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Engine started running rich (Miata with aftermarket ECU)


turbogrill
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Hi,

 

I have NA 1.6 Miata with Speeduino ECU, it's pretty similar to Megasquirt 2.

 

I got a dyno tune before summer and everything was fine. But today when I ran it it was very rich at 10.5-11 @ WOT. I assume after the tune it would run 12-13 AFR.

 

Would could have cause the engine to run rich after sometime, car has mostly been sitting.

 

All the sensors look good, IAT, CLT, MAP, TPS etc. Its just AFR that is out of whack. 

 

1. 
Battery was stone dead took a little effort to get the car running, the reported voltage when running is 12.8-13v. A little low, but not sure that could affect this.

 

2.

IAT was 135, it was a hot day. Previous runs have been with IAT 120F as hottest. But that shouldn't matter?

3.
If the air intake filter is clogged (for some reason), could that cause it?


Car also felt slow, but it's a 1.6 so they always feel slow...

 

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FPR, return line, new pump? stuck injector, ignition timing.

 

Verify afrs by looking at plugs, might be the wideband itself.  Ours would smoke anytime we welded anything on the car.

Edited by LuckyKid
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5 hours ago, LuckyKid said:

FPR, return line, new pump? stuck injector, ignition timing.

 

Verify afrs by looking at plugs, might be the wideband itself.  Ours would smoke anytime we welded anything on the car.


I will:

- Get new plugs and see what they look like after sometime.

- make sure FPR and the related vacuum hose looks good. 

- Verify timing


Whats the best way for to verify injectors? Just buy a new set from Motorman for $75?

 

Why would your car smoke when you welded stuff

 

2 hours ago, mender said:

Can you verify the AFR separately? Are you running a gauge and if so what brand? Can you read the ECU files and see if they're still the after-dyno tune?

 

 

I am running the 14.7 wideband that is connected directly to the ECU. It has a nice feature where the few seconds after power on it will set a predetermined value. At least that will make sure there are no voltage offset problems.

Let me double check the ECU files, but the table looks smooth and nice. After my tuning they looked like crap, the tuner smoothed them out.

 

thanks

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