Focus of diagnostic is another no start vehicle a 2017 Chrysler Pacifica this one though does crank over just refuse to fire up after a front end Collison. That alone eliminated the need for me to check the starter system circuits and components. Chatting with the shop owner to gain some background information and gave me enough to start on this vehicle. Power supply added and the diagnostic process was under way. Preforming a thorough visual while the a pre scan was under way. I found no damage to the PCM are wire harness and sensors in the front end of vehicle. I did noticed a pungent burnt oil/coolant smell and some dark staining around engine bloc and head matting surfaces.
Pre-scan report listed no dtcs in PCM or other modules that would impede vehicle from starting. Due to no dtc’s in PCM I chose to implement symptom based diagnostic strategy. After a quick check of power, ground and communication to PCM was verified.
A trip down back to the basics road fuel ,spark, air and compression was initiated.
First up fuel pressure is 54 psi while cranking and OEM specification is 58 + or – by 5 psi so it is in spec.
Inline spark tester shows cylinder 1 coil is receiving command from PCM to fire and it is present.
Also by using PCM bidirectional control all fuel injectors click and I could see them actuating using a graphing meter.
Engine air filter condition is dirty smells like burnt oil and coolant but otherwise air can still pass through it and throttle body bore is clean.
Communication is present can + and can – at pcm connector c1.
The source
Finally I checked compression and noticed right away cylinder 1 spark plug is soaked. Assuming it was only from PCM flooding the cylinder by increasing injector pulse width to start engine form multiple attempts. This bit of information I mentally cataloged for later. Only 25 psi was obtained on cylinder 1 using a normal analog pressure compression gauge. Baffled by my findings after checking multiple times. I chose to install a pressure transducer in cylinder 1 and 34 psi is the highest reading obtained!
The Visual clues and Data
The eureka moment! I’m use to obtaining had finally come and my data pointed to one thing.
A pattern had played out before me and my instincts led me to pick up the soaked spark plug and take a sniff. Yep it it reeked of burnt oil and coolant too! A trip down back to the basics road led me to my correct destination.
- Pungent burnt oil/coolant smell and some dark staining around engine bloc and head matting surfaces.
- Engine air filter condition is dirty smells like burnt oil and coolant
- Correct fuel pressure present
- Spark is present but spark plugs soaked in coolant/oily film
- Very low Compression way below 100psi OEM reference.
Recommendation
Due to sudden loss of coolant vehicle overheated and head gasket became compromised on bank 1 along with possible damage to the engine block itself. Engine replacement or at very least headgasket depending on what insurance is willing to cover and cam/crank relearn.
Tools Used
- N2 Neuron https://www.curienllc.com/shop
- Pico Scope 4425a
- Cornwell GSI1000 – Compression Tester
- Rotkee PS16 In-Cylinder Pressure Transducer for Petrol Engine
- Tool Aid 23970 in-Line Spark Checker Kit for Recessed Plug
IMAGE CREDITS FOR COMPASS: http://”Compass Map” by Vintage RS/ CC0 1.0