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-   -   Lumpy idle. (https://www.miataturbo.net/megasquirt-18/lumpy-idle-22832/)

Braineack 06-27-2008 11:38 AM

could be a issue with communications with the laptop if that's the case.

wes65 06-27-2008 11:40 AM


Originally Posted by Braineack (Post 276598)
could be a issue with communications with the laptop if that's the case.

that would make the car miss and the tach cut out?

ampz 06-29-2008 06:16 AM

Just out of curiosity, what are your req fuel numbers in youe engine constants page?

If that figure is too low, you may have to richen your VE table loads to balace it out?

paul 06-29-2008 08:31 AM

Req Fuel should be 6.7 for 460s on a 1.8 so according to the MSQ posted(req fuel 7.3) so he should be having the opposite problem actually.

This isn't your problem but I noticed in your AE settings you top entry for TPS base AE is wrong. You are telling the ECU when the rate of change of your TPS is 1 volt per second(pushing the gas pedal down relatively slow) to add 5ms of fuel injector opening time. Then the bottom entry is telling it to add .9ms at that rate. Change the top entry to 8.0 v/s, till you get around to tuning it. That's how it was set when you got it from DIY, must have hit a key when opening that page as that is the first cell the cursor would be in.



How warm was it the day you did these "lumpy idle" logs? I noticed your IATs are 94-96 degrees. If it was much cooler than that and your IATs are showing that high because of your sensor heat soaking that could be the cause. Try messing with Coolant-Related Air Density under the Advanced menu. Courtesy of Chad here are the settings I started with:

http://i28.tinypic.com/1z3xxjt.jpg http://i28.tinypic.com/k3ukgi.jpg

As air temps go up the density of the air goes down, IE the oxygen content of the air goes down. So to maintain a steady AFR fuel must also be reduced. The MS does that for you, it varies fuel based on air temp. That's all well and good until you start heatsoaking the IAT sensor and feeding the ECU incorrect data about the air actually going into the motor. The ecu thinks the air temps are higher so it leans out the fuel causing a lean issue. You can use the above settings to counter that at idle by telling it when the RPMs are below X and the air temps are Y add Z additional fuel.

paul 06-29-2008 08:37 AM

BTW, that's a REALLY LOW idle MAP. 19kpa max? WTF. I idle in the 30s. You didn't block off your Idle Air controller, did you?

wes65 06-29-2008 02:38 PM


Originally Posted by paul (Post 277048)
BTW, that's a REALLY LOW idle MAP. 19kpa max? WTF. I idle in the 30s. You didn't block off your Idle Air controller, did you?

The IAC is not blocked off, maybe it is bad? My idle is really high as you can see. This is with the little idle screw (dont know the actual name) all the way tightened. I have a leak somewhere but i am pulling really good vacuum still which doesnt make sense to me. Thanks for taking the time to look at my msq. I am running HR code but i am going to go back to lo res until i can get the time to tune it correctly. I had a pretty ballin tune on low res and it is all fucked to shit with HR.


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