88L98

ive been looking into this for a couple of days, and after a few words of wisdom and from some self analysis, you cannot gain HP from relocating the MAT sensor on a MAF TPI car. the MAT sensor has NOTHING to do with fuel or spark curve. the only thing that it controls is the egr function. just thought id let you guys know before you paid TPIS or someone like that for one of these kits.

NoWorries

$12, already paid for.

88L98

way to go man, thats 12 dollars beer money out the window

h rocks

Are you referring to the IAT sensor relo? If so, it's not going to *make* any HP, it will help you from losing HP. It has an impact on advance. The stock one gets cooked on the bottom side of the plenum. Relocating it to the front air box keeps it cooler and therefore is less likely to cause spark retard due to a "perceived" high temperature. There is a better solution that I'm going to try, that I got from TeamZR1. It's detailed on the member's website. Essentially, you go to Radio Shack and buy a $4 potentiometer and plug it in place of the actual sensor. It tells the computer that the motor is taking in nice and cool air, which allows maximum advance.

Aaron's 87

I haven't hacked the code, but I've also heard this. The 165 computer doesn't use IAT (MAT) for fuel and spark. Relocating it to a cooler place won't do a thing for fuel and spark.

h rocks

I should have gone to bed. I must have miss-read 88L98's post...I read MAT, but thought *MAP*. Sorry about that! Aaron, which computer is in a speed density '90 car? I was under the impression that the IAT did impact the timing on the '90 ECM. If you can clarify, I would appreciate it. The TeamZR1 setup was tested on a C5. There is documantation on the website.

[This message has been edited by h rocks (edited 07-30-2001).]

-=Jeff=-

I got one partly since I have a miniram and need all the ports for Vacuum

H rocks, the 90 vette has a 7727, GM also made the 7730 which is the underdash equivalent

Aaron's 87

I'll check on a 730 hack and see if I find MAT correction stuff.

Bobalos

I have heard both ways, that the IAT makes a difference in timing & not. if we are talking about the SD $8D, ecm's I dont think that it does, but one would think that it ought to. I would like to know for certain if it does or not.


BW

88L98

well i can tell you, 100% for sure on a 165ecm that it only has to do with egr function and nothing to do with either the fuel or spark curve.

mooibr

The relocated mat sensor will not gain HP, but after I relocated my sensor, starting goes a lot better. When the engine was hot, and I turned it off for about a half hour, it started very rough after that. Now with the relocated mat, starting with a hot engine is improved a lot.

vettenuts

I found the same thing, and to me it was worth the price for that alone.

Have not hacked code, but believe (on my 90) that it effects the fuel map.

Aggravated4life

Ive left mine alone in the stock location...never had problems..in fact I left everything alone( except the air pump which is removed)
to avoid any problems with the ECM system.

I noticed later model vettes have the sensor at the intake ducts or housing..if the owner didnt install it themselves..maybe GM caught on to this and is doing this in later cars?
Well if they did, seems to me it would be programmed for it.

Thanks for the heads up on the MAF set up cars.

88L98

i just looked, and on a speed density TPI, the air temp sensor does affect injector pulse width. so it might help a little bit but on MAF, its useless.

Bobalos

I follow what you are saying about injector pulse width, but if it affects timing, it can have a dramatic affect on power (not to the positive, but to the negative). this is assuming that the ignition curve is tuned to make "max power".

what does make sense to me, is that if the air is hotter, it is less dense, less dense air = less HP. for a given set of variables. Here is the stubling block for me. if this is the case then how would I want to change timing to compensate for it. do I want to advance it a deg or two or retard it a deg or two. the most important thing is that I dont want it to detonate, so I am thinking with hotter IAT's I want to take a bit of timing out. if that is the case, moving it might help me with hot starts, by "tricking" the ecm into a normal timing curve when starting, as the IAT sensor is going to be heat saturated after the motor gets turned off.

Just an observation is all.

BW

88L98

i dont have a SD setup, so im not that educated on it, but i will give my overview of what i *think* is happening. when the sensor heat soaks, possibly it is injecting less fuel (less fuel needed for higher temp/less dense air) therefore making it harder to start your car. during startup, the ignition timing is controlled by the ecm and is retarded quite a bit. so the sensor doesnt affect timing during a start up im guessing. only the injector pulse width. which moving it to a cooler location would give a true reading of the air going into the motor, causing the correct amout of fuel to be injected into the engine based on air density/temp. just a guess, but it sounds like its right to me. some one correct me if im wrong

85vet

88L98,
I would have to agrea with you. Before i relocated my MAT I talked to a few mechanics and they showed me that most new vehicles with a MAT have it located away from the engine for more realistic temps.