Topic: easy engine upgrades

[roadkill]

The idea is to move the IATS away from the manifold.  Cooler air would be more dense and the PCM would theoretically add a bit more fuel.

The other theory is that the IATS should be reading measurements on the incoming air and not pick up heat from the intake manifold which is right on top if the exhaust manifold.  If it's not tuned to work with the engine heat, it could be forcing the engine to run leaner then it should be.

I think what is happening is you are tricking the PCM into thinking the intake air is colder.  the PCM should have some formula to take into account the added heat of the exhaust manifold, after all I would assume that this was taken into account when programming the computer to operate the engine efficiently.  by moving the IATS you are doing the same thing as putting in a colder thermostat.

[Sparky Watts]

I just threw in a TBS on my '94 YJ the other day.  However, I haven't had a chance to drive it since I did it because I got ran over by a little old lady in a VW bug and sprained my ankle really bad. :cry:   It's snowing now, and come heck or high water, I'm taking it out of the garage today and testing the TBS!!!

[quicksand]

I stongly believe throttle bodys do work. The ones with ridges on the walls of the center bore only work with slow speeds and do add torque. A smooth bore would give you smoother air transitions and would also have benefits at higher speeds. As far as the IAT (intake air temp) sensor in your manifold it measures the air temp inside the manifold ( clearly ). If you relocated it will physically pickup cooler air temps and send it to be read. It is not tricking anything. The cooler temps is really cooler temp. This also tells the ecm that the engine temp in manifold is running cooler, then it will automaticaly enrich the fuel it sends to the fuel injectors. Just like on a cold day when you first start you engine and it seems to run at a higher RPM till it warms up. Thats why its running higher RPM it is sending more fuel until that air in there warms up. ( more fuel = more horse power ). It will also advance your timing just a tad. This mod works best in warmer climates. You can purchase another sensor and place it in a cooler place and keep your factory sensor in place and that way you could alway swicth between the two. And extending the wires will have no affect on the readings it picks up. And as far as the termomostat that is only for antifreeze flow and temp. ( coolant fluid only ). Its all a balance and all engines work different, AIR / FUEL / SPARK and O Yeah those infamous sensors. Trail and error FUN !

[sharpxmen]

[...]Thats why its running higher RPM it is sending more fuel until that air in there warms up. [...]

it runs at a higher rpm by the means of the IAC (Idle Air Control) being open more until the engine warms up.

[quicksand]

I not sure If you still relating to the sensor in the manifold. Intake air temp. Unless you are saying it also affects the Idle Air Control. I am not sure.

[sharpxmen]

I not sure If you still relating to the sensor in the manifold. Intake air temp. Unless you are saying it also affects the Idle Air Control. I am not sure.

the IAC is controlled by the PCM, IAT has no influence on the idle air control position. I was relating to what you said regarding the higher rpm in the morning - it is controlled by the PCM by opening the IAC more (so more air into the engine) to prevent the engine from dying and is not idling at higher rpm because the mixture is richer (which it is, you are right about that).

[quicksand]

Yeah it is strange because I did this mod about 2 months ago and did notice power increase and alot of increase in gas mileage. Ran it for about 3 days and went back to factory location, because for some strange reason my antifreeze raidiator fluid level went way down. Later I did find that I have a small master cylinder leak and got into the O2 sensor and somehow was sending mix signal causing a lot of bucking. I will try this mod again later and see what happens.

[sharpxmen]

what vehicle?

[quicksand]

97 wrangler. 4 banger of course.

[sharpxmen]

97 wrangler. 4 banger of course.

relocating the IAT would make a bit of a difference but while you're in closed loop only the timing would be affected, the AFR will remain the same as the PCM will target 14.7 based on O2 feedback. I assume you moved it into the airbox. The more dramatic results are with the forced induction engines as the air heats up when compressed, so relocating it before the supercharger or turbo would read the ambient air temperature rather than the compressed air temp.

[quicksand]

Actually I had it in a medium size container of its own wrapped in heat reflective wrap. I was not place in air tube it was placed all by itself away from any heat and was pickng up air from outside air flow near the drivers headlight. I do not under stand why it did not work for me.