Hi folks,
So the random rough-running situation I've previously written about ('90 GXE) may have just become not-as-random and now just "rough starting and smooth running".
One thing that has now recently been happening fairly regularly is that, upon startup, the engine sounds like it is backfiring out intake/pinging (almost sounds like a scary "mechanical sound"). It has become VERY hard to get going under this pinging and sometimes just refuses. IF I get it to fire, it is driving/idling nice and smooth, even under hard acceleration (previously and only on occasion, it would stumble). "Code 13/Temp sensor circuit" still present. Both temp sensors are new. Also good strong fuel pressure at factory specs and fuel pump check valve fine (Pressure Reg. checked OK, New inj. 1.5 yrs)

So, as an experiment, I cracked open the air filter box and propped it open with the filter (clean) to see if it would start. It STARTED UP much easier and idled really smoothly (once it's started, it has always idled smoothly). I've started the car this way twice on a cold engine, but you still hear a little backfire out intake/ping and longer-than-normal turnover times.

BUT, this is good info! I'm starting to wonder if I need to start testing/suspecting the MAF sensor, but I'd have expected a different code, not 13. Can anyone keep me from barking up the wrong tree? Please share your comments/advice on MAF sensor experiences, or anything that sounds similar to the hard starts described above (or misleading code 13's). I've been chasing this one way too long. Random problems are the worst and I could really use the help guys. Thanks!

 

Just wanted to get back with report. Problem solved. Faulty crank angle sensor, replaced it. No code for it ever showed up. Thanks for the help.

 

A good thing to do honestly is change all the pigtails to weather-pack style most can be ordered off eBay at pretty low cost. Fuel injectors, MAF, Water Temp Sensor, Distributor Crank sensor, etc....