the 5v not the input voltage and output is like square wave. QinteQ is the one for defining the scope signal from these sensors.

I only have a multi meter. The input voltage is 8 and the signal 5v.

I would think that the scope picture for the crank position sensor would be like this cam position one. Not a regular voltage of course. This 8v comes from the ECU and there should be no resistance or it will cause shutdowns. Pity you didn't have another one to try.

When I was testing the cam sensor the multi meter did drop to 100+_ mv between the 5v signal. This tells me that if it were to graph on a scope it would look like the picture.

I have test lighted the common wire (green with orange strip) for the coil pack and the injectors for cyls 2, 4, & 6. the light flashed for one sec during the run position and stayed on during the crank. I also got the same results when I test lighted the signal wire for the injectors. I would have thought the light would have flashed.

I had a brain fart this morning at 0230 and am ow considering the battery. Even though it is fully charge and reads 12.4 volts that does not mean all cells are working and the battery is fully amped up. I say this because when I test lighted the coil and cyls the test light dimmed when in the crank mode. I know the starter sucks a lot of amps but maybe the coil has a high enough resistance that the battery only has enough juice to push through for a few cycles. Your thoughts.? I will pull the battery from my silverado and hook it up and see if things change.

What was I saying yesterday, input voltage to crank sensor, there in no input voltage as the sensor is a generator in itself, sending an analogue signal to your ignition module which triggers your ignition coil to start...Output voltage is AC of course ocillating between lows and highs with no spikes as to giveaway fault...I was sort of thinking of the boost/temp sensor yesterday I think...getting old....Anyway petrol engine. Yes cam signal will be like crank signal. Does that tell you something. And yes the battery should be top whack.