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Old 02-07-2008, 10:54 AM   #1
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Default MS dealing with higher intake temps

Being that I am running a coldside MP62 SC, my intake temp sensor is mounted in the manifold about 8in from the blower outlet. I am currently seeing temps reaching 240*F+, but I don't have the WI working yet.

I don't know how much the WI will drop the temps, but I am guessing that I will be >100*F being that I am measuring the air in the intake manifold.

After searching here, it appears that most of you are registering intake temps <100*F.

I will only be spraying water when the car is above 4psi of boost. I am assuming that I will still see higher MATs when not in boost.

I found this statement on another forum. The poster is running a coldside MP62 like me with MSPNP. Do you think I am going to have trouble getting a good tune on my car with the standard correction tables.

Does anybody have any experience with a situation like this? At what temperature do the standard tables deviate?

"As for observations.. The MS IAT correction tables seem to assume a n/a setup that would not see the extremes of manifold intake temps that you can easily attain with a non-intercooled FFS coldside. Remember, I have no E-cool and have not yet installed my water-injection setup. When the FFS manifold heatsoaks, the MS IAT tables apply a little too much negative fuel correction, causing some lean conditions. In my car, this manifested itself as pinging under load during the onset of boost, primarily between 3k and 4k rpms. If I tuned for the heatsoaked condition, I'd be extremely rich when the motor was cool.

The solution is either to stop that IAT sensor from heatsoaking, or modify the MS IAT correction tables. I modified the tables, and recompiled the MS firmware. It seems to have mostly addressed the issue, although not entirely. I believe that the WI will quell remaining heatsoak issues, but for now I'm just careful not to lug the motor when it's heatsoaked. The 'lean when heatsoaked' problem can also manifest itself as a lean idle, causing oscillation of RPMs around the target idle. The MS has pretty sophisticated (and touchy) idle control, and there are a few tricks that you can use to tune out this condition also. And modifying the IAT tables probably helps there too. After several weeks of occasional fiddling, I have finally gotten my idle as stable as it was when running the MS prior to the FFS coldside installation. I'd say idle quality is about 90% of what it was stock."
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Old 02-07-2008, 10:59 AM   #2
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shouldn't really be an issue. the AIT temp correction works pretty well, but ive never seen that high driving so i dunno. i had heatsoak issues when i shut the car off, i would see +150 after shut off, turned the ait on and restarts were no issue.
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Old 02-07-2008, 11:31 AM   #3
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Are we assuming the standard closed-element MAT sensor, or the slightly expensiver open-element unit? Judging by the mechanical design of the open-element unit I can't imagine how it would heatsoak while the engine was running. It's just a tiny little sensor floating in space suspended by two little wires, with intake air all around it. If it's registering 200 then I'd believe the air really is 200.
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Old 02-07-2008, 11:41 AM   #4
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I am using a GM Open element temp sensor.

http://www.diyautotune.com/catalog/o...69b1b8f6506050
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Old 02-07-2008, 11:56 AM   #5
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Why would a wideband and some EGO correction not solve this?
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Old 02-07-2008, 04:15 PM   #6
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Quote:
Originally Posted by Joe Perez View Post
Are we assuming the standard closed-element MAT sensor, or the slightly expensiver open-element unit? Judging by the mechanical design of the open-element unit I can't imagine how it would heatsoak while the engine was running. It's just a tiny little sensor floating in space suspended by two little wires, with intake air all around it. If it's registering 200 then I'd believe the air really is 200.
cos it does I have a similar issue, but it's not the sensor overheating or missreading the IAT, it's just the stock compensation curve built into the MS isn't that good once you get into higher temps.

you can fix it by messing with the coolant related air density screen (and using IAT correction in the options). I've got it about 90% but once it's really heatsoaked it's still not right, and it only effects at low speeds/idle.

I'm not too fussed about it, as I'll be moving to a FMIC soon enough and I'll relocate the sensor into the exit tank of the FMIC, plenty of fresh air for the sensor
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Old 02-07-2008, 04:22 PM   #7
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Originally Posted by richyvrlimited View Post
cos it does I have a similar issue, but it's not the sensor overheating or missreading the IAT, it's just the stock compensation curve built into the MS isn't that good once you get into higher temps.

you can fix it by messing with the coolant related air density screen (and using IAT correction in the options). I've got it about 90% but once it's really heatsoaked it's still not right, and it only effects at low speeds/idle.

I'm not too fussed about it, as I'll be moving to a FMIC soon enough and I'll relocate the sensor into the exit tank of the FMIC, plenty of fresh air for the sensor

What kind of temps where you seeing?
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Old 02-07-2008, 04:41 PM   #8
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What kind of temps where you seeing?
I top out at about 60DegC, I think the hotter you go the worse the effect tho...
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