I drove the car in, it's been great the last few days. Went out for lunch and the fuel pump kicks in, light on MSPNP9093 turns on, cranks and nothing. I think my injectors aren't doing anything because my A/F gauge went lean. Usually i get a rich reading if she cranks and wont start.

Any quick tips on how to diagnose?

91 Miata 1.6l

 

unplug the AIT sensor and try again?

 

Check plugs to see/smell if there is any fuel on them?

 

Tried it- still nothing. I'm using the DIYAUTOTUNE IAT just fyi. I just checked for spark and it's sparking.

 

Do you have your laptop? If so, do you see RPM when cranking?
Have you looked at a sparkplug?
Fuel, spark, compression time. What's missing?

 

Fuel. My fuel gauge runs up to 40 when the pump kicks on, the injectors are not going off I think.. I don't have my laptop :(

 

I'm getting 12v to my injector harness... FML here.

 

MS switches the grounds. safe to say if youre getting spark youre getting fuel.

how long have you been on this MS?

 

a year? I'm quite sure it's not spitting fuel. I would defiantly smell it by now.. and the wideband is lean. Is it just a ground pulse that triggers injector? Can I connect a multi meter to the injector signal and see if it's alternating?

 

You would really want a scope to see the injector signal. Or a test light (the light would blink with injector pulses). A multimeter would be tough.

When you tested spark, did you pull out a plug? If so, what does it look like? I'm assuming you have a cam in your phone, so take a picture.

You can't really trust wideband readings taken while cranking. Also, the way they work, if there is no combustion, it will report full lean even if raw fuel is coming out the tailpipe.

Does this car have a TPS? WOT = fuel cut if you have a TPS.

 

As far as the o2 reading I'm just going off of what i've seen in the past. When i was flooding my engine it would show in the 11's.

I didn't remove a plug, I had a new set of plugs so i pulled a plug wire and laid it on my valve cover.

 

Problem solved. Not sure why it happened so bad yesterday - I hooked up a laptop to see if the injector DC was doing anything when I turn the ignition on and it was giving a very small prime.

I turned the key on and off a few times and it started up... so I increased the prime and she starts up just fine.. Maybe the warmer temperatures causing a different area of the table that I have not yet tuned.

 

i was going to suggest pinching the MAP line to the MS and have someone crank it, that would keep the MAP at 100kPa and cause you to dump in extra fuel. kinda where i was going with unplugging the AIT sensor, which would drop the AIT temp to 70*F had it been heatsoaked.

 

Well as usual. Thank you for the quick responses... I think recently I've been running too fat at my low cruising speeds causing the plugs to gunk up.. They are a couple of weeks old but that's been the only recent change. I've started to notice a few seconds of misfiring after starting the last day or two.