Running on 3 Cylinders Problem

[wishihadatalon]

Hi guys,

I have a car in my garage right now that has a problem running on 3 cylinders. The car used to have megasquirt engine management and the problem started on that. When it first started, it was random. Since then, we've installed ecmlink and the problem is now constant.

Trying to fix the problem, I've replaced the coil pack, PTU, cam angle sensor, plugs, and wires. Also, I've had the injectors cleaned and flow tested, verified injector pulse on all four injectors, verified spark on all four cylinders, and completed a compression test (~150psi on all 4 when warm). Also, when the car is running, I swapped the spark plug wires from cylinder 3 (dead cylinder) and cylinder 2. When I do this, cylinder 3 still does not work.

Based on the items that I've worked through, I'm beginning to believe the problem is mechanical. My question is, based on good compression, is it possible that something is wrong in this cylinder that would cause it not to work? If not, any recommendations on what to try next?

Thanks for your help,

TJ

 

[DSMPT]

Just my experiences. I had two similar issues with my customers cars and the issue was an injector wire was almost cut (wasn't totally cut, so happened randomly).
the other one was a bad injector connector. a terminal of the connector was barely contacted to the injector terminal when plugged in, so sometimes the injector wasn't getting the pulse from ECU. (it seemed all ok when I check the pulse with connectors unplugged)

 

[wishihadatalon]

Just my experiences. I had two similar issues with my customers cars and the issue was an injector wire was almost cut (wasn't totally cut, so happened randomly).
the other one was a bad injector connector. a terminal of the connector was barely contacted to the injector terminal when plugged in, so sometimes the injector wasn't getting the pulse from ECU. (it seemed all ok when I check the pulse with connectors unplugged)

I find this interesting. Unfortunately the injector plug on that cylinder doesn't clip in the best and it has the worst routing for the wiring. I'll focus on that tonight.