01-11-2016, 01:07 AM
Join Date: Mar 2014
Location: Seattle, WA
Total Cats: 0
Intermittent starting issue/running lean
Not sure if this is the appropriate section to post in but here it goes. Car is a 95 with full flyinmiata turbo and hydra. It's been intermittently losing power while running and also not starting. Car will not sputter, it just dies like the ignition was cut. It will always crank, but no spark. When this first started happening, I thought the problem was the main relay because when I turned the key on, the CEL would not come on and I wouldn't hear the relay under the dash click or fuel pump prime. I replaced the main relay from another working miata and now it starts... most of the time. When it doesn't start I have been able to troubleshoot the following:
Ecu is getting 12v at 1a and 1b harness pins with key on (=main relay is good)
No spark at any plugs
Injectors are getting 12v with key on
fuel pump is priming
coils are getting 12v with key on
resistance at coils is within specs
My best guess is ecu or CAS?
I don't know if this second problem is related or if it is something different. Most of the time the car does start since replacing main relay, and when it does it runs lean and rough. This just started happening and I haven't changed anything with the tuning. It is now idling at 15-18 AFR. One thing I noticed is the wiring from the stock O2 sensor got partially melted on the exhaust. Could that be shorting or grounding out and causing my problem(s)? Or possibly ruin the sensor? I am going to try replacing the O2 sensor and wire next but any other suggestions? Thanks!