just the fmu, base timing is set to 8 btdc

looiney may be right with the intercooler thing. even if your boost gauge reads 9, your intake may be recieving a bit less.

his gauge is reading off the manifold, so he'll see exactly what the engine sees.

you gotta have a vacuum leak of sorts thats causing the engine to run so rich. the ecu think it's getting X amount of air, but infact it doesn't so you go rich and runs like crap.

what's your vacuum at idle?

about 19in

If there were a bad leak, it should be lean at idle. 19 sounds dead on for idle.

Did you fix that blue wire going to the ECU? IIRC thats a O2 sensor signal wire. If that was not fixed properly, the ECU will go nutzzzzz. Do you have a CEL? Run the code?

i have replaced the damage ECU plug, no chang. no CEL right now. i will run the codes anyway tomorow

put in the stock injectors, new spark plugs, another new o2 sensor, and another ECU. helped some, but it stil randomly bogs and studders, and most of the time has a really rich cruise and randomly will go real rich

Talk about a real mystery. Reading thru the post, you are running rich and ignition stuff checks out okay, right? So running rich:

1) too high fuel pressure - you said pressures were okay so fuel pump/FMU seems to be working okay

2) bad injector (locking open/etc...) - you tried multiple sets so unlikely

3) bad AFM- again, you tried multiple sets with the stock injectors so unlikely



Assuming that your fuel pump, FMU, injectors, and AFM are all okay based on the above, there are only two other sensor that change fueling (aside from the gas pedal...haha) for the 1.6L:

1) o2 sensor - Since you changed sensors as well, is it possible you have a bad connection that is intermittently grounding out? Also, the stock ecu does not use the o2 sensor on a cold start until the car warms up so are your cold starts fine?

2) thermosensor at the back of the head - Again, a bad connection that grounds out the sensor intermittently would tell your ecu that the engine is really cold and dump in fuel.

For both, with a multimeter, you could find the ecu pin and test the readings.
My two cents. Interested to see what the final issue is.

you know what. i have no CEL, but i do remeber getting a thermosensor code before. i just went outside and ran the codes (eninge is completly cold) and i am getting NO codes. the temp guage works fine. but my tach and water temp guage are really jumpy ever sence i put in the MMR solid motor mounts in several months ago (well before the turbo). a new coolant temp sensor is only $15 for a new one, i might just replace it.

Make sure you get the right one. Your dash gauge can be fine even if the ecu sensor is broken as they are two separate sensors so a normal dash reading means nothing.

There are three thermosensors in the miata. One on top of the thermostat housing for the fans, one small spade connector at the back of the head for the dash gauge, and one green connector on the back of the head that feeds the ECU. Make sure it is the green one in the attached pic.

i have replace the one on top of the thermostat before, so that should be ok. i still have no idea why it will just studder for no reason

out of curiousity does this studder effect the idle on the guage? does it feel like the car is tripping on itself, then goes back to normal?

Get some contact cleaner and clean all your sensor leads, that couldn't hurt either.

the studder happens when your on the gas. it will do it at partial throttle and also at WOT and is completly random. idle speed and afr is also completly random

not trying to rag... but that engine bay needs some TLC :) looks like you'd get extremely dirty everytime you touch your engine bay

Ok, Dumbass question from the newbie: Since you are running an afm but no recirculation from the BOV, will it not run rich when the bov opens? And I see you have a breather on the valve cover, but still a PCV valve hooked up. Could the PCV valve leak?

i thought a blow off valve's only job is to let backpressure off the turbo?

the BOV only matters when you are shifting. i have enough spacers in it to keep it closed at idle. pcv is still hooked up. but a leaking pcv hsa nothing to do with running rich, that would cause a whole other set of problems

did you ever get this thing straightened out bryan?

some, but not all the way. i got stock injectors and AFM in. the super rich condition is gone. but the random bog and studder is still there. it will happen at partial throttle and at WOT also

you have an o2 clamp or aftermarket ecu?