So spent a couple hours today relocating my IAT sensor from the stock position(5th lower intake runner) to the discharge pipe. I also moved my main meth nozzle to the discharge tube also(it was in the 90dg elbow before the TB), but before the IAT sensor.
I was recommended to do this by the guy that tuned the car last, but I pretty much forgot about it until yesterday, when I was measuring the intake temps coming out of the bypass valve, which was 38dg. The intake temp on the haltech was showing 60dg. Now I get that the air is going to heat up more between the bypass and the lower runners, but that's a pretty big amount. Also, when boosting, the IAT sensor output doesn't reduce as much as it should with meth, most likely due to heat soak.
So by moving it to the discharge, it won't suffer as much heat soak. Now, I know it's not going to show true IAT's, as it's going to water/meth pretty much blowing straight onto it. But this is where that is a positive, and why the tuner recommended it.
1. You can tell straight away that the meth is working because you will see instant temp reduction by a big amount due to the water/meth blowing just before the IAT
2. You can use the IAT's more effectively as a fail safe, because the difference between meth and no meth is going to be huge now. Before, my IAT's were showing 60dg for eg, and after a 2nd gear pull, it would go down to 55dg. So trying to use IAT's as a fail safe for a meth failure is pretty useless.
That's where my meth nozzle is now, and the IAT sensor is on the other side of the bypass on the underside.
Last edited by Husky65 on Sat Jun 09, 2018 2:30 pm; edited 2 times in total
Not sure I agree with him that having false intake readings is a good thing. How is he going to tune around having abnormally low air temp readings when meth turns on?
Is your temp sensor open or closed element? Heat soak should not really affect an open element sensor too much because it directly touches the airflow. It will certainly affect it after the engine has been stopped and you start it again, but the element itself (if it's open element) should cool down to the true temperature pretty quickly.
I'm not a fan of using intake temp for fail safe at all, although having a sensor right in the meth flow will certainly help that. It won't help tuning though.
Surely the Haltech can have another temp sensor? You could leave the temp sensor used for tuning where it should be and have another temp sensor right with the meth and compare that temp for meth fail safe.
It's going to run a bit richer on boost with the colder IAT's so I'll just lean it out once I see the what the AFR's look like. Apart from that it shouldn't change anything.
I'm not going to advanced timing based on my intake temps. I am going to run a meth timing table the whole time, and will retard timing based on IAT's. Once I see what the IAT's look like on boost, I can get pretty aggressive with my timing retard once the IAT's go over a certain amount. Being a stock motor, I like this as it is something else in the bag to help me save my motor in case of a mishap.
I tried it briefly tonight, and under meth went from 40dg to 30dg instantly, and that was only 2 psi. So I think it can be useful for a fail safe, if it's tuned right like you said.
If you're advancing timing based on intake temps then no way would I do this. I dont' have any more inputs on the Haltech either. If I find I've made my life harder I'll just move it back, no dramas there.
So I've decided on a C4. Now to decide whether to go a full manual valve body or something like the stage 2 shift kits trans go sells. Will allow auto shifting with manual 1-2. I won't be using a kick down though. Also, stall converters. Anyone had experience with TCE in Melbourne? I've heard good things about them. Judging by my previous dyno curve something around 3500-3800 would be the ticket I think.
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