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Haltech air temp sensor install threw out tune

Murray_Calavera
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Murray_Calavera Mentor

Murray_Calavera

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Hi all,

I've got a r33gtst with a haltech platinum plug in, today I installed an air temp sensor and it seems like the car is running rich now. I don't understand why it would affect the tune when both timing and fuel correction is disabled for the air temp sensor. 

What I've done is, deleted the MAF, wired up the MAF signal and signal ground to the air temp sensor and re-pined the MAF signal to the air temp sensor signal on the ECU connector. The air temp sensor seems to be working perfectly. 

Unfortunately I don't have a wideband so can't say for sure that it's running rich, but there are flat-spots everywhere now and the popping and crackling on decel are a bit louder now so my guess is its running rich. 

The car is tuned on VE and I had deleted the MAF ages ago so I know that's not the issue. If anyone could shed some light on this it would be much appreciated!  

Murray_Calavera Mentor

Murray_Calavera

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Did some more reading online, seems like people are tapping the MAF ground into the coolant sensor ground. Doesn't make sense to me needing to tap a ground into a ground but I did it anyway... Still didn't fix anything. 

Pulled the air temp sensor out and it's all back to normal again. I'm out of ideas. 

Murray_Calavera Mentor

Murray_Calavera

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I'm using the, I guess you could call it 'standard' delphi air temp sensor. The ecu picked it up straight away as its using the factory GTR air temp sensor wiring now, I checked the main setup for inputs and there was already values there for the air temp sensor. It is a pretty liner table from 0.5 volts (120 degrees C) to 4.47 voles (17 degrees C). Do I still need to change this?

I still think it's really weird that its affecting the tune though. I thought it would only affect the tune if I enabled the correction tables?

Murray_Calavera Mentor

Murray_Calavera

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Umm from memory it was sitting around 45-50 degrees when idling in traffic and got down to low 40's when driving around. Does that sound right for stock turbo (10psi) and stock sidemount? I wasn't brave enough to push it hard as the tune felt terrible. 

HarrisRacing Proficient

HarrisRacing

Posted
Posted

Does pipe is correct (see #3 below) but I wanted to add two other things:

1) Get a wideband - ASAP. I am running their CANBUS. In all honesty it makes no sense to have spent this much on a Haltech and not have the wideband. It opens SO many more tuning and safety options that you don't have now and I would say this is CRITICAL for any standalone.

2) I also used a AFM wire back to the ecu for one of my sensors and just repinned at the ECU so there is not an issue there unless you crossed some voltage (but it sounds like you didn't because you are at least getting "normal" values).

3) Did the R33 GTST not have an air temp sensor? If not, then surely the ECU was assuming some value for this input in it's calculations of air density (air temp is one of the calculations). Basically they were assuming air temp didn't change I guess? If this is the case and you ADDED a sensor where one didn't previously exist, and you added it as an input (properly) and scaled it (properly) then you will need to retune the car for sure to match the ACTUAL air temp.

 

A final FYI. My air temp sensor is zero mapped up until around 120-130F and down to 50F. Meaning it only changes the tune on fuel % added above or below those values respectively.

Murray_Calavera Mentor

Murray_Calavera

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Point 3 makes sense about giving the car an actual input vs it's previously assumed ones (GTST's don't have air temp sensors). I just thought it would carry on as it was previously, using the assumed figures, if I didn't activate the correction tables. 

I agree about the wideband, it's very high on the priority list. My poor R33 has a few other things to fix first but I'll get it before I add any real performance mods (currently all I have is a cat-back & a bit more boost).

 

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

those temps appear some what "correct", if the car is doing other stuff then there is some other correction being applied.. because the factory haltech base map only shaves timing and pulls out fuel above 70 degrees Celsius...

you need a wideband!

HarrisRacing Proficient

HarrisRacing

Posted
Posted

Another quick test is to pull logs of injector duty cycles (or time) at known values to see what it is doing when you run the old way with no IAT vs the new way with IAT mapped. At least this could get you back quasi on target running. Nice thing about a wideband are the added protection in the engine protection menu. I set my car so that it will protect the engine (raise fuel % and lower boost) when I'm 12.5 AFR or higher over 15 psi. This will eliminate any potential fuel pump failures from giving me issues there.

I'm quite confident it's changing the map somehow.

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