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Old 03-15-2017, 11:51 AM   #1
turbotankshane
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Default can't correct enough with IAT

91 chevy s10, 92 b230ft, 16t, t5 blue injectors, microsquirt running ms2 extra code.

After the last thread, I installed a dw301 fuel pump and haven't run out of fuel since. The problem I'm having now is temp related; I can dial everything in with no correction at 70 degrees ambient temp, then when it gets cold outside it runs extremely rich and I have to pull a LOT of fuel from the IAT to get it to lean out enough. Similarly, its been very cold this last week so I tuned it from scratch with ambient temp at 34 degrees, then after it sits and IATs come up to 50-60 its so lean I have to dump all kinds of fuel in. This is after WUE and ASE are off, so the only correction is IAT.

I'm using a GM IAT sensor from the DIY website, in a small rubber hose off of what is normally the IAC port on the cold side piping.

I'm trying to get the msq posted, still a noob to this sub-forum.

I want to think that this would have to be related to injector dead time, but I get the same situation with dead time set anywhere from 0.850-0.950. Any suggestions?
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Old 03-15-2017, 10:12 PM   #2
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You want your IAT in the air flow going into the engine (between the intercooler and intake manifold if applicable). If there's no air flow around the IAT, it won't read well. Do you have the paid version of TunerStudio? Have you tried the warm up wiz (sort of hidden on the right under "TuneAnalyzeLive! -TuneForYou") ?

P.S. If you re-up'd your contribution, or pre-purchased a square on the next raffle, you could post your msq here
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Old 03-18-2017, 12:00 PM   #3
turbotankshane
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Placing the IAT directly in the airflow made almost no difference, it reacts slightly faster now.

I had better luck letting the car get warmed up, shutting off and heatsoaking, then setting all corrections to 100% and tuning from there.
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Old 03-18-2017, 12:10 PM   #4
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You can post your MSQ over on the MSExtra forum.
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Old 03-19-2017, 01:02 PM   #5
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Try reloading your MAT Air Density Table with the default one from the msextra firmware release. Your current table has a spike in the middle and a non-standard correction slope - AFAIK the default table should be left alone. Post a log, with commentary, if you're still having problems.

[msextra link: http://www.msextra.com/forums/viewto...?f=101&t=65518]
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Old 03-19-2017, 01:28 PM   #6
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Sounds like you have your injector dead times and battV correction off. The change in required fueling should only span +-10% or so.

Also, check your grounds. Are they exactly as specified by DIY? Is your wiring new?
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Old 03-19-2017, 01:29 PM   #7
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Quote:
Originally Posted by bobxyz View Post
Try reloading your MAT Air Density Table with the default one from the msextra firmware release. Your current table has a spike in the middle and a non-standard correction slope - AFAIK the default table should be left alone. Post a log, with commentary, if you're still having problems.

[msextra link: http://www.msextra.com/forums/viewto...?f=101&t=65518]
Even the standard msextra curve is too aggressive.
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Old 03-19-2017, 04:24 PM   #8
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I see my post on the msextra page finally got approved.

I set the MAT table to 100% in all cells, let the car warm up, and made sure total correction was at 100% before I tuned it this time. Since then I've been able to get the car running much more consistently in various ambient temps, but I still have to ADD fuel for IATs higher than 100, and I have to take fuel away once IATs are dipping into the low 40s. Overall the car is behaving much better now.

I also was having some issues getting the accel enrich to behave consistently, but I went from 1 squirt/simultaneous to 4 squirts/alternating and throttle response is much snappier.
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Old 03-21-2017, 04:11 PM   #9
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that all still sounds like an injector opening time setting that's not quite happy. you should (theoretically) be able to swap # of squirts around and it not affect fueling much if at all, but that's all off the top of my head.

any chance your injectors are acting funny at higher fuel temps?
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Old 03-21-2017, 06:20 PM   #10
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It's possible.

Blew the fpr vacuum hose off earlier today and found fuel in it. I wouldn't be surprised if that's a good portion of my problem.
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