I purchased my FD Auto last December from Zach Keller. So far the car has been great, other than running pig rich since I got it. The thought was that the IAS was possibly bad, causing an overly rich condition.

Fast forward 6 months and the CEL comes on and gives me code 11 (IAS). I removed the intake manifold and relo'd the new IAS to the small dimple about midway up the intake pipe leading from the IC to the manifold. At the same time, I replaced the oem thermoswitch with a Miata thermoswitch. (Is the oem switch nippondenso cause that's what was there. It looked to have been gerry-rigged.)

Now the stupid question is why in the heck am I still getting a CEL? Not only am I getting code 11, but I am also getting the code for the thermoswitch. Lastly, and I don't know if this is related because I can't get the car to do it again, but the tranny hold light started flashing.

Any ideas?

 

Also...

- rough idle at startup until the engine has warmed up.
- noticed tonight that the flashing hold light only seems to come on over 5K on the tach

 

Did you reset the ECU?

 

I had a local reputable shop do the grunt work and the mech said, "of course, I cleared it." Well, after reading a few posts and seeing that you have to depress the brake pedal in addition to disconnecting the neg post, I think that he may not have known to do both. My question is having to depress the brake pedal common across most makes and models, or is it another Mazda peculiarity?

Someone's going to ask...so here's my mods.

- RB catback
- apexi dual intake
- apexi t/t
- AM Boost Guage
- downpipe
- Greddy pulley kit (airpump rusting in a landfill where it belongs)
- Pioneer AVIC-N1 ;-D

 

If the sensors are good but you are still receiving the error code, then that means the wires are either damaged or reversed (I reversed the wires accidently when I relocated my IAT).

Try reversing the wires. If that doesn't fix it, use a multimeter and test wire continuity.

 

Good thought, Mahjik...that could easily have happened when extending the wires for the IAS.

 

Wires to the IAS are good. Still getting some nasty stumbling at cold startup with a lumpy idle when in neutral. I'm assuming that this is the ECU compensating and running the engine rich. The car is running fine at speed, except for the auto tranny hold light flashing after 5K and WOT.

Given that, shouldn't the car be safe to drive (conservatively) until I get it to a shop next week?

 

If you removed the airpump on the Stock ECU, it will run a little rough at idle because of that. Most people just increase the idle a little higher to smooth it out.

 

I noticed a slight rough idle after removing the pump back in March, but it wasn't until after replacing the IAS and the thermoswitch (w/Miata replacement) on Friday that it really started to begin idling much worse at startup; even stumbling and not wanting to start the first time you turn the key.

I suppose the ECU could have been compensating for a faulty IAS before, but the CEL never came on until a couple weeks ago...and even then it was intermittent. Now after replacing the sensors the CEL is on all the time AND the tranny hold light is now flashing. I haven't had time to jump the diagnostic pins for the tranny, but will do so today to see exactly what the tranny ecu is trying to tell me.

Lastly, the latest observation is some moderate hesitation at WOT around 5K RPM again.

 

I agree. With the stock ECU, the air pump needs to be there. That's the or some of the lumpy idle issue.

I am sure that you do not want to switch to a Power FC because then you would lose the hold button.

You might want to consider a hi-flo cat too.