Tuning Air Temp correction?

[highly]

Thanks to the help of HybridZ and its members, the car is running great. Good enough to drive it to work to show it off. On the drive home, it was quite cool out and I decided to log the trip. It looks like the cooler IAT's caused an overcorrection of fuel. Attached is an overlay of two nearly identical datalogs from the same .msq file on different days. The only significant differences are IAT and AFR. I currently have my IAT sensor in the intake manifold... would mounting it before the throttle plate help here? I know the manifold and IAT like to heatsoak, but I wasn't expecting this.

 

I'm not thrilled seeing AFR go from a normal cruise of 15.x to a cool-air cruise of 12.x even though temps were 56 degrees from each other. I've searched in the MSextra manuals, but haven't found anything to tune the IAT to fuel correction factors, but I may be using the wrong search terms.

 

Thanks!

 

[highly]

Well, after further searching, I came across this on the MSExtra forum:

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I think I will try moving the IAT to the upper intercooler pipe first and see how that does, then give this a try. My car is also rather unhappy with a hot restart, so it sounds like it may help. I am still open to any thoughts anyone might have on the issue!

[calpoly-z]

Thanks for posting that link. I was looking for a way to ease my hot start problems and this looks like the best way to go about it.

 

I used to have my IAT sensor mounted in the J-pipe before I went intercooled. Now I have it in the manifold where the cold start injector used to be. Both places suffered from really lean hot-starts so I don't think moving your sensor will help you that much. Come to think of it though, the J-pipe is steel and my intercooler pipes are aluminum so heat soak might not be as bad if I put the sensor in the aluminum pipes. Too late now.

[highly]

Glad to help. I am kinda surprised that there isn't more info on the board about correcting the little niggly things, but I am pretty picky. What bothers me may not bother everyone.

 

On the IAT location, I don't expect having the sensor in the UCIP will cure the cold weather over-enrichment, but telling MS "the truth" can't be a bad thing. Reducing the heat soak has got to help stabilize the tune. If nothing else it should help bring the base temps down from the 130-plus that I have been seeing. I'm in the middle of a clutch and transmission swap but should be done by the weekend, so I hope to report back then.

[coolhand]

I'm not a full blown master tech but,the IAT is "inlet air temp" and I would think it would be positioned in the hose or pipe just before the throttle body. I could be wrong but,like mentioned above,you want to give the ms ecu the correct temps in order for the unit to work properly. like I said,I am no master tech and I could be wrong on this.

[highly]

Part of my point; the easy location for the air temp sensor is to merely screw it into the intake manifold in an available tapped hole. For the initial install and to get the car running, I took the easy route. There are a couple of threads on the board that discuss the heatsoak of the manifold and sensor that happens when you take the easy route. I have now remedied that problem by drilling a hole in my UICP and installing a bung to allow the IAT sensor to be after the intercooler and before the throttle plate. The new location is behind the radiator support, but allows some airflow over the sensor. The car is currently up on stands gatting a transmission and clutch swap (the PO used a turbo 5-speed with a N/A flywheel and clutch. The turbo tranny groans and was full of metal shavings and the clutch slipped after 6psi, so that had to change.)

 

I should have the transmission in the car this afternoon and hopefully get a chance to drive it by Sunday afternoon. It will probably take a little while before I get a good feel for the changes with the new IAT location, but I can't imagine it's made things worse!

[blackwidow]

Are you using the open element IAT sensor?