'87IROCZOWNER69

iTrader: (1)

What is the part that I circled in this picture? It's not my car but mine has the same thing and I had a friend who thinks it is supposed to be connected to something.

bjm1206

i was wondering the same thing i have a 90 iroc and mine has the same connection with nothing connected to it

Twin_Turbo

iTrader: (25)

That's an intake air temp sensor, someone installed it there. Originally it's in the underside of the upper manifold plenum. This location will add more fueling because the ECM sees a colder IAT reading.

'87IROCZOWNER69

iTrader: (1)

So is there a wire that is supposed to be connected to it somewhere?

89RESTO

iTrader: (5)

That looks to be an air intake from a v6 with the mat sensor installed. as Twin_Turbo said, you should have a mat sensor at the rear of the plenum connected to the wireing harness.

JamesC

iTrader: (5)

JamesC

58mark

iTrader: (3)

yep. My V6 has that sensor, but it's actually hooked up to something

red rock

iTrader: (2)

So is there a wire that is supposed to be connected to it somewhere?

You can get a special wire harness that extends from the air temp sensor under the plenum to the sensor on your intake. For example;http://tpis.com/parts/view/157

JamesC

iTrader: (5)

Very interesting. Thanks Twin_ and Red.

JamesC

'87IROCZOWNER69

iTrader: (1)

So is it one from a V6 or is it just part of some kit? Does it make any noticable difference from having it plugged in vs having it unplugged? Pros/cons?

Twin_Turbo

iTrader: (25)

It moves the IAT from the hotter plenum to the cold airbox, adds a little fueling. May add some HP @ WOT. Cheap mod for a little gain.

'87IROCZOWNER69

iTrader: (1)

I might want to look into finding that plug then and try to plug it in!

Another question, where is the EST located on our cars? Mines throwing a code and Chilton says it will throw a code if unplugged.

Twin_Turbo

iTrader: (25)

Here it is, underside of plenum.

The wire runs near the distributor, 2 pin connector

'87IROCZOWNER69

iTrader: (1)

So is that the EST then? The picture in the Chilton manual is very confusing and doesnt give a reference to where the thing is, just has a picture of a jumble of wiring.

Twin_Turbo

iTrader: (25)

That's the IAT, intake air temp. I didn't read your post properly, thought you were looking for the iat.

The EST is the spark timing box, it's near the brake booster, there are a couple of relays on the firewall and a larger black box w/ a red weatherpack seal and a multi pin connector on the engine side. There's most likely a relay mounted on the front of it. It's a thin black box.

'87IROCZOWNER69

iTrader: (1)

Ok, so what sort of things will happen if the EST is unplugged (sorry if I seem stupid but Chilton doesnt say what it does either)?

Twin_Turbo

iTrader: (25)

The engine will run like crap, if it runs at all. the EST is the electronic spark timing controller, it controls your timing advance and retard as instructed by the ECM and info from the knock sensor.

This is the EST:



See the 3 relays on the firewall? The inner most one is mounted on a box w a big weatherpack connector on the left side , it's right next to the 2 big wire looms and under the black braided fuel lines.

'87IROCZOWNER69

iTrader: (1)

If mine is unplugged that would definatly explain why it is running like crap. Thanks for the help everybody. Twin_turbo I will go check on that in a little bit and see what it all looks like.

Twin_Turbo

iTrader: (25)

I added a pic to help you locate it

'87IROCZOWNER69

iTrader: (1)

What pic?

Twin_Turbo

iTrader: (25)

attached pic in post #17

camarosrock1989

iTrader: (1)

Twin_ turbo that's a really nice looking engine bay, and engine!

Twin_Turbo

iTrader: (25)

thanks, I have a lot of time and effort into it.

'87IROCZOWNER69

iTrader: (1)

Oh so the pack that branches off the left side then? I will go look for it then.

'87IROCZOWNER69

iTrader: (1)

Here's what mine looks like atm...

Right now the weather pack has 4 wires in it and the pack has room for 5?

'87IROCZOWNER69

iTrader: (1)

So I cracked open the black plastic tube that holds the wires and I cant find any wires hiding in it so I am wondering if that top wire is even very important. Is it?

Twin_Turbo

iTrader: (25)

I'll have to check how many are in mine. Don't think there was an empty pinout on the esc

RBob

iTrader: (1)

Only four of the five connections are used on the ESC module. Also known as the knock filter. With it unplugged the ECM should toss a SES light and code 43. Then pull a set amount of timing which will reduce power and mileage.

The EST control is the ignition control module in the distributor.

On the TPI MAF f-body's the MAT is only used for the EGR turn on temperature threshold.

RBob.

'87IROCZOWNER69

iTrader: (1)

So... that means...?

Twin_Turbo

iTrader: (25)

Oh I see I goofed, I mixed up est and esc, my bad. Yes, the est is inside the ign module.

'87IROCZOWNER69

iTrader: (1)

So how do I get to that to fix it? Would it have all the same symptoms?

Twin_Turbo

iTrader: (25)

Remove the distributor, pull the cap and rotor and you can unscrew the est. it's the black part where the 2 weatherpack connectors go in the base..

RBob

iTrader: (1)

An EST error will set code 42. This will also occur when the EST/BYPASS connector is open, such as when setting the distributor base timing. So if the SES is on and code 42 is active, then make sure that the EST/BYPASS connector is firmly connected. Found over on the passenger side near the A/C box. Single tan with black stripe wire.

If the code 42 is only stored (not active) and the timing has been recently set, then no worries about it. After 50 good start ups the ECM will clear the stored code(s) for you.

RBob.