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Intake Temps

Car-specific questions and tuning advice for the 1995-1999 Turbo Talon and Eclipse cars.

Intake Temps

Postby rvaughn » Mon Mar 09, 2009 2:01 am

Alrighty all, here is the question...

I know that on our 2g cars our intake reading from the ecu+ are from the MAF sensor, BEFORE the intercooler, but here is my problem... Its only 40-50 degrees F when I did the attached log of my car. I have a front mount, upgraded intake (BOV, piping, etc), fuel system, stock t25, and im seeing these ridiculous intake temps... 113 degrees?!?! Remember, its only 40-50 degrees out when I did the log, how the heck is my intake temp SO high? Any suggestions would be awesome... Im so confused and worried that something is very wrong! :?:
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Re: Intake Temps

Postby tlcoll1 » Mon Mar 09, 2009 6:42 pm

Try looking at the OBD-II data at idle, then look at the ECU+ readings at idle and see how close they are. That's a start to see if the ECU+ is logging the correct values.

Tom
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Re: Intake Temps

Postby rvaughn » Mon Mar 09, 2009 11:53 pm

Well I did some more logging tonight and have some mixed results. Tom I followed your recommendation and cross referenced the OBD-II readings with the ECU+ readings and all seems to match up. But I am still seeing some impressive intake temps when under boost, note its now -4 degrees here, gotta love montana weather, and at idle the car reads 20-25 degrees intake temp, that I can see as being close to legit I guess, but when I get under boost the temps spike up to 45-50 degree range! From -5 to 50 degrees under boost still seems high... And note that is the same kind of increase I saw with the log above. So I guess its going to be some more research and logging to try and see what the f is going on... And to boot my map sensor seems to be on the fritz, or so I just noticed tonight its not logging boost... damn DSMs! :x
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Re: Intake Temps

Postby rvaughn » Thu Mar 12, 2009 10:55 am

Well I did some more logging this morning in my spare time, just idling the car in its parking spot. The thermometer reads 2 degrees outside, so I went out, plugged in the ECU+ and got 11 degrees, give or take a degree, at startup. Not bad I figured, so I let it warm all the way up, and got about 20 degrees at the intake. So I figured I would change the test conditions to see if it made any difference and opened the hood. Logged for a bit, messing with the throttle and such and saw very similar temps.

My thoughts are as follows, the ECU+ is reading the proper timing according to my info at WOT at roughly 6000 rpm on a 2g we should see 15-16 degrees advance, and it reads that just fine. It is scaling my injectors perfectly, reading my GM 3 Bar map sensor correctly, and all other data points seem on target. So there is one of two things happening as far as I can see,

NOTE: In no way am I discrediting Toms amazing work, I am simply trouble shooting!
A.) (being super unlikely, but plausible via my open hood in 2 degree weather test) The ECU+ that I have is somehow off on its voltage to intake temp reading...
B.) (more likely but harder to believe) My intake temps are that high, but its not effecting performance as far as I can tell...

I am correct in my assumption that the intake temps are being drawn from the MAS, correct Tom?

Any more thoughts? Tom? Anyone? :?:
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Re: Intake Temps

Postby tlcoll1 » Mon Mar 16, 2009 10:18 pm

The ECU+ being off a good bit (10 degrees is not out of the question) on the temperature is probably ok - as long as the ECU+ pretty much matches the stock ECU readings via OBD-II, then the calculations are correct. Note that the calculation is pretty low resolution. It's also possible that the MAS temperature sensor isn't that accurate or varies with age. Also, consider that it gets pretty hot under-hood with boost. I don't really think the increase in temperatures that you see is all that strange, especially if you have an under-hood cone filter.

Tom
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