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Old 05-18-2009, 02:26 AM   #1
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Default rough idle, really rich AFR's...need help please

So, I just recently finished my turbo build (Garrett gt25, MSPNP, DSM 450's). After warping my cylinder head the day after, I just got her back running, this time with the new injectors and fuel rail. BTW, I'm a stock 97.

Had trouble getting the idle tuned. It's close, but not as smooth as stock idle. Plus it still gives you that hiccup if you mash the gas real quick, but idk if there's a way to smooth that out.

Main concern is overall AFR's. Idle can be anywhere from 10's to high 11's. The car is running so rich that it's causing the spark plugs to foul out and misfire because there is so much fuel.

I tuned the injector characteristics with the instructions in mega-manual. Also fyi, I'm running them low impedance. Yes, I did solder in the extra grounds from the board in my megasquirt.


I guess I'm just asking for some simple tuning help or experienced guidance, and maybe someone's AFR and VE tables if you have a similar setup. I will attach my .msq file so you can look through it if you choose.

thanks in advance for all the advice.

Alex
Attached Files
File Type: msq 5-17-2009megasquirt200905172125.msq (35.2 KB, 95 views)
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Old 05-18-2009, 05:52 AM   #2
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Have you tried going into the tuning window and lowering the amount of fuel in the area that it's too rich (aka tuning....)?

Because it sounds like you haven't, and that's all that's required.
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Old 05-18-2009, 10:30 AM   #3
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Right now I'm staring at Megatune and all the tables come up with the same view, but I think that's because I'm not connected to my megasquirt at the moment. Later today, I'm going to spend some time going over the Megamanual with my car and try to do some fine tuning.

I'm also new with Megasquirt. Only plugged into my car twice, once for the initial install, and yesterday to set the fuel injectors and tune the idle. So, please bear with my newb-ness.

thanks, Alex
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Old 05-18-2009, 11:09 AM   #4
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no point tuning the idle until you've tuned the VE table.

in Megatune:

Tuning>VE Table 1

Move the red x to where the green blob is, (green blob is current engine position on your map). shift and up/down arrow to add/remove fuel respectively.
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Old 05-18-2009, 11:17 AM   #5
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It hesitates when you nail the throttle because your accel enrich values are stupid high. I'm running stock 1.8 injectors (265s) and my values (ms) are less than half what your .msq says you're using with your 450s. Take that column where your values are 13, 10, 8, and 4, and cut them all in half and see where that gets you. You might need to reduce further too.

FWIW, my values are 5.0, 3.8, 2.0, and 0.9 and those are pretty close for me- I haven't spent any significant time optimizing them but they don't cause any problems either. Those are absolute values in milliseconds (MS doesn't scale them based on injector size) so I'd think you should be running my values or less. But you can search this forum and see what others with your injector size run for those values. 440s and 460s out of RX-7s are commonly used injectors among this crowd so try searching "+accel +460" or something like that.
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Old 05-18-2009, 11:24 AM   #6
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thanks a lot guys, I'll check both of these areas out.

Alex
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